CHAPTER: 1 FOOD QUALITY, ITS ROLE IN INDUSTRY AND FACTORS

AFFECTING QUALITY

Definition:

Food:

Food means any substances, whether processed, partially processed or

unprocessed, which is intended for human consumption and includes primary food

to the extent as defined, genetically modified or engineered food or food containing

such ingredients, infant food, packaged drinking water, alcoholic drink and any

substance including water used in to the food during manufacture but does not

include any animal feed, live animals unless they are prepared or processed for

placing on the market for human consumption, plants prior to harvesting, drugs

and medicinal products, cosmetics, narcotic or psychotropic substances.

Quality

Quality is a measure of the degree of excellence or degree of acceptability by the

consumer. By quality, one can differentiate the individual unit of a product from the

other units and can determine the degree of acceptability of the individual unit by

the consumer.

International organization for standardization defines quality is the totality of

features and characteristics of a product that bear on its ability to satisfy stated or

implied needs.

The quality may also be defined in term of end use and may vary depending upon

consumer's perception and need. Quality is the combination of attributes or

characteristics of a product that have significance in determining the degree of

acceptability of the product to the user. For industry, quality is the measure of

purity, strength, flavour, colour, size, maturity, workmanship and condition or any

other distinctive attributes of the product.

According to Code of Federal Regulations "Quality is the inherent properties of any

processed product which determine the relative degree of excellence of such

product and includes the effect of preparation and processing and mayor may not

include the effects of packaging or added ingredients/ additives" .

Quality includes size, color, shape, texture, cleanness, freedom from defects, and

other more permanent physical properties of a product which can affect its market

value. The following terms, when used in conjunction with “quality,” are interpreted

as meaning:

Fine: Better than good. Superior in appearance, color, and other quality factors.

Good: In general, stock which has a high degree of merchantability with a small

percentage of defects.

Fair: Having a higher percentage of defects than “good.” from a quality.

Role of quality attributes (determinants) in food industry

Mass-volume-area–related properties are one of five groups (acoustic, mass-

volume-area–related, morphological, rheological, and surface) of mechanical

properties. These properties are needed in process design, for estimating other

properties, and for product characterization or quality determination.

The geometric characteristics of size, shape, volume, surface area, density, and

porosity are important in many food materials handling and processing operations.

Fruits and vegetables are usually graded depending on size, shape, and density.

Impurities in food materials are separated by density differences between

impurities and foods. Knowledge of the bulk density of food materials is necessary

to estimate floor space during storage and transportation.

When mixing, transportation, storing and packaging particulate matter, it is

important to know the properties of bulk material.

Surface areas of fruits and vegetables are important in investigations related to

spray coverage, removal of residues, respiration rate, light reflectance, and color

evaluation, as well as in heat transfer studies in heating and cooling processes.

In many physical and chemical processes, the rate of reaction is proportional to the

surface area; thus, it is often desirable to maximize the surface area.

Density and porosity have a direct effect on the other physical properties. Volume

change and porosity are important parameters in estimating the diffusion coefficient

of shrinking systems. Porosity and tortuosity are used to calculate effective

diffusivity during mass transfer processes. Mechanical properties of agricultural

materials also vary with porosity.

Factors Influencing Quality of Food: There are mainly four factors which are

affecting the quality of food and these are depicted as shown below:

1. Genetic

2. Pre-harvest

3. Harvest

4. Post Harvest

Genetic Factors: Selection of cultivars and rootstock: Not all varieties of fruits and

vegetables are suitable for processing purposes. The choice of proper cultivar is

perhaps the most important single factor for preparation of quality product. Specific

recommended cultivars for one area of the country or even within the state may

not apply to another area. Although high visual quality is desirable for most

processing methods, the composition of the fruit in relation to flavour, texture,

colour and nutritional value is of paramount importance.

Pre-harvest Factors: These include climate / environmental, cultural and

harvesting

factors.

Environmental Factors:

Factors Quality affected

Temperature Maturity, colour, sugar, acidity. High temperature reduces the quality

of citrus, radish, spinach, cauliflower and increase the quality of

grapes, melon, tomatoes. Low temperature causes chilling and freezing

injury

Light Essential for anthocyanin formation. Fruits exposed to light develop

lighter weight, thinner pee, lower juice and acids, higher TSS than

shaded fruits

Rains Cracking of grapes, dates, litchi, limes, lemon, tomatoes and sweet

potatoes and reduces sweetness

Wind Bruising, scratching and corking scar on the fruits

Humidity High humidity reduces colour and TSS, increases acidity in citrus,

grapes and tomatoes, increases the quality of banana, litchi and

pineapples.

Nutritional factors and others:

Factors Quality affected

Mineral

Nutrition:

Nitrogen High nitrogen reduces ascorbic acid content, TSS / acid ratio and

keeping quality but increases vit B1, B2 and carotene, Deficiency

reduces fruit size

Phosphorous High P decreases size, weight, vit C. Deficiency causes poor

appearance in fruit

Potassium Increases size, weight and vit C. Deficiency causes uneven

ripening

Calcium Increases firmness of many fruits like apple, mango and guava.

Boron Deficiency causes flesh browning in fruits and gummy

discoloration of albedo in citrus fruits

Copper Due to deficiency irregular blotch occurs in citrus fruits and spoil

the appearance

Rootstock In citrus, Troyer and Carrizo rootstock produces the fruits of

excellent quality of oranges, mandarins and lemons.

Irrigation Excess irrigation causes high acidity and deficiency of moisture

reduces fruit size, juice content and increases thickness of peel

Maturity All vegetables except potatoes and onion are of higher quality

when less mature. Ripen fruits are of better quality when

harvested at proper maturity stage

Mechanical injury Reduces appearance and source of infection.

Harvesting factors: Stage of maturity, ripeness and physiological age are

important

factors affecting quality.

Factors Quality affected

Maturity All vegetables except potatoes and onions are higher

quality when less mature. Ripen fruits are of better

quality when harvested at proper maturity stage.

Physiological age /

Horticultural maturity

It is the stage of development when a plant or plant part

will continue ontogeny (further development) even if

detached.

Post harvest treatments / Factors: Environmental factors, handling methods,

processing times and storage methods.

Factors Quality affected

Temperature Higher temperature causes off flavour, weight loss and

wilting particularly of GLV and reduces vit C content. Low

temperature reduces the appearance of fruits by

checking carotenoid development and chilling injury

(below optimum).

Heat of respiration Deteriorate quality, increased spoilage during storage

and transport

Relative humidity Low RH causes weight loss and wilting, High RH causes

growth of microbes

Cleaning and Washing Improves appearance, removes microbes and dirt.

Chemical treatment Treatment with oil and wax reduces weight loss and

maintains freshness. Treatment with ethephon and Alar

increases colour and reduces astringency. GA, Cytokinin,

MH, CCC retard colour

development

Transportation Ambient temperature transport – weight loss, spoilage.

Refrigerated

transport – reduces / nil weight loss and spoilage.

Storage The temperature during storage affects the length of

storage and the

quality of fruits or vegetables.

CHAPTER: 2 QUALITY ATTRIBUTES : CLASSIFICATION OF QUALITY

ATTRIBUTES

Characteristics of Quality:

External or sensory

Internal

Hidden Characteristics

Quantitative Characteristics

There are three types of the quality characteristics viz. external, sensory, hidden

and quantitative by which quality of food can be judged . So, the quality criteria for

the consumers depend upon various attributes like appearance, texture, flavour,

nutritive value and safety.

External Internal Hidden

Appearance Odor Wholesomeness

Feel (touch) Taste Nutritive value

Defects Texture Safety

External attributes

It includes appearance, feel and defects which the consumer can evaluate with his

senses. External quality attributes are those that are observed when the product is

first encountered. They play an important role in a consumer‟s decision to purchase

produce.

Appearance / Colour: It is more important than taste and odour. It (colour)

increases the attractiveness of the product. It is the prime factor which also

determines the flavour, texture, nutritive value and wholesomeness. By the sense

of sight, size, shape and colour of the food and other characteristics such as

transparency, opaqueness, turbidity, dullness and gloss could be perceived.

Judgment of the ripening of the fruits is also influenced by colour. The strength of

coffee and tea is also judged on the basis of the colour of the beverage. Appearance

is first important attributes in selection of food. Appearance of any food commodity

can be judged by the eye. Appearance may be in term of colour, size, shape

uniformity and absence of defects. The second important attribute for sensory

evaluation of food is kinesthetic i.e. texture and consistency.

Texture: It is overall assessment of the feeling by mouth and hand or it is sense of

touch by hand and mouth. Mouth feeling include lips (hairy / smooth), tongue

(soft/mushy), teeth (rigidity) and ears. Objective instrumental methods are

available for measurement of these attributes which could be correlated to the

consumer's preferences. Mouthfeel is a product's physical and chemical interaction

in the mouth. It is a concept used in many areas related to the testing and

evaluation of foodstuffs, such as wine-tasting and rheology. It is evaluated from

initial perception on the palate, to first bite, through mastication to swallowing and

aftertaste. In wine-tasting, for example, mouthfeel is usually used with a modifier

(big, sweet, tannic, chewy, etc.) to the general sensation of the wine in the mouth.

Some people, however, still use the traditional term, "texture". Mouth feel is often

related to a product's water activity, hard or crisp products having lower water

activities and soft products having intermediate to high water activities.

Flavour: Flavour is a combination of taste, smell/aroma and feeling (astringency,

bite etc. especially in spices, wine and coffee) in short it is the combination of taste

and aroma. Flavour embraces the senses of taste, smell and a composite sensation

known as mouth feel. Taste is due to sensation felt by tongue. Taste is limited to

sweet, sour salty and bitter. The dimension of these can be measured chemically

and can be related to the consumer's preferences. Smell /odour, an important

factor in flavour can be estimated by gas chromatography and related to flavour

acceptability. Aroma is due to stimulation of olfactory senses with volatile organic

compounds. Aroma may be fragrant, acidic, burnt, pungent, enzymatic, spoilage.

Internal quality characteristics:

They are not perceived until the product is cut or broken.

Hidden Characteristics: Nutritive value and toxicity (toxic compounds) present in

food comes under hidden characteristics.

Quantitative Characteristics: Crop yield and finished product yield are the

quantitative characteristics for determination of food quality. The ratio of weight of

raw material to the weight of the pre-packaged finished product is known as

shrinkage ratio. Higher the ratio, greater will be the unit cost. So, low shrinkage

ratio is desirable.

Various methods used for determination of the quality in food industry

Subjective Method: In this method, individual is required to give his opinion about

qualitative/quantitative values. This method is also referred as sensory method. It

is by experience of the individual. Different subjective methods are used for

estimation like: 9 -point Hedonic Scale, Triangular test or Composite test.

Objective Methods: These are based on recognized standardsd scientific tests to

any sample of the product without regard to its previous history. They represent

the modern idea in quality control (QC) because the human element has been

excluded. This method divided into three groups:

(a) Physical methods

(b) Chemical methods

(c) Microscopic methods

Tests used for Objective Evaluation:

Physico-chemical methods

Measurement of hydrogen ion concentration can be found by the use of pH meter.

It utilizes a glass indicating electrode and a reference electrode to complete the

electrical circuit.

Digital salt meter:

This refractometer has electrodes built in the measurement unit and it indicates

salinity percentage in digits in three seconds with one ml sample dripped on it.

Brix or Balling hydrometer:

Sugar concentration can be found by refractometer. It gives directly the percentage

of sugar by weight in the syrup. It is always necessary to make a temperature

correction since the hydrometers are usually calibrated at 20°C. Each instrument

used by canners usually covers a range of only 10° Brix, e.g. 10 - 20, 20 - 30, 30 -

40, 40 - 50, 50 - 60 0Brix respectively and are graduated in 1/10th divisions. Brix is

defined as percent sucrose measured by a Brix hydrometer.

Polariscope is used for quantitative analysis of sugar.

Butyrometer: It is an instrument consisting of a calibrated glass tube for

measuring the butter content of milk. The milk is mixed with a certain volume of

ether which dissolves the butter. Then an equal volume of alcohol is added. The

butter floats on the surface in the form of an oily layer and its thickness, measured

by the graduation of the tube, clearly shows the proportion of butter.

Physical methods:

Weight:

Weight of a food indicates the quality like in case of apple or egg.

Volume:

Liquid volumes can be measured by using measuring cups.

Solid food volume can be found by displacement method.

Specific volume:

Measurement of bulk volume in a porous and spongy product like idli is difficult.

The volume may be measured by displacement with solvents like kerosene.

Specific volume = Bulk volume/Wt. of the substance

Index to volume:

It can be found by measuring the area of a slice of food with a planimeter. It is

important to use a slice that is representative of the product such as a centre slice.

Index to volume is a measurement made by first tracing detailed outline of a cross

section of the food. This tracing can be done with a sharply pointed pencil or a pen

or by making a clear ink blot of the cross section. The ink blot is made simply by

pressing the cross section of the sample lightly onto an inked stamp pad and then

making the imprint of the inked sample on paper.

Specific gravity:

It is a measure of the relative density of a substance in relation to that of water.

The measurement is obtained by weighing a given volume of the sample and then

dividing that weight by the same volume of water. This technique is used for

comparing the lightness of products physically unsuited for volume measurements

e.g., egg white foams.

Moisture:

Press fluids: Initial weight of the sample is noted. After the appropriate pressure

has been applied for a controlled length of time, the sample is again weighed. The

difference between the two weights represents the amount of juice contained in the

original sample

e.g. juiciness of meats, poultry and fish.

Drying :

The weight of the original sample is determined and then the food is dried until the

weight remains constant.

Moisture content(%) = Initial - dried weight/Initial weight X 100

Size :

This can be found by using photography or ink prints with stamp pad or sand

retention e.g. idli. Cut the idli into 2 pieces and take one piece and press it on the

stamp pad and take an impression on the paper. Ink prints may be less clear but

satisfactory for some purposes.

Physical factor Test Description

Colour Colour difference meter Measures differences in

tri-stimulus values

Munsell colour system Based on colour standards

Spectrophotometry Measure light reflectance

at different wavelengths

Viscosity Ostwald Viscometer Flow through a capillary

tube

Rotating Spindle A rotating cylinder is

immerged in the fluid and

stress measured.

Falling weight Measures the time

required for a weight to

fall through a tube

containing the sample.

Texture/Tenderness Finger feel Test of firmness and

softness

Mouth feel Test of chewiness,

fibrousness and grittiness

Texture value (texture

meter, Penetrometer)

Indication of texture,

firmness, tenderness and

shear value

Size and shape Weight, volume and

vacuum

Gross, net, drained weight

Seal integrity Seal evaluation

Length, breath and

diameter (Vernier

Callipers)

Uniformity and

classification.

Chemical methods -These are standard food analysis methods. These are used

for quantitative evaluation of nutritive value e.g. moisture, specific gravity, fat, oil,

protein, carbohydrates, fibre, enzyme, vitamin and pH. Some chemicals are

estimated in food spoilage like peroxides in fats. Adulterants in food e.g., presence

of starch in milk, metanil yellow in turmeric powder and loss of nutrients during

cooking can be estimated

Common chemical tests used for food products:

Chemical factor Test Description

Moiture Drying Measures weight loss due

to evaporation

Solids Hydrometer Concentration of dissolved

solids

Specific gravity Titration Reaction of water with

specific chemicals

Total soluble solids (TSS) Refractive index Measures TSS and

indicates the sugars

Ascorbic acid Dye method Measures Vit C content

Fat-oil Ether extraction Dried, ground material

extracted in petroleum

ether

Protein Kjeldahl method Total N2 determined and

N2 * 6.25 = Protein

Carbohydrates Molisch general test Colour reaction with

Naphthol

Fibre NaOH extraction residue Measures organic residues

including cellulose and

lignin

Ash / Minerals Burns at 550 0C in Muffle

Furnace

Determines total ash by

weight of residue after

incineration

Enzymes Catalase, peroxidase Chemical reaction with

H2O2 or indicators

Vitamins Bioassays for each vit Vitamin analysis using

analytical procedures

pH, acidity pH meter or titration Measures alkalinity or

acidity of samples

Chlorine Chemical titration Measurement of chlorine

residue

Microscopic methods: These methods are excellent in quality control. It is used

for detection of contaminants in foods. So, these methods prevent food from

adulteration and contamination.

CHAPTER: 3 COLOUR – ROLE OF COLOUR IN QUALITY, DIFFERENT

TYPES OF COLOR MEASURING SYSTEMS

THE SENSE OF SIGHT:

Stimuli –visible light

Perception-sight, vision, appearance

Receptor- retina of the eye.

Optical properties:

Vision:

Vision is a complex phenomenon consisting of several basic components. A

stimulus, light, from an external source interacts with the object and is brought to

focus on the retina of the eye. The retina is the receptor of vision and contains two

types of cells. The rods are responsible for vision in dim light and the cones are

responsible for colour vision. Light incident on these cells causes a photochemical

reaction that generates an electrical impulse which is transmitted to the brain via

optic nerve.

Light:

Visible light is that part of is electromagnetic spectrum which radiates between

wavelength of 380-770nm

Different wavelengths produce different colors

380-450 nm - Violet

450-475 nm - Blue

500-570 nm - Green

575-590 nm - Yellow

590-770 nm - Red

Light object interactions

Light incident on an object may be absorbed, reflected, transmitted, and refracted.

The relationship between and within each of these components is responsible for

the colour and gloss characteristics of the food. The main light / object interactions

produced are

Lightness/value

Color/hue

Chroma/purity

Gloss

Physical form

The second class of product appearance is physical form that can be subdivided into

three parts.

Shape

Surface texture

Visual consistency

Shape and size are important from a food technologist‟s point of view because

these can be altered during the manufacture of processed products. Eg. sliced

,chunked ,cut up parts.

Surface texture can indicate product texture Eg. Open dry structure of meat,

wrinkling of peas.

Visual consistency can indicate product viscosity as in

Setting of jelly

Syrups of different concentration

Factors that should be considered in evaluating product appearance

include:

Use of standard conditions

Light source

Background

Style of presentation

Selection of appearance attributes

Use of colour charts / standard help rating.

Color

Colour is the first quality attribute a consumer perceives in food. Change of colour

is generally accompanied by flavour changes. It is one aspect of appearance; a

stimulus based on visual response to light, consisting of the three dimensions of

hue, saturation, and lightness.

Gloss

An additional parameter to consider when determining a color standard, along with

hue, value, chroma, the texture of a material and whether the material has metallic

or pearlescent qualities. Gloss is an additional tolerance that may be specified in the

Munsell Color Tolerance Set. The general rule of evaluating the gloss of a color

sample is the higher the gloss unit, the darker the color sample will appear.

Conversely, the lower, the gloss unit, the lighter a sample will appear.

Glossmeter

An instrument used to measure the amount of gloss (a term used to describe the

relative amount of mirror-like (specular) reflection from the surface of a sample).

These instruments measure the light reflected at select specular angles, such as 20

degrees from the perpendicular, 45, 60, 75, and 85 degrees. Results obtained are

very dependent on instrument design, calibration technique used, types of samples,

and so forth.

Role of color in qulity:

Many circumstances exist where some form of colour measurement is necessary to

quantify and assess a product‟s colour or where colour is an indirect measure of

product quality or processing performance:

To Ensure Uniformity of Colour in Production

If the colour of a product varies from one batch to another, it may be perceived as

being an inferior product.

To Achieve Aesthetic Quality

Presentation of an acceptable and consistent colour is of tremendous importance to

consumers.

As a Performance Indicator

For example, to assess the performance of decolorising materials or to determine a

product‟s suitability for a particular purpose.

To Indicate Product Condition

For example, as an indication of the level of purity, the degree of deterioration over

time, adverse growing conditions experienced by natural raw materials or the

condition of used product.

To Indicate the Level of Refining/Processing Undergone

In oil refining processes, the colour provides a good indication of the degree of

refinement and allows optimisation of the refining process.

As a Content Indicator

There is often a correlation between colour and chemical/physical content (for

example, the amount of chlorophyll in oil). In these cases, colour measurement

may offer a simple alternative to more complex means of testing.

Color measurement systems:

Three main things required to see the color

A light source

An object

An observer

Light

Visible light is a small part of the electromagnetic spectrum. The wavelength of light

is measured in nanometers(nm). One nanometer is one-billionth of a meter. A plot

of the relative energy of light at each wavelength creates a power distribution curve

quantifying the spectral chararcteritics of the light source. A light source is a real

source of light. An illuminant is a plot, or table, of relative energy versus

wavelength that represents the characteristics of different types of light sources.

Light is the basic stimulus of colours, it is important to consider the electromagnetic

spectrum. Visible light forms only a small part of the electromagnetic spectrum,

with a spectral range from approximately 390 nm (violet) to 750 nm (red). The

sensitivity of the eye varies even within this narrow visible range. Under conditions

of moderate-to-strong illumination, the eye is most sensitive to yellow-green light

of about 550 nm.

There are three characteristics of light by which a colour may be specified: hue,

saturation, and brightness. Hue is an attribute associated with the dominant

wavelength in a mixture of light waves, i.e., it represents the dominant colour as

perceived by an observer. Saturation refers to relative purity or the amount of

white light mixed with a hue. Brightness is a subjective term, which embodies the

chromatic notion of intensity. Hue and saturation taken together are called

chromaticity. Therefore, a colour may be characterized by brightness and

chromaticity.

Colour Dictionaries: The dictionary of Maerz and Paul is most commonly used.

The dictionary consists of 56 charts. Seven main groups of hues are presented in

order of their spectra. For each group there are 8 plates. In place of colour

dictionary, colour reproduced on secondary standards such as painted test panels,

rings, discs or plastic models may be used. A mask of neutral grey having two

openings is used. The size of each opening should be equal to the size of the

individual colour patch in the sheet. An opening should be placed over the sample

and the other over different patches on the chart until a match is achieved and the

colour is noted.

Disc colorimeter: Here the discs have radial slits so that a number of them may

be slipped together with varying portions of each showing. The discs are spun on a

spindle at about 2700 rpm so that the colours merge into a single hue without

flickering. The test sample is placed adjacent to the spinning disc under controlled

illumination and both are viewed simultaneously.

Colored chips: A simple method is to match the colour of the food with the colour

chips or colour glass, chart or colour tiles. This method is not very small block of

colour or the chart. The data are difficult to tabulate and analyse also.

Spectrophotometer: Visual matching of colours is subject to shortcomings of

human observers. To overcome this spectrophotmeter can be used. In this, tube

with the liquid is placed in a slot and light of selected wavelength is passes through

the tube. This light will be differentially absorbed depending upon the colour of the

liquid and the intensity of the colour. Two liquids of exactly the same colour and

intensity will transmit equal fractions of the light directed through them. If one of

the liquid is a juice and the other is the juice diluted with water, the latter sample

will transmit a greater fraction of the incoming light and this will cause a

proportionately greater deflection of the sensing needle on the instrument. Such an

instrument can also measure the clarity cloudiness of a liquid depending on the

amount of light the liquid allows to pass.

CIE System

The Commission Internationale de l‟Eclairage (CIE) defined a system of describing

the colour of an object based on three primary stimuli: red (700 nm), green (546.1

nm), and blue (435.8 nm). Because of the structure of the human eye, all colours

appear as different combinations of these. The amounts of red, green, and blue

needed to form any given colour are called the‟ „tristimulus” values, X, Y, and Z,

respectively. Using the X, Y, and Z values, a colour is represented by a set of

chromaticity coordinates or trichromatic coefficients, x, y, and z, as defined below:

x = X/X+Y+Z; y = Y/ X+Y+Z; z = Z/ X+Y+Z

It is obvious from the equations above that x + y + z = 1.

The tristimulus values for any wavelength can be obtained from either standard

tables or figures.

Sometimes, tristimulus systems of representation of colours are not easily

understood by the users in terms of object colour. Other colour scales therefore

were developed to relate better to how we perceive colour, simplify understanding,

improve the communication of colour differences, and be more linear throughout

colour space. This gave the birth of opponent colour theory, which states that the

red, green and blue responses are re-mixed in opponent coders as they move up

the optic nerve in human brain. Based on this theory a 3-dimensional rectangular L,

a, b, colour space was evolved, in which at L (lightness) axis – 0 is black and 100 is

white, a (red-green) axis – positive values are red; negative values are green and

zero is neutral, and b (blue-yellow) – positive values are yellow; negative values

are blue and zero is neutral. All colours that can be visually perceived can be

plotted in this L, a, b, rectangular colour space. There are two popular L, a, b colour

scales in use today – Hunter L, a, b, and CIE L*, a*, b*. They are similar in

organization, but will have different numerical values. Hunter L, a, b and CIE L*,

a*, b* scales are both mathematically derived from X, Y, Z values . Neither scale is

visually uniform, Hunter scale is over expanded in blue region of colour space, while

CIE scale is over expanded in yellow region. The current recommendation of CIE is

to use L*, a*, b*.

Munsell System and Atlas

The Munsell colour system divides hue into 100 equal divisions around a colour

circle. This is similar in approach to the Newton colour circle except that the circle is

distorted by assigning a unit of radial distance to each perceptible difference in

saturation (called units of chroma). Since there are more perceptible differences for

some hues, the figure will bulge outward to 18 for some hues compared to only 10

for others. Perpendicular to the plane formed by hue and saturation is the

brightness scale divided into a scale of “value” from zero (black) to 10 (white). A

point in the colour space so defined is specified by hue, value, and chroma in the

form H, V and C. The Munsell colour-system is

therefore a way of precisely specifying colours

and showing the relationships among them.

Every colour has three qualities or attributes:

hue, value, and chroma. A set of numerical

scales with visually uniform steps for each of

these attributes has been established. The

Munsell Book of Colour displays a collection of

coloured chips arranged according to these

scales. Each chip is identified numerically using

these scales. Comparing it to the chips under

proper illumination and viewing conditions can

identify the colour of any surface. The colour is then identified by its hue, value,

and chroma. These attributes are given the symbols H, V, and C and are written in

a form H V/C, which is called theMunsell notations. Using Munsell notations, each

colour has a logical relationship to all other colours. This opens up endless creative

possibilities in colour choices, as well as the ability to communicate those colour

choices precisely. The Munsell system is the colour order system most widely

quoted in food industry literature. Food products for which the US Department of

Agriculture (USDA) recommends matching Munsell discs to be used include dairy

products such as milk and cheese, egg yolks, beef, several fruits, vegetables, and

fruit juices. Other colour atlases and charts are available for use in the food

industry, such as the Natural Colour System and Atlas, Royal Horticultural Society

Charts, etc. These atlases and charts are used for comparison of a product colour

with that of a standard colour diagram, which is also commonly practiced in the

food industry. The evaluation of potato chip colour is a very good example. Other

colour scales, such as the RGB, CMY, HSI, HSV, HLS etc. also exist, but are very

similar to the CIE system. RGB system is generally used in analysis of colour of an

image, while others are now not in much use for measurement of colour of food

items.

The lovibond tintometer :

The lovibond tintometer is a visual colorimeter used widely in the oil industry. The

instrument has as set of permanent glass color filters in the three primary colors

red, yellow, and blue. The colors are calibrated on a decimal scale in units of equal

depth throughout each scale. The oil sample is placed in a glass cell and the filters

are introduced into the optical system until a color match is obtained under

specified conditions of illumination and viewing. Color of oils is measured with

transmitted light. Either transmitted light for molten waxes and fats or reflected

light against a white background for solid samples is used. Attachments to the

lovibond tintometer provide means of converting the readings from lovibond units

into trichromatic coordinate values. In addition, modifications for determining the

color of liquid, solid, powder, or paste materials are available.

CHAPTER: 4 VISCOSITY AND CONSISTENCY – ROLE OF VISCOSITY AND

CONSISTENCY IN FOOD QUALITY

Rheology:

Rheology is the science of flow and deformation of matter and describes the

interrelation between force, deformation and time. The term comes from Greek

rheos meaning to flow. Rheology is applicable to all materials, from gases to

solids. Fluid rheology is used to describe the consistency of different products,

normally by the two components: viscosity and elasticity. By viscosity is usually

meant resistance to flow or thickness and by elasticity usually stickiness or

structure.

The science of rheology deals with the measurement of various mechanical

properties of foods. A study of rheological properties of foods is important for two

reasons.

1. To determine the flow properties of liquid food stuffs.

2. To ascertain the mechanical behavior of solid foods when consumed and

during processing.

Viscosity/consistency:

Viscosity or consistency is an important factor in influencing the quality of a large

number of food products. The more important among these are cream style corn,

salad creams, tomato products, jellies, jams, mayonnaise, syrups, and fruit pulps

where the acceptability largely depends on their having proper consistency or

viscosity. Measurement of this factor for the raw material or the product at various

stages of manufacture serves as an aid in checking or predicting the consistency of

the final product. Further, such quality control measurements also serve as

indicators in calculating the amount of an ingredient (thickening agent, etc.) that

should be added in a particular food product. Duration and amount of heat applied

in a process may also be suitably regulated to some extent by viscosity

measurements as heat penetration and consistency are closely interrelated

Viscosity is the resistance to deformation or flow. It is the measure of the internal

friction of a fluid. Different fluids deform at different rates under the same shear

stress. The greater the friction, the greater the amount of force required to cause

this movement, which is called „shear‟. Shearing occurs whenever the fluid is

physically moved or distributed, as in pouring, spreading, mixing, etc. highly

viscous fluids, therefore require more force to move than less viscous materials.

Kinematic viscosity is a measure of the rate at which momentum is transferred

through a fluid. It is measured in stokes . Dynamic viscosity is a measure of the

ratio of the stress on a region of a fluid to the rate of change of strain it

undergoes. It is measured in pascal-seconds or poises.

Role of viscosity and consistency in food quality:

Viscosity is more easily measured than some of other properties that affect it,

making it valuable tool for material characterization.

Viscosity is essential in the evaluation of food that will be subjected to temperature

variations in use or processing, such as starch, paste, vegetable oils.

Aging phenomena: Gradual changes in the viscosity of many materials can occur

overtime even though the material is not being sheared. Food materials will

undergo changes in viscosity during the process of chemical reaction.

The composition of a material is a determining factor of its viscosity. When this

composition is altered, either by changing the proportions of the component

substances, or by the addition of other materials, a change in viscosity is quite

likely.

CHAPTER: 5 SIZE AND SHAPE – WEIGHT AND VOLUME – WEIGHT AND

VOLUME RATIO – LENGTH AND WIDTH – DIAMETER –

SYMMETRY – CURVATURE AREA

Volume:

Volume is defined as the amount of space occupied by a three-dimensional object

or region of space. Volumes are expressed in cubic units.

Boundary volume: It is the volume of a material considering the geometric

boundary.

Pore volume: It is the volume of the void or air inside a material.

Density:

Density is the mass of a material per unit volume. The density of a substance is the

quantity of matter contained in a unit volume of the substance.

Mass density, ρ is defined as the mass of substance per unit volume. SI Unit: kgm-3

In the case of non homogeneous materials, such as foods, consisting of solid,

liquid, and gaseous phase(s), a number of different forms of density have been

defined for the sufficient relation between mass and volume.

True density (ρt): It is the density of a pure substance or a composite material

calculated from its components‟ densities considering conservation of mass and

volume.

Material density (ρm): It is the density measured when a material has been

thoroughly broken into pieces small enough to guarantee no closed pores remain. It

is also known as substance density.

Particle density (ρp): It is the density of a particle that has not been structurally

modified and includes the volume of all closed pores but not the externally

connected pores.

Apparent density (ρa): It is the density of a substance including all pores remaining

in the material.

Bulk density (ρb): It is the density of a material when packed or stacked in bulk

and is defined as the mass of the material per the total volume it occupies. The

bulk volume of packed materials depends on the geometry, size, and surface

properties of the individual particles.

The density of food materials depends on temperature and composition. Mass-

volume-area properties are needed for process design, estimation of other

properties, and product characterization.

CHAPTER: 6 DEFECTS – CLASSIFICATION AND MEASUREMENT OF

DEFECTS

Classification of Defects:

Defect - Deterioration/spoilage affecting the appearance or

usability of the produce.

Based on extent of deterioration:

Slight defect - Does not have a major impact on the acceptance of the

produce by the consumers. Slight defects include: bruising, blemishes, and other

non extensive outside defects.

Major defect - Without being critical, major defects do have a

considerable impact on the acceptance of the produce by the consumers. Produce

may show evidence of pests or disease, scabs, and similar blemishes not affecting

the flesh.

Critical defect - The defect on the flesh of the produce is

likely to cause rejection by the consumer. It may consist in severe cases of pest

attack or disease, unscarred blemishes and other damage affecting the flesh.

Defective unit - Unit showing one or several defects

Minor defective unit - Unit showing one or several minor defects, while

being free of major or critical defects

Major defective unit - Unit showing one or several major defects, in

addition to minor ones, although none of a critical nature

Critically defective unit - Unit showing one or several critical defects, in

addition to major and minor ones

Based on causative agent

Genetic – physiological - Due to hereditary abnormality or to unfavorable

environmental conditions during growth and development

Entomological - Due to actions linked to insect feeding,

spawning and biting

Microbiological - Due to fungal, bacterial, yeast, or viral action

Mechanical (Extraneous) - Due to inappropriate manipulation of the produce

during and after harvesting

Meteorological - Due to a variety of natural atmospheric phenomena

such as hail, rain, wind, and frost

Commonest defects in fruits and vegetables:

Deformation - Anomaly in the shape of the produce measured

against those typical of species and variety.

Color variation - Evident in superficial areas showing a color not

corresponding to the produce, in terms of maturity, species, or variety.

Damage caused by citrus red spider mite - This particular damage occurs

in pomegranate, avocado and especially citrics. It is caused by several species of

Tetranychus attacking the skin cells of the produce. Produce attacked by

Tetranychus sexmaculatus (Riley) show white or silvery areas, while those attacked

by Brebipalpus californicus show dark areas with scarred corky plates.

Sooty mould - Damage produced in citrics by the Phylocoptruta

oleivora mite, which bites the epidermic cells of the produce. Cells take on a

reddish (brownish gray – blackish) hue due to the oxidization of the oils exuded by

the attacked cells. Sometimes, the fumagina caused by fungi of the genus

Capnodium (see 2.5.3.7) is also called “Sooty mould”.

Anthrachnose - Fungal disease which, after attacking the

stem, leaves, and fruits of a variety of plants, causes typical brown or darker

colored necrotic lesions likely to cover wide areas. It is caused by fungi pertaining

to Colletotrichum, Glomerella, Gloesporium, Gnomonia, Marssonina,

Mycosphaerella, Neofabrae and Pseudopeziza genuses.

Powdery Mildew

A variety of diseases caused by certain fungi, which after developing on the surface

of the infested tissue, produce very thin layers of powder-like spots.

Fumagina

Disease attacking the surface of certain tropical and subtropical fruits, caused by

fungus Capnodium sp. The mycelia affix on the skin surface forming a thin film with

the appearance of soot layers.

Melanosis

Disease common in citrics, and caused by fungus Diaporthe citri Wolf. At the

beginning, the skin shows small stains or gummy cells clusters irregularly

scattered, which are likely to form dark rough scabs.

Rot

Destruction and decay of fruit cells and flesh, paired with extraneous odor and taste

due to microorganism invasion.

Dry rot

Rot by fungal infection.

Soft rot

Rot by bacterial infection.

Peduncular rot

Fungal or bacterial rot attacking the fruit from the stem cavity and often

penetrating into the flesh to reach the seeds of the fruit.

Crusts

Scabs on the surface of the fruit.

Bruising

Softened areas or spots on the skin or flesh of the fruit, caused by blows, packing,

tight ties in package or other reasons.

Bites

Variably deep lesions either mechanically caused or inflicted by predators such as

birds, rodents or others.

Limb rub

Injuries caused by violent friction on the skin of the fruit. Cover irregular areas.

Scarred lesion

Areas of fibrous tissue replacing normal skin after destruction of some of the

dermis.

Unhealed lesion

Any kind of penetrating injury with no regenerated tissue and showing raw flesh

unprotected from the environment.

Oleocelosis

Occurs on citrus skin when the flavedo oil cells break. The defect is usually due to

harvesting at the wrong hours or rough handling. Hardly detectable on the first day,

oleocelosis usually becomes apparent by the next day.

Cracks

Fissure on fruit surface, caused by mechanical, physiological, or meteorological

actions. They may or may not be healed.

Sunburns

Discoloration in some area of the fruit surface due to over exposure to sunrays.

Latex burns

Discoloration caused by latex dripping on the skin of certain fruits. The affected part

takes on a darker shade.

Hail damage

Produced by the action of hail, multifarious damage can be seen on the surface

and/or flesh.

Frostbite

May be due to deficient refrigerating, and have different effects such as

discoloration, external or internal flesh darkening, softening, etc.

Extraneous matters

Presence of any kind of extraneous matter on the fruit, such as mud, stems, leaves,

animal excrement, or other impurities.

Measurement of defects:

Macroanalytic methods

Microanalytic methods

Macro analytic methods:

Macroscopic analysis of a product refers to an evaluation of the substances through

the use of the unaided senses of an individual. There are several advantages to the

use of macro analytical procedures. They are inexpensive and require little

specialized equipment. They generally permit the analysis of a large quantity of

product in a relatively short period of time and thus allow the analyst to assess the

overall condition of the lot quite rapidly. The analyst can quickly identify and isolate

those portions of the lot which may contain defects and thus limit the amount of

material which may need a more detailed, microscopic evaluation.

Microscopic Methods:

Microscopic methods of analysis involves the detailed examination of a very small

portion of the sample. These procedures have been designed to provide a different

type of information than macroscopic methods. They are used to describe and

quantify defects on a different scale than macroscopic methods and to identify

hidden defects that cannot be detected through a gross evaluation of the sample.

Imitations of microscopic methods are they tend to be more time consuming and

more expensive and they require more specialized equipment. These tests are

limited to the analysis of very small sample, the results are not always

representative of the overall condition of the lot.

Sorting / Screening:

Sorting/ Screening is the separation of raw materials and/or food slurries into

categories on the basis of shape, size, weight, image and color. The size sorting is

especially important for food products which have to be heated or cooled, as large

differences in size might lead to an over-processing or under processing of the

product. Sorting also allows the separation at first sight of some (undesirable)

addition of material (eg. Leaves, stones) or inappropriate raw material (immature

or rottled berries), and aims at ensuring that only good quality material is

preserved and passed through for further processing.

Size sorting:

Various types of screens and sieves, with fixed or variable apertures can be used.

The screens may be stationary, rotting or vibrating.

Shape sorting can be accomplished manually or mechanically with same

equipments eg: belt roller sorter.

Weight sorting:

Weight sorting is a very accurate method and is therefore used for more valuable

foods.

Image processing:

Image processing is used to sort foods on the basis of length, diameter and

appearance i.e surface defects and orientation of food on a conveyer colour sorting

can be applied at high rates using microprocessor or controlled colour sorters.

Electronic sorting:

CHAPTER: 7 FLAVOR: DEFINITION AND ITS ROLE IN FOOD QUALITY,

TASTE QUALITIES, RELATIVE INTENSITY, REACTION TIME,

EFFECT OF DISEASE, TEMPERATURE, AND TASTE MEDIUM

ON TASTE, BASIC TASTES, INTERACTION OF TASTES

THE SENSE OF TASTE

Stimuli – soluble chemicals which are solubilised during chewing

Receptors – taste buds in mouth

Perception – taste, flavour

Taste/flavor is a combination of taste, smell, touch, temperature. Strictly speaking

taste involves only those sensations mediated by gustatory nerve fibers and these

sensations have basic qualities

Salt

Sweet

Bitter

Sour

Umami

Taste stimuli

Taster response requires an aqueous solution of the substance to contact the taste

buds. Therefore, saliva secretions are important in terms of ensuring contact

between the product and the taste buds. The tongue is important as it brings the

food into contact with the taste buds and also provides a mixing action which

enables or even distribution of food about the taste buds as well as preventing the

development of concentration gradients.

Taste receptors

The receptors for taste are the taste buds and these are mounted on papillae. The

area of greatest response is the top of the tongue, other areas in the mouth and

throat.

Taste buds are mainly located at the tip, sides and rear of the tongue. There is little

response in the centre of the tongue.

Different areas of the tongue are most responsive to different sensations.

Tip-sweet

Sides-salty, sour

Rear –bitter

The taste cells constantly degenerate and regenerate their life cycle is 10 days and

they are easily destroyed by heat.

A basic taste is one for which specific taste buds have been identified as being

physiologically responsible for the particular taste sensation.

Sourness

This is the simplest taste as only acids produce sourness and as the H+ ions

increases the sourness increases. However there are some exceptions to this:

organic acids are more acidic than expected

sourness of aliphatic organic acids relates to chain length.

some amino acids are sweet(aspartame).

picric acid is bitter.

sugar may enhance or depress sourness.

sourness is also affected by pH and acid.

presence of buffer affects sourness.

Sweetness

The common substances that produce sweet taste are the sugars and other

hydroxyl compounds such as alcohols and glycols. Other substances such as Lead

salts, amino acids, proteins, non nutritive sweeteners (cyclamates, saccharin,

aspartame) also taste sweet.

Saltiness

Many crystalline water-soluble salts yield a salty taste, but only sodium chloride

gives a pure salty taste.

Bitterness

Many chemically different compounds have a bitter taste however bitterness is

mainly associated with alkaloids such as caffeine, strychnine, nicotine and quinine.

It was thought that bitterness was an indication of danger. However many alkaloids

are used as drugs eg.codeine and many other bitter substances are harmless

eg.glycosides, esters, aldehydes, tannins in wine and tea.

Umami

It is the taste that has been associated with substances that contain glutamate.

MSG is well known as a flavor enhancer and can cause adverse reactions in some

sensitive individuals. Many foods contain naturally high levels of glutamate.

Taste thresholds and sensitivity:

There is a great variability between individuals in their levels of sensitivity.

Sensitivity is affected by

Temperature

Sleep

Hunger

Age

Sex

Absolute threshold and recognition threshold will vary between individuals. Most

people can detect taste within 0.2 to 0.6 seconds and therefore if there is no

response within this time the level is sub-threshold.

Salt - 0.3 sec vision – 0.02 sec

Sweet - 0.4 sec Hearing – 0.01 sec

Sour - 0.5 sec Touch – 0.005 sec Bitter – 1.0 sec

Reaction times also relate to retention times for example bitterness has the longest

reaction time (1.0 sec) and the sensation lingers considerably after tasting.

CHAPTER: 8 ODOUR : DEFINITION, CLASSIFICATION, NEUTRAL

MECHANISMS, OLFACTORY ABNORMALITIES, ODOR

TESTING, TECHNIQUES, THRESHOLDS, ODOR INTENSITIES,

THE SENSE OF SMELL

Stimuli – volatile chemicals

Receptors – olfactory cells in the nose

Perception – smell, odour, aroma.

Smell is one of the four primate senses. The human nose is capable of detecting

thousands of different odour substances. Smell is detected both before and during

eating. Smell is an important aspect of flavour. There are 20x106 olfactory

receptors but only about 1000 taste receptors. Odour description requires the

development of an odour/memory. This is the basis of flavour/odour memory

development by graders. Individuals vary a great deal in their sensitivity to

different odour/aroma.

Olfactory intensity

Human nose is about 10- 100 times more sensitive to odours than any physico

chemical analysis eg. Gas chromatography. It has been demonstrated that human

nose is capable of detecting ethyl mercaptan of a concentration of 0.01mg/230 m3

of air, which is equivalent to about 8 molecule/ receptor.

Olfactory threshold

Detection threshold is the concentration where smell is detected. Recognition

threshold is the concentration where the smell is recognized.

Olfactory interactions

Nature of the response may change with concentration eg. Perfumes.

Interaction of odours are

Additive – increase intensity

Suppressive – decrease intensity

Blending – when new odour unrelated to originals

Olfactory adaptations:

Initial sensation may be strong but weakens and makes identification difficult. This

is due to adaptation of olfactory receptors.

In testing we therefore need to allow for this by

Taking first impression of odour

Waiting between tests to allow receptors to recover.

CHAPTER: 09 VISUAL, AUDITORY, TACKLE AND OTHER SENSES, VISION,

AUDITION, ORAL PERCEPTION OTHER THAN TASTE

THE HUMAN SENSES IN SENSORY EVALUATION

The sensory properties of food are related to three major attributes

Appearance - colour, size, shape

Flavour - odour, taste

Texture - mouth feel, viscosity and hearing.

Human possess about 30 different senses. However the sensory properties of food

are perceived through the senses of sight, smell, taste, touch, and hearing.

Stimuli:

A stimulus is any chemical or physical activator that causes a response in a

receptor E.g. eye is receptor for light. An effective stimulus produces a sensation

the dimension of which are

Intensity/strength

Extent/separation

Duration/retention

Hedonics/like or dislike.

Receptor:

Receptors are the stimuli detecting cells of the sensory organs

Eg: taste buds on tongue

Perception:

Perception is the psychological interpretation of sensations determined by

comparison with past experience.

THE SENSE OF HEARING

Stimuli – Physical movement of sound waves in a medium.

Receptor – Ear drum

Perception – Hearing, sound.

Hearing:

Sound is the perception by humans of vibrations in a physical medium. The sound

of food when it is being eaten is an important aspect in the determining quality.

Positive aspects:

Snap, crackle, pop

Fizz of champagne or beer

Crispiness of lettuce or celery

Tapping a melon for quality

THE SENSE OF TOUCH:

Stimuli - Physical contact between the food and body tissue.

Receptors - Muscles and nerves in mouth and fingers.

Perception -Touch, feel, texture, viscosity.

Texture usually relates to solid food while viscosity relates to homogeneous liquid

foods and consistency relates to non-homogeneous liquid foods.

FINGER FEEL:

Firmness/goodness indicates the eating quality of some food product.

Ripeness level of fruit such as mango

Crumb texture of bread

Firmness of cheese

Spreadability of butter

Juiciness can be used as subjective quality index.

MOUTH FEEL:

Liquids:

Viscosity - thin to viscous eg. Milk, cream.

Consistency - thin to thick eg. Fruit, yoghurt.

Solids:

Classification of textural characteristics assessed mainly by chewing

Hardness - soft, firm, hard. eg. Fruit ripeness, chesse maturity

Brittleness - Crumbly,crunchy,brittle. Eg. Biscuits.

Chewiness -Tender, chewy,tough eg.meat

Grittiness - gritty, grainy,coarse eg.Storecells in fruits, „sand‟ in icecream.

Fibrousness- fibrous, cellular eg. Fibre in vegetable

Moistness -Dry, moist, wet eg.watermelon

Oiliness -oily,greasy,fatty eg.chips

Analysis of texture

Objective evaluation:

Methods of evaluating food quality that depend on some measure other than the

human senses are often called objective methods of evaluation.

Advantages:

Confidence can be gained as they are reproducible.

The results would be accurate. Human sensitivity is not involved. Minute differences

can be noticed by doing objective tests.

They are less subjected to errors when compared to sensory methods.

These methods provide permanent record so that comparison can be made over a

period of time.

They are not affected by factors other than the one being measured.

Emotional burdens and individual ability can be overcome.

Disadvantages:

It is time consuming.

It is expensive.

Technical knowledge is required.

Instruments may not be available sometimes.

Some aspects of food cannot be evaluated by objective methods e.g.flavour.

Usually both sensory and objective methods are done. Objective evaluation

supplements or reinforces the data obtained subjectively through sensory

evaluation.

Instruments used for texture evaluation:

Various instruments are used to measure the texture of liquids, semi solids and

solids.

Rheology is defined as the science of deformation and flow of matter. It has three

aspects-elasticity, viscous flow and plastic flow.

Instruments used for testing Viscosity:

The resistance or internal friction to the flow of liquids is normally known as

viscosity.

Stormer viscometer:

It is used to measure the viscosity or consistency of certain food products and to

give an index of the resistance of the sample to flow. The number of seconds

required for the rotor to make 100 revolutions has been used to measure the

consistency of some food samples.

Percent Sag: The depth of a sample such as jelly is measured in its container by

using a probe. The product then is unmolded onto a flat plate. The greater the

percent sag, the tenderer is the gel.

Percent Sag = depth in container - depth in plate/depth in container x 100

Brookfield Synchrolectric Viscometer:

This is based on measurement of resistance to rotation of a spindle immersed in the

test material. This can be used successfully in measuring the consistency of

custards, pie fillings, tomato products, mayonnaise, salad dressings and dairy

products.

Bostwick Consistometer:

This is used for measuring the consistency of tomato ketchup and sauce. The

Bostwick consistometer consists of a channel (2x12") with sides which are 2" high.

It has triggered gate on one side. A centimeter scale is etched on the floor of the

channel. The use of this instrument is based on the theory that the length of flow

is proportional to consistency.

Efflux-Tube Viscometer: It measures the time necessary for a quantity of fluid to

pass through an orifice or capillary under standard pressure, e.g. tomato puree.

Adams Consistometer:

While this Consistometer was designed primarily for measuring consistency of

cream style com, there are possibilities of using it in measuring the consistency of

other products like tomato puree, apple sauce and fruit pulps. The Adams

consistometer has been designed and constructed to accommodate a greater mass

and measure the unrestrained flow in all directions by means of concentric circles.

It consists of a large metal disc upon which are engraved 20 concentric circles,

increasing 0.25 inch in radius.

A steel truncated cone, which can be lifted vertically, fits tightly against the disc so

that the circumference of the cone coincides with the inner most circle.

Fill the cone with the sample to the level. Then raise the cone quickly and after 30

seconds, measure the consistency of the cream style com by recording the extent

of flow of the product at four equidistant points as indicated on the calibrated disc.

Average the four values thus determined to obtain an average consistency value for

the product. A simpler version of this principle is used in Line spread test.

Penetrometer:

A Penetrometer also may be used to measure tenderness of some foods. This

device consists of a plunger equipped with a needle or cone that is allowed to

penetrate the sample by gravitational force for a selected period of time. The larger

the reading the longer the distance the more tender is the product. Gels and many

baked products are particularly well suited to tenderness measurements using the

penetrometer The Bloom gel meter is a special type of penetrometer in which lead

shot drops into a cup which forces a plunder into the sample. When sufficient

weight has been added to the cup to move the plunger a set distance, the test is

completed and the amount of shot required is determined as the measure of the

test.

Brabender Farinograph:

This is used to measure the plasticity of wheat dough for preparing bread products.

It is designed to study the physical properties of the dough by recording the force

required to turn the mixer plates through the dough. The force required increases

as the solution develops during mixing and later decreases as solution is slowly

broken down by over mixing.

Instruments used for solids: Food texture can be termed as measurements of

resistance to force.

If we squeeze food so that it remains as one piece this is called compression, e.g.

bread.

If we apply a force so that one part of the food slides past another it is shearing,

e.g. chewing gum.

If the force goes through the food so as to divide it like in cutting.

If the force is applied away from the material, the food pulls apart by which we

measure tensile strength, e.g. chapatti

Magness-Taylor Pressure tester (compression):

It consists of a plunger of variable diameter which is pressed into the fruit to a

given depth. The sprint attached to the plunger contracts and measures the

compression force,

e.g. peas (suitability of peas for the harvest or to find out the correct stage of

ripening of a food).

Succulometer (compression):

This instrument is used to measure the maturity of com and storage quality of

apples as determined by the volume of juice extracted under controlled conditions

of pressure and time.

Tenderometer (compression and shearing):

This is an example of an instrument based on shearing force in which compression

is preceded by shearing action, e.g. suitability of peas for preservation.

Fibrometer:

This is based on the cutting principle and used to differentiate mature stocks from

the tender stocks, e.g. green beans.

Christal texturometer (cutting):

This is designed with series of rods which are pushed into the meat sample. The

harder the meat more force is required to penetrate.

Compressimeter:

The Compressimeter is related to the shear press, but it measures only

compressibility not shear strength. The usual technique for operating the

compressimeter is to apply pressure until the sample has been deformed specific

amount and then to measure the force that is required to accomplish this amount of

deformation. The greater the force required, the firmer the product.

Warner-Bratzier Shear:

It is a device used to measure the tenderness of meat. The instrument consists of a

stainless steel blade having a hole, with an equilateral triangle circumscribed

around a circular hole. It is generally used to measure the tenderness of meat by

knowing the maximum force encountered during the cutting action.

Shear press:

The shear press, a related device, is a machine that compresses, extrudes an,

shears the sample at the same time. This is a suitable method for measuring

textual characteristics of some fruits and vegetables.

Universal Testing Machine: The Universal testing machine can provide a record

showing seven aspects like texture from various food samples These are

cohesiveness, adhesiveness, hardness, springiness, gumminess, chewingness and

fructurability.

Classification of textural characteristics

Mechanical characteristics

Primary parameters Secondary parameters Popular terms

Hardness Soft -> Firm -> Hard

Cohesiveness Brittleness Crumbly -> Crunchy - >

Brittle

Chewiness Tender -> Chewy -> Tough

Gumminess Short -> Mealy -> Pasty Gummy

Viscosity Thin -> Viscous

Springiness Plastic -> Elastic

Adhesiveness Sticky -> Tacky Gooey

Geometrical characteristics

Class Examples

Particle size and shape Gritty, Grainy, Coarse, etc.

Particle shape and orientation Fibrous, Cellular, Crystalline, etc.

Other Characteristics

Primary parameters Secondary parameters Popular terms

Moisture content Dry -> Moist -> Wet ->

Watery

Fat Content Oiliness Oily

Greasiness Greasy

Definitions of mechanical parameters of texture

Physical Sensory

Primary properties

Hardness Force necessary to attain a given deformation

Force required to compress a substance between molar teeth (in the case of solids)

or between tongue and palate (in the case of semi-

solids).

Cohesiveness Extent to which a material

can be deformed before it ruptures.

Degree to which a substance

is compressed between the teeth before it breaks.

Viscosity Rate of flow per unit force. Force required to draw a liquid from a spoon over the tongue.

Springiness Rate at which a deformed material goes back to its

un deformed condition after the deforming force

is removed

Degree to which a product returns to its original shape

once it has been compressed between the teeth

Adhesiveness Work necessary to

overcome the attractive forces between the surface of the food and

the surface of the other

Force required to remove the

material that adheres to the mouth (generally the palate) during the normal eating

process.

materials with which the

food comes in contact

Secondary Properties

Fracturability Force with which a material fractures a

product of high degree of hardness and low degree of cohesiveness

Force with which a sample crumbles, cracks, shatters

Chewiness Energy required to masticate a solid food to a

state ready for swallowing: a product of

hardness, cohesiveness and springiness

Length of time (in sec) required to masticate the

sample, at a constant rate of force application, to reduce it

to a consistency suitable for swallowing.

Gumminess Energy required to disintegrate a semi-solid food to a state ready for

swallowing: a product of a low degree of hardness

and a high degree of cohesiveness

Denseness that persists throughout mastication; energy required to

disintegrate a semi-solid food to a state ready for

swallowing.

Classification of mouthfeel terms

Category Typical words

I Viscosity – related terms Thin, thick, viscous

II Feel on soft tissue Surfaces Smooth, pulpy, creamy

III Carbonation – related terms Bubbly, tingly, foamy

IV Body-related terms Heavy, watery, light

V Chemical effect Astringent, burning, sharp

VI Coating of oral cavity Mouth coating, clinging, Fatty, oily

VII Resistance to tongue movement Slimy, syrupy, pasty, sticky

VIII Afterfeel –Mouth Clean, drying, lingering, cleansing

IX Afterfeel – Physiological Refreshing, warming, thirst – quenching, filling

X Temperature – related Cold, hot

XI Wetness – related Wet, dry

CHAPTER: 10 FACTORS INFLUENCING SENSORY MEASUREMENTS

FACTORS AFFECTING SENSORY MEASUREMENT

Unlike the instruments, human judgments can easily be affected by psychological

and physiological factors. We have to be aware of these factors and ensure that the

chosen procedure or experimental design eliminate or reduce such bias.

PSYCHOLOGICAL FACTORS:

Expectation error

Knowledge of experimental objectives or the sample to be evaluated can influence

an assessor‟s judgment. People tend to find what way they expect to find. For

example codes such as „A‟ or „1‟ or round numbers can be associated with higher

score.

Strategies for reducing such errors:

Provide assessors with minimum amount of information required to perform the

test.

Use codes such as random three digit numbers and not letters or colours.

Do not include people with product knowledge on the panel.

Do not disclose information regarding the samples unless if necessary for ethical

procedures.

Suggestion effect

Comments or noises made out loud, eg, urghh or mmmm!., can influence sensory

judgment.

Strategies for reducing such errors:

Isolate assessors during sample evaluation e.g. use of sensory booths.

Discourage assessors from discussing samples before or after evaluation.

Distraction error:

Assessors can be easily distracted from the taste in hand, either by stimuli in the

test environment, e.g. radio or by personal preoccupations, time pressure.

Strategies for reducing such errors:

Ensure that the test area is quiet.

Create an environment that encourages professionalism amongst the assessors.

Prohibit the use of electronic devices.

Stimulus or logical error:

Stimulus error occurs when assessors use additional information to make a

judgment about the samples under assessment. When this stimulus is logically

associated with one or more of the characteristics under evaluation this is called

logical error. E.g., products of a deeper colour or larger size are presumed to be

more flavour intense; using more luxurious containers may lead assessors to think

that the product is of higher quality.

Strategies for reducing such errors:

Ensure sample characteristics are consistent and/or mask irrelevant differences

where possible.e.g, use of colored lighting, blindfolds, nose clips and ear

defenders where appropriate.

Halo effect and proximity error:

Judgments concerning the rating of one attribute may influence the rating of

other attribute when assessor are asked to judge several attributes at

once.

E.g. sweeter sample maybe rated as softer or stickier.

Strategies for reducing such errors:

Where possible evaluate one or at least a limited number of attribute, at

a time

Where possible use trained assessors,

Where appropriate, randomize the order of attribute evaluation, if several

attributes have to be rated at once.

Attribute dumping:

If assessors are not given the opportunity to rate all the attributes they

perceive as changing in the products under evaluation, they may still record

this observation using the scales available. For (e.g.) if products are changing

in terms of sweetness but no sweetness scale exists, they may register

these changes on a flavor intensity scales such as strawberry flavor. This is

known as attribute dumping.

Strategies for reducing such errors:

Enable assessors to all attributes which vary or indicate that opportunities to

rate all varying attributes will be given.

Habituation:

Assessors can develop a habit of assigning similar scores each time rather than

scores which truly represent the samples when they evaluate similar products on a

regular basis.

Strategies for reducing such errors:

Vary products or introduce spiked samples from time to time.

Order effect:

The score assigned to a sample can be influenced by the sensory character

of the preceding products. For example, a sample may be rated as less sweet if it

follows one of greater intensity.

Strategies for reducing such errors:

Randomize or balance the order of presentation of samples.

For affective tests, use a dummy sample in position one.

Contrast and convergence effects:

If the products in the sample set are strikingly different, assessors may exaggerate

their ratings of this difference (contrast). If similar products are rated as part of a

widely varying sample set, then the difference between may be rated smaller than

actually it is (convergence).

Strategies for reducing such errors:

Randomize or balance the order of presentation of samples.

Central tendency error:

When using scales, assessors tend to avoid the extremes and confine their ratings

to the middle of the scale. This is more likely to occur with untrained assessors are

not familiar with the product range.

Strategies for reducing such errors:

Train assessors in the use of the scale expose them to a wide products range

where possible.

Use large enough scale to differentiate between the products, particularly with

untrained assessors.

Motivation error:

A motivated panelist will learn better and, ultimately perform more reliably. If

assessors do not respect the panel leader or product manufacturer, they may rate

samples based on how they feel.

Strategies for reducing such errors:

Respect assessors.

Give regular feed back to the assessors.

Carryout tests in a professional manner.

PHYSIOLOGICAL FACTORS:

Adaptation:

Continued exposure to a stimulus results in a decrease in sensitivity to that

stimulus or a change in sensitivity to other stimuli. They are known as carryover

effects.

Remedies:

Limit the number of samples presented.

Ensure appropriate time intervals between samples to allow the sensory system

to recover.

Ensure assessors take adequate breaks between single and sets of samples.

Provide assessors with appropriate palate cleansers, which ensure removal of

any sample lingering in the oral cavity.

Perceptual interactions between stimuli:

Certain stimuli can interact to cause the following:

Enhancement (potentiation)-The presence of one substance increases the

perceived intensity of another. (e.g.) salt increases perceived intensity of

chicken flavor.

Synergy: The intensity of mixture is greater than intensity of the sum of the

individual components. E.g. sweetness and sourness impact on strawberry

flavour.

Suppression: The presence of one substance decreases the perceived intensity

of another. E.g. sourness reduces peach flavor.

Remedies:

Employ careful experimental design to ensure that the effects of combined and

individual stimuli are understood.

Physical condition:

Health and nutritional disorders, together with the drugs prescribed to treat them,

can affect sensory performance. Age and stress can also impact on sensory

characteristics.

Remedies:

Screen assessors prior to testing or remove assessor if medical conditions or

associated drugs affect the sensory performance.

Instruct assessors to refrain from eating for at least an hour before sensory

sessions.

Schedule sessions for around a similar time each day.

Cultural factors:

When working with assessors from different cultures or geographical location,

the sensory professionals needs to be aware of the impact the cultural effects can

have on sensory data. In addition, literal translations of questions and scale

terminology may result in loss or change of meaning.

Remedies;

Be sensitive to coding issues.

Clarify translations of sensory scales or questionnaires into other languages.

Build up information on cultural norms from different cultures or countries.

Be aware of cultural tendencies.

CORRELATION OF SENSORY WITH CHEMICAL AND PHYSICAL

MEASUREMENTS

Sensory response to a product of concern to the developer, it is essential to

knowhow any chemical or physical method used compares with the human senses

that is the panels ability to detect and quantify sensory characteristics. Descriptive

test methods with trained panelists are generally used for this purpose.

CHAPTER:11 QUALITY MEASUREMENTS: LABORATORY MEASUREMENT

SENSORY TESTING METHODS:

There are two main types of testing.

1) Affective – which involves consumer preference or acceptance.

2) Analytical – which are involved with analyzing specific product attributes in

terms of

i) Discrimination or difference

ii) Description

Classification of methods by function

Analytical Test:

Analytical tests are used for laboratory evaluation of products in terms of

differences or similarities and for identification and quantification of sensory

characteristics. There are two major types of analytical tests – discriminative and

descriptive. The interest of sensory analyst is to find out the differences among the

treatments, products or samples the panels being the means of measurement. The

quality attributes of the products are assessed keeping the same panel. This test

employs inexperienced or trained panelists.

Affective tests:

These are based on tendency and are entirely different from analytical tests and are

also termed as consumer tests. These tests are used to evaluate preference and/or

acceptance of products. These panelists are not trained but are selected at large to

represent target or potential target populations.

Difference tests:

Difference tests may be subdivided into two classes.

Simple difference test

Simple difference tests are those that have no direction or characteristics

associated with the difference between its products. The judge indicates whether

there is a difference between the samples. The judge is told beforehand that the

sample in each trial set to be tested maybe identical or different. Complete

randomness of presentation is essential so that the panelists response to each set

independently.

Examples of different tests are:

Triangle test

Duo trio test

Difference from control

Directional difference test:

Directional difference tests are those that have a direction or characteristics

associated with the difference between products. Examples of directional difference

tests are:

Paired comparison test

Ranking

Rating

Two out of five test

A not A

The judge chooses the sample within each pair that has the greater amount of a

specified characteristic. A forced choice is required.

Paired comparison test:

Used to determine how a specific sensory property differs between the samples. It

can be applied to determine a directional difference (e.g. which sample is sweeter).

A paired comparison tests has numerous applications in product or process

development. It can also be used to determine a more advanced sensory test

should be applied. It can be used for multiple comparisons but this result in a large

number of pairs to assess which uses a lot of sample and can cause sensory

fatigue.

The most common paired comparison tests are two sided (bilateral) where there is

no prior expectation of the result. Conclusions that can be drawn are that there is

no evidence of a difference or that one sample has a greater intensity of chosen

attribute is preferred.

One sided tests (unilateral) also exist when there is prior expectation of the

direction of difference. Conclusions to be drawn include that there is no evidence of

a difference or that the previously declared sample is greater in attribute intensity

is preferred. Bilateral and unilateral score sheets are different. The chance of

probability of selecting one sample over another within individual pairs is one half.

The panel members receive several pairs of samples. These may be different or the

same samples in each pair. Samples are always given in code numbers. Different

samples are given in each pair which differs in the intensity of one characteristic,

e.g. sweetness, bitterness or rancidity. In each pair the sample with more or less

intense taste will have to be picked out.

Duo trio test:

This test employs three samples, two same and one different. One sample is

identified as the standard and presented first followed by two coded samples one of

which is identical to the standard. The judge is required to identify the sample

which matches the standard. The sample used as standard may be constant are

alternated. Trained or untrained panelist can be used. With the paired comparison

and triangle tests a forced choice is required and statistics may be applied to

determine significance. The chance of probability of selecting the matching sample

is one half.

Triangle test:

This test employs the coded samples two identical and one different presented

simultaneously. None of the sample is identified as the standard. Controlled and

experimental treatments are systematically varied so that each is presented odd

and identical sample positions on equal number of times. The judge must determine

which of the three samples (odd sample) presented differs from the other two. A

forced choice is required. Statistical analysis is used to determine whether a

significant difference between treatments exists. Probability of choosing the

different or odd sample by chance alone is one third.

Two out of five test:

It is used to determine whether there is a sensory difference between two samples

and to select and monitor panelists. It is statistically very efficient as the probability

of guessing correctly the different two samples from its five samples presented is

low. It can be useful when only a small number of panelists are available. However

sensory fatigue memory effects may affect the test.

As with the triangle and duo – trio tests, assign 3- digit random codes to the

samples & then make up the score sheets, taking to prepare the samples in

identical fashion. There will be 20 possible combinations. Panelists are instructed to

assess each product from left to right, then select the two samples that are

different from the other three samples.

A –not – A test:

It is used to determine whether the test samples in a series are the same as or

different from the reference sample. It is especially used where triangle and duo

trio test cannot be used. It is also used to determine assessor‟s sensitivity to a

stimulus.

Initially panelists require familiarization with reference or „„A‟‟ sample. They are

then presented with a series of samples, some of which are reference sample “A

“and some are “not A”. Generally the panelists do not have access to the reference

sample A while evaluating the samples. The panelists must determine whether the

samples is the same A or different from A . So it is a forced choice test. Only one

type of not A sample exists per test series. Panelists may test 1, 2, or up to 10

samples in a series. These samples are presented randomly with a three digit code

& one at a time. All samples are prepared in an identical way & are representative

of the product.

Rating tests: These tests give more quantitative data than difference tests and

can be used for the analysis of more than two samples at the same time.

Ranking tests:

This test is used to make simultaneous comparisons of several samples on the basis

of a single characteristic (It is used to determine how several samples differ on the

basis of a single characteristic). A control need not be identified as test samples are

coded. Samples are presented simultaneously and ranked according to intensity of

characteristics designated. No ties are allowed. Rank totals or average ranks are

obtained for each sample. Differences are interpreted through statistical analysis of

the data. In consumer analysis, the panelists are asked to rank the coded samples

according to their preference.

Single Sample (Monadic) Test: This test is useful for testing foods that have an

after taste or flavour carry over which preclude testing a second sample at the

same session. The panelist is asked to indicate the presence or absence and/ or

intensity of a particular quality characteristic. With trained panelists, the completed

analyses of two or more samples evaluated at different times can be compared.

Also, in market and consumer analysis, the results of different samples evaluated at

different times by a different set of untrained panelists can be compared.

Two Sample Difference Test: This test is a variation of the paired comparison

test and measures the amount of difference. Each taster is served four pairs of

samples. Each pair consists of an identified reference and coded test sample. In two

pairs, the test sample is a duplicate of the reference sample. In the other two pairs,

the test sample is the test variable. The panelist is asked to judge each pair

independently as to the degree of difference between the test sample and standard

on a scale of '0' representing no difference to '3' representing extreme difference.

Additional questions on direction of difference can also be asked. The panelist is not

to guess and he is panelised for guessing through the coded duplicate standards in

two pairs.

Multiple Sample Difference Test

In this test, more than one test variable can be evaluated per session but with

reduced reliability. Each panelist is served 3-6 samples depending upon the number

of test variables. One sample is a known standard. The panelist compares each

coded sample with the known standard. One coded sample is a duplicate of the

standard. Whatever score the panelist assigns to the blind standard is subtracted

from the score he assigns to the test variables. The panelist does not guess.

Direction and degree of difference is also to be judged.

Hedonic Rating Test: Hedonic rating relates to pleasurable or unpleasant

experiences. The hedonic rating test is used to measure the consumer acceptability

of food products. From one to four samples are served to the panelist at one

session. He is asked to rate the acceptability of the product on a scale, usually of 9

points, ranging from 'like extremely' to dislike extremely'. Scales with different

ranges and other experience phrases could also be used. The results are analysed

for preference with data from large untrained panels.

Numerical Scoring Test: One or more samples are presented to each panellist in

random order or according to a statistical design. The panellist evaluates each

sample on a specific scale for a particular characteristic indicating the rating of the

samples. The panelists are trained to follow the sensory characteristics

corresponding to the agreed quality descriptions and scores. Without this

understanding the rating will not be of any use.

Composite Scoring Test: The rating scale is defined so that specific characteristic

of a product are rated separately. The definition of the rating scale is weighed so

that the most important characteristics will account for a large part of the total

score. The resulting scores are compounded for anyone panelist to arrive at a

composite score. This method is helpful in grading products and comparison of

quality attributes by indicating which characteristic is at fault in a poor product. It

gives more information than the straight numerical method. The panelists are

trained to evaluate the dimensions of the individual quality characteristic critically,

and in the use of the weighed scale.

Rating difference or Scalar difference from control:

This test may be used when a control sample is available for comparison with one is

more experimental samples. Judges receive all samples simultaneously identified

controlled and coded experimental treatments. The control may be introduced as

unknown sample. Category scales ranging from “No difference from control” to

“Very large difference from control” are typical. Stastical analysis of the data is

used to show whether the degree of difference from the control is significant.

Sensitivity tests: Sensitivity tests are done to assess the ability of individual to

detect different tastes, odours and feel the presence of specific factors like

astringency or hotness (pepper). These tests are used to select and train panel

members for evaluating the quality of products containing spices, salt and sugar,

e.g. tomato ketchup or sauce. For this purpose threshold tests for the recognition of

basic tastes (sweet, sour, bitter and acid) are employed for selecting the panel

members.

Sensitivity threshold test:

Threshold Value is defined as a statically determined on point the stimulus scale at

which transaction in series of sensation or judgment takes place. it is also defined

as a number which is denominator of dilution where its odor or flavor is recognized

. There are three types:

1. Stimulation threshold:

It is a magnitude of stimulus at which transition occurs from no sensation to

the sensation.

2. Identification threshold:

It is the minimum concentration at which a stimulus correctly identified.

3. Termination / saturation threshold :

It is a magnitude of a stimulus at which no increase in the perceived intensity

of stimulus takes place.

Threshold value is an important tool to find out the minimum detectable difference

of an additive or off flavor. It is numerically expressed by scoring pattern.

Dilution test:

It is employed basically to determine the quantity of unknown material developed

as substitute of a standard product such as margarine, in butter. Upper & lower

limits of substances can be detected using preliminary testing. Series of mixture

with upper & lower limits are prepared for testing by dilution tests. The quality of

the test material is represented by the dilution number which is the percent of the

test material in the mixture of the standard product such that there exists adjust

identifiable difference in odour and taste between them. The bigger the dilution

number the better is the quality of the test material.

Affective tests:

Paired preference test:

It is used to establish whether there is a preference between two samples. A pair of

samples is presented to each assessor and is asked to choose the samples they

prefer. This is a forced choice test i.e. they must select one sample as being more

preferable. Responses indicating no preference are not permitted. A preferred to B,

B preferred to A.

Ranking for preference:

Judges are asked to 2 or more samples in order or preference i.e. most preferred

sample is ranked first. It is a forced choice test i.e. no ties are allowed.

Rating for preference:

Assessors are asked to evaluate 1 or more samples & indicate degree of liking for

the product or some characteristic of the product.

Descriptive test:

Descriptive test is used to identify and provide a picture or „profile‟ of the

important sensory characteristics of a product. In this testing method more than

two samples can be assessed simultaneously. This type of test interprets whether

or not there is a difference between samples but also the nature and magnitude of

these differences. Appearance, odor, flavor, and texture can be assessed in this

way and the characteristics can be quantified using various techniques and scales.

Applications:

Tracking changes in the sensory characteristics of a product over time

for sensory evaluation.

Examining the sensory properties of a target product for new product

development.

Examining sensory characteristics of different variety of a product.

Sensory diagnostics of ingredient, processor packaging changes.

Correlation with instrumental methods.

Flavor profile method:

Flavor profiling was developed by Arthur. D Little Co in 1949. Aroma, flavor

and mouth feel are assessed in terms of quality intensity on a 5 point absolute

“degree of intensity” category scale, order of appearance, after taste and overall

impression. This is conducted by using 4-6 trained panelists. Panelists are selected

by screening for sensory acuity, interests, attitude and availability. The trained

assessors assess samples individually and then discuss their evaluations as a group

to determine a consensus score. The scales used with this technique involve the use

of numbers and symbols and therefore cannot be analyzed statistically. This

method is therefore a qualitative descriptive test. The main disadvantage with this

type of test is that a dominant panel member or the panel leader could easily

influence the panel‟s decision.

Profile attribute analysis:

The flavor profile method was renamed the profile attribute analysis with

the introduction of numerical scales. Mean score could be calculated and the data

statistically analyzed.

Texture profile method:

This method was developed at general foods in the 1960‟s. It was based on

the principles of flavor profile method to assess the textural characteristic of a

product. Textural characteristics are categorized into three groups, mechanical,

geometrical, and other characteristics.

1. Mechanical- Relating to the reaction of food to stress e.g. hardness,

chewiness, and adhesiveness.

2. Geometrical charateristics - Relating to size, shape and orientation of the

particles within the food e.g. grainy, fibrous and aerated.

3. Other charateristics - Relating to the perception of the moisture and fat

content of the food.

The order in which the characteristics are assessed is also very important.

The order of assessment is first bite, “chewing” or masticatory second and

residual or third phase. Panelists are selected on their ability to discriminate

between textural differences in the product area. Size two to ten panelists is

suggested.

Standardized terminology and rating scales are used for the

assessments and each scale point is anchored with a specific food. A panelist

each make their own individual judgment and then depending of the type of

scale used, a consensus decision is reached on statistical analysis is

performed on the data.

QUANTITATIVE DESCRIPTIVE ANALYSIS:

It was developed at the Stanford research institute by stone and to provide

descriptive data that could be analyzed statistically, in contrast to the methods

described earlier. It can produce a full qualitative and quantitative sensory

description. Assessor (8-15) selected for their ability to describe and discriminate

products in the category to be studies, agree on a list of qualitative attributes on a

line scale with indented anchors. The panel leader facilitates discussions rather than

leads them. Assessments are made in replicates of 2-6 repeat evaluations, data are

translated into mean scores and statistically analyzed using ANOVAs, individual

assessors performance is monitored and compared to that of the panel, and results

are presented graphically in spider plots.

SENSORY PANELS AND THEIR TRAINING

CONSUMER AND SPECIALISED PANELS

CONSUMER PANEL

Information on consumer likes and dislikes. Preferences and requirements for

acceptability can be obtained with the help of consumer oriented testing. Consumer

panel may consist of 100 or more number of person‟s representative of the target

population of potential product users. This testing can be conducted at any central

location such as market. Community centre, retail shop or at consumers‟ homes. A

true consumer panel test requires selection of a panel representative of target

population which is both costly and time consuming. Therefore, in-house consumer

panels are commonly used to provide initial information on product acceptability

and are generally conducted prior to true consumer test. An in-house consumer

panel usually consists of 30-50 untrained panelists selected from the personnel

working in the organization. They should be similar to the target population of

consumers. This type of panel can indicate the relative acceptability of the product

and can identify the product defects.

SPECIALISED PANEL

Specialized or product oriented panel testing uses small number of trained panelists

who function as testing instruments. Such panelists can easily identify difference

among similar products or intensities of flavor, texture, appearance etc..,because

they are selected on the basis of their sensory ability and specially trained for such

a task.

TRAINED PANEL

They are carefully selected and trained but need not be expert panelists. They are

used to establish the intensity of a sensory character or overall quality of a food.

The trained panels should be small in number, varying from 5-10 and may be used

in all developmental and processing studies. A small but highly trained panel will

give more reliable results than a large untrained panel.

SEMI TRAINED PANEL:

This type of panel is constituted from amongst the persons normally familiar with

quality of different classes of food. Such a panel is capable of discriminating

differences and communicating the differences or their reaction, though it may not

have been formally trained. The panel should normally have 25 to 30 members and

is used for preliminary screening program to select a few products for large scale

consumer trails.

REQUIREMENT FOR A GOOD PANELIST:

Should be in good health.

Capable to response to the changes in the taste, smell or other sensory

function.

Have motivation and interest in the sensory program.

Should be emotionally balanced state.

Should refrain from smoking, chewing gum, eating or drinking for at least 30

minutes before the test.

Should remain available for evaluation.

RESOURCES NEEDED FOR SENSORY TESTING:

Sensory team:

A sensory team typically includes the following notes: manager, sensory analyst,

panel leader, technician, consumer researcher, statistician and assessors.

All the sensory staff must have the appropriate knowledge about how to conduct

sensory testing e.g. methods, practices, procedures, data analysis, reporting and so

on.

How to work with sensory and consumer assessors, e.g. motivation,

professionalism, confidentiality, safety, ethics, adverse event procedures and so on.

How to work in a sensory laboratory, e.g. quality (SOP) safety and hygiene.

How to work with clients and project team, e.g. presentation skills, professionalism

and project management.

The sensory is highly specialized and technical requiring knowledge of many

disciplines including psychophysics, psychology, experimental design, statistics,

food technology, physical chemistry etc… In addition the sensory professional needs

to have the ability to work well with clients often from diverse backgrounds and

organizational skills to manage projects to time and cost.

DESIGN OF A SENSORY TESTING AREA:

The main considerations to keep in mind when preparing an area for sensory

testing concern the requirement for an atmosphere conducive to concentration,

where conditions can be controlled.

Sensory panelists need comfortable and free distractions, product characteristics

can be markedly affected by temperature and humidity and appearance is affected

by lighting intensity.

The conditions should be controlled in order to

Reduce bias

Improve accuracy

Improve sensitivity

International standard(ISO 8589-1988) looks at the design of the testing area for

both new and existing buildings.

It also specifies which recommendations are considered essential and which are

only desirable.

Important points summarized from the standard are listed below total area should

include:

Testing area with individual booths and a group area

Preparation area/kitchen

Office

Cloak room

Rest room

Toilets

General testing area:

Easily accessible but in quiet position

Location – Close proximity to preparation area, but separate entrance, and with

complete „close-off‟ capability.

Temperature and relative humidity - Constant, controllable and comfortable.

Noise - Keep to a minimum, sound proof area as much as possible.

Odours - Keep area free from odours, use odourless materials in construction and

decoration, use odourless cleaning agents.

Decoration- Use neutral, light colours for walls and furniture (eg.off white, light

grey)

Lighting- Ambient lighting must be uniform, shadow- free and controllable.

Booths:

Number - Minimum three, normally 5-10.

Space - Allow sufficient space for movement of tasters and for serving samples

Setup - Permanent booths recommended, temporary acceptable. It adjacent to

preparation area include openings in the wall to pass samples through. Size and

shape specified. Consider space for samples, utensils, spittoons, rinsing agents,

score sheets, pens, and computerized equipment include comfortable seats.

Lighting - Uniform, shadow free, controllable, adequate intensity for assessing

appearance. Devices to mask appearance (eg.dimmer, colour light/filters)

Group work area:

General - Necessary for discussion and training purpose. Include large table and

several chairs. It also includes board for discussion notes etc….

Preparation area:

General-located close to assessment areas but no access to testers. Design for

efficient work flow. Well ventilated, flexible services.

Equipment:

Depending on testing required. Include working equipment, working surface, sinks,

refrigerator, freezers, dish wash etc.. Storage space for crockery, glass wares etc…

for serving sample.

Testing area:

Comfortable chairs for panelist, minimum space for four panelist. Table which can

be easily divided into booths if required, well placed efficient lighting.

Office area:

General - separate but close to testing area, reasonable size, desk, filling

cabinet, computer, book case, photo, copying services.

Additional areas:

Useful to include rest room, cloak room, toilets. Sensory area should contain

minimum of three areas. Preparation area requires adequate storage for utensils

and equipment. Adequate working surfaces to set out the samples. Washing up

facilities-minimum double sink with hot and cold running water. Refrigerator-

minimum two door with separate freezer. Cooking-depending on sample

requirement. Rubbish bin- large with liner bags. Source of boiling water, cold water

and hand washing facilities.

TESTING FACILITIES:

GENERAL CONSIDERATION:

The scope of the sensory testing program will determine the type and size of

facilities needed.

Experimental conditions are carefully controlled and experiments are carefully

designed.

Several functional areas including a sample preparation area, a serving area, an

assessment area with booths, a discussion / training area, staff offices and a

storage area.

Food samples need a hygienic flow to avoid cross contamination between freshly

prepared samples and waste. Ideally, the sample preparation area should be a

separate room from the assessment area to avoid bias due to strong odours, noise

and overhead conversation related to testing. The facilities should be designed to

accommodate disabled assessors.

LOCATION:

The facilities should be in a location that is odour free and quiet, e.g.

avoiding sites that are adjacent to odorous and nosily, busy roads and so on. There

should be adequate parking available at the times when assessors arrive for testing

section.

MATERIALS:

In order to minimize bias, the facilities need to be as neutral as

possible. The colour and content and patterns used for decoration may cause

distraction and bias, potted plant may generate odour and branded display items

may introduce bias. Use non odorous materials, e.g. surfaces, paint and neutral

colours (pale grey) throughout the facility.

AIR HANDLING:

Appreciate air handling is particularly important to ensure temperature

control and minimize odour build-up. Air handling should be sufficient to counter

internal sources of heat, such as computer, lighting and with external sources of

heat, such as extreme heat in summer. It should be able to clear strong odours

such as those generated by cooling or fragrances. An odour filter is necessary to

clean both incoming and outgoing air. Humidity control also necessary.

LIGHTING:

All testing areas need appropriate and adequate lighting. The

recommended intensity of light is between 755 to 1070 lux. Care should be taken

to ensure that avoids shadowing in the test area. Coloured lights may be necessary

to disguise appearance of sample. For tests to be carried out safely, the intensity of

light needs to be at least 300 lux. Light contamination from computer monitors and

open serving batches should be minimized.

FUNCTIONAL AREAS:

RECEPTION / WAITING AREA:

This is where assessors register their arrival. Care should be taken to

ensure assessors leaving a test do not influence / bias assessors arriving for a test.

Ideally there should be minimal contact between the two.

SAMPLE PREPARATION AREA:

This is the area where samples are prepared for assessment. Preparation typically

includes making many small identical portions of samples in/on cups, bowls, plates,

pots etc. and laying them out in serving order on trays. It is important that there is

adequate working surface to do this. Adequate space should also be available for

preparation equipment example: Cookers & storage.

For laboratories testing food the area must be designed to strict hygiene including

hygienic materials (example: filling) and construction (example: sealing of cracks

and gaps.

Ideally there should be an area at the entrance for storing protective clothing.

Lockers may also be useful for storage of personal items that cannot be brought

into the lab such as jewelry.

Hand washing facilities must be present at the entrance.

For laboratories testing both food and non food products and those testing meat

and dairy food samples separate areas must be allocated for sample preparation to

avoid cross contamination.

SAMPLE SERVING AREA:

This is a space adjacent to the booth area from which samples can be served to

the booths. Depending on how serving is to be accomplished it may need to be

wide enough to accommodate trolleys and have enough work space to lay out

samples and equipments necessary to keep samples at certain temperature. It is

more convenient to have the height of the serving counter at the same height as

the booth counters.

Ideally, serving area should not be visible from the booth area to minimize bias

through knowledge of the test and samples. It may be necessary to keep lighting at

lower intensity than the booth area and use the same color lighting used in the

booths.

CHAPTER: 12 QUALITY MEASUREMENTS: CONSUMER MEASUREMENT

CONSUMER MEASUREMENT:

Although the fate of a food product has always rested on acceptance by the

consuming public, formal studies of consumer preference are a comparatively

recent development. Consumer reactions are difficult to measure but the necessity

for such studies will continue to grow as competition for the consumer food

increases.

We must distinguish carefully between studies of consumer preference and studies

of consumer practice. Those who prefer may not be those who buy, preference

studies are designed to determine consumer‟s subjective reactions to external

phenomena, and their reason for having them.

Practice studies are designed to determine what consumers actually do under given

circumstances, such as the numbers of ripe and under ripe peaches purchased

when ripe peaches cost certain amounts more.

The techniques for these two types of studies are usually quite different, although

some approaches can be used for both types. Both acceptance and preference are

primarily economic concepts.

Acceptance of food varies with standards of living and cultural background, whereas

preference refers to selection when presented with a choice Preference are

frequently influenced by prejudice, religious principles, group conformance, “status

value,” and snobbery, in addition to the quality of the food.

FACTORS INFLUENCING ACCEPTANCE AND PREFERENCE:

Many complex factors combine to influence the public‟s acceptance and selection of

food as indicated. The extent to which the sensory properties modify the selection

and utilization of a food is difficult to ascertain since all of these factors interact and

influence the consumer‟s decisions.

Attributes of the food product

1. Availability

2. Utility

3. Convenience

4. Price

5. Uniformity and dependability

6. Stability, storage requirements

7. Safety and nutritional value

8. Sensory properties

Attributes of the consumer

1. Regional preference

2. Nationality, race

3. Age and Sex

4. Religion

5. Education, socio-economics

6. Psychological motivation

Symbolism of food

Advertising

7. Physiological motivation

a. Thirst

b. Hunger

c. Deficiencies

d. Pathological conditions

d. Temperature

e. Pain

Appearance probably has the greatest initial influence. Once the food has been

tasted, color and texture become secondary to flavour. Flavour is mentioned by an

overwhelming proportion of consumers as the reason for over-all preference and

continued use of a product. The reason cited most often for disliking a given food is

that “it does not taste good”. It is possible that degree of liking and flavour quality

are synonymous in the minds of many consumers, but that would be difficult to

measure.

Preference in Relation To Cost: Price is an important limitation on the freedom

with which the consumer selects foods. Consumer buying behavior for 'canned

pears indicated that 68% of 179 families said selection of a specific brand was

made on the basis of flavour whereas 59% of the 128 families who purchased eight

minor brands did so because of lower price.

Regional preferences:

Some regional food preferences exist for specific food such as coffee (variation in

roasts and blends), eggs white vs. brown shells, wieners, and the many interesting

food items associated with nationality and ethnic groups. it is generally believed

that in the United States most regional or national or nationality preferences for

specific food items are diminishing because of

1. Population mobility and intermarriage.

2. Standardization of processing.

3. Increased use of partially prepared food and decreased consumption of dishes

“Prepared from scratch”.

4. Greater availability as result of refrigeration controlled ripening development

varieties, improved distribution.

5. Impact of national advertising via television, newspapers, radio.etc

Age:

The age of the consumer has been reported to influence preferences for some food

products Children under 16 and adults over 50 preferred sweeter canned fruit than

did the participants in the middle age group. A definite preference for 3% sucrose

in rose wine was shown by all consumers tested, regardless of frequency of

consumption, and the preference increased with the age of the consumer.

Sex:

Difference in personality, sensory acuity and likes and dislikes are usually more

pronounced between people of the same sex than between the two sexes as

groups. There are, however, group differences between the sexes which can be

used effectively in

planning and conducting marketing campaigns.

Other Factors:

Interest, motivation, discrimination, intelligence and many other attributes of the

consumer undoubtedly influence responses to food the role of the sensory

stimulation of food is not completely understood. The nutritional value of food as

well as sensory properties like appearance, flavour and texture properties are

considered.

OBJECTIVES OF CONSUMER PREFERENCE STUDIES

Determination of market potential: Whether consumers will purchase a product

at a rate commensurate with the supply and at a price high enough to ensure a

continuous flow of the product into the market is of constant concern to the

producer. An awareness of market conditions may be of greater interest to

producer of convenience food, specially items and new product than to distributors

of standard staple and product, but all food producers‟ benefits from studies of

market potentials for their products.

Differentiating between total sales and repeat sales can yield useful information.

Differentiation between food fads and food trends is difficult but may mean the

difference between success and failure for an item. This is always an unpredictable

amount of risk involved in applying results from market surveys. This is

complicated by the time lapse between the survey and the actual marketing of the

product.

The producers may follow these:

1. Don‟t change a product until it has been product tested, market tested and

actively promoted.

2. Build a different feature into the product which can be promoted.

3. Pioneer a new field rather than imitate successful leaders.

4. Enter market that are growing

5. Seek rapid acceptance through products featuring convenience in preparation,

performance or packaging.

6. Design a reliable test program of ample sample size adequate cross section with

proper collection and interpretation of the data.

7. Be patient, testing takes time.

Introduction of New Products:

Years ago a manufacturer could maintain a loyal clientele for a product of

acceptable quality through advertising and special services. Increased competition

has infringed upon brand loyalty, necessitating development of new products to

attract consumer attention and to meet the needs of constantly changing society.

Quality Control of Existing Products:

When a specific brand of foods has enjoyed popularity as indicated by repeated

sales over the years, there is reluctance to change the product unless the alteration

increases sales. Consumer testing can serve as a quality- control measure to assure

uniformity and to maintain standards. As a check on quality, a processor may

conduct consumer studies on his product against that of his nearest competitor

where the identity of the sample is not known to the consumer.

Establishment of specific factors to the consumer:

A food product may sell well because of quality, price size, packaging, promotion,

availability or a combination of all or any of these factors.

The processor may wish to study consumer criteria for selection groups of foods in

order to concentrate on influential characteristics:

(a) What is the maximum price the consumer will pay?

(b) What is the minimum quality the consumer will tolerate?

(c) How great a deviation in colour, size, texture, uniformity, or flavour can a

product has and still have good acceptance?

(d) How important are the sensory properties of a production relation to other

characteristics?

(e) Where will consumers purchase specific items in what quantities, and how

often?

(f) How often do consumers switch brands and why?

(g) Which items are planned purchases and which are selected on impulse?

(h) How do changing socio-economic pattern influence food selection?

Effects of Advertising Campaigns and Educational Programs:

Survey research groups are actively involved in evaluating the effectiveness of

promotional campaigns and programs by government and industry to educate

consumers in wise use of their money. Population may be interviewed and oral

and/or written responses obtained, other behaviour of consumers in the market is

observed directly. Whenever possible, both the magnitude and duration of the

influencing medium are measured. Producers may investigate market

conditions to eliminate less popular food items.

Methodological and Statistical studies:

Consumer may be surveyed to test the adequacy of sampling methods, type of

interview, and length and wording of the questionnaire, or to compare the opinions

of laboratory panels with those of the public pilot testing, i.e. pretesting of the

methodology prior to the distribution of samples, can orient the participants to the

method and check on the clarity of the questions. A large number of reactions may

be collected to test the sensitivity of various statistical methods of analyses.

Assure of this nature is sometimes included as part of another study of food habits

or preferences

INFORMATION OBTAINED FROM CONSUMER STUDIES:

Past behavior of consumers:

Information may be obtained on food selection and preparation, meal planning,

quantities consumed, use of leftovers, or amount of waste. A consumer may not be

able to recall accurately the quality and quantities of food selected and consumed.

The questionnaire must be carefully worded to avoid influencing the type of

response; since many consumers will give what they consider to be “correct or

desirable" answer rather than describe the true situation. All survey methods are

limited by the inability of the subject to remember, to generalize and to identify

motives, by biases and by desire to please the interrogator.

Present behavior of consumers:

The consumer's behavior in the grocery store may be observed, oral or written

opinions may be recorded, specific preferences obtained between two experimental

food products. In each case the past experience of the consumer influences the

response, and there is no assurance that retesting in the future will give the same

response.

Estimate the Future Behavior:

It would be presumptuous to state that consumer preferences of the future can be

adequately predicted. Estimates of future consumption patterns are based on past

behavior under known conditions and extrapolations made to fix expected market

conditions of the future. However, a more accurate estimate would be of great

value to the food industry.

FACTORS INFLUENCING RESULTS FROM CONSUMER SURVEYS

Population sampled: The reasons for conducting a survey of course, determine

the methodology selected, the population sampled, and the type of questions asked

in evaluating results obtained by consumer sampling, it is well to consider what

population the investigators used for their consumer panel.

Amount of pilot testing: Pretesting of the questionnaire, the commodity or the

population can yield important information that can save time and money.

Ambiguous and misleading question can be eliminated from the questionnaire,

antagonistic or apathetic can be determined from the sample or the experimental

sample may be modified in packaging size or method of presentation to

accommodate unanticipated condition of testing.

In pilot testing the emphasis is on the inherent properties of the products aroma,

flavor, texture, shape, colour and consistency. There is no effect of marketing

factors such as brand, label, price, packaging, distribution or advertising, one

important use of pilot testing in the food industry is to provide an estimate of the

relative importance of the flavor of the product in comparison with other properties

such as convenience storage stability, or brand identity.

To test first impressions, the consumer may be given only enough of the samples

for a single use the single exposure method. This method is a valuable tool when

the amount of sample to be tested is limited, when time and money are limited,

when few consumer are available, or when only an estimate of consumer

preference, is desired. Single exposure tests can be given in supermarkets, mess

halls, fairs, conventions, or other public gatherings.

Method of sampling, amount of replication, size of statistical error:

Techniques employed in consumer preference studies are often deficient because of

failure to define the universe samples or the use of inadequate sampling methods

which gives immeasurable degrees of error. If the population is small, it is

sometimes convenient to sample the entire population to obtain the desired

information. Usually time and money can be saved by studying only a sample

portion of the population.

Method of collecting and analyzing data : Carefully worded questionnaires are

frequently used to obtain consumer reactions on a multitude of topics related to

selection and use of commodities. The questionnaire may be range from one short

question to several hundred inquiries about past, present and future behaviour. The

effectiveness of this method depends on the questionnaire and degree of

cooperative spirit elicited from the consumer, as well as the type of approach

employed.

Retesting and/or follow-up studies :

Retesting is advisable:

(a) if a survey shows inconclusive results

(b) if the investigator suspects that the consumer misinterpreted the questionnaire

(c) if there is any question whether the samples May have been served or tested

incorrectly; or

(d) if there is a possibility that the sampling procedures may not have been

adequate. A follow-up testing at a specific interval after the first server can be used

effectively for establishing the persistence of the preference over a given period and

can measure the degree to which the preference has been affected by changes in

the market or in the general economy.

Interpretation of results:

As with any investigation, results are not necessarily valid except under the

conditions of the study, the investigators should be conservative in projecting

findings to other populations or to other commodities unless the prediction is

adequately supported by the data obtained. There are always a number of

consumers who, when approached, refuse to cooperate, Between 60 and 95% of

those who agree to cooperate actually return their questionnaires. We know nothing

about the preferences of the non-cooperating consumers, but as the number of the

noncooperators increases, conclusions reached on the basis those who did

cooperate become less reliable, and it is more difficult to estimate the way in which

the opinions of the non co-operators might change the direction of the response.

Correct interpretation and projection of results requires that consumer opinion be

viewed in its proper perspective, Undue importance should not be placed on

selection of a specific food Item on a single occasion, since the decision is but one

of hundreds that the consumer makes each day.

Psychological consideration:

Some of the psychological factors which; influence laboratory panels can affect the

consuming public also Some of these apparent variations can be minimized or

accounted for by dose control and/or observation of all details of the testing

procedure and the testing environment and by interviewing a sufficiently large

number of consumers to reduce the standard error the mean.

METHODS OF APPROACH

Historical Methods: Statistics of food distribution, sales, and product turnover

rate should be consulted to understand present market activities and to estimate

future market events in the food industry, where the mark up on certain

commodities is very low, it is essential that trends be observed accurately to assure

achieving the volume of sales necessary for profit.

Observational Method: A person trained to observe group behaviour can gather

quantitative and qualitative data on food habits and selection. Hidden observers

have watched consumer in supermarkets to determine whether purchases are

planned or

impulsive, to establish what displays and packaging appeals to them, to determine

whether certain food items are selected more often by men than by women.

Merchandisers may be interested in knowing the effect of background music,

product location or other physical or physiological factors.

Advertisers and producers are interested in how the consumer appraises the

product does she smell it, squeeze it, weigh it, read the label, study the

instructions, or compare it with others on shelf? The value of observational method

can be enhanced if the same customers are observed during a second or third

shopping session and if they are interviewed in the home about preparation

methods, serving and food waste. Results obtained from observational studies may

be difficult to interpret because of the complexity of the environmental factors

influencing the behaviour.

A combination questionnaire and observational technique was used to establish

consumer preference for six brands of bottled beer. On each of seven days, families

were provided with more beer than they needed so they could have an unrestricted

choice of brands (identified only by code).Each day, the remaining bottles and

empties were collected as well as questionnaires, with preferences recorded.

Questionnaires:

Carefully worded questionnaires are frequently used to obtain consumer reactions

on a multitude of topics related to selection and use of commodities. questionnaire

may be range from one short question to several hundred inquiries about past,

present and future behaviour. The effectiveness of this method depends on the

questionnaire and degree of cooperative spirit elicited from the consumer, as well

as the type of approach employed.

METHODS OF APPROACH:

The Market Research Corporation of America developed some methods to approach

consumers are

(a) Depth interviews

(b) Word association

(c) Sentence completion

(d) Projective questioning

(e) Role playing

(f) Recorded group discussion and

(g) Pre-test questionnaire.

With the questionnaire method the four most common approaches are: telephone,

mail, personal interview, and public test. The telephone approach is economical

provided no long-distance calls are made. It has the disadvantage of not reaching

those in the population who are not telephone subscribers. Also, decisions made on

the telephone may lack depth and sufficient though, and questions can be

misinterpreted by people with hearing defects or by those who are not fluent in the

vernacular language.

Approach by mail has the advantage of economy and allows the respondent to

answer at his leisure. However, the replies constitute only a percentage of the total

number sent out, since not all people return their questionnaires. In addition, some

recipients of the questionnaires may not be able to read and many may

misunderstand the questions.

Personal interview has the advantage of collection observational data concomitantly

but is more expensive and introduces the potential bias of non authoritative, does

not argue or give advice and is difficult to measure. Often, mailing techniques and

personal interview are used together. At times the personal interview is the only

reliable way of obtaining information on food preferences that need to be classified

by race, age, education, political affiliation, or income level.

In experiential studies, sample of the food product are tasted by the consumers,

and opinions are obtained. The consumers may be approached in a public meeting

place, such as a market or a country fair, at private function such as a meeting or

dinner or in the home.

Development of the Questionnaire

One of the most difficult aspects in measuring consumer response is wording of the

questionnaire to obtain the exact information desired.

Questionnaires :

A question should not be ambiguous. The inquiry “What kind of oil do you use?"

does not indicate whether the oil is auto fuel, mineral, salad, or hair oil. Even if the

type was specified, the respondent might give the brand name, the weight, the

color, or the price range. In each case, he/she would be answering the question

but his/her answer might be useless to the researcher, depending upon the specific

information desired.

Questions should be realistic:

The respondent cannot be expected to recall specific details of meals consumed

several weeks previously or to predict specific behavior accurately into the distant

future. The average consumer cannot be expected to evaluate the sensory

properties of a food as thoroughly, as rapidly, or as consistently as a highly trained

judge can.

Use of Appropriate Terminology:

The wording should not appear to be above or below the intelligence of the

population being sampled. A pretesting of the level of understanding of the specific

population would be useful, although expensive and time-consuming.

Avoid stereotype answers:

Questions must be worded to elicit the participant's true opinion rather than the

answer the participant thinks is the most "proper." To a question on belief in

freedom of speech, 97% of a certain population indicated they believed in it.

However, when asked specifically who was to be allowed the freedom, most of

these same people thought it should be limited to certain individuals, which, of

course, would not be freedom of speech at all.

Placement:

Placement of questions on the ballot is important since, in long questionnaires,

often only the first few are answered. Placement of selections on the menu can

influence the frequency with which they are ordered. Arrange questions in logical

order, since one question can influence the response to the following question.

Allowance for no opinion:

In planning the original experimental design, the investigator must decide whether

he will allow a respondent to express a "no preference" or "don't know" opinion.

Some participants may have a "don't care" attitude. A large percentage of "no

preference" votes by the respondents may mean either that differences between

the products were undetected or that there was no preferences between detectable

differences. The questionnaire can be worded so as to distinguish between these

two types of "no preference" response.

COMPARISON OF LABORATORY PANELS WITH CONSUMER PANELS:

Although members of a laboratory panel are consumers, their opinions and

preferences may not be representative of the general population. The laboratory

group is carefully selected, highly trained, and hypercritical as compared to the

consumer. Distribution of age, sex, income, and general intelligence will reflect the

consuming population only by accident. Test booth conditions, coded containers and

scoring methods are certainly not typical of normal conditions food consumption.

In addition, the opinions of the laboratory panel are not influenced by extraneous

factors such as packaging, advertising. Easy of preparation, price, or prestige, as

the opinions of the consumer may be. In general, consumers agree with laboratory

panel findings maintains but not in magnitude.

LIMITATIONS OF THE CONSUMER SURVEY:

Consumer surveys are expensive, time consuming, and subject to numerous

uncontrollable variables. Although most surveys yield valuable information,

investigators experience many problems and should recognize the limitations of

their methods. Careful consideration must be given to the manner in which

participation is solicited since they may be which rapport is established with the

consumer not only influences the cooperative attitude of the respondent but may

influence the answers given.

Prospective participants may react differently depending upon whether the survey

is being conducted by a nearby university, a commercial processing firm, or an

advertising agency.

In addition, answers are biased by methods of sampling, techniques of sample

presentation, amount and type of instruction provided, and the construction of the

questionnaire, as previously indicated. Consumer opinion, as individuals or as a

group, can easily be under estimated or overestimated.

Most surveys do not reveal why people buy that is the conscious and unconscious

factors that control behavior. In most surveys it is impossible to duplicate market

conditions, so responses are not obtained under normal buying conditions. What

consumers say they do may not represent actual behavior? It is extremely difficult

to estimate potential patterns of behavior on the, basis of past purchases, just as it

is to predict whether the item will have short-time or long-time acceptance.

Surveys seldom identify the leaders and the followers i.e., the consumers with

definite preferences who set the styles, tastes, and trends, versus those who are

easily swayed and merely "follow the crowd."

CHAPTER:

13

QUALITY OF RAW MATERIALS

CHAPTER:

14

FACTORS INFLUENCING THE FOOD QUALITIES

CHAPTER:

15

RECORDING AND REPORTING OF QUALITY

CHAPTER:

16

SENSORY EVALUATION AND ITS IMPORTANCE

SENSORY EVALUATION

Sensory evaluation is often described using the definition of Institute of Food

Technology - A scientific method used to evoke, measure, analyze and interpret

those responses to products as perceived through the sense of sight , smell, touch,

taste and hearing.

IMPORTANCE OF SENSORY EVALUATION IN RELATION TO CONSUMER

ACCEPTABILITY AND ECONOMIC ASPECTS:

It is the responsibility of the sensory scientist to select and implement proper

testing methodologies. A thorough understanding of experiment‟s objectives is

essential. The most commonly occurring industrial applications are as follows:

NEW PRODUCT DEVELOPMENT

Some new products are unique (i.e. there is no prototype) but most new products

are imitations or variations of some established standard. In either case, product

developers need information on the sensory quality and relative acceptability of

experimental prototype samples as input for marketability.

PRODUCT MATCHING

Duplicating a standard (a prototype, a competitor‟s product etc.) requires a sensory

testing sequence similar to that for new product development. The objective of

product matching is to verify that there is no difference between the standard and

the experimental product, and that the two have equivalent acceptability.

PRODUCT IMPROVEMENT

Real improvement of a product can be measured in a number of ways. The

following is a logical testing sequence;

Difference test to determine whether the experimental product is different

from the control (if it is not different it cannot be better).

Affective test, if products differ, to establish whether the experimental

product is liked more than the control (i.e. represents an improvement).

PROCESS CHANGE

A process change should maintain or improve the product. The testing sequence is

similar to that for product improvement.

Difference tests to determine whether the experimental product is different

from the control (if it is not different, it cannot be poorer).

Affective test, if products differ, to establish whether the experimental

product is liked as well as or more than the control.

COST REDUCTION AND/OR SELECTION OF NEW SOURCE OF SUPPLY

A successful cost reduction program based upon lower priced ingredients, a lower

cost process, or production in a different location must yield an end product

comparable to the product formally produced. Change to a new supplier of raw

materials should also results in an end product comparable to the standard or

control. The sequence of sensory evaluation in these situations usually is as follows:

Difference test to establish whether the experimental product is different

from the control (if it is not different, it must be as good as the control).

Affective test, if products differ, to establish whether the experimental

product is liked as well as or more than the control.

QUALITY CONTROL:

Quality control procedures are used during production, distribution, and marketing

to ensure that the end product is as good as the standard. Representative

samples are usually evaluated as follows:

Difference test to determine whether the experimental sample is different

from the standard (if it is not different it must be as good as the standard).

Descriptive test, if the sample is found to be different, to indicate how the

sample differs from the standard. Results of these tests may be used to

guide remedial action, such as changes in processing procedure.

STORAGE STABILITY:

Product stability during transportation, warehousing, retailing and during storage in

the home is essential to consumer satisfaction. To establish information on product

shelf life, representative samples are obtained, evaluated initially, and subjected to

controlled storage conditions for subsequent tests. At specific intervals, storage

samples are withdrawn and evaluated, generally in comparison with a control. The

control must be of the same lot or batch as the test samples and must be held

under conditions known to maintain the original quality. Sensory tests to determine

product storage stability may include the following:

Difference tests to determine whether the storage samples are different from

the control (if no significant difference is found, product stability is assumed).

Descriptive tests, to characterize and/or quantify the changes that may have

occurred during storage.

Acceptance tests, to determine the relative acceptance of stored products.

PRODUCT RATING OR GRADING

Product grading or rating requires an accurate classification of samples

according to grade standards defined for the product, as well as an evaluation of

samples in relation to each other.

Category scoring or ratio scaling based on the presence and intensity of

selected characteristics may be used to measure samples against standard

specification set for the product.

CONSUMER ACCEPTANCE /OPINIONS

After laboratory screening, it may be desirable to submit to central location

or home placement test to obtain consumer reaction. Acceptance tests will indicate

whether the current product can be marketed or improvement is needed.

CONSUMER PREFERENCE

Preference tests among consumers of the product can be used to determine

which sample is preferred. Preference screening tests may not represent random

sampling of the target population, directional information may be gained for

designing subsequent consumer tests.

TERMINOLOGY:

Appearance

All the visual characteristics of a substance or sample is known as

appearance

Analyst/assessor

Any person taking part in sensory test

Bilgy

The aromatic associated with anaerobic bacterial growth. The term bilgy can

be used to describe fish of any quality which has been contaminated by bilge water.

Bitter

One of the four basic tastes; primarily perceived of the back of the tongue

common to caffeine and quinine.

Briny

The aroma associated with the smell of clean seaweed, a beach and/or ocean

air.

Brothy

Aromatic associated with boiled meat usually accompanied by an umami

sensation in the mouth.

Burnt

Aromatic associated with heated, scorched or blackened substances.

Cardboardy

Aromatic associated with slightly oxidized fats or frozen fish that has taken

on a “cold storage” off flavour.

Chalky

In reference to texture, a product which is composed of small particles which

imparts a drying sensation in the mouth. In reference to appearance, a product

which has a dry, opaque, chalk like appearance.

Cheesy

Sour aromatic associated with aged cheese and butyric acid. Sometimes

found in advanced decomposition of fish.

Chickeny

Aromatic associated with cooked chicken meat.

Firm

A substance that exhibits moderate resistance when force is applied in the

mouth or by touch.

Fishy

Aroma associated with aged fish, as demonstrated by tri methylamine or cod

liver oil.

Flavour

Sensory perceptions when food is placed in the mouth resulting from the

stimulation of basic tastes, aromatics, and feeling factors.

Gamey

The aroma associated with the heavy, gamey characteristics of some species

of fish such as mackerel.

Glossy

A shiny appearance resulting from the tendency of a surface to reflect light.

Grainy

A product in which the assessor is able to perceive moderately hard, distinct

particles.

Intensity

The perceived magnitude of a sensation.

Iridescent

An array of rainbow like colours, similar to oil seen on water.

Mealy

Describes the product that imparts a starch like sensation in the mouth.

Metallic

Aroma or taste associated with ferrous sulfate, rust, or tin cans.

Mouth coating

The perception of a film in the mouth.

Mouth filling

The perception of the fullness dispersing throughout the mouth.

Mushy

Soft, thick, pulpy consistency.

Musty

The aromatic associated with the moldy, cellar or attic.

Nose feel/burn

Chemical feeling factor describes as warmth or burning or irritating sensation

in the nasal passages when a product is sniffed.

Odour/aroma

Sensation due to stimulation of the olfactory receptors in the nasal cavity by

the volatile material.

Opaque

Describes product which does not allow the passage of light.

Oxidized

Aromatic associated with old oil that is stale or cardboardy. Leaves a

lingering off flavor in the mouth or nasal cavity that is moderately lingering and

coating.

Putrid

An irritating with decayed, rotting meat. Aroma is lingering and often gives a

heavy, cloying nose and throat feel.

Pungent

An irritating, sharp or piercing sensation felt in the nose, mouth or throat.

Quality

A degree of excellence. The collection of characteristics of a product that

confers its ability to satisfy stated or implied needs.

Rancid:

Odor or flavor associated with rancid oil. Gives a mouth coating sensation

and/or a tingling perceived on the back of the tongue. Sometimes described as

„sharp‟ or / painty‟.

Rotting:

Aroma associated with decayed vegetables, in particular the sulphur

containing vegetables.

Slimy:

A fluid substance which is viscous, slick, elastic, gummy, or jelly like.

Sour:

An odor and/or taste sensation, generally due to the presence of organic

acids.

Stale:

Odor associated with wet cardboard or frozen storage.

Translucent:

Describes an object which allows some light to pass, but through which clear

images cannot be distinguished.

Transparent:

Describes a clear object which allows light to pass and through which distinct

images appear.

Umami:

Taste produced by substances such as monosodium glutamate (MSG) in

solution, a meaty, salty, or mouth filling sensation.