Aroma and Odor -Food Chemistry II

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Flavor and AromaticFlavor and Aromaticcompounds in Foodscompounds in Foods

Polytechnic University of the PhilippinesPolytechnic University of the Philippines

Sta. Mesa ManilaSta. Mesa ManilaCollege of Nutrition and Food ScienceCollege of Nutrition and Food Science

Department of food technologyDepartment of food technology



Structure And Properties of

Compounds in Aroma

Reported by: Roschell Agregado



Flavor

is the sensory impression of a food or

other substance, and is determined mainly by

the chemical senses of taste and smell.

results from compounds:

1. Responsible for Aroma

2. Responsible for Taste



Aroma Compounds

Volatile.

Recognized by receptor cells called Olfactory

Cells. Can be classif ied in families based on their

chemical structure and physicochemical

sensory properties.



Non Enzymatic Reactions

observed only after prolonged storage of food.

Lipid Peroxidation, Maillard Reaction, and

Strecker degradation of Amino Acids.

Furanones

Caramel-like odor

Meat broth, soya sauce, strawberry, coffee

etc.



4-Hydroxy-5-methyl

Norfuraneol

4-Methoxy-2,5-dimethyl

Mesifuran

The hydroxy group in furanone II is

methylated to form IV, the caramel-like

aroma disappears.



Phenols

Smoke generated by burning of wood is used

for cold or hot smoking of meat and f ish

products.

Ferulic acid was identif ied as an important

precursor in model experiments.



Thermal degradation of ferulic acid,

4-Vinyl-guaiacol (I), vanillin (II), and

guaiacol (III).



Enzymatic Reactions

Esters

chemical compounds derived by reactingan oxoacid with a hydroxyl compound such asan alcohol or phenol.

are ubiquitous.

Nitrate esters, such as nitroglycerin, are

known for their explosive properties,while polyesters are important plastics.

Used as flavoring agents for its fruity aroma.



Lactones

a cyclic ester

it is characterized by a closed ring

consisting of two or more carbon atoms

and a single oxygen atom, with a ketone

group =O in one of the carbons adjacentto the other oxygen.

4-Decanolide

(-decalactone)



Terpene

are a large and varied class of organic

compounds, produced primarily by a wide

variety of plants, particularly conifers.

are also known as isoprenoids (isoprenes).

primary constituents of the essential oils of

many types of plants and flowers.

Vitamin A is an example of a terpene.





Other Aroma Compounds

Sulfur Compounds

Possess powerful and distinctive odours which

contribute to both, pleasant and unpleasant.

±Brassica

- cabbage, cauliflower, brussel sprouts,

broccoli

- milder than allium family.



±Alliums

- onion, garlic

- the flavor compound is formed from a

precursor by the action of an enzyme.

- the characteristic odour of garlic is due to

allicin by the action of enzyme allinase





Carbonyl compounds, Alcohol

Obtained by degradation of carotene

Fatty acids and amino acids are precursors of

aldehydes. Carbohydrate degradation is the source of

ethanal only.

Aldehydes formed by Strecker degradation canalso be obtained as metabolic by products of

the enzymes.





1. Introduction

i. Definition of flavors

"Flavor is the sensation produced by a material taken in the mouth,

perceived principally by the senses of taste and smell, and also by the general pain,

tactile and temperature receptors in the mouth. Flavor also denotes the sum of the

characteristics of the material which produce that sensation." Flavor has been

defined by Hall (1968).

2. Classification of food flavors

Flavors can be classified by the general sensations that one feels when eatingdifferent foods. Flavor comes from three different sensations: taste, trigeminal and

aroma (odor). It is generally agreed that taste sensations are divided into four major

categories: saltiness, sweetness, sourness and bitterness. However, some Japanese

scientists also include a fifth category called umami (savory) that can be

represented by the flavor of glutamate.

Chemical compounds responsible for flavor andChemical compounds responsible for flavor and

Théories on taste perception



Sweet Taste

Sweet taste is produced by several different classes of compounds (Fig. 5),

such as sugars, aldehydes, ketones, esters, amino acid, and synthetic sweeteners.

Sour Taste

Sour taste results from the presence of hydrogen ions on the tongue;

however, sourness and acidity (pH) are not directly related, but there is some

correlation. Sour taste produced by several different classes of compounds, such asesters, terpenoids, and organic acid (Citric, malic, tartaric)

Salty Taste

Salt taste is stimulated by most soluble salts having low molecular weights.

Salty taste produced by several different classes of compounds, Maillard reaction.

Bitter Taste

Three major classes of organic compounds encountered in food materials are

associated with bitterness: alkaloids, glycosides, and peptides.



Chemical compounds responsible for f lavor andChemical compounds responsible for f lavor and

Théories on taste perception

1. Aldehydes (sweet taste)

Is an organic compound containing a formyl group.

This functional group, with the structure R-CHO, consists of a carbonyl

centre bonded to hydrogen and an R group. The group without R is

called the aldehydes group or formyl group.

Acetaldehyde (systematically ethanal) is an organic chemical compound with

the formula C2H4O or MeCHO. It occurs naturally in coffee, bread, and

ripe fruit, and is produced by plants as part of their normal metabolism.

Vanillin is a phenolic aldehyde, an organic compound with the molecular

formula C8H8O3. It is the primary component of the extract of

the vanilla bean. It is also found in roasted coffee.



2. Sugars (Sweet flavor)

Sugar is a term for a class of edible crystalline carbohydrates,mainly sucrose, lactose, and fructose, characterized by a sweet flavor. In food,

sugar almost exclusively refers to sucrose, which in its fully ref ined (or free

sugar) form primarily comes from sugar cane and sugar beet, though is present

in natural form in many carbohydrates.

Sucrose C12H22O11 Combustible, white crystals soluble in water, decomposes at 160 to 186C;

derived from sugarcane or sugar beet; used as a sweetener in drinks and foods and to make

syrups, preserves, and jams. Also known a saccharose; table sugar.

Guanidines

Derivatives of guanidino acetic acid are among the sweetest compounds

known until now.

Guanidine Strongly alkaline member of the organic nitrogen compounds,

commonly used in the hydrochloride form for the denaturation of

proteins.



Sourness is always assumed to be a property of solutions of low pH, but it

appears that the hydrogen ion H+* is much less important for taste than the

undissociated forms of the organic acids that occur in acidic foodstuffs.

Organic acid - is an organic compound with acidic properties.

Citric acid is a weak organic acid. It is a natural preservative/conservative and

is also used to add an acidic, or sour, taste to foods and soft drinks.Commercially important, versatile organic acid, widely used, along with its

salts (citrates), in the food and beverage industries. Highly soluble in water

and used in acidulants, antioxidants, flavourings, antimicrobial compounds and

chelating agents. Usually obtained commercially by extraction from citrus

fruits (it is the predominant acid in lemons, oranges and limes).

Phosphoric Acid

With its salts account for 25% of all the acids used in food industries.

Main f ield of use is in the soft drink industry

Used in fruit jellies, processed cheese and baking powder

Active buffering agent in fermentation process.



Bitterness is exhibited by alkaloids such as quinine, picric acid,and heavy metal salts.

Quinine is permitted as an additive in beverages, such as soft

drinks, that also have tart-sweet attributes.

Caffeine C8H10O2N4H2O An alkaloid found in a large number

of plants, such as tea, coffee, cola, and mate.

occurs in coffee, tea, and cola nuts



Flavor antagonism - when one or more compounds are mixed

together and interfere with flavor detection, i.e., the response

(actual) is less than the arithmetic sum (theory).

Flavor synergism - when one or more compounds are mixed

together and enhance the ability to detect the flavor, i.e., the

response (actual) is greater than the arithmetic sum (theory).

Theories of taste perception



Shallenberger and Acree f irst proposed the AH/B theory for the saporous

(taste eliciting) unit of all compounds that cause sweetness.

The saporous unit is a combination of a covalently bound H-bondingproton and electronegative orbital positioned at a distance from the

proton

One of the atoms must also posses a hydrogen bonding atom. Oxygen,

Nitrogen and Chlorine atoms frequently fulf ill these roles.



FLAVORFL

AVOR

ENHANCERSENHANCERS



FLAVOR ENHANCERSFLAVOR ENHANCERS

Flavor enhancersare used in savoryfoods to enhance

the existing flavor in the food.



COMMON FOODCOMMON FOODFLAVOR ENHANCERSFLAVOR ENHANCERS

Monosodium glutamate,MSGMonosodium glutamate,MSGMonosodium glutamateMonosodium glutamate is one of the chief

flavor enhancers that are used as a flavor

in protein rich food.Monosodium glutamateMonosodium glutamate is a natural flavor

that is used as a food additive under thecategory of food flavor enhancers.



M

onopotassiumM

onopotassium gl

utamategl

utamateMonopotassiumMonopotassium glutamateglutamate is a potassium

and acid salt of glutamic acid. It is one of

the non-sodium food flavor enhancers.

CalciumCalcium diglutamatediglutamate

This flavor enhancer is also called calcium glutamate or CDG.



Monosodium Glutamate (MSG)

C5H8NNaO4 H2O

Monosodium glutamate is the sodium salt of

glutamic acid.

Glutamate is a naturally occurring amino acid

that is found in nearly all foods, especially high

protein foods such as dairy products, meat

and f ish and in many vegetables.

It acts as a flavor enhancer and adds a f ifth

taste, called UMAMI.



5-NU

CLEO

TID

ES5 -Inosine monophosphate (IMP) and

5 -guanosine monophosphate (GMP)

Their mixture are white crystals or crystalline

powder.

Their flavor enhancing ability at 75500 ppm is

good in all food.

some other specif ic effects, besides the MSG

effect, have been described for nucleotides.



MALTOL White crystalline powder having a

characteristic caramel butterscotch odor.

Maltol's sweetness adds to the odor of freshlybaked bread.

Sparingly soluble in water, soluble in ethanol

and in propylene glycol.

Maltose is produced from plant starch during

the process of saccharification.



Control of Flavor and Aroma in

Processed food



Control of flavor and Aroma in processed foodis the utmost importance in determining the

quality and selling price of the f inished

product.



Factors must be considered:

The quality of the ingredients

Conditions of processing must be carefullycontrolled

Avoidance of contamination by flavorfulcompounds during processing or storage must bewatched

Foods must also be protected from contamination by bacteria and molds and storedunder conditions where these microorganismscannot grow rapidly



Good f lavor in a food product is desired byeveryone who works in food production

whether a housewife or the director of a

nation-wide industry.



Caul has analyzed pattern of good flavor as

the ff. sensations:

1. An early impact of appropriate flavor

2. Rapid development of an impression of

highly blended and usually full-bodied

3. Pleasant mouth sensations

4. Absence of isolated unpleasant notes

5. Anticipation of next mouthful



Measurement of Flavor

>Since the flavor of food products is so

important in determining their commercial

value, many methods for measuring flavorhave developed.



Expert taster

through interest and opportunity hehas developed a discriminating palatefor the food of his company.

Panel of tastersthe panel may indicate its

preference or judgment of quality by

scoring a food on some well def inedqualities.



Panel of tasters use:

Numerical scaleis used so that the scoring of the individuals can

be added readily to give a composite score.

Difference tests

are sometimes used in an attempt to get a moreprecise and reproducible test in flavor foods.

Dilution test is a type of difference testing. A sampleis presented to the judges and then other samples that

may or may not contain the unknown at a def inite levelof dilution are offered.



Ranking

a series of samples are supplied to each

member of the panel and he arranges them inorder to increasing or decreasing quality of the

characteristics.

Flavor prof ileis a method for evaluating a flavor by

describing it either as a whole or by

characteristics.the reactions are broken down into

(1)character notes,(2)order of

appearance,(3)aftertaste, and (4)amplitude.



o Character notes are the protruding sensations,

often exceedingly diff icult to distinguish in a

blend.o The Order of appearance may appear at f irst

sight to be little importance or even absent.

o Aftertaste is particularly common with foods thatleave a residue in the mouth after swallowing.

o Amplitude is the term used to express the total

effect of flavor

>it is rated by very low ,low, medium or high



Consumer acceptance or preference

If a new food is introduced, only onesample is offered to a large panel consumer

panel, but if a food is modif ied, then two

samples are submitted and a preference

requested.



Flavor Intensif ier: Monosodium Glutamate

It is claimed by some authors that thiscompound has little or no flavor itself butintensif ies the flavor of meats and vegetables

through a rounding or blending effect. It is widely used in stews, canned meats,

soups, chowders, etc.

They also reported that the effect isnoticeable in the pH range 3.5 to 7.2, therange in which most foods are eaten.



FLAVORING

EXTRACTS



Flavoring extracts

The Food and Drug Administration def ines an

extract as a solution in ethyl alcohol of proper

strength of sapid and odorous principles derived

from an aromatic plant, or parts of the plant, withor without its coloring matter, conforming in

name to the plant used in its preparation.

Flavoring extracts are made by adding the

essential oil to alcohol or to water and alcohol, or

by percolating the chopped plant or plant part

with a mixture of water and alcohol.



Vanilla extract is prepared by percolating

macerated vanilla beans with alcohol,frequently in the presence of glycerol or

sucrose.

The flavorful compounds extracted are

numerous but the most abundant is vanillin.





Synthetic Flavoring Substances



A synthetic banana flavouring. The concentrations in

the final product of even the most abundant of these

components will still be of the order of parts per million.

Major c omponents Mi nor c omponents Trace c omponents

Amyl acetateAmyl butyrate

Ethyl butyrate

Isoamyl acetate

Isoamyl butyrate

Linalool

Amyl valerateBenzyl propionate

Cyclohexyl

propionate

Ethyl caproate

Geranyl propionateHeliotropin

Vanillin

AcetaldehydeButyl acetate

2-Hexenal

Isoamyl alcohol

Lemon oil

a-IononeMethyl heptanone

Orange oil



Non sugar sweeteners



Aspartame

A non-saccahride sweetener used as a sugar substitute insome foods and beverages

White, odorless, crystalline powder

approximately 200 times sweeter than sucrose, or tablesugar.

It is a methyl ester of a dipeptide.

± Aspartic acid and phenylalanine

Slightly soluble in water and sparingly soluble in alcohols.Not soluble in fats and oils





Alitame

Formed from the amino acids and an amide

High quality sweetness without an aftertaste

Exhibit synergy

Very soluble in water

Used in hard candies and heat pasteurized foods



Acesulfame-K

Calorie free artif icial sweetener

dihydrooxathiazinone dioxides

Approximately 200 times sweeter than sucrose but has slight bitter

aftertaste

The shelf-life of pure solid acesulfame K seems to be almost unlimited atroom temperature

Acesulfame K does not show a def initive melting point

Soluble in water but slightly soluble in alcohols

Exhibits synergism with other sweeteners

pH stable

Used in yogurts, soft drinks, candies and other confectionaries



Saccharin

a noncaloric substance produced from methyl anthranilate, a substance

naturally found in grapes

White, odorless, crystalline powder

300 times sweeter than sucrose but has a bitter or metallic aftertaste

Taste is maintained over a long shelf life High stability in aqueous solution over a wide pH range

Cyclamate the sodium or calcium salt of cyclamic acid

30 50 times sweeter than sugar

Stable under heating



Sucralose

Sucralose is derived from sucrose in a process that substitutes chlorine

atoms for hydroxyl group

It has a pleasant sweet taste similar to sucrose and has no unpleasant

aftertaste.

The sweetener is highly soluble in water, ethanol, and methanol and hasnegligible effect on the pH of solutions.

Soluble in water and ethanol





Monellin From the pulp of Dioscoreophyllum cumminsii

Sweet protein

Thaumatins From the fruit Thaumatococcus daniellii

Synergestic effect

Curculin and Miraculin From the fruit C urculigo latifolia and Synsepalum dulcificum

tasteless



REFERENCE

BELITZ, H. D. ET AL. 2009. FOOD CHEMISTRY, 4TH ED..pdf

Fisher C., Scott T.R. Food Flavors - Biology and Chemistry (RSC,

1997)(0854045384).pdf

Food - The Chemistry of its Components.pdf

deMAN, J. M. 1999. PRINCIPLES OF FOOD CHEMISTRY. 3RD

ED..pdf

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Aroma and Odor -Food Chemistry II