ELEMENTS OF FOOD PROCESSING

7/30/2019 ELEMENTS OF FOOD PROCESSING

1/75

pdfcrowd.comopen in browser PRO version Are you a developer? Try out the HTML to PDF API

ELEMENTS OF FOODPROCESSING

METHODS AND EQUIPMENT

[Return to Index]

There are over 18,000 different food items in today's supermarkets, which are processed to a greater or lesser

degree, and thousands of new products are introduced each year.

Modern food processing has three major aims:

1. To make food safe (microbiologically, chemically).

2. To provide products of the highest quality (flavor, color,texture)

3. To make food into forms that are convenient (ease of use)

The following table summarizes the item to be controlled and comments on the major approaches involved in this

control.

To be

Controlled

Heat Cold Chemicals Aw* Mechanical

Micro-organisms

Preventsgrowth

Reducesgrowth rate

Preserva-tives re-

tard

growth

Do notgrow

below Aw

of 0.6

Reducesnumbers

.Enzymes Destroyed

by heat

activity

Decrease

reaction

rate

Modify

activity

Alters

rate of

enzyme

increase

ES

complex
http://pdfcrowd.com/http://pdfcrowd.com/redirect/?url=http%3a%2f%2fclass.fst.ohio-state.edu%2ffst401%2fInformation%2fElements-Food-Processing.html&id=ma-130109130114-7f00b5b7http://pdfcrowd.com/customize/http://pdfcrowd.com/html-to-pdf-api/?ref=pdf


2/75


activity formation

Chemical

Reactions

Increases

chemical

rate,

browning,

oxidation

Reduces

reaction

rate

May inhibit

or activate

Can alter

rate of

reaction,

especially

oxidation

Not

applicable

Physical

Structure

Increases

effects

Decreases

effects

May

modifiy

structure

High. Aw

may

cause

caking

Can

destroy

structures

*Aw = water activity

Safety:

Insuring the safety of food involves careful control of the process from the farm gate to the consumer. Safety includes

control of both chemical and microbiological characteristics of the product. Most processing places emphasis on

microbial control, and often has as its objective the elimination of organisms or prevention of their growth.

Processes that are aimed at prevention of growth include:

RefrigerationFreezing

Drying

Control of water activity (addition of salt, sugars, polyols, etc.)

Processes that are aimed at minimizing organisms include:


3/75


Pasteurization

Sterilization (canning)

Cleaning and sanitizing

Membrane processing

A further method of processing that is aimed at the control of undesirable microflora is the deliberated addition of

microorganisms and the use of fermentation.

Safety from a chemical viewpoint generally relates to keeping undesirable chemicals, such as pesticides,

insecticides and antibiotics out of the food supply.

Making sure that food products are free from extraneous mater (metal, glass, wood, etc.) is another facet of food

safety.

Quality:

Quality of a food product involves maintenance (or improvement) of the key attributes of the product - including color,

flavor and texture.

To maintain quality it is important to control:

microbiological spoilage

enzymatic degradation

chemical degradation

Convenience:

Today's consumers want food products that are convenient to use and still have all the qualities of a fresh product.

UNIT OPERATIONS:


4/75


Most food processing is comprised as a series of physical processes that can be broken down into a number of

basic operations. The "unit operations" can stand alone and depend upon coherent physical principles.

Unit operations include:

1. Fluid flow - moving a fluid product from one point to another with varying degrees of turbulence.

2. Heat transfer - in which heat is either removed or added and includes heating

cooling

refrigeration

freezing

3. Contact equilibrium processes or mass transfer, which may or may not require a change in state. Generally amolecular species is transferred to or from a product. Processes that use mass transfer include distillation, gas

absorption, crystallization, membrane processes, drying, evaporation.

4. Mechanical separation, such as filtration, centrifugation, sedimentation, sieving

5. Size adjustment either through size reductions (slicing, dicing, cutting, grinding) or size increase (aggregation,

agglomeration, gelation).

6. Mixing - to make homogenous blends or dry or liquid ingredients. This may include solubilizing solids, preparing

emulsions or foams - or - dry blending of ingredients such as for dry cake mixes.

7. Fermentation, while not a physical operation, is for the purpose of this course included as a unit operation.

UNIT PROCESSES:


5/75


Some food processing operations may utilize a single unit operation, but most food processing includes a

combination of unit operations to achieve the total process.

For example, the manufacture of a dried coffee whitener from a combination of fluid and dry ingredients includes the

following unit operations in sequence:

-Mixing

-Fluid flow

-Size reduction (homogenization)

-Heat transfer (heating)

-Fluid flow

-Heat transfer (cooling)

-Mass transfer (conversion of water to vapor during drying)

Pasteurization of milk to destroy the most heat resistance vegetative pathogen includes the unit

operations of fluid flow and heat transfer (both heating and cooling).

Some other examples of unit processes, and their associated unit operations include:

-freeze drying (heat transfer, mass transfer)

-extrusion (fluid flow, heat transfer, mass transfer, size reduction in the case of cereals and

-snack foods)


6/75


-ice cream manufacture is comprised of two unit processes:

mix making (mixing, fluid flow, heat transfer, size reduction)

freezing (fluid flow, heat transfer, mass transfer of air into the ice cream)

FOOD PROCESSING EQUIPMENT

Fluid Flow:

Transport of fluids is achieved either by gravity flow or through the use of pumps. In gravity flow the flow is "laminar",

where the flow is transfer from the fluid to the wall between adjacent layers. Adjacent molecules do not mix. In most

instances, however fluids are transported from one unit operation or process to another by pumps and in "turbulent"

flow where there is mixing of adjacent particles. Two different types of pumps are commonly used for different

purposes:

The centrifugal pump utilizes a rotating impeller to create a centrifugal force within the pump cavity, so that the fluid

is accelerated until it attains its tangential velocity close to the impeller tip. The flow is controlled by the choice of

impeller diameter and rotary speed of the pump drive. The capacity of a centrifugal pump is dependent upon the

speed, impeller length and the inlet and outlet diameters. Product viscosity is an important factor affecting centrifugal

pump performance. If the product is sufficiently viscous, the pump cavity will not fill with every revolution and the

efficiency of the pump will be greatly reduced. Centrifugal pumps are used to transport fluid and for cleaning

operations. Centrifugal pumps may be high speed or low speed, with high speed pumps being used for cleaning

(CIP). .

A positive pump generally consists of a reciprocating or rotating cavity between two lobes or gears and a rotor. Fluid

enters by gravity or a difference in pressure and the fluid forms the seals between the rotating parts. The rotating

move of the rotor produces the pressure to cause the fluid to flow. Because there is no frictional loss, positive pumps


7/75


are used where a constant rate of flow is required (timing pump), for high viscosity fluids or for transporting fragile

solids suspended in a fluid (such as moving cottage cheese curd from a vat to a filler).

Mixing:

An agitation device may be placed in a tank for a number of purposes. The mixing device may need to produce bulk

circulation in the tank, a controlled velocity at some surface of the tank or a controlled rate of shear. Two major

purposes of mixing are either heat transfer or ingredient incorporation. Different mixer configurations will be used toachieve different purposes. The efficiency of mixing will depend upon: -design of impeller -diameter of impeller -

speed -baffles

Heat Transfer:

Heat is either transferred into a product (heating) or removed from a product (cooling).

Heating is used to destroy microorganisms to provide for a healthful food, prolong shelf life through the destructionof certain enzymes and to promote a product with acceptable taste odor and appearance.

The factors that influence the heat transfer into or out of the product include:

1. Heat exchanger design

2. Heat transfer properties of the product

a. specific heat (amount of heat required to change the temperature of a unit mass of product a specific

temperature without change in state of the material)

b. thermal conductivity (rate by which heat is transferred through a material)

c. latent heat (heat required to change the state of a material)

3. Density (weight per unit volume)


8/75


4. Method of heat transfer

a. conduction (transfer from molecule to molecule through the material)

b. radiation (transfer from electromagnetic radiation of a body due to the vibration of its molecules

c. convection (transfer through movement of mass )

5. Viscosity (related to the amount of force required to move the fluid product)

A variety of heat exchanges are utilized in the food industry, which include:

-plate heat exchanges

-tubular heat exchanges

-swept surface heat excahngers.

Plate heat exchanges pass fluid over a plate where a heating or cooling medium is being passed up or down on the

other side of the place. The thin film makes for rapid heat transfer and is the most efficient method of heat fluids of

low viscosity.

Tubular heat exchanges general are compose of a tube within a tube, in which product and heating or cooling

medium are flowing in opposite (counter current) directions. This a low cost method of heating or cooling and is

applicable to fluids of higher viscosities that generally passed through a plate heat exchanger.

Swept surface heat exchanges have blades that scrape the surface of the heat exchanger and bring new product

continuously to the heat or cooling surface. There are utilized for fluids of very high viscosity. An ice cream freezer is

an example of a swept surface heat exchanger.

Common unit processes that include heat transfer as a unit operation include:

-Pasteurization (heat)


9/75


-Sterilization (heat)

-Drying (heat)

-Separations (based on density, size or shape)

-Evaporation (heat)

-Refrigeration (cold)

-Freezing (cold)

Pasteurization: Pasteurization is a process of heating a product at a specific temperature for a controlled periodof time to destroy the most heat resistant vegetative pathogenic organism. Originally developed for fluid dairy

products, the process is also applied to other fluids, including fruit juices and juice products. In addition to destruction

of microorganisms, pasteurization also achieves almost complete destruction of undesirable milk enzymes - such aslipase.

Pasteurization was originally conducted in jacket vats equipped with an agitator to give compete mixing and the

ability to heat and cool. For milk vat pasteurization required a heat treatment of 145F for 30 minutes, with the airspace above the product being heated to a higher temperature to insure all molecules of the product were

adequately pasteurized. The component parts of a vat pasteurizer are the tank body, heating/cooling channels; inlet

port, outlet valve with leak detector; agitator and drive motor; product indicating thermometer; recording devices; air

space heater and indicating thermometer; steam inlet and outlet, cooling water inlet and outlet.

Next plate heat exchanger were used with a higher temperature and shorter time (161.5/15 seconds)being used to

achieve the same bacterial destruction. This is called HTST pasteurization. To improve efficiency the cold milk is

used to partially cool the pasteurized milk and the hot milk partially heats the cold milk in a processed call

regeneration. In this section of the pasteurizer cold milk is on one side of the plate and the hot milk on the other. The

component parts of an HTST pasteurizer include the balance tank, cold side of regenerator, timing pump, heating

section, holding tube, flow diversion valve, hot side of regenerator, cooling section, controls.


10/75


Ultra high temperature (UHT) pasteurization is achieved with plate heat exchanges operating at temperatures of at

least 190 F for 2 seconds. The same principles are used as for HTST, except that higher temperatures are used and

the equipment is designed for very rapid heating and cooling.

Sterilization: The primary object of sterilization is to destroy the most heat resistant pathogenic spore formingorganism

Flame Sterilizer - conveyor, preheater, gas jets

Still Retort - retort body, product basket, steam inlet, water inlet, pressure gage, pressure relief valve

Hydraulic cooker = a continuous sterilizer, where the cans are rotating during the sterilization process

Still Retort = A type of batch sterilizer used for canning food, where the cans are not in motion during the sterilization

process.

Baking: Baking is the process by which moisture is removed from wheat based (or other cereal grain, products.Batch or continuous oven are utilized to heat the products resulting in an increase in volume of the product,

gelatinization or starch of protein "elation to set the final structure of the product. Baking is an essential process for

bread, cakes, cookies and crackers.

A rotary oven is a fairly simple device which has a cabinet, oven trays, heating element, thermostat and temperature

controls. Many commercial ovens are continuous in that the product moves though the oven on a continuous belt.

Concentration: Concentration can be achieved through evaporation and through reverse osmosis.

Evaporation generally involves heating the fluid in a vessel under vacuum to cause a change in state of water from

liquid to vapor and then recovers of water by passing the vapor through a condenser. The component parts of the


11/75


evaporator include an enclosed vessel with product inlet, manhole, heating rings, finished product outlet, condenser,

steam inlet, vacuum and condenser pump. In some product evaporation causes the loss of flavor volatiles and this

case, a low temperature unit is added to recover the flavor volatiles so that they can be added back to the product.

To reduce operating costs, multiple effect evaporators are utilized, which have 2 or more evaporators placed in

series to provide a means for the continuous concentration of a fluid product. This increases the efficiency of the

evaporation process.

Reverse osmosis (RO) is a process where the fluid is passed through a semi-permeable membrane with very small

pores that permit only the transfer of water. Most systems consist a the membrane cast on a solid porous backing -

usually in the form of a tube. High pressure is applied to force the water (called permeate) through the membrane the

concentrated fluid (called retentate) is retained in the tubing. The rate of water removal decreases as the fluid is

concentrate, until it is no longer economically feasible to remove more water.

Concentration is often used as a pre-step to drying to reduced the amount of water that needs to be removed in

drying and reducing drying costs. Evaporation can achieve higher solids economically than can reserve osmosis.RO is preferred over evaporation for heat sensitive fluids.

Drying: Three common methods of drying are: (a) sun or tray drying, (b) spray drying and (c) freeze drying.

Sun or tray drying is least expensive, followed by spray drying and freeze drying. The drying method of choice is

generally based on the characteristics of the product.

Products that are already solid lend themselves to sun or tray drying. These include fruits and vegetables. Theproducts may be dried by exposure to sun or place in trays and dried in a current of warm or hot air.

Products that are very heat sensitive are freeze dried. Commercially only instant coffee is widely freeze dried. Some

freeze dried fruits are beginning to reach the market, but these are in limited quantities. In freeze drying the moisture

is removed without a phase change (sublimation). A freeze drying is comprised of a dryer cabinet; drying chamber

with: heating/cooling shelves, trays and door; vacuum pump, condenser, controls and digital readout.


12/75


The most common drying method is spray drying, which is applicable to fluid products. The bulk density (weight per

unit volume) is controlled to a large extent by the solids that are sent to the dryer. A spray drying has an air inlet, air

heater, drying chamber, inlet atomizer, cyclone chamber, cyclone separator, dry product collection vessel, hot air

inlet and outlet, drying fan and motor, controls. There are several different designs of spray nozzles through which the

fluid is atomized into the heated air. These generally are either centrifugal nozzles or high pressure spray nozzles.

The type of nozzles will vary with the product being dried.

For some products that are very hydroscopic, the dried product may be partially re-wetted and the redried. Thisproduces agglomerated products that are easily dispsered in solution. Spray dried powders with a surfactant is also

a method for improving dispersion.

Another method, no longer in common use, is roller drying -- where the product is allow to flow over a hot, rotating

drum and the dried product is scraped off. This was a low cost method of drying, but created a lot of heat damage to

the product.

Freezing: Lowering the temperature below the freezing point of the product stops microorganisms from growingand reduces the activity of enzymes. Vegetables and some fruits are heat treated (blanched) before freezing to

eliminate enzymes.

One of the most common frozen foods is ice cream .An ice cream freezer can be operated either in batch or

continuous mode. A batch ice cram freeze consists of a freezer cylinder; dasher assembly with scraper blades,

counter rotating agitator; mix inlet, ice cream outlet gate; motor. A continuous ice cream freezer consists of an inlet

pump; air injector assembly; freezer cylinder; dasher assemble with scraper blades; outlet pressure gage; ice cream

back pressure regulating valve; refrigeration unit inside cabinet. The continuous freezer provides much better controlof drawing temperature and overrun than batch machines and is the machine of choice for commercial ice cream

operations. The product from these machines is place in low temperature freezers to freeze out additional water and

produce the packaged products found in super markets.

Soft serve machines are generally some modification of the batch freezer and the product is served directly from the

machine without further hardening.


13/75


For frozen fruits and vegetables, the products are generally frozen in the package and generally is blast freezers,

where the product is moved through the freezer in a continuous manner.

Separations: Separations can be achieved on the basis of density or size and shape.

Separations that are based on density differences include the separation of cream from milk, recovery of solids

from suspensions, and removal of bacterial from fluids.

Cream Separator: Milk can be separated into skim milk and cream based on the density difference

between fat and non-fat solids of milk. A cream separator is used to obtain the cream from milk and is a

disc type centrifuge in which the fluid is separated into low and high density fluid streams that permits the

separate collection of cream and skim milk. The machine consists of a regulating cover with float; cream

outlet cover; skim milk outlet cover; bowl assembly with inlet, cream outlet, skim outlet, spindle, disc

stack and cream disc with cream adjusting screw skim milk outlet, motor, adjusting screw.

Clarification: Sediment and microorganisms can be remove centrifugally in a clarifier, which is

generally a disc-type centrifuge that employs forces of 5 to 10 thousand times gravity and forcing the

denser material to the outside. By periodically opening the bowl, the solids can be continuously removed

from the remainder of the fluids. A centrifugal machine call a Bactofuge was used in Europe to reduce

the bacterial count by two log cycles in fluid foods. This same principle has been used to recover yeastcells from spent fermentation broths and to continuously concentrate bakers cheese from whey.

Membrane Processes: Reverse osmosis (RO), ultrafiltration (UF) and microfiltration (MF) areprocesses that use membranes with varying pore sizes to affect separation on the basis of size and


14/75


shape. Reverse osmosis has membranes with the smallest pore and is used to separate water from

other solutes. Ultrafiltration has membranes with larger pores and will retain proteins, lipids and colloidal

salts, while allowing smaller molecules to pass through to the permeate phase. Microfiltration, with pores

>0.1 micron, is used to separate fat from proteins and to reduce microorganisms from fluid food

systems.

A typical ultrafiltration Plant is comprised of a: feed tank, circulating pump, membrane housing,

membranes, product inlet, permeate outlet, retentate outlet, controls. The components for RO and ME

are similar expect for the pumps that are required. High pressure pumps are required to RO and low

pressure pumps for UP and MCF.

Size reduction:

Size reduction can be through the use of high shear forces, graters, cutters or slicers.

Emulsions with very small fat globule droplets are frequently made with a homogenizer which is a high shear

positive pump that forces fluid though a very small orifice at very high pressure to form or reduce the size of an

emulsion. The positive pump uses a reciprocating or rotating cavity between two lobes, gears or between a

stationary cavity and a rotor. The fluid forms the seal between the rotating parts. The components of a homogenizer

consist of a suction manifold; suction check valves, plungers and cylinders; discharge check valves, discharge

manifold; discharge pressure gage; 1st and 2nd stage homogenizing valves; plunger seals;

Typical equipment for size reduction in meat products and their component parts include:

1. Grinder which forces pieces of meat out through small openings consists of a motor, product tray, grinder

screw, die

2. Bacon Slicer - product holder, cutting blade, conveyor belt, slicer arm

3. Sausage Stuffer - inlet, stuffer body, stuffer drive assembly, product feeder, product outlet, product horn


15/75


4. Vertical Chopper - bowl, cutting blade, motor, cover

Powdered products are frequently ground into find particles through ball mills.

Fermented Products:

Useful microorganisms are used to preserve a number of food products, which include:

-Yeast fermentations

-beer

- wine

-champagne

- bread

Lactic acid fermentations

-cultured buttermilk

- yogurt

- cheese

-sour kraut

-pickles


16/75


-fermented sausages

All fermentations results from the action of microorganisms growing on carbohydrates in the product and producing

some material (alcohol, or acid) which minimizes the growth of undesirable organisms and preserves the product.

The equipment used for fermentation varies as a function of the product. Generally, a fermentation vessel is used -

which may be open or closed. Modern beer, wine and cheese operations utilize closed vessels for the initial

fermentation, where careful sanitation practices can be employed to present contamination. Cultures used for thefermentations are prepared under close sanitary control.

Pictures of Processing euipment:

buttermaking.jpg butterchurn.jpg

beerclarif.jpg beerprocessing.jpg

drumdryer. jpg Impingement dryer.jpg spraydryer.jpegbatchretort.jpg

corncutter.jpg

meatgrinders.jpg

OSU FST Course 401
http://pdfcrowd.com/http://pdfcrowd.com/redirect/?url=http%3a%2f%2fclass.fst.ohio-state.edu%2ffst401%2fInformation%2fElements-Food-Processing.html&id=ma-130109130114-7f00b5b7http://pdfcrowd.com/customize/http://pdfcrowd.com/html-to-pdf-api/?ref=pdfhttp://class.fst.ohio-state.edu/fst401/401%20product/equipment%20pics/buttermaking.jpghttp://class.fst.ohio-state.edu/fst401/401%20product/equipment%20pics/butterchurn.jpghttp://class.fst.ohio-state.edu/fst401/401%20product/equipment%20pics/beerclarif.jpghttp://class.fst.ohio-state.edu/fst401/401%20product/equipment%20pics/beerprocessing.jpghttp://class.fst.ohio-state.edu/fst401/401%20product/equipment%20pics/Drying/drumDRYER1.JPGhttp://class.fst.ohio-state.edu/fst401/401%20product/equipment%20pics/Drying/DRYERIMPINGEMENT.jpghttp://class.fst.ohio-state.edu/fst401/401%20product/equipment%20pics/Drying/spraydryer.jpeghttp://class.fst.ohio-state.edu/fst401/401%20product/equipment%20pics/Canning/batchretort.jpghttp://class.fst.ohio-state.edu/fst401/401%20product/equipment%20pics/corncutter.jpghttp://class.fst.ohio-state.edu/fst401/401%20product/equipment%20pics/meatgrinders.jpg


17/75

OSU FST Course 401

Food Sc ience & Tech n olo gy4 0 1

I n t r o d u ct i on t o

Food Pr ocessin g

Home

Syllabus

a. Aub. Wi

c. Sp

Assignments

MW Calendar

TR Calendar

Contact

Links

Glossary

Quick page for

class

HOW TO FI ND TECHNI CAL I NFORMATI ON

MAKI NG TEAMS WORK SUCCESSFULLY!

PRODUCTS YOU CAN MAKE

SAFETY

LAB REPORTS

RECI TATI ON NOTES

OSU FST Course 401
http://class.fst.ohio-state.edu/fst401/401%20Syllabus%20Au%2006.htmhttp://class.fst.ohio-state.edu/fst401/syllabus/401Syllabussp12.htmhttp://class.fst.ohio-state.edu/fst401/assignments,%20quizzes%20&%20exam.htmhttp://class.fst.ohio-state.edu/fst401/FST%20401%20MW%20%20Schedule.dochttp://class.fst.ohio-state.edu/fst401/FST%20401%20TR%20%20Schedule.dochttp://class.fst.ohio-state.edu/fst401/contact.htmhttp://class.fst.ohio-state.edu/fst401/references.htmhttp://class.fst.ohio-state.edu/fst401/glossary.htmhttp://class.fst.ohio-state.edu/fst401/class/index.htmlhttp://class.fst.ohio-state.edu/fst401/class/index.htmlhttp://class.fst.ohio-state.edu/fst401/Information/FindingTechnical-Information.htmlhttp://class.fst.ohio-state.edu/fst401/Products_to_Make.htmlhttp://class.fst.ohio-state.edu/fst401/safety.htmhttp://class.fst.ohio-state.edu/fst401/Recitation%20Notes/recitation_material.htmhttp://class.fst.ohio-state.edu/fst401/Recitation%20Notes/recitation_material.htmhttp://class.fst.ohio-state.edu/fst401/safety.htmhttp://class.fst.ohio-state.edu/fst401/Products_to_Make.htmlhttp://class.fst.ohio-state.edu/fst401/Information/FindingTechnical-Information.htmlhttp://class.fst.ohio-state.edu/fst401/class/index.htmlhttp://class.fst.ohio-state.edu/fst401/class/index.htmlhttp://class.fst.ohio-state.edu/fst401/glossary.htmhttp://class.fst.ohio-state.edu/fst401/references.htmhttp://class.fst.ohio-state.edu/fst401/Links.htmlhttp://class.fst.ohio-state.edu/fst401/contact.htmhttp://class.fst.ohio-state.edu/fst401/FST%20401%20TR%20%20Schedule.dochttp://class.fst.ohio-state.edu/fst401/FST%20401%20MW%20%20Schedule.dochttp://class.fst.ohio-state.edu/fst401/assignments,%20quizzes%20&%20exam.htmhttp://class.fst.ohio-state.edu/fst401/syllabus/401Syllabussp12.htmhttp://class.fst.ohio-state.edu/fst401/401%20Syllabus%20Au%2006.htm


18/75

OSU FST Course 401

0 9/ 1 4/ 0 3Copy r igh t The Oh io S ta te Un ivers i t y , 2003

h t t p : / / c lass .f s t .oh i o - st a t e .edu / FST 401 / 401 i ndex .h t m

OSU FST Course 401 - Making Teams Effective


19/75

OSU FST Course 401 Making Teams Effective

I n t roduc t ion toFood Proce ss ing

Home

Syllabus

Assignments

Calendar1

Calendar2

Contact

Search

Links

Glossary

Mak ing Teams Ef fec t ive

Working in teams is a "way of life" in the modern food industry -- as a means of being more

effective in a competitive world. Students in FST 401 will gain experience in how to make teams

effective.

A good team has diversity of backgrounds, providing an opportunity to utilize the particularstrengths of each individual to permit the team to achieve what can not be achieved by a single

individual working alone. For the team to be successful, it is essential that each student contribute

to the overall effort of the group.

In this course the membership of the teams will be decided by the instructor on the basis of the

background of the students -- to insure diversity.

The success of a team is frequently secured through the organizing ability of the team leader. For

products 3, 4 & 5, the group will appoint a different team leader for each project. The leader, with

concurrence of the team members will divide the responsibilities for each project -- using the

particular background of each individual. [For example - one person might take primary responsible

for planning, another take major responsibility for organizing processing and a third lead the work

on product evaluation. All team members should review the project report before it is submitted.]

MAK ING TEAMS EFFECTIVE

Effective teams do not just happen. It takes real effort of the team leader and the team members.

For most students working in a team is a new experience It can be frustrating especially in the OSU FST Course 401 - Making Teams Effective
http://class.fst.ohio-state.edu/fst401/syllabus.htmhttp://class.fst.ohio-state.edu/fst401/assignments,%20quizzes%20&%20exam.htmhttp://class.fst.ohio-state.edu/fst401/calendar1%20mw.htmhttp://class.fst.ohio-state.edu/fst401/calendar2%20tth.htmhttp://class.fst.ohio-state.edu/fst401/contact.htmhttp://class.fst.ohio-state.edu/fst401/search.htmhttp://class.fst.ohio-state.edu/fst401/references.htmhttp://class.fst.ohio-state.edu/fst401/glossary.htmhttp://class.fst.ohio-state.edu/fst401/glossary.htmhttp://class.fst.ohio-state.edu/fst401/references.htmhttp://class.fst.ohio-state.edu/fst401/Links.htmlhttp://class.fst.ohio-state.edu/fst401/search.htmhttp://class.fst.ohio-state.edu/fst401/contact.htmhttp://class.fst.ohio-state.edu/fst401/calendar2%20tth.htmhttp://class.fst.ohio-state.edu/fst401/calendar2%20tth.htmhttp://class.fst.ohio-state.edu/fst401/calendar1%20mw.htmhttp://class.fst.ohio-state.edu/fst401/assignments,%20quizzes%20&%20exam.htmhttp://class.fst.ohio-state.edu/fst401/syllabus.htm


20/75


To minim ize problems, dec ide on som e operat ion ru les at the very beginning -- i tw i l l make for a smoother operat ing team.

As problems arise, develop a set of rules to live by. It will be helpful to decide this as a group during

the first laboratory and to put it in writing. Some questions to answer include -- How will you handle:

Members not being on time?

People who don't show up?

Conflict - without hurting feelings?

Bossy people?

Shy people?

People who talk too much?People who never talk?

People who don't carry out assignments on time?

What role do you want the instructor to play? Let him/her know if you expect him to be an

arbitrator. Use the instructor only as a last resort -- it is much better if you solve your own

problems-----you may not like the instructor's solutions.

Organiz ing you team operat ions:

Set up a plan -- divide responsibilities -- build on individual strengths

Be specific and fair about assignments -- try to use individual strengths and backgrounds

Allow plenty of time for group effort -- getting started with a group is more time consuming than

doing it alone. Once operating effectively, the team will accomplish much more than any individual

can working alone.

Withhold judgment about ideas until all information is available

Be flexible

The team leader for each project needs to lead, and the team members need to be supportive and let

her/him lead.

Be specific about deadlines for planning, operations and report preparation -- consider a written

h d l

OSU FST Course 401 - Making Teams Effective


21/75


http://www.3M.com/meetingnetwork/readingroom/meetingguide_processes.html

http://www.3m.com/meetingnetwork/readingroom/meetingguide_brain.html

05/26/00Copyr ight The Ohio Stat e Univers i t y , 2000

http:/ /c lass.fst .ohio-state.edu/FST401/401index.htm

OSU FST Course 401 - Syllabus
http://www.3m.com/meetingnetwork/readingroom/meetingguide_processes.htmlhttp://www.3m.com/meetingnetwork/readingroom/meetingguide_brain.htmlhttp://www.3m.com/meetingnetwork/readingroom/meetingguide_brain.htmlhttp://www.3m.com/meetingnetwork/readingroom/meetingguide_processes.html


22/75

OSU FST Course 401 Syllabus

In t roduc t ion t oFood Proc essing

Home

Syllabus

Assignments

Calendar1Calendar2

Contact

Search

Links

Glossary

LA B REPORTS

Pro ject 1 Report

Project 1 Equipment List and Pictures

Pro ject 2 Report

Pro ject s 3 , 4 & 5 Repor ts

Project planning

Planning worksheet

Ice Cream

Spread Sheet EQUIPMENT:
http://class.fst.ohio-state.edu/fst401/assignments,%20quizzes%20&%20exam.htmhttp://class.fst.ohio-state.edu/fst401/calendar1%20mw.htmhttp://class.fst.ohio-state.edu/fst401/calendar2%20tth.htmhttp://class.fst.ohio-state.edu/fst401/contact.htmhttp://class.fst.ohio-state.edu/fst401/search.htmhttp://class.fst.ohio-state.edu/fst401/references.htmhttp://class.fst.ohio-state.edu/fst401/glossary.htmhttp://class.fst.ohio-state.edu/fst401/Lab%20Reports/icecream.xlwhttp://class.fst.ohio-state.edu/fst401/Lab%20Reports/Project-g2-%20spreadsheets.xlshttp://class.fst.ohio-state.edu/fst401/Lab%20Reports/Project-g2-%20spreadsheets.xlshttp://class.fst.ohio-state.edu/fst401/Lab%20Reports/icecream.xlwhttp://class.fst.ohio-state.edu/fst401/glossary.htmhttp://class.fst.ohio-state.edu/fst401/references.htmhttp://class.fst.ohio-state.edu/fst401/Links.htmlhttp://class.fst.ohio-state.edu/fst401/search.htmhttp://class.fst.ohio-state.edu/fst401/contact.htmhttp://class.fst.ohio-state.edu/fst401/calendar2%20tth.htmhttp://class.fst.ohio-state.edu/fst401/calendar2%20tth.htmhttp://class.fst.ohio-state.edu/fst401/calendar1%20mw.htmhttp://class.fst.ohio-state.edu/fst401/assignments,%20quizzes%20&%20exam.htm


23/75

Q

EQUIPMENT:

Equipment, with major component parts are listed for each pilot plant:

A. Parker Hall Pilot Plant

Centrifugal pump: pump head, impeller, back plate, shaft and shaft seal, motor

Rotary lobepositive displacement pump:pump head with face plate, suction (inlet) and

discharge (outlet) ports, impellers, shafts, shaft seals, motor.

Cream separator:regulating cover with float, cream outlet cover, skim milk outlet cover,

bowl assembly with inlet, cream outlet, skim outlet, spindle, disc stack and cream disc

with cream adjusting screw, skim milk outlet, motor.

HTST (high temperature, short time) pasteurizer: balance tank, booster pump, coldside of regenerator, positive timing pump, heating section, holding tube, flow diversion

valve, hot side of regenerator, cooling section, controls.

Homogenizer: Manifold, plungers and cylinders; discharge pressure gauge, 1st and 2nd

stage homogenizing valves, plunger seals.

Batch ice cream freezer: freezer cylinder, dasher assembly with scraper blades, mix inlet,

ice cream outlet gate, motor. EQUIPMENT:
http://class.fst.ohio-state.edu/fst401/ParkerEQ/cpump.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/cpump.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/ppump.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/ppump.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/ppump.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/separ.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/separ.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/htst.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/htst.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/homo.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/homo.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/freezer.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/freezer.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/freezer.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/homo.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/htst.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/separ.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/ppump.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/ppump.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/cpump.htm


24/75

Q

pump, product outlet, laminar flow hood.

Liquifier:Tank, water jacket, product outlet, motor, stator.

Hobart mixer: Bowl, motor, bowl raising handle, paddle, whisk, controls (on/off, speed)

Extruder: extruder cylinder and sections, steam and water inlets, product inlet, extruder

screw, outlet with die, cutter, motor drive, controls

Tomato processing line: lye tank, lye application chamber, conveyor belt, water sprayers,

peel removing disks, chopper, heater, pasteurizing unit

Proofing oven: temperature controls, humidity controls, oven body, water chamber and

heater

Potato peeler:Product inlet, rinse water, abrasive disk, product outlet, motor.

Slicer:Product inlet, slicing blade

Electric kettle:Steam jacket, pressure relief valve, scraper blade, pressure gauge, speed

control, heater control.

Pi D k D k d h dl t t t l (l d it h EQUIPMENT:
http://class.fst.ohio-state.edu/fst401/Pilot%20Plant%20Equipment/microtherm_files/progressing%20cavity%20pump%20moyno.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/liquify.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/homixer.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/extruder.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/extruder.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/tomline.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/tomline.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/oven.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/oven.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/peelerslicer.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/peelerslicer.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/eleckettle.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/oven.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/oven.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/eleckettle.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/peelerslicer.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/peelerslicer.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/oven.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/tomline.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/extruder.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/homixer.htmhttp://class.fst.ohio-state.edu/fst401/ParkerEQ/liquify.htmhttp://class.fst.ohio-state.edu/fst401/Pilot%20Plant%20Equipment/microtherm_files/progressing%20cavity%20pump%20moyno.htm


25/75

Q

Coating andFrying line:Coating drum, batter applicator, vibrating shaker, fryer

(product inlet, product outlet, heat exchanger, oil reservoir), controls

Rotary retort:retort body, retort chamber, rotating basket, steam inlet, pressure gauge,

motor, temperature gauge

Still retort:retort body, product basket, steam inlet, water inlet, pressure gauge, pressure

relief valve, controls and recorders

Donut maker:oil reservoir, ingredient supply hopper, inlet, belt assembly, outlet.

Vacuum evaporator:product inlet, product outlet, steam inlet, vacuum pump, condenser,

controls.

Spray dryer:(Diagram only) air inlet, air heater, drying chamber, product inlet and

atomizer, cyclone chamber, cyclone separator, dry product collection vessel, hot air inletand outlet, controls

Note: Other equipment to note (but not to include in report) includes form fill and seal

filler, popcorn popper, tubular evaporator, freeze drier, can sealer, electrostatic coater

Grinder: motor, product hopper, grinder screw or auger, die or plate

EQUIPMENT:
http://class.fst.ohio-state.edu/fst401/HowletEQ/onionringl.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/onionringl.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/rotretort.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/rotretort.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/stilretw.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/stilretw.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/donutma.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/donutma.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/vackettle.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/Howlett/spraydryer.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/Howlett/spraydryer.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/Howlett/bagfiller.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/Howlett/bagfiller.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/closingmachine.htmhttp://class.fst.ohio-state.edu/fst401/MeatLabEQ/grinstuf.htmhttp://class.fst.ohio-state.edu/fst401/MeatLabEQ/grinstuf.htmhttp://class.fst.ohio-state.edu/fst401/MeatLabEQ/grinstuf.htmhttp://class.fst.ohio-state.edu/fst401/MeatLabEQ/grinstuf.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/closingmachine.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/Howlett/bagfiller.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/Howlett/bagfiller.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/Howlett/spraydryer.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/Howlett/spraydryer.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/vackettle.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/donutma.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/stilretw.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/rotretort.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/onionringl.htmhttp://class.fst.ohio-state.edu/fst401/HowletEQ/onionringl.htm


26/75

pH meter(234 Parker): electrode, electrode fill hole, control unit, calibration

standards

Colorimeter(234 Parker): Light source, button to initiate reading, control unit,

calibration plate

Texture analyzer(234 Parker): probes, probe arm, sample corers, platform for

sample, computer control unit

Particle size analyzer(334 Parker): pump head, computer control unit,

Water activity meter(334 Parker): sample cup, sample drawer

Moisture analyzer (360A Parker): control panel, balance air shield, balance pan and

stem, glass fiber pads

Viscometer(340C Parker): control panel, leveling screws, spindles, immersion

groove on spindle shaft

FOOD SCIENCE AND TECHNOLOGY 401
http://class.fst.ohio-state.edu/fst401/Instruments/pH%20meter.htmhttp://class.fst.ohio-state.edu/fst401/Instruments/colorimeter.htmhttp://class.fst.ohio-state.edu/fst401/Instruments/texture%20analyzer.htmhttp://class.fst.ohio-state.edu/fst401/Instruments/particle%20size%20analyzer.htmhttp://class.fst.ohio-state.edu/fst401/Instruments/water%20activity%20meter.htmhttp://class.fst.ohio-state.edu/fst401/Instruments/moisture%20analyzer.htmhttp://class.fst.ohio-state.edu/fst401/Instruments/viscometer.htmhttp://class.fst.ohio-state.edu/fst401/Instruments/viscometer.htmhttp://class.fst.ohio-state.edu/fst401/Instruments/moisture%20analyzer.htmhttp://class.fst.ohio-state.edu/fst401/Instruments/water%20activity%20meter.htmhttp://class.fst.ohio-state.edu/fst401/Instruments/particle%20size%20analyzer.htmhttp://class.fst.ohio-state.edu/fst401/Instruments/texture%20analyzer.htmhttp://class.fst.ohio-state.edu/fst401/Instruments/colorimeter.htmhttp://class.fst.ohio-state.edu/fst401/Instruments/pH%20meter.htm


27/75

Project 1 Report:

You will receive color pictures of each instrument or piece of equipment. Each student will submit his

or her own report.

1. For each piece of pilot plant equipment listed below, do the following:

a. Label the pictures with the components listed for each piece of equipment. Use arrows and neatly

written labels to identify the parts.

b. Indicate the flow pattern of the food product through the equipment

c. Indicate the purpose of the equipment in food processing (ex: HTST pasteurizer - to kill the most

heat resistant, vegetative pathogen in a fluid food)

d. Name the primary unit operation(s) performed by the piece of equipment (fluid flow, heat transfer,

size adjustment, mass transfer, separation, mixing)

2 F h l ti l i t t li t d b l d th f ll i FOOD SCIENCE AND TECHNOLOGY 401


28/75

Food analysis instruments

pH meter

Colorimeter

Texture analyzer

Particle size analyzer

Water activity meter

Moisture analyzer

Viscometer

Meat Pilot Plant ( Animal Sciences Building )

Grinder

Meat slicer

Piston sausage stuffer

FOOD SCIENCE AND TECHNOLOGY 401


29/75

HTST (high temperature, short time) pasteurizerHomogenizerBatch ice cream freezerContinuous ice cream freezerCheese vatColloid millUltrafiltration unitUHT processor and aseptic filler (Microthermics)

Liquifier

Howlett Hall Pilot Plant

ExtruderTomato peeling lineDicerAbrasive peelerSlicer

Electric kettlePizza or Deck ovenConvection ovenProofing ovenSteam injection ovenSheeterHobart MixerFryer

Rotary retortStill retortDonut makerVacuum evaporator

FST 401
http://c/Documents%20and%20Settings/courtney.25.FOODSCIENCE/My%20Documents/Teaching/FST%20401/Lab%20Manual/microtherm.htmhttp://c/Documents%20and%20Settings/courtney.25.FOODSCIENCE/My%20Documents/Teaching/FST%20401/Lab%20Manual/microtherm.htm


30/75

FST 401INTRODUCTION TO FOOD PROCESSING

LABORATORY 2: UNIT OPERATIONSREPORT

Each team will turn in one report. All team members will receive the same grade. Every team

member should participate in generating the report. Each member should review and edit the

final report before it is submitted. Distribution of effort by team members is left up to the team.

For the report, include all of the items listed in section D, For lab report, for each exercise. Be

thorough and use complete sentences when answering the questions.

FST 401


31/75

FST 401

INTRODUCTION TO FOOD PROCESSING

LABORATORY REPORT FORMAT

FOR PROJECTS 3,4 & 5

Number in parentheses indicates point value for that topic.

1. (10) Introduction

Description of product and its formulation and processing.

Background information on the product, including quality

and safety issues.

Include unit operations, unit processes and chemical

operations involved

2. (5) Variables

FST 401


32/75

Explain the functions of each ingredient in the product

4. (15) Procedures

Describe the process used to make the product

Make a flow chart showing equipment, sequence of

operations, unit operations and include details of the

process and where applicable:

-times, temperatures, pressures, speeds of mixers, etc.

Describe the procedures used for evaluation of your

products

5. (20) Results

Show data in table of graph format. Include means and

standard deviations where appropriate. Briefly summarize theresults in the text

FST 401


33/75

what you know now?

7. (5) Conclusions

Concisely state the conclusion(s) of your project.

8. (5) References

Cite any reference you used. Use at least 2 references. Less than

half of your sources should be web pages.

Use the following format:

Within the text, put the reference in parentheses after the cited

text as: (1st authors last name, year of publication, page

numbers)

FST 401


34/75

Pre-planning e-mail.

Planning day form.

10. Appendix

Include all sensory evaluation sheets.

FST 401


35/75

PROJECTS 3, 4 & 5

PREPARATION FOR PRODUCT PLANNING DAY

To save time and frustration during the planning session, the group must do the following

BEFORE arriving to the planning lab session:

Read any product information in the manual.

Go to the library and read background information about your product. Use books on

reserve, other books, and journals to gather information about the processing and formulation

of your product. You may use web sites as well, but web sites should not be your only sources.

What are the attributes of your product that the consumer expects and what processing and

formulation factors can change these attributes?

Review the lab report format and product checklist to see what you need to know.

The better prepared you are, the faster the planning session will go. Instructors and TAs will help

revise the plans of the group, but will not do all of the work.

One week before the product-planning day, the project leader must send the following to the

instructor by e-mail ([email protected]):

FST 401


36/75

PLANNING

Product formulation, equipment requirements and product information

DUE ON PLANNING DAY

Team: ______ Product ______________ Date of Manufacture _______

1. Variables:

Variable Reason for selection Expected result

FST 401


37/75

2. Ingredients:

Ingredient Total amount

needed*

Function of ingredient

FST 401


38/75

*Attach diskette with spreadsheet

3. Equipment and Utensils Required:

FST 401


39/75

4. Evaluation of Product:

Test Method Reason for evaluation/Expected results

FST 401


40/75

5. Summarize the quality attributes of your product:

6. What processing, formulation, and/or storage factors ensure that this product is safe to eat?

FST 401


41/75

8. What unit operations and chemical/biochemical operations are involved in making this product?

Include the step(s) in the process that will use each operation.

ELEMENTS OF FOOD CHEMISTRY


42/75


[Return to Index]

Food is made up of chemicals that include primarily water, proteins, lipids, carbohydrates and minerals.

The major components that are altered by processing include proteins, lipids and carbohydrates.

The chemical nature of foods is important in two ways in respect to food processing:

Food chemicals are altered by processing and these changes results in changes in the characteristics of the

food and consumer acceptance of the product

Because of the lability of some food chemicals, the parameters used in food processing, such as

temperature and shear, are limited to achieve minimal changes in the characteristics of the food and to

maximize consumer acceptance.

Minimal processing results in the least change in the chemicals of food, provide the highest quality and result in

foods with a very short shelf-life. As processing is performed to extent shelf-life (drying, canning), the is more

chemical change and loss of perceived quality.

Composition of typical food products (%)

Food water lipid protein carbohydrates

Wh l ilk 87 4 3 5 5 ELEMENTS OF FOOD CHEMISTRY


43/75

The products listed in the table differ in gross composition and also differ in the specific chemical nature of their

lipid, protein and carbohydrates that influence processing methods and the effects of processing on the

characteristics of the food.

pH:

The pH of foods (negative log of the hydrogen ion concentration) is important both in respect to the flavor, texture

and food safety. The FDA generally regards foods with a pH of less than 4.6 to be of less concern from a

microbiological view point. Examples of foods with ranges of different pH values are shown in the following

table. Values greater than 4.6 are marked in red.

Product pH Product pH Product pH

Lemon Juice 2.00 - 2.60 Tomatoes, Canned 3.50 - 4.70Pea Soup, Cream of,

Canned5.7

Vinegar 2.40 - 3.40Cheese, Cream,

Philadelphia4.10 - 4.79 Peas, canned 5.70 - 6.00

Orange, Marmalade 3.00 - 3.33 Dates, Dromedary 4.14 - 4.88 Beans, Black, cooked 5.78 - 6.02

Apple Sauce, canned 3.09 - 3.40 Pimiento 4.20-4.90 Milk, evaporated 5.90 - 6.30

Sauerkraut, cooked 3.16 - 3.50 Tomatoes, whole 4.30 - 4.90 Corn 5.90 - 7.30

Cherries, Maraschino 3.47 - 3.52 Pimiento 4.40 - 4.90 Spaghetti, cooked 5.97 - 6.40

Fruit cocktail 3.60 - 4.00 Soy Sauce 4.40 - 5.40 Clams 6.00 - 7.10

Prune Juice 3.95 - 3.97 Buttermilk 4.41-4.83 Rice, Brown 6.20 - 6.70



44/75

The relationship between water activity and factors relating to food quality (microbiological and chemical) are

shown in the following figure.

Generally bacterial require a water activity of >0.9 to growth and most yeasts and molds are inhibited by a water

activity of


45/75

and c) packing in light protective packages and/or oxygen free packaging.

Hydrogenation (addition of hydrogen and removal of double bonds) is used to covert vegetable oils into semi-solid

or solid fats to be used as ingredients in baked goods. These partially hydrogenated products are less susceptible to

oxidation than the original oils.

Some lipids, such as phospholipids and mono- and di glycerides are used as emulsifiers. Phospholipids are

normally occurring and have a phosphate and amine base substituted for one of the fatty acids. Mono- and di-

glycerides are derived from triglycerides by the hydrolysis of the ester bond for one (mono-) or two (di) of the fatty

acids

diglyceride

monoglyceride

Carbohydrates:

The carbohydrates in foods are mixtures of carbon, hydrogen and oxygen and can be classified as: a) simple sugars

and polysaccharides.

Simple carbohydrates



46/75

Reducing sugars contain a reactive aldehyde (CHO) group that is absence in non-reducing sugars. Thermal

processing can cause reactions between reducing sugars and the amino-group of proteins, causing browning and

altering flavors. This reaction is termed the Maillard reaction. Very high heat processing in a low water

environment can cause carmelization (polymerization) of also results in a browning reaction.

Monosaccharides may have 6 carbons and are called hexoses or they may have 5 carbons and are called pentoses.

Glucose (sometimes called dextrose), fructose and galactose are three common hexoses. Ribose and deoxyribose

are two common pentoses. Two monosaccharides may be linked together to form a disaccharides.

Sucrose is the most common disaccharide and is made of one molecule each of glucose and fructose. Sucrose is

commonly referred to as sugar. Lactose is the major sugar in milk and is made up of one molecule of glucose and

one of galactose. Maltose is a disaccharide made from two molecules of glucose. This linkage is formed by theremoval of water(dehydration) and is broken by adding water back (hydrolysis)

Complex carbohydrates

Cellulose is the most common polysaccharide and the major component of plant cell walls. Cellulose is a polymerof glucose molecules linked together by beta 1-4 linkages and cannot by digested by humans. Thus, cellulose is a

major component of dietary fiber. Starch is also a polymer of glucose, but the glucose molecules are joined

together by alpha 1-4 linkages that can be digested by humans. In plants, starch is an energy reserve. In animals,

small amounts of energy are stored in liver and muscle as glycogen, a highly branched polymer of glucose. Pectin

is a polymer of galcturonic acid and is not digested. In plants, pectin "cements" cells together. Polysaccharides

may be added to foods for a variety of reasons. Nutritionally, they are generally added to increase the dietary fiber

content. Functionally, polysaccharides are added to thicken, form gels, bind water, and stabilize proteins. Starch isthe most common polysaccharide added to food products. For some uses, starch may be chemically modified to

improve stability or to alter its functional properties. Cellulose and cellulose derivatives are also added to a number



47/75

Regular starches require heating to replace the hydrogen bonds between starch molecules with starch-water bonds,

which causes "gelatinization" and creates the thickening effect. Starches that are pre-gelatinized and dried are cold

water soluble and are termed "instant" starches.

Proteins:

Proteins are polymers of amino acids linked together through a peptide bond.. The shape and thus the function of a

protein is determined by the sequence of its amino acids. Digestion of proteins produce amino acids, some of

which are essential to the nutritional well being of the human.

Amino Acid - contain an amino group ( -NH2 ) and an acid group ( - COOH ).

There are twenty amino acids that are found in proteins.

Peptide Bond- A bond formed by the condensation of the amino group ( -NH2 ) of one amino acid with the acid

group ( -COOH ) of another amino acid resulting in the loss of water.

Condensation Reactions - Removal of water ( H2O ) and formation of a bond. The reversal of this is hydrolysis

which involves the addition of water.

Peptide bonds are not easily broken. Mild thermal processing does not normally result in the breaking of peptide

bonds to yield amino acids from proteins.

The function of protein in foods include:

Furnish essential amino acids

Add to structure ( Texture )

Appearance ( myoglobin browning ) ELEMENTS OF FOOD MICROBIOLOGY AND SANITATION


48/75

ELEMENTS OF FOOD MICROBIOLOGY AND SANITATION

[Return to Index]

Both the safety and quality of foods require an understanding of the basics of food microbiology.

Organisms important in food include:

bacteria

yeasts

molds

viruses

Although not living organisms, viruses are generally included as biological agents of concern. Thesematerials are combinations of proteins and nucleic acids that can take over cellular functions. In addition

of causing disease, they also can infect microorganisms used in beneficial fermentation.

Microorganisms either can be beneficial or harmful.

Harmful effects of microorganisms include:

spoilage of foods ELEMENTS OF FOOD MICROBIOLOGY AND SANITATION


49/75

cheese

yogurt

fermented sausages

wine

beerpickles

sour kraut

tea

coffee

cocoa

Factors affecting microbial growth:

The effect of organisms on the safety and quality of foods is dependent on the initial numbers of

organisms present, processing to eliminate the organisms, control of environment to prevent growth and

sanitation.

The major factors that influence the growth of microorganisms in food are:

pH

oxygen availability

moisture availability

nutrient availabilitystorage temperature

lag time



50/75

Aerobic organisms require air (oxygen) to growth and will not grow in the absence of air. These include

yeasts and molds and a number of bacteria. It is a common practice to hot fill foods and seal them so

that a slight vacuum is formed in the package. A number of foods will be labeled "refrigerate after

opening" and this is because yeasts and molds can growth one the product is open and contains air.

Anaerobic organisms only growth in the absence of acid. One such organisms is Clostridium botulinum,

which produces a toxin that can be lethal if ingested. Where foods are packed under a vacuum, the

protection against Cl. botulinum growth is to heat treat the food (sterilization) to a time and temperature

where any organisms present are destroyed.

Some organisms, such as lactobacilli, either can grow (or grow best) under slightly reduced conditionswith low levels of oxygen but do not grow anaearobically.

Moisture availability:

Organisms need free moisture in order to grow. Drying foods removes the available moisture and

prevents growth of bacteria, yeasts and molds.

Control of water activity is a common method of preventing the outgrowth of microorganisms. Water

activity is a measure of free (unbound) water available for chemical and biological activity.

Aw = vapor pressure of food product at a specified temperature

Aw is a measure of the relative humidity of the food where:



51/75

Most foods contain adequate nutrients to support the growth of microorganisms, especially foods that

contain both a fermentable carbohydrate and a protein source.

Sugar is the most common carbon source. In starch based foods, the action of amylases will frequently

increase the available sugar source.

Storage temperature:

Organisms can be classified on the basis of their ability to grow at different temperatures:

-psychrophiles grow best at temperatures 40 C

-psychrotrophic - tolerate low temperatures and can grow under refrigeration

-thermotrophic - tolerate high temperature and can grow at 55-60 C.

Most pathogenic bacteria are mesophilic, although a few (such asListeria monocytogenes or Cl

botulinum type E) can growth under refrigeration conditions.

Organisms that spoil refrigerated products are generally psychrotrophic, and frequently belong to the

genus Psuedomonas ELEMENTS OF FOOD MICROBIOLOGY AND SANITATION

6


52/75

undesired flavors is one million/g. (106/g). Thus for food born toxification (such as caused by Cl.

botulinum, Staph. aureous and Bacillus cereus), there has to have been large number produced.

Similarly, the numbers of organisms required for fermented foods (such as yogurt) is also very large.

However, in the case of organisms causing infectious disease (E. coli 0157, Listeria monocytogenes and

Salmonella), the numbers of organisms that can cause the disease can be very small. FDA generally

requires that no organisms can be recovered from 100 g of food after suitable incubation.

Under ideal growth conditions it can take a relatively short period of time to increase from 1/g to 1

million/g. (20 generations). At 4 generations/hour, the food can reach >1 million in just 5 hours. If the

initial load is 1000/g, then the time required to reach 1 million would be 2.5 hours (10 generations).

Minimizing Microorganisms during processing and handling:

Keeping microbial loads at minimal levels is essential to provide safe food of high quality. This requires

care in food handling and minimizing microorganisms in the product during processing. Key to this goal

is preventing contamination of the food during contact with equipment (or food contact) surface.

Cleaning and sanitizing are important steps in the operation of any food plant and will become moreimportant in the future as the industry deals new and emerging microorganisms such as E. coli 0157

that first began to be associated with food borne infections in the 1980s

Cleaning:

Cleaning of food plant equipment generally involves the use of relatively strong chemicals and can beconsidered a 4 step process: a) rinsing away excess soil, b) bringing the cleaning compound in contact

with the soil, c) removing the soil from the equipment surface and final cleaning.


Th il f d t t f b f th f ll i


53/75

The soil on a food contact surface may be one or more of the following:

protein

fat

minerals

soluble solids (sugars, etc)

Heated surfaces, especially those containing protein, are always more difficult to clean that unheated

surfaces.

Alkaline cleaning compounds are used to remove fat and proteins, whereas acid is used to remove

mineral soils. Minerals are frequently complexed with proteins and the addition of chlorine to thealkaline cleaner increases the ease of removal.

Cleaning compounds perform their cleaning via different functions, which include:

emulsification (making fat into an emulsion that is water soluble and easily removed.

peptizing (chemically degrade proteins into smaller units and thus more easily removedsaponification (chemically convert oils and fats into soaps through interaction with sodium

hydroxide

wetting (reducing the surface tension of the water)

water conditioning (removal of divalent cations that impede the action of the cleaning compound

Cleaning may be achieved by hand or by circulation of the cleaning compound over or through theequipment. Circulation cleaning may be in place or may be the circulation of cleaning solution of

cleaning compound of equipment components in a tank.



54/75

Common sanitizers include:

chlorine (100 - 200 ppm)

iodine (25 - 50 ppm)

acid/surfactant blends (100-200 ppm)

quaternary ammonium germicides. (200 ppm)

The sanitizers are listed in order of decreasing effectiveness. The halogens are most effective over the

widest range of different organisms.

Chlorine is especially affected by organic matter. Iodine sublimes at high temperatures. Quaternary

ammonium compounds have a residual effect, but are not effective against viruses or gram - organisms.

Destruction of Microoganisms:

Microbial destruction is achieved either by heat or chemicals. The most common method of making

foods safe is to use thermal processing to eliminate pathogens and then to use good sanitation practicesto prevent them from re-entering the food after thermal processing.

Spores are more resistant than vegetative cells and thus require more heat to kill.

Two general heat processes are used:

Pasteurization - heating to a specific temperature for a specific time to kill the most heat resistant

vegetative pathogen ELEMENTS OF FOOD MICROBIOLOGY AND SANITATION

f d i hi h th th i d f id f d (S Ch t C d f d )


55/75

foods is higher than than required for acid foods (See Chapter on Canned foods)

ELEMENTS OF FOOD PROCESSING


56/75

ELEMENTS OF FOODPROCESSING

METHODS AND EQUIPMENT

[Return to Index]

There are over 18,000 different food items in today's supermarkets, which are processed to a greater or

lesser degree, and thousands of new products are introduced each year.

Modern food processing has three major aims:

1. To make food safe (microbiologically, chemically).

2. To provide products of the highest quality (flavor, color,texture)

3. To make food into forms that are convenient (ease of use)

The following table summarizes the item to be controlled and comments on the major approaches

involved in this control.

To be

Controlled

Heat Cold Chemicals Aw* Mechanical

Micro- Prevents Reduces Preserva- Do not grow Reduces


*A t ti it


57/75

*Aw = water activity

Safety:

Insuring the safety of food involves careful control of the process from the farm gate to the consumer.Safety includes control of both chemical and microbiological characteristics of the product. Most

processing places emphasis on microbial control, and often has as its objective the elimination of

organisms or prevention of their growth.

Processes that are aimed at prevention of growth include:

q Refrigeration

q Freezing

q Drying

q Control of water activity (addition of salt, sugars, polyols, etc.)

Processes that are aimed at minimizing organisms include:

q Pasteurization

q Sterilization (canning)

q Cleaning and sanitizing

q Membrane processing

A further method of processing that is aimed at the control of undesirable microflora is the deliberated ELEMENTS OF FOOD PROCESSING

microbiological spoilage


58/75

q microbiological spoilage

q enzymatic degradation

q chemical degradation

Convenience:

Today's consumers want food products that are convenient to use and still have all the qualities of a

fresh product.

UNIT OPERATIONS:

Most food processing is comprised as a series of physical processes that can be broken down into a

number of basic operations. The "unit operations" can stand alone and depend upon coherent physical

principles.

Unit operations include:

1. Fluid flow - moving a fluid product from one point to another with varying degrees of turbulence.

2. Heat transfer - in which heat is either removed or added and includes heating

q coolingq refrigeration

q freezing ELEMENTS OF FOOD PROCESSING


59/75

UNIT PROCESSES:

Some food processing operations may utilize a single unit operation, but most food processing includes

a combination of unit operations to achieve the total process.

For example, the manufacture of a dried coffee whitener from a combination of fluid and dry

ingredients includes the following unit operations in sequence:

-Mixing

-Fluid flow

-Size reduction (homogenization)

-Heat transfer (heating)

-Fluid flow

-Heat transfer (cooling)

-Mass transfer (conversion of water to vapor during drying)

Pasteurization of milk to destroy the most heat resistance vegetative pathogen includesthe unit operations of fluid flow and heat transfer (both heating and cooling).



60/75

FOOD PROCESSING EQUIPMENT

Fluid Flow:

Transport of fluids is achieved either by gravity flow or through the use of pumps. In gravity flow the

flow is "laminar", where the flow is transfer from the fluid to the wall between adjacent layers. Adjacent

molecules do not mix. In most instances, however fluids are transported from one unit operation or

process to another by pumps and in "turbulent" flow where there is mixing of adjacent particles. Two

different types of pumps are commonly used for different purposes:

The centrifugal pump utilizes a rotating impeller to create a centrifugal force within the pump cavity, so

that the fluid is accelerated until it attains its tangential velocity close to the impeller tip. The flow is

controlled by the choice of impeller diameter and rotary speed of the pump drive. The capacity of a

centrifugal pump is dependent upon the speed, impeller length and the inlet and outlet diameters.

Product viscosity is an important factor affecting centrifugal pump performance. If the product is

sufficiently viscous, the pump cavity will not fill with every revolution and the efficiency of the pump

will be greatly reduced. Centrifugal pumps are used to transport fluid and for cleaning operations.

Centrifugal pumps may be high speed or low speed, with high speed pumps being used for cleaning

(CIP). .

A positive pump generally consists of a reciprocating or rotating cavity between two lobes or gears and a

rotor. Fluid enters by gravity or a difference in pressure and the fluid forms the seals between therotating parts. The rotating move of the rotor produces the pressure to cause the fluid to flow. Because

there is no frictional loss positive pumps are used where a constant rate of flow is required (timing ELEMENTS OF FOOD PROCESSING

Heating is used to destroy microorganisms to provide for a healthful food prolong shelf life through the


61/75

Heating is used to destroy microorganisms to provide for a healthful food, prolong shelf life through the

destruction of certain enzymes and to promote a product with acceptable taste odor and appearance.

The factors that influence the heat transfer into or out of the product include:

1. Heat exchanger design

2. Heat transfer properties of the product

a. specific heat (amount of heat required to change the temperature of a unit mass of product a

specific temperature without change in state of the material)

b. thermal conductivity (rate by which heat is transferred through a material)c. latent heat (heat required to change the state of a material)

3. Density (weight per unit volume)

4. Method of heat transfer

a. conduction (transfer from molecule to molecule through the material)

b. radiation (transfer from electromagnetic radiation of a body due to the vibration of its molecules

c. convection (transfer through movement of mass )

5. Viscosity (related to the amount of force required to move the fluid product)

A variety of heat exchanges are utilized in the food industry, which include:


Swept surface heat exchanges have blades that scrape the surface of the heat exchanger and bring new


62/75

Swept surface heat exchanges have blades that scrape the surface of the heat exchanger and bring new

product continuously to the heat or cooling surface. There are utilized for fluids of very high viscosity.

An ice cream freezer is an example of a swept surface heat exchanger.

Common unit processes that include heat transfer as a unit operation include:

-Pasteurization (heat)

-Sterilization (heat)

-Drying (heat)

-Separations (based on density, size or shape)

-Evaporation (heat)

-Refrigeration (cold)

-Freezing (cold)

Pasteurization: Pasteurization is a process of heating a product at a specific temperature for a

controlled period of time to destroy the most heat resistant vegetative pathogenic organism. Originally

developed for fluid dairy products, the process is also applied to other fluids, including fruit juices and

juice products. In addition to destruction of microorganisms, pasteurization also achieves almostcomplete destruction of undesirable milk enzymes - such as lipase.


Ultra high temperature (UHT) pasteurization is achieved with plate heat exchanges operating at


63/75

Ultra high temperature (UHT) pasteurization is achieved with plate heat exchanges operating at

temperatures of at least 190 F for 2 seconds. The same principles are used as for HTST, except that

higher temperatures are used and the equipment is designed for very rapid heating and cooling.

Sterilization: The primary object of sterilization is to destroy the most heat resistant pathogenic spore

forming organism

Flame Sterilizer - conveyor, preheater, gas jets

Still Retort - retort body, product basket, steam inlet, water inlet, pressure gage, pressure relief valve

Hydraulic cooker = a continuous sterilizer, where the cans are rotating during the sterilization process

Still Retort = A type of batch sterilizer used for canning food, where the cans are not in motion during

the sterilization process.

Baking: Baking is the process by which moisture is removed from wheat based (or other cereal grain,

products. Batch or continuous oven are utilized to heat the products resulting in an increase in volume of

the product, gelatinization or starch of protein "elation to set the final structure of the product. Baking is

an essential process for bread, cakes, cookies and crackers.

A rotary oven is a fairly simple device which has a cabinet, oven trays, heating element, thermostat andtemperature controls. Many commercial ovens are continuous in that the product moves though the oven

on a continuous belt ELEMENTS OF FOOD PROCESSING

very small pores that permit only the transfer of water Most systems consist a the membrane cast on a


64/75

very small pores that permit only the transfer of water. Most systems consist a the membrane cast on a

solid porous backing - usually in the form of a tube. High pressure is applied to force the water (called

permeate) through the membrane the concentrated fluid (called retentate) is retained in the tubing. The

rate of water removal decreases as the fluid is concentrate, until it is no longer economically feasible to

remove more water.

Concentration is often used as a pre-step to drying to reduced the amount of water that needs to be

removed in drying and reducing drying costs. Evaporation can achieve higher solids economically than

can reserve osmosis. RO is preferred over evaporation for heat sensitive fluids.

Drying: Three common methods of drying are: (a) sun or tray drying, (b) spray drying and (c) freeze

drying.

Sun or tray drying is least expensive, followed by spray drying and freeze drying. The drying method of

choice is generally based on the characteristics of the product.

Products that are already solid lend themselves to sun or tray drying. These include fruits and

vegetables. The products may be dried by exposure to sun or place in trays and dried in a current ofwarm or hot air.

Products that are very heat sensitive are freeze dried. Commercially only instant coffee is widely freeze

dried. Some freeze dried fruits are beginning to reach the market, but these are in limited quantities. In

freeze drying the moisture is removed without a phase change (sublimation). A freeze drying is

comprised of a dryer cabinet; drying chamber with: heating/cooling shelves, trays and door; vacuumpump, condenser, controls and digital readout.


Freezing: Lowering the temperature below the freezing point of the product stops microorganisms from


65/75

Freezing: Lowering the temperature below the freezing point of the product stops microorganisms from

growing and reduces the activity of enzymes. Vegetables and some fruits are heat treated (blanched)

before freezing to eliminate enzymes.

One of the most common frozen foods is ice cream .An ice cream freezer can be operated either in

batch or continuous mode. A batch ice cram freeze consists of a freezer cylinder; dasher assembly withscraper blades, counter rotating agitator; mix inlet, ice cream outlet gate; motor. A continuous ice cream

freezer consi