food and food by-product processing industry

8/8/2019 Food and Food By-Product Processing Industry

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Xavier University Ateneo de CagayanCorrales Avenue, Cagayan de Oro City

Food and Food By-Product Processing Industry

Submitted to:Engr. Edwin Richard R. Ortiz

ChE 511 Instructor

Submitted by:Ilea A. Verano

BS ChE 5

July 15, 2010


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INTRODUCTION

Definition

Food processing is a procedure in which raw ingredients are transformed into food for

human or animal consumption by employing special methods and techniques. Basically,anything done to make a raw material into food is a form of food processing even the

simple process of grilling vegetables in the backyard.

Goals of Food Processing

It cannot be emphasized further that the basic goal of food processing is to prepare

palatable food for consumption of humans and animals. In addition, food processing has

been extended to include the following goals:

1. extend the edible time frame or the preservation of food,

2. make better tasting food,

3. make more varieties of food,

4. maintain and/or improve nutritional properties of food,

5. prevent, reduce, eliminate infestation of food with microbes, insects or other

vermin,

6. prevent microbial growth or toxin production by microbes, or reduce these risks

to acceptable levels,

7. stop or slow deteriorative chemical or biochemical reactions,

8. make foods for special groups of people (allergic, diabetic, and other people who

cannot consume some common food elements),

9. increase seasonal availability of many foods,

10. develop ready-to-consume products, hence saves time for cooking,

11. generate employment,

12. help marketing and distribution tasks; and

13. enable transportation of delicate perishable food across long distances.


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The History of Food Processing

Food processing in not a new technology since its origin traces back to prehistoric ages.

Bread-making started in Egypt and the origins of beer also go back to Babylon and

Egypt in the period of 3,000 to 5,000 BC. During the beginnings of food processing, salt-preservation, sun-drying and fermentation were very popular choices of method

especially among warriors and sailors who needed to process their food to prolong its

shelf life during long travels. The crude methods of food processing remained

unchanged until the beginning of the Industrial Revolution in the 18th century when the

method of canning was introduced in the food processing industry with credits to

Nicolas Appert who developed the vacuum bottling process and Peter Durand, who

eventually developed canning using tin cans.

In the 20th century, the methods of food processing eventually grew to accommodate a

vast number of advances including spray drying, freeze drying, artificial sweeteners,

colouring agents, juice concentrates and preservatives such as the sodium benzoate.

Several advances have also emerged in the late 20th century such as dried instant

soups and reconstituted fruit juices.

Nowadays, the processed foods that are thriving in grocery shops are modern

processed foods and traditional foods, but their manufacturing technology,

process control and manufacturing and packaging environmental facilities have

been advanced and rationalized to an incomparable extent in the last 30 years.

As a result, products with high quality and uniformity are now being

manufactured. (United Nations Conference on Food Processing Energy Use,

1995)

The production and small-scale processing were formerly done on farms and in homes,

but with the increasing specialization and reduction in the number of people, centralized

processing became essential. With central processing, the establishment of grade and

quality standards has become necessary. Early development grew from cottage and

community programs into larger-scale units. Milling of grain, fluid milk processing and


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distribution, baking and processing of sugar and candy products developed early. More

recently, freezing has been applied to meat, fruits, vegetables and manufactured food

products ready to cook or serve.

TYPES OF FOOD PROCESSING

Refining and Milling

Milling is the process of converting grain into flour by mechanical means. The grain is

cleaned and a small amount of water is added to prevent the outer part of the kernel fro

pulverizing. The moistened grain is crushed slightly between two steel corrugated rolls

rotating at high speed and with one roll rotating faster than the other. This exerts a

shearing action into chunks. The product is sifted to remove the germ and bran, and the

chunks are size separated with the larger ones being re-crushed and the intermediate-

sized ones ground between smooth rolls. The resulting flour is sieved to remove large

particles.

The modern milling industry uses many innovations in measuring, metering, weighing,

conveying, blending, applying power, sanitation, etc. A new development is the

production of free-flowing flour made by agglomerating the flour particles into clusters

by the addition of moisture and spray-drying. The use of air classification has made

possible the separation of high-protein and high-starch fraction and thus permits a wide

range of custom blending.

Canning

Canning is the method of preserving fresh food such as fruit, vegetables, meats, fish,

and etc. by heat treating the food and sealing it in an airtight container. Usually, these

containers are metallic in material tinned or untinned steel often plastic-lined,

aluminium or special-strength glass.

The raw food is packed into the container, the container sealed and the whole package

is then heated to cook the food and sterilize both the container and the contents. The


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usual method of heat treating is to place the containers in a steam pressure vessel and

process them at 121oC for a time dependent upon the size of the container and the

nature of the contents. Acid foods require less time to process than non-acid food. To

prevent the food from being spoiled before and during containment, several methods

can also be employed including freezing, drying, pasteurization, refrigeration, vacuum

treatment, addition of antimicrobial agents, dosing of ionizing radiation, and submersion

to a strong saline, acid, base, osmotically extreme (for example very sugary) or other

microbe-challenging environments. Whatever the method, it cannot be perfectly

dependable at all times as a preservative. For example, spore-forming, thermal-

resistant microorganisms, such as Clostridium botulinum (which causes botulism), can

still survive.

Although heating may degrade the odor and taste of food, a method of solution can be

employed to minimize its effects. Short time-high temperature treatment may be used

so that there is less deterioration in the product compared to long time-low temperature

treatment. To ensure sufficient penetration of heat in the cans, an agitated cooker is

often used. This agitated cooker is composed of a preheater, cooker, and a cooler. The

cans are placed in individual compartments and are rotated by a revolving reel on a

spiral track.

Concentration

A concentrate is a form of substance which has had the majority of its base component

(in the case of a liquid: the solvent) removed. Typically this will be the removal

of water from a solution or suspension such as the removal of water from fruit juice. In

the case of milks, it is often evaporated from a solids content of 8.6% to a much more

concentrated 45% solids of evaporated milk. Concentrating products is an

advantageous method of food processing since it reduces the weight and volume of a

product, therefore aiding its transportation. One-third of the original volume of usually

reduced in concentration.

Three processes are available for food concentration: evaporation with evaporators,

reverse osmosis, and freeze concentration. Depending on the nature of the food, the


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that if food can be frozen quickly and maintained at a low enough temperature, the

quality will not be greatly deteriorated and microorganisms will not increase. Food

preservation by freezing has to be done quickly because ordinary slow freezing can

rupture the cells of the food and may cause a breakdown in the structure of the food.

Slow freezing also allows undesirable enzymes to react even at low temperature,

although this can be prevented by blanching the food prior to freezing. In general, actual

freezing may be accomplished by either still or forced air, by direct contact with a metal

surface cooled by a refrigerant or by immersion in a liquid refrigerant such as nitrogen.

If the amount of water in a food can be reduced before freezing, the quality of the final

product will generally be improved since the increase in volume in liquid during freezing

can be reduced. Freezing does not kill the microorganisms present in the food that

cause spoilage, but it does inactivate them. However, on thawing, the microorganisms

are reactivated and the food tends to spoil faster than fresh, unfrozen food. Nutrients

are not destroyed by freezing.Drying

Drying, as a method of food preservation, works by the removal of water from food

thereby inhibiting the growth of microorganisms and hinder quality decay. Drying is an

effective method of food preservation since bacteria, yeasts and moulds would not grow

in dry environments. Moulds will grow if the water content is 12% or higher, although a

few moulds will grow at 5%, while most bacteria require at least 30% moisture. Since

grains are usually dried to about 12% moisture, fruits to 16 to 25% and non-fat dry milk

to less than 5% moisture, only few microorganisms can survive in the food. As a food

preservation method, drying, however, reduces the vitamin content of the food although

its nutritive content remains unchanged.

Sun drying is the cheapest drying method available and it has been used for

generations to dry fruits, grains, meat and fish. However, sun drying is limited only to

certain areas where the sun always shows up. As economical as it is, sun drying can

open the risk for contamination of the product by dust, insects, birds and rodents. The


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colours of fruits also change in drying. When fruits are dried, their bright colour turns

dark brown unless the fruit is treated with SO2 prior to drying. Because consumers

prefermoist dried fruits, glycols are used to rehydrate and thus soften the harder sun

(or mechanically) dried product without adding moisture, which would allow the growth

of microorganisms.

A table of mechanical driers and the food for which they are used is shown below. In the

table, meat is usually dried using freeze drying, that is, water is removed by sublimation

from a frozen food.

Types of Driers and Food Products

Drier Product

Drum Milk, vegetable juices, cranberries, bananas,

Vacuum shelf Limited products of certain foods

Continuous vacuum Fruits and vegetables

Atmospheric continuous belt Vegetables

Fluidized bed Vegetables

Foam mat Juices

Spray Eggs, milk, coffee

Rotary Some meat products, usually not used as food

Cabinet Fruits and vegetables

Kiln Apples, some vegetables

Tunnel Fruits and vegetables

Freeze Meat, coffee

SOURCE: Shreves Chemical Process Industries, 1984

Pasteurization and Sterilization

Pasteurization is a process of heating a food, usually liquid, to a specific temperature for

a definite length of time, and then cooling it immediately. The basis of this process is the

principle that most harmful bacteria can be killed by heat. Although the most effective

way to kill bacteria is through boiling, it could compromise the flavour of the liquid. Most

especially in milks, most people object to the taste of boiled or cooked milk. To strike a


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balance between the need for a safe food and the desire for flavour, processors only

partially sterilize or the right term, pasteurize, milk for human consumption.

Two primary methods exist for the pasteurization of milk: HTST and the LTH. The

HTST or the high-temperature short-time method is the most common method for the

pasteurization of milk. In this method, milk is exposed to a temperature of 73oC for not

less than 16 seconds and is then followed by rapid cooling. This method is also known

as flash pasteurization. The next method, the LTH or the Low Temperature Holding

method pasteurizes milk by heating it to 63oC for at least 30 minutes.

The purpose of pasteurization is to kill pathogenic microorganisms, thus eliminating

food-borne disease and to inactivate enzymes to improve storage and keeping quality.

But because this method does not kill all the bacteria present, the product must be kept

under refrigeration until used.

In comparison to pasteurization, milk sterilization is the process where the milk is

exposed to more intense treatment to kill or completely inactivate all microorganisms

whether pathogenic or non-pathogenic. The sterilized product must be placed in a

sterile container under aseptic conditions and sealed. Milk treated in this way can be

stored for a very long time, maybe months at room temperature.

Fermentation

Fermentation may be defined as the conversion of carbohydrates to alcohols and

carbon dioxide or organic acids with the aid of yeasts, bacteria, or a combination

thereof, under anaerobic conditions. In contrast to pasteurization and sterilization where

microorganisms are killed and destroyed, the fermentation process harnesses the ability

of certain microorganisms to digest food and give off the desired product we need.

Fermentation is based on the idea that not all microorganisms are detrimental and some

of these microorganisms can be used to our advantage. Most people confuse

fermentation with putrefaction or the other way around, thus it is important to

differentiate the two from one another. In fermentation, the microorganisms decompose


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carbohydrates; while in putrefaction, the action of microorganisms involves protein.

Aside from that, fermentation releases no putrid odour; while in putrefaction, a

combination of sulphur-containing protein products and hydrogen sulphide is released.

Irradiation

Food irradiation is the process of exposing food to ionizing radiation to destroy

microorganisms, bacteria, viruses, or insects that might be present in the food. The

main target of food irradiation is the organisms DNA. What the radiation does to the

microorganisms DNA is that it destroys it beyond its ability to repair. Microorganisms

can no longer proliferate and continue their pathogenic activities.

Doses of several joules per kilogram (equivalent to several hundred rads) are lethal tohuman beings and it requires up to a hundred joules per kilogram (104 rads) to kill most

insects. Microorganisms, on the other hand, require 104 joules per kilogram (106 rads).

In general, the more complex the organism is, the more sensitive it becomes to

radiation.

In food processing, it has been proven that radiation can be used to preserve food,

especially protein food such as meat, without causing undesirable protein denaturation

or appreciably altering the taste, and without leaving any residual radioactivity in the

food. With low doses of radiation, there is less loss of vitamins in all food than that seen

with canning, freezing or drying.

Packaging

The purpose of packaging food is to make it possible to ship and store and to prevent

deterioration during storage by insects, moulds, yeasts, microorganisms and enzymes.

For much food, the container is filled before the food is processed. Examples of this are

rigid metal cans, glass containers, and plastic pouches. These containers are sealed so

that no outside contaminant can enter and cause food spoilage.


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Dry foods such as cereal, flours, dried fruits and various convenience mixtures like cake

and biscuits are usually packed in cardboard boxes lined with wax paper or plastic-

coated paper. For larger quantities, sack made of finely woven cloth or coated paper

may be used.

FOOD BY-PRODUCTS

Leather

History of Leather

Leather is one of the oldest commodities known. It has played an important role in the

development of civilization for its function as clothing, shelter, carpets and decorative

attire. The first leather was made when hides were treated with vegetable extracts to

make them weather-resistant. These early leather were made by first immersing the

raw hides and skins in a fermenting solution of organic matter in which bacteria grew

and attacked the hides or skins, resulting in a loosening of the hair or wool and some

dissolving out of skin protein. The hair or wool was then scraped off with primitive blunt

stone or wooden scrapers and fat or meat still adhering to the flesh side was removed in

a similar manner.

During the Middle Ages leather was used for all kinds of purposes such as: footwear,

clothes, leather bags, cases and trunks, leather bottles, saddles and harness, for the

upholstery of chairs, and couches, book binding and military uses. It was also used to

decorate coaches, sedan chairs and walls. The majority of the leather was tanned with

oak bark but soft clothing, gloving and footwear leathers were tanned with alum, oil, and

combinations of these two materials. With the discovery and introduction of basic

chemicals like lime and sulphuric acid, tanners gradually abandoned their traditional

methods and leather production slowly became a chemically based series of processes.

The growth of industrialization in the 18th and 19th centuries created a demand for

many new kinds of leathers, e.g., belting leathers to drive the machines being

introduced into industry, special leathers for use in looms in the textile industry, leathers

for use as diaphragms and washers, leathers for use in transport and for furniture

upholstery.


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Manufacture

The manufacture of leather through vegetable tanning and chrome tanning is shown

below.

In chrome tanning process, the pickling bath consists of a mixture of salt and sulphuric

acid. After picking, the hides are soaked in a solution of sodium dichromate and then

treated with sodium thiosulfate in the reduction drum. From the reduction drum, the hide


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is treated in settling drums with borax to set the chrome salt on the fibres. Washing

completes the tanning process.

In vegetable tanning, tannins from bark extracts of quebracho, eucalyptus, chestnuts

and other trees are used in the treatment of hides. These tannins react with the collagen

fibres of the skin. The pH is regulated by the use of sulphuric acid. The protein in the

skin absorbs large quantities of tannin, and the absorbed material fills up the holes and

stiffens the leather.

The time is takes to create leather differs for every tanning method. In the vegetable

tanning method, it will take 2 to 4 months to create leather; while in chrome tanning, it

will only take 1 to 3 weeks.

Gelatin

Gelatin, often spelled as gelatine, is a translucent, colourless, brittle, nearly

tasteless solid substance, derived from the collagen inside animals' skin and bones. It is

described as an organic nitrogenous, colloidal protein substance whose principal value

depends on its coagulative, protective and adhesive powers. Gelatin obtained from

animals is created through hydrolysis of collagen, the white fibres of the connective

tissues of animal body, particularly the skin, bones and tendons.

Manufacture

Type A gelatin is made from skins which are first washed and then swollen fro 10 to 30

hours in HCl, H3PO4 or H2SO4 at very low pH of 1.0 to 3.0. After swelling, the skins are

washed, the pH adjusted to 3.5 to 4.0, and then extracted with hot water. Four o five

extraction tanks are used, and the extractive water becomes progressively hotter in

each succeeding tank. The first extraction is at 55 to 65oC and the last at 95 to 100oC.

Each extraction requires 4 to 5 hours. After the last extraction is completed the liquid is

degreased, filtered, deionized, and then concentrated in two stages to 30 to 40% solids

by continuous vacuum concentration. The high-solids solution is chilled, cut into noodles


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and dried below 60oC on a continous wire-mesh belt. The dried material is ground and

blended with other gelatins to produce the desired specifications.

Type B is made from bones and sometimes skin and hides as shown in the figure. The

degreased bones are demineralized with 4 to 7% HCl over a 1- to 2-week period. After

washing, the bones are agitated daily for 3 to 16 weeks in a lime slurry in lime pits or

tanks. When the lime treatment is complete, the mix is washed for 15 to 30 hours,

acidified to pH 5 to 7 with HCl, H3PO4, H2SO4, or HC2H3O2 and extracted and

concentrated as for Type A.

Both processes require the use of stainless steel for most equipment although the

liming tank may be concrete or wood.


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Adhesives

Anadhesive, orglue, is a mixture in a liquid or semi-liquid state that adheres or bondsitems together. Adhesives may come from either natural or synthetic sources. The types

of materials that can be bonded are vast but they are especially useful for bonding thin

materials. Adhesives cure (harden) by evaporating a solvent (these are most adhesives

that cure at room temperature) or by exposing them to an elevated temperature.

History

The earliest date for a simple glue is 200,000 BC and for a compound glue 70,000 BC.

Glues have been discovered from stone spear flakes glued to wood with birch-bark-tar.

They have also been found in ceramics and statues from the ancient times.

The Egyptians made much use of animal glues to adhere furniture,ivory, and papyrus.


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In medieval Europe, egg whites were used as glue to decorate parchments with gold

leaf. The first actual glue factory was founded in Holland in the early 1700s, and the

English introduced fish glue in the 1750s.

Animal Glue

The manufacture of animal glue is almost the same with the manufacture of gelatine.

The procedure include grinding bones, cutting hides and scraps into small pieces,

degreasing the material by percolating a grease solvent through it, liming and plumping,

washing, making several extractions by hot water, filtering liquors, evaporating, chilling,

and drying the jelly slabs in a tunnel. When dry, the slabs of glue are flakes or ground,

blended, graded and barrelled or bagged for shipment.

Other Protein Adhesives

Fish glues are liquid glues processed from the skin and waste material of certain fishes,

principally cod. Practically, fish glue has the same application as other animal glues with

application in gummed tape, letterpress printing plates and blueprint plates. Casein, a

milk-derivative protein, is the basis of another large class of adhesives and can made

both water and non-water-resistant. Casein adhesives are widely employed in

woodworking industry and in the manufacture of drinking cups, straws, and ice cream

containers. Other proteins used as an adhesive include soybean protein, albumin, zein

from corn, and peanut protein hydrate.

Starch Adhesives

Starch adhesives are liquid adhesives made from any of the following: cornstarch,

tapioca flour, wheat flour, or potato starch. Starch adhesives are principally used for

bonding paper with the production of corrugated boxboard as an example of its

application. Starch adhesives are readily available in the market, are low in cost and are

easy to apply from water dispersion. Starch adhesives are considered to be the least

expensive class of paper packaging adhesive with an advantage over animal glues as

having no strange characteristic odour. However cheap, starch adhesives are low in

strength and are not resistant to water.


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Native starches are prepared from grains or roots. Dextrins, the polysaccharide

obtained from starch, are made by heating a dry starch with dilute acid, causing partial

hydration. White and yellow dextrins, called British gums, are a result of heating native

starch with small amount of catalyst; they are gummier and more adhesive than the

normal dextrins.

Synthetic Resin Adhesives

Synthetic resin is a thermosetting resin principally used as a strong adhesive and

coating. Comparing to starch adhesives, the synthetic resin adhesives are used where

water resistance is required. Synthetic resin adhesives may be classified as solvent-

borne systems, water-borne systems, non-volatile solids and liquids, hot melts,

powders, radiation curable systems, two-part systems, and reactive systems. Water-

borne systems, both naturally derived and synthetic-rein based, represent more than

two-thirds of the adhesive demand. Another classification of synthetic-resin adhesives

are solvent releasing, hot melt and pressure sensitive, depending on its method of

setting.

Chemically, there are two types of synthetic adhesives: those used merely as an

adhesive and those which form primary bond linkages with the materials being bonded.

One classification includes rigid thermosets, rubbery thermosets, thermoplastics,

copolymers, polymer mixtures and inorganic adhesives.

Rigid thermosets include epoxies, silicones, polyesters, cyanoacrylates, and phenolic,

urea-formaldehyde and resorcinol-formaldehyde resins. Rigid thermosets are heat and

chemical resistant.

Rubbery thermosets include silicones, urethane, and polysulfide rubbers. Many of these

are used as sealants.


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Thermoplastics include vinyls, polystyrenes, acrylates, polyamides, rubber-based

adhesives, rosin, animal glues and starch and dextrin glues. Most hot-melt, nonsolvent

glues belong to this group.

Copolymers and mixtures are formed to obtain better properties than those with single

components.

Miscellaneous Adhesives

Inorganic adhesives are included under miscellaneous adhesives. They include glasses

and ceramics used for very high temperature service and sodium silicate used for

manufacturing corrugated boxes.

Other adhesives include asphalt, sulphur, shellac, miscellaneous natural gums and

mucilage and a variety of cellulose esters dissolved in volatile solvents.

FOOD PROCESSING EQUIPMENTS

Processing equipment for food is similar to that for other processing. Liquids, solids and

other materials must be handles without adding to the deterioration of the product or

damage to the equipment. Sanitary conditions are also an important consideration since

the food being processed is basically intended for human consumption. Extra care must

be taken that the design of every equipment and the materials used for its construction

does not create a problem or harm in the maintenance of sanitation inside the plant.

Three organizations the International Association of Milk, Food and Environmental

Sanitarians, the Dairy Industry and the Food and Industry Supply Association listed a

set of standards for the design of equipment to ensure sanitary conditions. Included in

their list is the provision for the use of stainless steel, the regulation on square corners,

slope of the drainage and the interchangeability of parts for every design.


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Cleaning

Manual cleaning involves cleaning in place with guidelines as follows:

1. Using alkali or acid solution appropriate for the product and equipment surface

2. Providing a time exposure of 10 to 60 min to remove substance without damage

to the metal

3. Utilizing a velocity flow of 1.5 m/s

4. Maintaining a slope of surface and tubing to provide for drainage

5. Avoiding dead end flows

6. Using connections and joints that are cleanable

food and food by-product processing industry

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