lec 5.the science of food processing

8/8/2019 Lec 5.The Science of Food Processing

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COLLEGE OF DRYLAND AGRICULTURE AND NATURAL RESOURCES

MEKELLE UNIVERSITY

INTRODUCTION TO FOOD SCIENCE AND TECHNOLOGY ( FoST 111)

HAND OUT 1

LECTURE 5. THE SCIENCE OF FOOD PROCESSING

Food and Bioprocess TechnologyFood and Bioprocess Technology is a multidisciplinary field of engineering and science

of all types of food processing technologies. It includes the following steps Postharvest technologies Agri-food processing technologies Physical and chemical properties of agri-food Preservation and storage Packaging Processing equipment Waste treatment and management

Post Harvest TechnologyAfter harvest, foods (e.g. fruits, vegetables, milk, meat, fish,) are liable to accelerated

physiological, chemical, and microbial processes that invariably lead to deterioration and loss ofwholesomeness. It is then necessary to institute some measure of processing such as reduction in

moisture content, denaturation of endogenous enzymes and microorganisms, or packaging inorder to curtail perishability. In the absence of such processing, massive post harvest losses can

ensue. It is the responsibility of the food scientist or technologist to understand the underlying processes contributing to food deterioration and spoilage and, to device appropriate measures

and methods of preservation in order to ensure availability, acceptability, and safety of foods.

Post Harvest Technology- Importance and Role

Post harvest loss reduction technology encompasses the usage of optimum harvestfactors, reduction of losses in handling, packaging, transportation and storage with modern

infrastructure machinery, processing into a wide variety of products, home scale preservationwith low cost technology. Use of thermal processing, low temperature, drying, chemical and

biological reactions coupled with other preservation techniques are applied to enhance thestorability. Containers and packaging materials confer portability as well as extend the shelf-

life. Adoption of these techniques could make available a large quantity of food by avoidinglosses and provide better quality food and nutrition, more raw materials for processing, thus

ensuring better returns to the farmers.Importance ofPost-harvest technology lies in the fact that it has the capability to meet

food requirement of growing population by eliminating losses making more nutritive food itemsfrom raw commodities by proper processing and fortification.

Post-harvest technology has potential to create rural industries. ethiopia, where 80percent people live in the villages and 70 percent of them depend on agriculture has experienced

that the process of industrialization has shifted the food, feed and fibre industries to urban areas.This process has resulted in capital drain from rural to urban areas, decreased employment

opportunities in the rural areas balance trade in favour of urban sector and mismatched growth ineconomy and standard of living between rural and urban people. It is possible to evolve

appropriate technologies which can establish agricultural based rural industries. The farmerwhose role has been reduced to producer can be transformed into producer cum processor and


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COLLEGE OF DRYLAND AGRICULTURE AND NATURAL RESOURCE

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Prof.Dr.B.ANNADURAI,M.Sc.,Ph.D.,D.H.Ed.,FLS.,SBC(I).,

thus getting more dividends for hard labour, input, kind of risk taken and generating resource forsocio-economic advancement keeping pace with the modern times.

Status of food processing IndustryImportant sectors in agro processing industries are: fruit and vegetable processing, grain

processing, fish processing, milk processing, meat and poultry processing, packaged/

convenience foods, alcoholic beverages and soft drinks etc.Agricultural processing may be defined as an activity, which is performed to maintain or

improve the quality or to change the form or characteristics of the agricultural product.

Processing operations are undertaken to add value to agricultural materials after their production.The main purpose of agricultural processing is to minimize the qualitative and quantitative

deterioration of the material after harvest.Primary processing:Purification of raw materials by removing foreign matter, immature grain

and then making the raw material eligible for processing by grading in different lots orconversion of raw material into the form suitable for secondary processing.

Secondary processing: Processing of primary processed raw material into product which issuitable for food uses or consumption after cooking, roasting, frying etc.

Tertiary processing: Conversion of secondary processed material into ready to eat form.Food items are marketed in different forms as raw, primary processed, secondary processed and

tertiary processed. The farmers in general prefer to sell their agricultural produce immediatelyafter harvest leaving a part for own consumption and seed purposes. It has estimated that the

farmers retain 44 per cent of the total wheat and 48 per cent of the paddy. Mandies and graintraders procure the balance for processing and / or for marketing.

Sector wise food processing

Fruits and vegetable processingThe processed products from fruits and vegetables are beverages, jams, jellies, candies,

preserves, canned fruits and vegetables, dehydrated fruits and vegetables, pickles, soup mixes,

sauces and ketchups. Products that have growing demand, especially in the Middle Eastcountries include pickles, chutneys, fruit pulps, canned fruits and vegetables, concentrated pulps

and juices, dehydrated vegetables and frozen fruits and vegetables.People generally prefer fresh fruits and vegetables in Ethiopia due to abundance of

seasonal fruits throughout the year available at low price. The production of pickles and chutneyshas traditionally been rural level cottage industrial activity. However, in the recent years,

processed foods in the form of canned fruits such as pineapple, mango slices and pulps, grapes,apple, peaches etc have increased considerably. The uses of fruits in the form of concentrated

juice, dry powder, jam and jelly have also increased. The percentage production of processedfruits and vegetables are fruit juice and fruit pulp - 27, jams and jellies - 10, pickles -12, ready to

serve beverages -13, synthetic syrups - 8, squashes - 4, tomato products - 4, canned vegetables- 4and others -18.

The main fruits that enter the export market are mangoes, grapes, apples, citrus but otherfruits identified for export are bananas, sapota, litchis etc. The main destinations for export of

fruits being Middle East, U.K., Europe and to some extent Singapore, Malaysia etc. Theimportant vegetables exported are potatoes (28.0%), onions (7.1%), cauliflower and cabbage (4.0

% each), okra (3.0%), peas (3.0%) and others (50.0 %).The exports are limited to Middle East,Europe, U.K and Singapore etc. At rural level solar assisted dehydrators could be promoted for

preparation of ethnic food products like raisins, onion flakes and powder, chips, vegetables etc.

Food grain sector


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Grains could emerge as a major export earner . The Major food grains include rice, jowar,bajra, maize, wheat, gram and pulses.

Rice milling: Conventional rice hullers with a population of 91287 are very popular for millingof rice in rural areas. In conventional rice hullers, bran and husk are produced together and

cannot be separated. The by - product is generally burnt. The modern rice mills have separate

processing mechanism for dehusking and polishing of the paddy.Wheat milling:Wheat production in the country has increased to more than 73.53 milliontonnes. Burr mills are very common for milling of wheat in rural and urban areas.At present

flours made by the roller mills are sold to institutional buyers like defence, hotels etc., and thehousehold purchase is limited to only 1.0 per cent due to absence of open policy for sale of

wheat flour through public distribution system. Sale of soy blended and branded wheat flour islikely to increase due to better quality flour and thus scope of organized wheat milling will

increase in future.Pulse milling:Pulses are the major sources for protein for the vegetarians . In a total world

production of 60 million tonnes of pulses, India, China, Brazil, Turkey and Mexico account for 2/ 3 rd of the output. The pulses are made into dhal by dehusking and dehulling.

Oil extraction: The Technology Mission on oilseeds has helped in increasing the oilseedsproduction to 24.5 million tonnes. The introduction of high capacity mechanical expellers and

solvent extraction technology has brought in modernization. Small capacity oil expellers havebeen developed which could be installed in rural areas for promoting agri - business and that

might provide more employment. Soybean is not only a good source of oil but also rich inprotein.

Processing of commercial cropsSugarcane, tea and coffee are major commercial crops grown in India. Tea emerged as

major foreign exchange earner. India is the largest producer and exporter of black tea. Of course,the scope of foreign investment in this sector is good.The production of sugarcane has increased

to more than 299 million tones. A bout 50 per cent sugarcane is estimated to be processed bysugar mills.

Packed and convenience foodModern packed and convenience foods such as bread, biscuit, confectionery, chocolates,

ready to eat foods like noodles, cereal flakes, etc have become popular in recent years especiallyin urban areas although traditional foods have been used in the country in the form of roasted,

puffed, sweet meat and baked products..

Fishing and Fish Processing

One of the catchy investment sectors is fisheries. The marine fish include prawns,shrimps, tuna, cuttlefish, squids, octopus, red snappers, ribbon fish, mackerel, lobsters, cat fish

etc. There is growing canned and processed fishes from India.

Meat and Poultry Processing

India ranks first in world cattle population, 50 per cent of buffalo population and one -sixth of total goat population of the world. There is vast scope to set up modern slaughter

facilities and cold store chains in meat and poultry processing sector. Compared with meat,poultry industry has registered significant growth. India ranks fifth in the world and both poultry

and egg processing units have come in a very big way in the country. India is exporting egg powder, frozen egg yolk and albumin powder to Europe, Japan and other countries. Poultry

exports are mostly to Maldives and Oman. Indian poultry meat products have good markets inJapan, Malaysia, Indonesia and Singapore. Presently there are only five egg powder plants in


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India which is considered insufficient in view of growing export demand for different kind ofpowder - whole egg, yolk and albumin.

Milk and Milk productsThe total milk production is now around 100 million tones and the demand for milk is

estimated at even higher level. Manufacture of casein and lactose, largely being imported

presently, has good scope.Alcoholic beverages and soft drinksAlcoholic beverages are another area where India witnessed substantial foreign

investment. The Local Made Foreign Liquor primarily comprise wine, vodka, gin, whisky, rumand brandy. The Ethiopian beer market is estimated at 7000 million a year. One of the major

advantages for any investor eyeing the Indian liquor market is that India offers enough rawmaterials like molasses, barley, maize, potatoes, grapes, yeast and hops for the industry.

Processing can always fetch an additional income to the growers and help in stabilizingthe prices with economic returns. The best overall indicator of the economic contribution of food

processing to the food system is the value addition. It represents the firms contribution to anindustrys value addition and the value addition is the indicator of the industrys contribution to

GDP Processing units are a boon for the welfare of the orchardists as they can save their crop

from wastage and at the same time their produce becomes more valuable, price fetchingcommodity with suitable post harvest treatment packaging and by processing into various

products.

A sealed pack of diced pork from Tesco. It shows the cooking time, number of servings,'display until' date, 'use by' date, weight in kg, price, price to weight ratio in both /kg and /lb,

freezing and storage instructions. It says 'Less than 3% Fat' and 'No Carbs per serving' andincludes a barcode. The Union Flag, British Farm Standard tractor logo, and British Meat

Food Preservation


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Throughout history humans have applied scientific concepts and engaged differenttechnologies to help preserve food, and as a consequence improve food safety. Through

scientific discovery, automation and technological innovation traditional methods of preservation, such as sun drying and pickling, have been supplemented with pasteurization,

sterilization, canning and freezing irradiating etc. So lets try to get familiarize with what this

concept actually is.Principles of Food Preservation The principles historically underlying food preservation remain the same today. They can

be summarized as: Chill or freeze food to stop the growth of micro-organisms and inhibit enzyme activity. Heat food to destroy micro-organisms and prevent enzyme activity (e.g. pasteurized

milk)

Place food in an acidic or alkaline solution to inhibit the growth of micro-organisms (e.g.pickled onions)

Place food in a sugar or salt solution to make water unavailable to micro-organisms (e.g.jam)

Keep food in airtight containers to deprive micro-organisms of oxygen and preventfurther contamination (e.g. canning)

Modify the atmosphere for the packaging of a food product (e.g. bacon) Reduce the moisture content of food to make the water essential for micro-organism

growth unavailable (e.g. grapes to raisins) Use fermentation to produce products with an extended shelf life (e.g. milk to cheese)

PicklingPickling vegetables and fruits with vinegar prevents the growth of micro-organisms. This

is due to the food being placed in a low pH solution in which micro-organisms cannot grow.

Curing

Curing is one of the oldest forms of food preservation. It is used to preserve meat andfish, yielding common products such as bacon, ham, frankfurters, and corned beef. Curing

involves adding some combination of salt, sugar, spices, vinegar, or sodium nitrite to animalfoods. Smoking, a flavoring technique and preservation method is another ancient technique that

is commonly used with curing. In addition, cured products tend to be very salty, and the sodiumin salty foods has been linked to high blood pressure. Smoked meats and fish may contain toxic

and even carcinogenic compounds that they absorb from wood smoke.

Fermentation

Fermentation is a chemical reaction carried out by many types of microorganisms toobtain energy. In fermentation, microorganisms break down complex organic compounds into

simpler substances. Although chemical changes and microbial growth usually mean foodspoilage, in some cases fermentation is desirable and microorganisms are actually added to

foods. For example, in the production of beer, wine, and other alcoholic beverages, yeastsconvert sugar into ethyl alcohol and carbon dioxide. In the making of yogurt and cheese, bacteria

convert lactose, a sugar found in milk, to lactic acid. Alcohol, acids, and other compoundsproduced in fermentation act as preservatives, inhibiting further microbial growth. In addition to

its use with alcoholic beverages, cheese, and yogurt, fermentation is used to produce yeast bread,soy sauce, cucumber pickles, sauerkraut, and other products.


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Fermentation is the use of biological processes to make products. Its major uses are in the production and preservation of food. Fermentation is not a new process. For many centuries

fermentation has used micro-organisms to make beer, yogurt, and cheese.

The basis of the fermentation process is the conversion of glucose (sugar) to alcohol or

lactic acid by enzymes. Fermentation acts as a preservation method by producing an acid whichlowers the pH of the product, converting a perishable food into one that has a longer shelf-life,

such as fresh milk to cheese.

Addition of Sugar or Salt

The addition of large quantities of sugar inhibits the growth of micro-organisms bymaking water unavailable. Jams, marmalades and jellies use this principle in their

manufacturing. Coating food in salt or placing it in a salt solution (brine) reduces the moisturecontent of the food (i.e. it reduces the availability of water to micro-organisms). With little

moisture, micro-organism growth is retarded. However, the taste of the food may changeconsiderably.

Salting is a method for preservation of fish, meat, vegetables and fruits like tamarind, raw

mango, lemon, goose berries, bitter gourd, green chilies etc. The high concentration of saltprevents the water from being available for bacterial growth. This is because the concentration ofsalt in the water is higher than that in the bacterial cells. Thus the cellular membrane of the

bacteria cannot absorb the water and actually it loses water.

Sun Drying

Sun drying is one of the most traditional methods of drying. It is slow and only practicalin hot, dry climates. The food may be vulnerable to contamination through pollution and vermin,

e.g. rodents and flies.

Other forms of drying foods have been developed in the food industry; these are usually

suitable for particular types of products. For example:1. Spray drying: suitable for dried milk and coffee powder. A fine spray of liquid is injected intoa blast of hot air in a chamber. Water evaporates in seconds, leaving the solid part of the product

behind in a powdered form.2. Tunnel drying: hot air is blown over a food in a tunnel, e.g. vegetable pieces.


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Dehydration

Drying has been used to preserve food by cultures throughout the world since prehistoric

times, when people learned that dried foodsfor example, fruits left out in the sunremainwholesome for long periods. In modern times, the dried foods industry greatly expanded after

World War II (1939-1945) but remains restricted to certain foods, including milk, soup, eggs,

fruits, yeast, some meats, and instant coffee, that are particularly suited to the process. Three basic methods of drying are used today: sun drying, a traditional method in which foods drynaturally in the sun; hot air drying, in which foods are exposed to a blast of hot air; and freeze-

drying, in which frozen food is placed in a vacuum chamber to draw out the water. Dried foodscan be transported easily due to its lightweight and volume. In this method vitamin C and beta-

carotene are lost mainly but the sugar and fiber concentrates. This method also causes severe lossof taste, aroma, texture etc.

PasteurizationThe process of pasteurization extends the shelf life of foods by killing most food spoiling

and pathogenic (disease-causing) organisms through the application of heat. Pasteurizationextends shelf life by several days and pasteurized products are usually stored under refrigerated

conditions, such as fresh milk. This type of product would have a use by date marked on itslabel.

Milk is pasteurized using the following process: Raw milk is fed into the plate heat exchanger. The raw milk is heated to 72C for 15 seconds. After the milk has been heated it is passed through a regenerator, which brings it into

close contact with the cold, raw milk pipe. The heat is recycled as the cold raw milk is warmed through close contact with the heated

milk. This in turn is cooled. It is strongly recommended that unpasteurized milk not bedistributed or consumed in schools.

FreezingFreezing is based on two principles:

Very low temperatures which inhibit the growth of microorganisms and retard enzymicand chemical activity.

The formation of ice crystals which draw available water away from the food, thereforepreventing the growth of microorganisms.

Blanching may be necessary to inactivate the enzymes that cause browning.In a domestic situation, food is frozen by placing it in a freezer and allowing heat transfer

to occur by conduction (i.e. the removal of heat from the food). This process can take severalhours, depending on the nature of the food being frozen.

Other forms of freezing have been developed in the food industry to speed-up the freezingtime. This ensures that products are frozen in the shortest time possible, reducing the risk of

micro-organism growth. Three methods are: Blast freezing: Batches of food are subjected to a constant, steady stream of cold air (-40

degrees Celsius or lower) in a tunnel or cabinet. Scraped heat exchange: Products such as ice cream are frozen using this method to

reduce the formation of large ice crystals. The product is scraped against a cooled surfaceand then immediately scraped away.


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Cryogenic freezing: Liquid nitrogen or carbon dioxide issprayed directly onto small fooditems such as soft fruits or prawns. Due to these liquids extremely low temperatures (-

196C and -78C respectively), freezing is almost instantaneous.

Refregeration

Low-temperature storage as a preservation method probably began when prehistoric

humans stored meat and other foods in ice caves. However, mechanical refrigeration and large-scale freezing are relatively recent innovations.Storage at low temperature slows many of the enzymatic reactions involved in spoilage

and reduces the growth rate of microorganisms (though it does not kill them). To minimizemicrobial growth, refrigerators should be kept at 0 to 4 C (32 to 40 F) and freezers at or

below 0 C (32 F). Refrigeration is advantageous because it does not cause chemical or physicalchanges to food. Freezing allows foods to be stored for longer periods than refrigeration because

it inhibits enzyme activity and microbial growth to a greater degree.Foods that should be refrigerated include meats, fish, eggs, milk, some fruits, and some

vegetables. Many of these foods can also be frozen. Frozen produce is often high in quality andcan rival the flavor of fresh. In many cases, produce frozen and stored under proper conditions

contains more nutrients than produce picked unripened and allowed to mature duringtransportation. Briefly cooking vegetables in boiling water before freezing, a process known as

blanching, inactivates enzymes altogether and reduces discoloration and nutrient loss.Refrigeration works on the principle that bacterial and enzymatic activities are minimal

at low temperatures. Foods should be placed in the refrigerator as quickly as possible and itshould be covered. This will also prevent foods from acquiring the flavor of the other foods.

Whole fruits and vegetables can be wrapped in brown paper or newspaper to keep freshfor a longer period. Hot foods must be allowed to cool to room temperature before they are

placed in the refrigerator. Top shelves maintain a lower temperature than the bottom ones soeasily perishable foods such as milk must be kept in the upper shelves where as curd, vegetables,

and fermented batters can be placed in the lower shelves. If cooked foods have been lying atroom temperature for a long time they should be heated again and cooled at room temperature

before they are placed in refrigerator. When vegetables are brought in bulk they take up a lot ofspace in the refrigerator for short-term preservation. The vegetables can be cleaned and cut and

kept in closed containers. Tomatoes can be blanched, crushed boiled a little and packed in bottlesand can be stored.

Use of AcidsW

hen the medium in which the food is preserved is strongly acidic, most organismscannot survive. The use of acetic acid (vinegar) and citric acid (lime juice) is commonpreservatives used in household. These are used in pickles, sauces, ketchup, fruit squashes etc.

Pasteurization involves heating foods to a certain temperature for a specific time to killharmful microorganisms. Milk, wine, beer, and fruit juices are all routinely pasteurized. Milk, for

example, is usually heated to 63 C (145 F) for 30 minutes. Ultra-High Temperature (UHT) pasteurization, a relatively new technique, is used to sterilize foods for aseptic packaging. In


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UHT pasteurization, foods are heated to 138 C (280 F) for 2 to 4 seconds, allowing the food toretain more nutrients and better flavor.

SterilisationThe process of sterilization uses a combination of high temperature and time to destroy

nearly all micro-organisms in food. This process is more severe than pasteurization, and can

sometimes affect the appearance and taste of the food. This is important as some micro-organisms can form spores which have the ability to survive at high temperatures. If the correcttemperature is not reached there is the possibility that the spores will germinate and grow and

food poisoning could result. Some organisms can survive the sterilization process if notprocessed for enough time or at a high enough temperature, e.g. clostridium botulinum.

Food products that have been sterilized have a very long shelf life and are stored atambient (room) temperature, e.g. canned ham or long-life milk. These types of products would

have a best before date mark on the label.

Canning

Canning is used to preserve a wide variety of foods, including soups, sauces, fruits,vegetables, juices, meats, fish, and some dairy products. Canning preserves food by heating it in

airtight, vacuum-sealed containers. The can is filled with food, and air is pumped out of thespace remaining at the top of the can to form a vacuum. The container is sealed, heated in a

cooker called a retort, and then cooled to prevent overcooking of the food inside. This processremoves oxygen, destroys enzymes involved in food spoilage, and kills most microorganisms

that may be present in the food.

The basic stages of canning are:

Filling the cans with product Sealing the cans Washing the cans Sterilizing the cans Cooling the cans


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Food products that have been canned have very long shelf life and are stored at ambient(room) temperature, e.g. canned baked beans. Canned products would have a best before date

mark on the label.

Irradiation

The process of irradiation is the process of exposing food to carefully controlled amount

of ionizing energy. Irradiation is a process in which food is passed through a chamber where it isexposed to gamma rays or x rays. These high-energy rays are strong enough to break chemicalbonds, destroy cell walls and cell membranes, and break down deoxyribonucleic acid (DNA), the

substance that carries genetic information in all cells.Irradiation kills most bacteria, molds, and insects that may contaminate food. Irradiation

also delays the ripening of fruits and sprouting of vegetables, permitting produce to be stored forlonger periods of time.

Irradiation is used to: Inhibit sprouting of vegetables Delay ripening of fruits Reduce numbers of micro-organisms which cause food spoilage or poisoning, e.g.

salmonella in poultry and Escherichia coli O157:H7 in red meat

Modified Atmosphere Packaging

Modified Atmosphere Packaging is the enclosure of food in a package in which theatmosphere has been changed by altering the proportions of carbon dioxide, oxygen, nitrogen,

water vapor and trace gases. The process retards microbial and biochemical activity. Productssuch as bacon, red meat, poultry, vegetables and bakery products use this method to increase

shelf life by retarding micro-organism growth.

Fruits and vegetables are sometimes stored in sealed warehouses where temperature andhumidity are closely controlled, and perhaps most importantly, the composition of gases in the

atmosphere is altered to minimize spoilage. Usually, the concentration of oxygen is reduced, the

concentration of carbon dioxide is increased, and ethylene, a gas naturally produced by plantsthat accelerates ripening, is removed from the atmosphere.

Aseptic Packaging

Aseptic packaging is now commonly used for packaging milk and juice. Like canning,aseptic packaging involves heat sterilization of food, but unlike canning, the package and food

are sterilized separately. Food can be sterilized more rapidly and at lower temperatures in aseptic packaging than in canning, allowing the food to retain more nutrients and better flavor.

Containers are sterilized with hydrogen peroxide rather than with heat, permitting the use of


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plastic bags and foil-lined cartons, which would be destroyed by heat sterilization. Thesecontainers cost less than the metal and glass containers used in canning and also weigh less,

reducing transport costs. Aseptically packaged foods will keep without refrigeration for longperiods of time, perhaps even years. They are growing in popularity because of their low cost,

good taste and nutrition, and convenience

AdditivesFood additives are any substances added to food. Sugar, salt, and corn syrup are the mostcommonly used food additives. Food additives keep foods fresh, slow microbial growth, give

desired texture and appearance, and aid in processing and preparationFood additives are chemicals that are added to food in small amounts. Direct additives

are added deliberately during processing to make food look and taste better, maintain or improvenutritive value, maintain freshness, and help in processing or preparation. Some additives help

preserve food by preventing or slowing chemical changes and the growth of microorganisms infood. As many as 3000 substances are approved by the Food and Drug Administration (FDA) for

use as direct additives. An additional 10,000 substances are present in foods as indirect additives.These substances enter food incidentally during handling or from processing equipment or

packaging.The development of new chemical additives has also played an enormous role in the

growth of convenience foods. Additives that help ensure the quality of convenience foodsinclude anticaking agents, such as calcium silicate and magnesium stearate, to prevent lumps in

dry mixes; humectants, such as glycerol, propylene glycol, and sorbitol, to help retain moisturein breads and cakes; emulsifiers, such as egg yolk, lecithin, and monoglycerides, which bind oil

and water to improve the uniformity and smoothness of foods; and stabilizers and thickeners,such as guar gum, carrageenan, and gelatin.

As the use of food additives has grown, so has public concern about the type and amountof these additives and their potential to cause cancer or other illnesses in human beings. Some

studies have suggested that saccharin, nitrites, and other additives may cause cancer, but theseresults remain controversial.

At the same time, some additives may actually provide a health benefit. For example, thevitamins used to fortify foods such as bread and milk are additives.

Food PackagingRegardless of the processing or preservation method used, proper packaging of food is

essential to make sure the food remains wholesome during its journey from processor toconsumer. Packaging contains food and makes it easier to handle, and protects it from

environmental conditions, such as temperature extremes, during transport. It locks outmicroorganisms and chemicals that could contaminate the food, and helps prevent physical and

chemical changes and maintain the nutritional qualities of food. For example, milk is often storedin opaque containers to prevent vitamins from being destroyed by light.


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Both the type of food and the processing method used affect the choice of packaging. Forexample, since oxygen makes fats go rancid, oils are packaged in containers that are

impermeable to oxygen. On the other hand, oxygen-permeable plastic wraps allow fruits andvegetables to breathe and ensure that meats will maintain a vibrant red color. Metal and glass

containers have traditionally been used in canning because these materials can withstand the high

temperatures and changes in pressure that are involved in this processing method.Main food preservation methodsMethod Effect on microbial growth or survival

Refrigeration or chilling Low temperature to retard growth Freezing Low temperatureand reduction of water activity to prevent growth.Drying, curing and conserving Reduction in

water activity sufficient to delay or prevent growth Vacuum and oxygen free modified atmosphere packaging Low oxygen tension in inhibit strict aerobes and delay growth of facultive anaerobes Carbon dioxide enriched modified atmosphere packaging Specific inhibition of some micro-organisms by carbon dioxide Addition of acids Reduction of pH value and sometimes additional inhibition by the

particular acid Lactic fermentation Reduction of p H value in situ by microbial action and sometimesadditional

inhibition by the lactic and acetic acids formed and by other microbial products ''e.g.ethanol, bacteriocins

Emulsification Compartmentalisation and nutrient limitation within the aqueous dropletsin water-in-oil emulsion foods

Addition of preservatives Inhibition of specific groups of micro-organisms Pasteurization and appertization Delivery of heat sufficient to inactivate target micro-

organisms to the desired extent

Radurization, radicidation and radappertization Delivery of ionising radiation Application of high hydrostatic pressure Pascalization Pressure-inactivation of vegetative bacteria, yeasts and moulds steel with various

coatings to resist corrosion. Beverage cans are made of aluminum because it islightweight and easy to manufacture.

In addition to metal, glass is often used for packaging heatsterilized foods. Glass isimpermeable to oxygen and water and does not change the flavor of food. Another advantage of

glass is that it is transparent, enabling the consumer to see the product inside. However, glass isnot impact-resistant and is relatively heavy.

Plastic, by contrast, is lightweight and unbreakable, and it has become an extremelycommon material for use in food packaging. Most plastics used in food packaging are heat

resistant so that they can go through high-temperature sterilization processes. Plastic is made intoa wide variety of shapes, including bottles, jars, trays, and tubs, as well as thin films that are used

as bags and wraps.

Quality Standard logo imply that it is British pork.

Food packaging is packaging for food. It requires protection, tampering resistance, andspecial physical, chemical, or biological needs. It also shows the product that is labeled to show

any nutrition information on the food being consumed.


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Functions of food packaging

Packaging has several objectives:

Physical protection - The food enclosed in the package may require protection from, amongother things, shock, vibration, compression, temperature, etc.

Barrier protection - A barrier from oxygen, water vapor, dust, etc., is often required.P

ermeation is a critical factor in design. Some packages contain desiccants or Oxygen absorbersto help extend shelf life. Modified atmospheres or controlled atmospheres are also maintained insome food packages. Keeping the contents clean, fresh, and safe for the intended shelf life is a

primary function.Containment or agglomeration - Small items are typically grouped together in one package for

reasons of efficiency. powders, and granular materials need containment.Information transmission - Packages and labels communicate how to use, transport, recycle, or

dispose of the package or product. Some types of information are required by governments.Marketing - The packaging and labels can be used by marketers to encourage potential buyers

to purchase the product. Package design has been an important and constantly evolvingphenomenon for several decades. Marketing communications and graphic design are applied to

the surface of the package and (in many cases) the point of sale display.Security - Packaging can play an important role in reducing the security risks of shipment.

Packages can be made with improved tamper resistance to deter tampering and also can havetamper-evident features to help indicate tampering. Packages can be engineered to help reduce

the risks of package pilferage: Some package constructions are more resistant to pilferage andsome have pilfer indicating seals. Packages may include authentication seals to help indicate that

the package and contents are not counterfeit. Packages also can include anti-theft devices, suchas dye-packs, RFID tags, or electronic article surveillance tags, that can be activated or detected

by devices at exit points and require specialized tools to deactivate. Using packaging in this wayis a means of retail loss prevention.

Convenience - Packages can have features which add convenience in distribution, handling,stacking, display, sale, opening, reclosing, use, and reuse.

Portion control - Single serving packaging has a precise amount of contents to control usage.Bulk commodities (such as salt) can be divided into packages that are a more suitable size for

individual households. It also aids the control of inventory: selling sealed one-liter-bottles ofmilk, rather than having people bring their own bottles to fill themselves.

Food packaging typesThe above materials are fashioned into different types of food packages and containers such as:

Packaging typeType of

containerFood examples

Asepticprocessings

Primary Liquid whole eggs

Plastic trays Primary Portion of fishBags Primary Potato chips

Boxes Secondary Box of Coca-Cola

Cans Primary Can of Campbell's Tomato soup.

Cartons Primary Carton of eggs

Flexible

packaging Primary Bagged salad


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Pallets TertiaryA series of boxes on a single pallet used to transport from the

manufacturing plant to a distribution center.

Wrappers Tertiary Used to wrap the boxes on the pallet for transport.

Primary packaging is the main package that holds the food that is being processed.Secondary packaging combines the primary packages into one box being made. Tertiary

packaging combines all of the secondary packages into one pallet.There are also special containers that combine different technologies for maximum

durability:Bags-In-Boxes (used for soft drink syrup, other liquid products, and meat products)

Wine box (used for wine)

Packaging machines

A choice of packaging machinery includes technical capabilities, labor requirements,worker safety, maintainability, serviceability, reliability, ability to integrate into the packaging

line, capital cost, floorspace, flexibility (change-over, materials, etc.), energy usage, quality ofoutgoing packages, qualifications (for food, phamaceuticals, etc.), throughput, efficiency,

productivity, ergonomics, etc.

Packaging machines may be of the following general types: Blister, Skin and Vacuum Packaging Machines Capping, Over-Capping, Lidding, Closing, Seaming and Sealing Machines Cartoning machines Case and Tray Forming, Packing, Unpacking, Closing and Sealing Machines Check weighing machines Cleaning, Sterilizing, Cooling and Drying Machines Conveying, Accumulating and Related Machines Feeding, Orienting, Placing and Related Machines Filling Machines: handling liquid and powdered products Package Filling and Closing Machines

Form, Fill and Seal Machines Inspecting, Detecting and Checkweighing Machines Palletizing, Depalletizing, Pallet Unitizing and Related Machines Product Identification: labelling, marking, etc. Wrapping Machines Converting Machines Other speciality machinery

Reducing Food PackagingReduced packaging and sustainable packaging are becoming more frequent. The

motivations can be government regulations, consumer pressure, retailer pressure, and costcontrol. (Reduced packaging often saves packaging costs.)

[2]

In the UK, A Local Government Association survey produced by the British Market ResearchBureau, compared a range of outlets to buy 29 common food items, found that small local

retailers and market traders "produced less packaging and more that could be recycled than thelarger supermarkets.

Biodegradable PackagingPlastic packaging being used is non biodegradable as it causes ecological imbalance and

aesthetic deterioration of nature. There is, therefore, great need to develop environment friendlybiodegradable packaging materials which do not cause environmental pollution. Biodegradable


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packaging materials neither promote any waste disposal problems nor affect the trade and safetyof the food product.

Agitators / Blenders / Mixers Boilers Cleaning / CIP Equipment

Material Handling Evaporators & Dryers FILLERS

Heat Exchangers / HTST Pulpers and Finishers Homogenizers

Packaging Pumps Refrigeration

Size Reduction Stainless Tanks

Sweco 60 stainless steel screen

Unused sanitary double ribbonmixers

BinBlancherBlowerBoilerBreaderCan CloserCap SorterCase Sealer &

GluerCarbo CoolerCartonerCase TaperCaserCentrifugeChillerChopperCIP SystemCoaterCoating PanCompactorCompressorConveyor

CookerCooker/CoolerCoolerCrimperCutterDe-DusterDepositor

DetectorDicerDryerDumperDust CollectorEncrusterEvaporatorExpeller

ExtructorExtruderFeederFillerFilling LineFilterFlakerFryerGeneratorGranulatorGrinderHeat ExchangerHomogenizerHopper

KettleLabelerLidderMetal DetectorMillMixer

OvenPasteurizerPeelerPelletizerPressPrinterPulperRoaster

PumpRefrigerationScaleScreenSheeterShredderSlicerSmoke HouseStufferTankTenderizerTunnelUnloaderValve

VotatorWasherWater TreatmentWrapper


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Waste water treatment:Industrial wastewater treatment covers the mechanisms and processes used to treat waters

that have been contaminated in some way by anthropogenic industrial or commercial activitiesprior to its release into the environment or its re-use.

Most industries produce some wet waste although recent trends in the developed world

have been to minimise such production or recycle such waste within the production process.However, many industries remain dependent on processes that produce wastewaters.

Food industry

Wastewater generated from agricultural and food operations has distinctivecharacteristics that set it apart from common municipal wastewater managed by public or private

wastewater treatment plants throughout the world: it is biodegradable and nontoxic, but that hashigh concentrations of biochemical oxygen demand (BOD) and suspended solids (SS). The

constituents of food and agriculture wastewater are often complex to predict due to thedifferences in BOD and pH in effluents from vegetable, fruit, and meat products and due to the

seasonal nature of food processing and postharvesting.

Processing of food from raw materials requires large volumes of high grade water.Vegetable washing generates waters with high loads of particulate matter and some dissolvedorganics. It may also contain surfactants.

Animal slaughter and processing produces very strong organic waste from body fluids,such as blood, and gut contents. This wastewater is frequently contaminated by significant levels

of antibiotics and growth hormones from the animals and by a variety of pesticides used tocontrol external parasites. Insecticide residues in fleeces is a particular problem in treating waters

generated in wool processing.

Processing food for sale produces wastes generated from cooking which are often rich in

plant organic material and may also contain salt, flavourings, colouring material and acids oralkali. Very significant quantities of oil or fats may also be present.

Water treatmentWater treatment for the production of drinking water is dealt with. Many industries have

a need to treat water to obtain very high quality water for demanding purposes. Water treatment produces organic and mineral sludges from filtration and sedimentation. Ion exchange using

natural or synthetic resins removes calcium, magnesium and carbonate ions from water,replacing them with hydrogen and hydroxyl ions. Regeneration of ion exchange columns with

strong acids and alkalis produces a wastewater rich in hardness ions which are readilyprecipitated out, especially when in admixture with other wastewaters.


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Treatment of industrial wastewaterThe different types of contamination of wastewater require a variety of strategies to

remove the contamination.

Solids removal

Most solids can be removed using simple sedimentation techniques with the solids

recovered as slurry or sludge.V

ery fine solids and solids with densities close to the density ofwater pose special problems. In such case filtration or ultrafiltration may be required. Although,flocculation may be used, using alum salts or the addition of polyelectrolytes.

Oils and grease removalMany oils can be recovered from open water surfaces by skimming devices. Considered a

dependable and cheap way to remove oil, grease and other hydrocarbons from water, oilskimmers can sometimes achieve the desired level of water purity. At other times, skimming is

also a cost-efficient method to remove most of the oil before using membrane filters andchemical processes. Skimmers will prevent filters from blinding prematurely and keep chemical

costs down because there is less oil to process.However, hydraulic oils and the majority of oils that have degraded to any extent will

also have a soluble or emulsified component that will require further treatment to eliminate.Dissolving or emulsifying oil using surfactants or solvents usually exacerbates the problem

rather than solving it, producing wastewater that is more difficult to treat.

A typical parallel plate separator

Parallel plate separators are similar to API separators but they include tilted parallel plateassemblies. The parallel plates provide more surface for suspended oil droplets to coalesce into

larger globules. Such separators still depend upon the specific gravity between the suspended oiland the water. However, the parallel plates enhance the degree of oil-water separation. The result

is that a parallel plate separator requires significantly less space than a conventional APIseparator to achieve the same degree of separation.

Removal of biodegradable organicsBiodegradable organic material of plant or animal origin is usually possible to treat using

extended conventional wastewater treatment processes such as activated sludge or trickling filter.Problems can arise if the wastewater is excessively diluted with washing water or is highly

concentrated such as neat blood or milk. The presence of cleaning agents, disinfectants,pesticides, or antibiotics can have detrimental impacts on treatment processes.

Activated sludge processA generalized, schematic diagram of an activated sludge process.

Activated sludge is a biochemical process for treating sewage and industrial wastewaterthat uses air (or oxygen) and microorganisms to biologically oxidize organic pollutants,

producing a waste sludge (or floc) containing the oxidized material. In general, an activatedsludge process includes:

An aeration tank where air (or oxygen) is injected and thoroughly mixed into the wastewater.A settling tank (usually referred to as a "clarifier" or "settler") to allow the waste sludge to settle.

Part of the waste sludge is recycled to the aeration tank and the remaining waste sludge isremoved for further treatment and ultimate disposal.

Trickling filter processImage 1: A schematic cross-section of the contact face of the bed media in a trickling filter

A typical complete trickling filter system


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Prof Dr B ANNADURAI M Sc Ph D D H Ed FLS SBC(I)

A trickling filter consists of a bed of rocks, gravel, slag, peat moss, or plastic media overwhich wastewater flows downward and contacts a layer (or film) of microbial slime covering the

bed media.Aerobic conditions are maintained by forced air flowing through the bed or bynatural convection of air. The process involves adsorption of organic compounds in the

wastewater by the microbial slime layer, diffusion of air into the slime layer to provide the

oxygen required for the biochemical oxidation of the organic compounds. The end productsinclude carbon dioxide gas, water and other products of the oxidation. As the slime layerthickens, it becomes difficult for the air to penetrate the layer and an inner anaerobic layer is

formed.

Treatment of other organics

Synthetic organic materials including solvents, paints, pharmaceuticals, pesticides,coking products and so forth can be very difficult to treat. Treatment methods are often specific

to the material being treated. Methods include Advanced Oxidation Processing, distillation,adsorption, vitrification, incineration, chemical immobilisation or landfill disposal. Some

materials such as some detergents may be capable of biological degradation and in such cases, amodified form of wastewater treatment can be used.

Treatment of acids and alkalisAcids and alkalis can usually be neutralised under controlled conditions. Neutralisation

frequently produces a precipitate that will require treatment as a solid residue that may also betoxic. In some cases, gasses may be evolved requiring treatment for the gas stream. Some other

forms of treatment are usually required following neutralisation.

Waste streams rich in hardness ions as from de-ionisation processes can readily lose the

hardness ions in a buildup of precipitated calcium and magnesium salts. This precipitation process can cause severe furring of pipes and can, in extreme cases, cause the blockage of

disposal pipes. A 1 metre diameter industrial marine discharge pipe serving a major chemicalscomplex was blocked by such salts in the 1970s. Treatment is by concentration of de-ionisation

waste waters and disposal to landfill or by careful pH management of the released wastewater.

Treatment of toxic materials

Toxic materials including many organic materials, metals (such as zinc, silver, cadmium,thallium, etc.) acids, alkalis, non-metallic elements (such as arsenic or selenium) are generally

resistant to biological processes unless very dilute. Metals can often be precipitated out bychanging the pH or by treatment with other chemicals. Many, however, are resistant to treatment

or mitigation and may require concentration followed by land filling or recycling. Dissolvedorganics can be incinerated within the wastewater by Advanced Oxidation Process.

lec 5.the science of food processing

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