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CHEESE PRODUCTION

Cheese production

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Page 1: Cheese production

CHEESE PRODUCTION

Page 2: Cheese production

INTRODUCTION-ETYMOLOGY

Word ‘cheese’ – Latin “casues”, meaning to ferment/become sour

HOW OLD IS THE CHESE YOU ENJOY? Gorgonzola 879 AD. Roquefort 1070 Grana 1200 Cheddar 1500 Gouda 1697 Gloucester 1697 Stilton 1785 Camembert 1791

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INTRODUCTION Ultimately a milk product Widely used all over the world as

food product Purely a product of microbial

fermentation Flavor and aroma changes depending

upon the microorganism being used. Before long, people learned that

curds can be aged for over weeks and months and then pressed together to form large cakes of cheese.

The art of cheese making have traveled from Asia to the Europe and then spread all over the world

CHEDDAR CHEESE

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DISCOVERY Though it is not certain that who made the first

cheese but it is certain that it was accidental. Nomadic tribes of Central Asia are considered to

be the legends who “discovered” cheese. Carried milk in saddlebags that made from animal

skin probably from the stomach, which contains the coagulating enzyme known as rennin

Fermentation and curdling would have happened due to the galloping motion of the horse

Effective separation of milk into curds and whey. Whey had been used as an energy drink and curd

was drained in perforated earthenware bowls and slightly salted to have a highly proteinaceous food.

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Saddlebags

Earthenware bowl

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Valued for portability, long life, and high content of fat, protein, calcium, and phosphorus.

More compact than milk- longer the shelf life. Hard cheeses last more than soft cheeses

Eg: Cheddar cheese Made from raw milk. Since it is not pasteurized,

higher vitamin contents. Salmonella, Mycobacterium and Brucella are

the pathogens that might have seen in raw milk. U.S Federal Law- the cheese made from raw

milk should be aged for over 60 days to prevent the development of pathogens.

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DIFFERENT TYPES

Roquefort Cheese

Camembert Cheese

Brie

Swiss cheese

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Gorgonzola

Gouda

Stilton

Grana

Gloucester

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Cheese is completely a milk product. Whole milk- compressed, processed and stored to

produce cheese. Wide range of cheese can be produced in

countries where milk is legally allowed to process without pasteurization.

In most of the countries the range of cheeses is smaller because of this reason

Whey is a byproduct of cheese production Like most of other fermented food products such

as beer, wine, etc. cheese also can be stored for longer periods, say years.

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PRINCIPLES OF CHEESE PRODUCTION

Cheese – a way of storing milk over years Nowhere near as big as the market for cow’s

milk cheese, considerable amount of cheese is made from other milk such as goat and sheep.

Cheese – by coagulating milk (separating curd and whey)

Both raw milk and pasteurized milk can be used for cheese making.

Needs more rennet (up to twice) for homogenized milk than the raw milk.

This milk produces a curd that is smoother and less firm than that of raw milk, so most people add calcium chloride to the cheese

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CHEESE MANUFACTURE

The manufacture of most cheeses involves the followingPasteurization Kills nearly all microorganisms including pathogens that cause diseases and other undesirable organisms such as yeasts and coliforms (may alter the characteristics by producing CO2z and undesirable proteolysis)Regular HTST pasteurization at 72-730C for 15-20 seconds is commonly applied.Spore forming bacteria Clostridium tyrobutyricum can survive pasteurization and produces butyric acid and large volumes of hydrogen gas by fermenting lactic acid, which will destroy the structure of cheese.Chemical inhibitors such as NaNO3 or H2O2 can be used but in several countries, it has been banned and mechanical modes have been preferred.

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Bactofugation Process in which a specially designed centrifuge-

bactofuge is been used to separate the bacteria and spores that present in milk.

Efficient way of reducing the number of spores in milk since their specific gravity is lesser than that of milk.

Normally separate milk into a fraction which is more or less free from bacteria and a concentrate which contains both spores and bacteria.

Example- spore load in cream by Bacillus cereus is reduced.

Typically 60-630C is the temperature applied in Bactofugation

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BACTOFUGE

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Microfiltration A membrane filter with a pore size of

approximately 0.2 micron can filter bacteria from a water solution

Most of the fat globules and some of the proteins are as large as, or larger than, the bacteria.

This results in the filter fouling very quickly when membranes of such a small pore size are chosen.

In practice, membranes of a pore size of 0.8 to 1.4 micron are chosen to lower the concentration of protein.

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In addition, the protein forms a dynamic membrane that contributes to the retention of micro-organisms.

Provides an indirect sterilization Due to the high bacteria-reducing efficiency,

microfiltration allows production of hard and semi-hard cheese without any need for chemicals to inhibit growth of Clostridia spores.

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Additives in cheese milk The essential additives in the cheese making

process are the starter culture and the rennet Under certain conditions it may also be necessary

to supply other components such as calcium chloride (CaCl2) and saltpetre (KNO3 or NaNO3)

An enzyme, lysozyme, has also been introduced as a substitute for saltpetre as an inhibitor of Clostridia organisms

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StarterTwo principal types of culture are used in cheese

making: Mesophilic cultures with a temperature optimum

between 20 and 40°C Thermophilic cultures which develop at up to

45°C. The most frequently used cultures are mixed strain

cultures, in which two or more strains of both mesophilic and thermophilic bacteria exist in symbiosis

These cultures not only produce lactic acid but also aroma components and CO2.

Carbon dioxide is essential for creating the eyes in round-eyed and granular types of cheese

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Three characteristics of starter cultures are of primary importance in cheese making

1. ability to produce lactic acid2. ability to break down the protein3. ability to produce carbon dioxide (CO2).

Calcium chloride (CaCl2 ) If the milk is of poor quality for cheese making, the

coagulum will be soft. This results in heavy losses of fines (casein) and fat

as well as poor syneresis during cheese making. 5 – 20 grams of calcium chloride per 100 kg of milk

is normally enough to achieve a constant coagulation time and result in sufficient firmness of the coagulum.

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For production of low-fat cheese, and if legally permitted, disodium phosphate (Na2PO4), usually 10 – 20 g/kg, can sometimes be added to the milk before the calcium chloride is added.

This increases the elasticity of the coagulum due to formation of colloidal calcium phosphate, which will have almost the same effect as the milk fat globules entrapped in the curd.

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Carbon dioxide (CO2 )

Addition of CO2 is one method of improving the quality of cheese milk.

Carbon dioxide occurs naturally in milk, but most of it is lost in the course of processing

Adding carbon dioxide by artificial means lowers the pH of the milk: the original pH is normally reduced by 0.1 to 0.3 units.

This will then result in shorter coagulation time. The effect can be utilized to obtain the same

coagulation time with a smaller amount of rennet

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Rennet All cheese manufacture depends upon formation

of curd by the action of rennet or similar enzymes except in cottage cheeses.

Coagulation of casein is the fundamental process in cheese making.

It is generally done with rennet, but other proteolytic enzymes can also be used.

The active principle in rennet is an enzyme called chymosin, and coagulation takes place shortly after the rennet is added to the milk.

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The two major processes occurs after the addition of rennet are1. Transformation of casein to paracasein under

the influence of rennet2. Precipitation of paracasein in the presence of

calcium ions The whole process is governed by the

temperature, acidity, and calcium content of the milk as well as other factors

The optimum temperature for rennet is in the region of 40°C, but lower temperatures are normally used in the practice, basically to avoid excessive hardness of the coagulum

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Rennet is extracted from the stomachs of young calves and marketed in form of a solution with a strength of 1:10000 to 1:15 000, which means that one part of rennet can coagulate 10000 – 15000 parts of milk in 40 minutes at 35°C.

Bovine and porcine rennet are also used, often in combination with calf rennet (50:50, 30:70, etc.).

Rennet in powder form is normally 10 times as strong as liquid rennet.

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Diagram showing the action of rennet on the casein micelle. The enzyme in rennet cleaves the casein releasing a large peptide. The surface of the micelle changes from being hydrophilic and negatively charged to hydrophobic and neutral. As a consequence, the micelles aggregate to trap fat globules and microorganisms in developing curd.

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Substitutes for animal rennet Found substitutes for animal rennet about 50

years ago, concerning the vegetarians in India, Israel and the Middle East who refused to accept the cheese with animal rennet.

Use of porcine rennet is out of the question in Muslim world, also was a reason to find substitute for animal rennet.

In recent years the quality of the animal rennet is a concern which also is a reason.

There are two main types of substitute coagulants

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1. Coagulating enzymes from plants and,2. Coagulating enzymes from microorganisms Coagulation ability is best shown by plant enzymes,

but the cheese will be having a bitter taste during storage.

Enzymes from thistle or cynara are used in some traditional cheese production in the Mediterranean

Phytic acid, derived from unfermented soybeans, or Fermentation-Produced Chymosin (FPC) may also be used

Today, the most widely used Fermentation-Produced Chymosin (FPC) is produced either by the fungus Aspergillus niger or Kluyveromyces lactis

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Acid coagulation Any soft cheeses are produced without use of

rennet, by coagulating milk with acid, such as citric acid or vinegar, or the lactic acid produced by soured milk.

Cream cheese, paneer, and rubing are traditionally made this way

The acidification can also come from bacterial fermentation such as in cultured milk

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CHEESEMAKING

A: vat during stirring

B: vat during cutting

C: vat during whey drainage

D: vat during pressing

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Disturbances in cultures Slow rate of production of lactic acid or failure to

produce lactic acid. Antibiotics used to cure udder diseases. Bacteriophages, thermo-tolerant viruses found in

the air and soil. Detergents and sterilising agents used in the

dairy.

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Acidification Important for the proper release of curd from whey, and to control the growth of undesirable bacteria

Achieved by the addition of lactic acid bacteria that convert lactose to lactic acid.

Such, carefully selected culture of lactic acid producing bacteria is called “starter”, without which cheese cannot be made.

New Zealand Diary Research Institute- an agency which identifies and distributes special starter cultures in deep frozen form to different cheese plants.

The starter will be added to the homogenized milk for culturing in large volumes and the temperature will be set to 220C, ideal for the growth of starter.

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Fermentation continues for about 6 to 16 hours. Amount of starter varies with the variety of

cheese to produce. The amount of lactic acid produced and the

moisture in the finished cheese regulate and control the biochemical activities that takes place during the maturation/ripening of the cheese.

Coagulation of casein The pH is lowered and rennet is added Rennet- extracted from the stomach of calves;

chymosin and bovine pepsin are active components.

Chymosin- responsible for the coagulation of casein (curdling), gives the curd a smooth texture

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About 30 ml of rennet is enough for a 100 liters of milk, to yield 10 kg of cheese and 90 L of whey.

Most of the chymosin is removed with whey Chymosin can also be produced by genetically

modified yeasts and bacteria, but such chymosin is not preferred in Sweden

Some fungi produced proteases can also be used which have similar function as that of chymosin.

Since this enzyme has some other functional characteristics compared to animal chymosin, used only in certain circumstances (for “vegetarian” cheeses)

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The milk has to set for about 30 minutes after the rennet has been added.

The milk coagulum is cut into cubes with special tools.

The size of the cubes differs depending on the kind of cheese being made.

Rennet- partial proteolysis of casein by cleavage at the Phe105-Met106 .

A rennet coagulum consists of a continuous matrix of strands of casein micelles, which incorporate fat globules, water, minerals and lactose and in which microorganisms are entrapped

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Syneresis Syneresis, or shrinking, of the coagulum is

largely the result of continuing rennet action. It causes loss of whey, and is accelerated by

cutting, stirring, cooking, salting or pressing the curd, as well as the increasing amount of acid produced by the starter, and gradually increases during cheese making.

As a result, the cheese curd contracts and moisture is continuously expelled during the cooking stages.

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Salting Salt is added to cheese as a preservative and because

it affects the texture and flavour of the final cheese by controlling microbial growth and enzyme activity.

The salt can be added either directly to the curd after the whey is run off and before moulding or pressing into shape,

Also can immerse the shaped cheese block in a salt brine for several days following manufacture.

Addition of salt to the cut curd draws more whey from the cheese curd and some of the salt diffuses into the curd.

The pH of the curd, the contact time and the salt particle size and structure are all important in determining how much salt is absorbed by the curd.

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Curd ManipulationHeat treatments The application of heat to cheese curd at any of

several different times during the manufacture of particular cheese varieties, such as Cheddar, Mozzarella or Emmentaler, is to selectively stop the growth of certain types of bacteria and consequently influence the maturation pathway of the cheeses

It also alters the composition and texture of the cheese by increasing the syneresis without increasing the acidity.

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Stretching the curd Stretching the curd is an important operation for

several kinds of cheese, in particular the pasta filata style, Mozzarella being the best known.

Traditionally the curd was immersed in hot (about 800C) water, and the fluid mass of cheese was pulled into strands to align the protein fibers and then poured into a container to cool.

It was then immersed in brine Large scale production means that special

machines are used for stretching.

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Pasta filata style Mozarella

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Cheddaring Cheddaring is a mild form of stretching in which

the cheese curd is piled up and held warm so that water flows under the force of gravity.

The pH of the curd falls during this process and whey continues to exude.

Again, in large scale manufacture, this is done in large machines

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Washing Washing the curd either in the cheese vat or after de-

wheying helps remove more lactose which changes the pH of the cheese.

It also reduces syneresis and is important in the manufacture of cheeses such as Colby, Gouda and Egmont.

Moulding The formation of the final cheese shape into spheres,

flattened spheres, discs, cylinders or rectangular blocks is traditional but for some varieties, e.g. Camembert, it affects the maturation pathway.

Some cheeses are pressed in moulds (nowadays made of plastic or stainless steel) under the whey for a short time whereas others are compressed at high pressures for several hours.

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Moulding

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Maturation or ripening  Cheese ripening is basically about the

breakdown of proteins, lipids and carbohydrates (acids and sugars) which releases flavour compounds and modifies cheese texture. 

Ripening varies from nil for fresh cheese to 5 years for some hard ripened cheese.

Like a good wine, a good aged cheese should get better and better with age.

Ripening processes are broadly classified as interior and surface ripened.

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Cheese which depend mainly on interior ripening (most hard ripened cheese such as Cheddar and Italian types) may be ripened with rind formation or may be film wrapped before curing. 

In the broadest terms there are three sources of cheese flavor: Flavors present in the original cheese milk, such as

natural butter fat flavor and feed flavor. Breakdown products of milk proteins, fats and

sugars which are released by microbial enzymes, enzymes endogenous to milk, and enzyme additives.

Metabolites of starter bacteria and other microorganisms. These include products from catabolism of proteins, fats and sugars.

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Flavour and texture development are strongly dependent on pH profile Composition Salting Temperature Humidity Experience

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The ripening of cheese involves three major biochemical events. Glycolysis: Lactose is metabolized to lactic acid,

which may then be catabolised (broken down into smaller molecules) to form acetic and propionic acids, carbon dioxide, esters and alcohol by the enzymes of the microorganisms in the milk, including the added starter.

Lipolysis: The lipids are broken down to form free fatty acids, that may then be catabolised to form ketones, lactones and esters by natural milk enzymes and those that are added to create the flavour in particular cheese varieties, e.g. Romano, Blue Vein and Feta cheese.

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Proteolysis: Proteins (caseins) are gradually broken down to form peptides and amino acids by the enzymes of the coagulant, the natural milk enzymes and the enzymes of the starter bacteria and other added microorganisms,

e.g. moulds such as Penicillium camemberti used in the manufacture of Camembert and Penicillium roqueforti used in the manufacture of blue-veined cheeses such as Roquefort, Camembert and Stilton.

The enzymes of these mould species typically result in a high level of proteolysis in these cheese types

The rind formation on he cheese depends on the mold being added during ripening

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The breakdown of the proteins to peptides (proteolysis) transforms the rubbery and flavourless cheese curd into a cheese that has a desirable texture and flavour

Further proteolysis produces amino acids and the further biochemical glycolysis and hydrolysis result in the formation of amines, aldehydes, alcohols and sulphur compounds that add to the flavour of the cheese.

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Packaging Many cheeses are made and matured in large

blocks (e.g. 20 kg) and they are exported as such. When they are to be sold in supermarkets, they

are usually cut into appropriate size blocks and either shrink wrapped in an atmosphere of carbon dioxide, which dissolves into the body of the cheese.

The subsequent anaerobic environment prevents mold growth on the cheese surface.

Many cheeses, such as the Brie and Camembert, are ready for sale at maturation and are packaged in special aerating wrapping and in porous boxes.

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RIPENING CHEESES

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HEALTH ASPECTS OF CHEESE

Nutrition - There is a very high concentration of essential nutrients in cheese including high quality proteins and calcium .

There are also other elements in cheese such as phosphorous, zinc, vitamin A, riboflavin, and vitamin B12.

PREVENTS THE FOLLOWING HEALTH PROBLEMS

Cavity Prevention Cancer Prevention Weight Gain Bone Strength Osteoporosis

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REFERENCE http://www.cheesemaking.com/shared/pdf/

amandatitus.pdf http://nzic.org.nz/ChemProcesses/dairy/3D.pdf http://www.ales2.ualberta.ca/afns/courses/

nufs403/PDFs/chapter14.pdf https://www.uoguelph.ca/foodscience/cheese-

making-technology/section-e-manufacture-ripening-process-control-and-yield-efficiency/ripen-0