Milk Cheese- preparation, technology, utilization

cheese- preparation, technology, utilization

1. CHEESE Dr. Zanwar S.R. Assistant professor , MGM CFT , Gandheli FPT-238

2. Definition According to PFA rules (1976) cheese (hard cheese) means the product obtained by draining after the coagulation of milk with a harmless milk coagulating agent , under the influence of harmless bacterial cultures. Cheese shall not contain any ingredients not found in milk, except coagulating agent, sodium chloride, calcium chloride not exceeding 0.02 per cent by weight, annatto or carotene colour; and may contain certain emulsifiers and / or stabilizers, namely citric acid, sodium citrate or sodium salts of orthophosphoric acid and polyphosphoric acid not exceeding 0.2 per cent by weight; wax used for covering the outer surface should not contain anything harmful to the health. In case the wax is coloured, only permitted food colours may be used. Hard cheese shall contain not more than 43% moisture and not less than 42% milk fat on dry matter. Hard cheese may contain 0.1% sorbic acid or its sodium, potassium or calcium salts; or 0.1% of nisin .

3. Classification of cheese I. Classification based on the source of milk Most of the world's commercially available cheese is made from cow's milk, however some produce cheese from goat and sheep milk. Well-known examples include Roquefort (produced in France) and Pecorino Romano (produced in Italy) from ewe's milk.

4. II. Classification of cheese based on method of coagulation Majority of cheeses are coagulated by rennet, where the milk is converted to a gel by the action of an enzyme – Rennet . Rennet coagulated cheeses e.g . Cheddar, Gouda, Mozzarella, Swiss, Blue, Camembert. Acid-coagulated varieties, including Cottage cheese and Quark, differ from yoghurt by the fact that some moisture is removed in the form of whey, whereas yoghurt has nearly the same moisture as milk.

5. III. Classification based on Firmness (moisture content) All cheeses, whether rennet or acid set, can be classified as soft, semi-soft (semi-hard), hard, or very hard, depending on their moisture content. Categorizing cheeses by moisture content or firmness is a common practice. The lines between ‘ Soft ’, ‘ Semi-soft’ , ‘ Semi-hard’ , and ‘ Hard ’ are arbitrary. Types Moisture content Example Very hard Less than 25% Parmesan and Romano Hard 25-36% Cheddar Semi hard 36-40% Limburger Soft 40% above Cottage

6. IV. Classification based on processing Much cheese is consumed in the form of processed cheese, e.g. on cheeseburgers. Processed cheese is produced by shredding and melting young, natural cheese together with emulsifying salts into a smooth molten mass which is then cooled and molded into the shape desired.

7. V. Classification based on non-dairy ingredients used Cheese analogues: Another commercial product is analogue (or imitation cheese). Cheese analogues are cheese-like products formulated from ingredients, usually a form of casein powder known as rennet casein and a source of fat (either butterfat or usually vegetable oil). Cheese analogues are used mainly as ingredients in consumer-ready meals.

8. VI. Classification based on mold used for ripening Mold cheeses: There are three main categories of cheese in which the presence of mold is an important feature. These are soft-ripened cheeses, washed rind cheeses and blue cheeses. Soft-ripened: Soft-ripened cheeses begin firm and rather chalky in texture, but are aged from the exterior inwards by exposing them to mold. The mold may be a velvety bloom of Penicillium candida or P. camemberti that forms a flexible white crust and contributes to the smooth, runny, or gooey textures and more intense flavour of such aged cheeses.

9. Flowsheet of cheddar cheese Receiving of milk   Preheating (35-40 C)   Filteration   Standardization (Casein / Fat 0.68-0.7%)   Pasteurization (63 C for 30 min)   Addition of CaCl 2 (@ 0.01-0.03%)   Adding starter culture (Heart of cheese) (Streptococcus lactis / cremoris @ 0.5 – 1%)   Adding color (30-200 ml/1000kg of milk)   Renneting (Rennin & pepsin enzyme @ 1.3g/ 100 kg milk)   Cutting  

10. Cooking (42.5 C for 20 min)   Drainage of whey   Cheddaring ( packing+turning+piling+repiling )   Salting (1-2% for 15 min)   Dressing & Pressing   Drying (For rind formation)(2 days, 10oC, 60% RH)   Paraffining

11. Procedure 1. Standardization of milk : Milk is standardized before cheese making to optimize the protein to fat ratio to obtain good quality cheese with high yield. The ratio of casein to fat (C/F) 0.68-0.7 determines cheese composition in terms of the amount of fat in the total solids (TS) portion of cheese, i.e. fat-in-dry matter (FDM). 2. Pasteurization of milk: The cheese milk is subjected to mild pasteurization (63 C for 30 min) (72-74 C/15 sec.) to reduce the number of spoilage organisms. It inactive heat labile enzymes, and improve the environment for the starter cultures to grow 3. Addition of calcium salt : In addition to milk solids, calcium chloride (@ 0.01-0.02% by wt.) may be added to milk to enhance enzymatic milk clotting. 4. Adding starter : Milk is cooled after pasteurization to about 90°F (32°C) and then inoculated with starter culture (Streptococcus lactis / cremoris @ 0.5 – 1%). The milk is left at such temperature for 30-40 minutes to ripen. Such temperature will be conducive for the starter bacteria to grow. The ripening step allows the bacteria to grow and begin fermentation, which lowers the pH and develops the flavor of cheese.

12. 5. Renneting and curd formation: Coagulation, or clotting of the milk, is the basis of cheese production. Coagulation is brought about by physical and chemical modifications to the constituents of milk and leads to the separation of the solid part of milk (the curd) from the liquid part (the whey). The enzyme rennin is used for coagulation, aided by the starter activity. Most of the fat and protein from the milk are retained in the curd, but nearly all of the lactose and some of the minerals, protein, and vitamins escape into the whey. The rennet is a proteolytic enzyme that is added to milk (usually 1 g/100 lit. milk) to form a curd. The enzyme is usually diluted in cold water and added uniformly to milk in the vat. It takes about 30 minutes to form a curd, firm enough for cutting.

13. 6. Cutting the curd and cooking: Cheese maki n g is basically a de-watering process. After the curd is formed, it is cut into small pieces to speed up whey expulsion and increase the surface area. The curd particles are cut into various sizes, depending on the variety of cheese being made. Cutting the curd into small cubes (~1 cm 3 ) reduces the moisture content of the curd, whereas creating larger cubes increases the moisture content. Cutting leads to expulsion of whey from the cheese curd, the whey may be used as a medium to cook (scald) the cheese curd. In case of Cheddar cheese, the curd is then cut with cheese knives into small pieces and heated to 42.5 C in about 30-40 minutes. Cooking of cheese curd contracts the curd particles and acts to remove whey, develop texture, and establish moisture control. The cut curds and whey are heated and agitated. 7. Draining of whey: The drainage step involves separating the whey from the curd. The whey is drained from the vat and the curd forms a mat.

14. 8. Cheddaring : The curd mats are cut into sections and piled on top of each other and piled & replied periodically. This step is called cheddaring . Cheddaring helps to expel more whey, This step leads to the characteristic texture of different cheeses. 9. Milling of cheese curd: The curd mats are then milled (cut) into smaller pieces to facilitate uniform salting of cheese curd. 10. Dry salting or Brining: To salt the cheese, coarse salt is spread over the surface of the cheese or the pressed cheese is immersed in a salt solution. Salting further completes the drainage of the cheese and also affects rind formation, growth of microorganisms and enzyme activity. It also helps to retard lactic acid activity. 11. Dressing/Formation of cheese into blocks: The salted curd pieces are placed in cheese hoops and pressed into blocks to form the cheese. 12. Pressing: the characteristic shape of the cheese by compacting the texture, extruding free whey from the curds, and completing the curd knitting. 13. Store and Age: The cheese is stored in coolers until the desired age is reached. Depending on the variety, cheese can be aged from several months to several years.

15. 14. Packaging: Cheese may be cut and packaged into blocks or it may be waxed . Modern cheese packaging protects the food from microorganisms and prevents moisture loss. The ripened cheese packaging involves applying laminated cellophane films to unwaxed cheese surfaces. The most common packaging film consists of two laminated cellophane sheets and a brown paper overlay necessary for shipping. A variation includes a metal foil wrap. 15. Ripening: During the ripening or curing stage, the cheese varieties acquires unique texture, aromas, appearance, and taste through complex physico -chemical changes that are controlled by adjusting temperature, humidity, and duration of ripening. The purpose of ripening is to allow beneficial bacteria and enzymes to transform the fresh curd into a cheese of a specific flavor, texture, and appearance.

16. Cottage Cheese This is a soft unripened cheese usually made from skim milk. It has mildly acid flavour . It consist of small particles of flakes of curd which have a meal consistency (when made from rennet curd). Creamed cottage cheese has cream mixed into it so that the finished product contains not less than 4 percent fat. Both varieties are usually salted (a) Acid curd (b) Rennet curd

17. Method of manufacture

18. Yield The yield of cottage cheese before creaming depends essentially upon. 1. The composition of milk 2. Manufacturing losses, and 3. The moisture content of the cheese. While the approximate yield of uncreamed cottage cheese is 15 % of milk, that of creamed cottage cheese (with 20 % fat in cream and 4 % fat in the finished product) is 18.3 %.

19. Keeping quality The keeping quality of cottage cheese, whether uncreamed or creamed, is short even under refrigerated storage (5-10 deg C). Uncreamed cottage cheese may be preserved for 90 days or longer by freezing or by brine storage. However, it will deteriorate in quality because freezing often leads to graininess and curd shattering, particularly with rennet cheese.

20. Processed Cheese According to the PFA rules (1976). Processed cheese refers to the product obtained by heating cheese with permitted emulsifiers and / or stabilizers, namely citric acid, sodium citrate, sodium salts of orthophosphoric acid and polyphosphoric acid with or without viz. Vinegar, lactic acid, acetic and citric acid and phosphoric acid, Processed cheese may contain not more than 4.0 percent of anhydrous permitted emulsifiers and / or stabilizers provided that the content of anhydrous inorganic the finished product, should not be more than 47.0 percent Moisture, milk fat content should not be less than 40.0 percent of the dry matter. Processed cheese may contain 0.1 % or calcium salts (calculated as sorbic acid) or 0.1 % of nisin , either singly or in combination.

21. Processed cheese food is cheese blended with legally limited amounts of dairy products such as milk, skim milk casein, cream or whey and certain optional ingredients. Processed cheese food may also contain condiments , flavour made with cheese as a base but with the addition of optional ingredients, similar to those used in cheese foods, for properties. For processed cheese foods and spreads, higher heating temperature such as 71 to 85 deg C are normally required than in processed cheese.

22. Flow diagram for preparation of processed cheese

23. Selection of Natural Cheese The natural cheese is selected on the basis of its age, texture, taste, odour , acidity and composition. The manufacture usually prefers to control the ripening of the cheese is processed so that the quantity and quality of the same should meet the requirements

24. Analysis After receiving the cheese blocks, representative samples are drawn from each block and then analysed for acidity fat, moisture , salt, pH etc.

25. Preparation of Blend Blending is an important step, where cheese of different age-groups is mixed together for processing . Proper blending requires judgement , experience and technical skill, it produces the desired rheological properties in the finished product. It is desirable to use 75 % of one to three months old, 50 % four to five months old and 25 % of six to eight months old cheese. Highly acidic cheese can be incorporated up to 5 %, whereas gassy cheese should not be more than two percent.