Cheese is a generic term for a diverse group of milk based food products. Cheese consists of proteins and fat from milk, usually the milk of cows, buffalo, goats, or sheep. It is produced by coagulation of the milk protein casein.

1. Cheese fermentation
M.Sc. microbiology
3rd semester
By: Abdul satar sirat
1

2. Outline
 Fermentation
 Cheese
 General cheese process
 type of cheese
2

3. Fermentation
• is a metabolic process that consumes sugar in the absence of
oxygen and produce organic acids, gases and alcohol.
• Fermentation in food processing : is the process of converting
carbohydrates to alcohol or organic acids using microorganisms
like yeasts or bacteria under anaerobic conditions.
3

4. Cheese
• Cheese is a generic term for a diverse group of milk based food
products.
• Cheese consists of proteins and fat from milk, usually the milk
of cows, buffalo, goats, or sheep.
• It is produced by coagulation of the milk protein casein.
4

5. General cheese process
• Standardize Milk/Collection
• Pasteurization
• Culturing
• Coagulation
• Draining
• Cutting
• Stirring, Heating & Draining
• Addition of Salt or Brine
• shaping
• Store and Aging(maturation)
• Packaging
5

6. Collection and Standardized of milk
• Raw milk (as such )
• sick cow milk (antibiotic treatment)
• Pasteurized
6

7. Pasteurization
High temp short time 72 C for 15-30 sec
• Low temp long time 63 C for 30 min
• Hydrogen peroxide treatment
After pasteurization ,cooled at 32 C/90 F
• Favorable temperature for bacterial growth
7

8. Culturing
• Add starter culture.
• Ripen it at 32 C for 30 min.
• Thus fermentation starts.
• Starter culture is small amount of bacteria ,added in milk to
start ripening by lowering the pH.
8

9. coagulation
• Rennet is added to further encourage the milk to solidify ,
forming a custard like mass
• In 29 C/ 85 F
• Rennet contain enzyme chymosin which convert k casein
into para-k casein and smaller protein macropeptide.
• Cheek the coagulation after 30 minutes
9

10. draining
• When cheese curd is ready, remove cheese whey.
• Presence of water and bacteria cause decomposition of food.
• So perform partial dehydration.
10

11. Cutting
• The curd is cut into small cubes to 'scald' the curd particles.
• By hand or automatic curd- cutting mechanism
• Cheese whey is expressed from the particles.
• And settling down of the curd
11

12. Stirring, Heating & Draining
Cheese makers cook and stir the curds and whey until the desired
temperature and firmness of the curd is achieved. The whey is
then drained off, leaving a tightly formed curd.
12

13. Addition of salt
• Salt adds flavor and also acts as a preservative so the
cheese does not spoil during long months or years of ageing.
• It also helps a natural rind to form on the cheese.
• There are several ways to use salt. Salt can be added
directly into the curd as the cheese is being made. The
outside of the wheel of cheese can be rubbed with salt or
with a damp cloth that has been soaked in brine. The cheese
can also be bathed directly in vat of brine.
13

14. Shaping
• The cheese is put into a basket or a mold
to form it into a specific shape.
• During this process, the cheese is also
pressed with weights or a machine to
expel any remaining liquid.
• Pressing determines the characteristic
shape of the cheese and helps complete the
curd formation.
• Most cheeses are pressed in three to 12
hours, depending on their size.
14

15. Storage and again(maturation)
• The pressed blocks of cheese are either bound with muslin-like
cloth, or waxed or vacuum packed in plastic bags to be stored for
maturation
• Depending on the variety, cheese can be aged from several months
to several years.
15

16. packaging
• Store it in vacuum packed or
• airtight plastic bag.
16

17. 17

18. Type of cheese
Several types on the basis of:
1. Length of aging (cheese maturation)
2. Texture
3. Making method
4. Fat content
5. Milk source
18

19. 1. Soft Cheese:
• Soft, smooth, creamy texture
• No heating and pressing
• 50-80% moisture content
• As a spread on bread and crackers
• Usually not for cooking
Example:
• Cottage, Ricotta, Mozzarella, Cream, Camembert, Brie, Caciotta
19

20. 2. Semi-soft Cheese
• More firm and compact
• 39-50% moisture content
• Can be used for cooking purposes
Example:
Roquefort, Stilton, Gorgonzola, Danish blue
20

21. 3. Semi-Hard Cheese:
• Considered as “all purpose” cheese
• Pressed to remove most whey during production
• 34-45% moisture content
• Can be used for sandwiches and snacks
Example:
Cheddar, Colby, Edam
21

22. 4. Hard Cheese:
• < 39% moisture content
• Long maturation period
• Very long shelf life
• Can last for 2 years in refrigerator
Examples
Cheddar, Caciocavallo, Emmental, Gruyere,
Swiss
22

23. 5. Very Hard Cheese:
• 13-34% moisture content
• Very long aging period
• Can be up to 2 years
Examples
Asiago old, Parmesan, Romano, Grana
23

24. 6. Processed Cheese:
• Made by melting a blend of grated cheese, milk, more
salt, food coloring, flavors and seasonings
• Can be used for cooking
• Long shelf life
Examples
Processed cheese slices, Cheese spreads
24

25. Thank you
25