Industrial Production Of Cheese

Cheese is a means to conserve many of the nutrients in milk. A well- ripened cheese is so attractive and sometimes it is hard to understand how something that has distinctly bad smell can yield wonderful flavors.

Two thousand distinct varieties of cheese are produced throughout the world. There are approximately twenty types used commonly. There are two groups of cheese:
1.Fresh cheese- which is made by coagulating milk with acid or high heat. Example is cottage cheese.
2.Ripened cheese-made through fermentation by lactic acid bacteria and then coagulated by an enzyme.

There are three categories of ripened cheese:
1.Soft cheese-ripened by enzymes from yeast and other fungi.
2.Hard cheese-ripened by lactic acid bacteria that grows throughout the cheese.
3.Semisoft cheese-ripened by proteolytic (protein degrading) and lipolytic (lipid degrading) organisms.

Microorganisms Involved In Cheese Making:

Most of the cheeses making processes employ starter organisms such as strains of Lactococcus lactis and its subspecies, thermophilic starters such as Lactobacillus helveticus, Lactobacillus casei, Lactobacillus lactis, Lactobacillus delbrueckii subspecies bulgaricus and Streptococcus salivarius subspecies thermophilus.

The role of starter organisms is:
1.Fermentation of milk sugar lactose to lactic acid.
2.Decrease pH of cheese, to increase its shelf life. As the pH decreases, the cheese develops a good flavor.

Mechanism Involved In Fermentation Of Milk Sugar Lactose:

Different microorganisms employ different metabolic pathways for breaking down of lactose.
1.In Lactobacilli and Streptococcus salivarius, a specific permease takes up the lactose and then is broken down by beta galactosidase enzyme. The glucose that is formed is converted to galactose. Galactose is eventually converted to glucose-6-phosphate. If lactose is not available in sufficient amounts to the microorganism, galactose accumulates leading to a brown discoloration of cheese that is unwanted.
2.In most Lactococci and some Lactobacilli such as Lactobacillus casei, take up lactose by a PTS system (phosphoenolpyruvate-dependent phosphotransferase system). This system adds a phosphate to the lactose and then this lactose phosphate is broken down by phosphor-beta-galactosidase enzyme to glucose. Glucose is first converted to galactose-6-phosphate and then eventually to pyruvate.
3.Starter organisms such as Lactococcus lactis subspecies diacetylactis or Leuconostoc cremoris lead to citrate fermentation and form diacetyl. Carbon dioxide is one if the end products and it produces small eyes in Dutch cheese like Gouda.

Steps Involved In Making Cheddar Cheese:

·  Before the cow's milk is processed, it is treated with heat, so that the milk is free from antibiotics and sanitizing agents that might interfere with fermentation.

·  In the next step, milk is cooled to fermentation temperature 29-31 degrees centigrade.

·  After cooling the milk to fermentation temperature, starter culture is added. A good starter culture will multiply rapidly producing acidity.

·  To stop the multiplication of the microorganism salting is done.

·  After forty five minutes rennet is added.
Rennet is prepared from stomach of suckling calves, lambs or goats. Rennin or chymosin is an enzyme that is extracted and purified from rennet. It is added, to coagulate the protein 'casein' in the milk and also for good smell and structure of cheese. It prevents the development of bitter taste. 
Now –a-day's rennin that is extracted from microorganisms is widely used. It is extracted mostly from Fungi such as Aspergillus, Candida, Mucor, Rhizopus, Pencillium etc.

·  After thirty to forty five minutes, coagulation of milk will be completed. Then the whey is removed by cutting the curd to approximately 1cm cubes and then heating them to thirty eight to forty two degrees centigrade.
The process of expulsion of whey is called 'cheddaring' and the process is carried out in a cheddaring tower.

·  Salt at a level of 1.5-2% W/w is added. And, the salted curd is then pressed to expel trapped air and whey.

·  Finally, the cheese is ripened or matured at ten degrees centigrade for flavor development. The ripening is carried out for five months. At this stage, a combination of microbial and enzymatic reactions takes place that give the cheese characteristic flavor.

This ancient Roman food is a major industry worldwide. Brillat savarin once said "Dessert without cheese is like a pretty woman with only one eye."