The process for making cheese

What is cheese?

Cheese is a fresh or matured solid or semi-solid product that is created from whole or partially skimmed milk, cream, buttermilk or a mixture of some or all of these products, and which has been totally or partially coagulated.

What are the steps for manufacturing cheese?

Milk production

Milk is the most important raw material in the manufacture of cheese. Milk is defined as the lean lactate secretion, fresh and clean, that is obtained by milking one or more cows. Milk contains not less than 3% of milk fat and not less than 8.25% non-fat solids.

The preparation of milk consists, in some cases, of the partial or total removal of the cream by the application of a heat treatment, allowing the elimination of pathogenic bacteria present and the incorporation of certain additives such as calcium chloride and lactic cultures.

This heat treatment is known as pasteurization  and involves heating every particle of milk to a temperature of 65 º C for 30 minutes and then cool to 35 - 36 º C (slow pasteurization) or 72 ° C for 15 seconds and then cooled to 20 ° C (rapid pasteurization). The pasteurization process must be conducted in approved equipment that is in perfect working order and has been properly washed and sterilized before use.

Addition of lactic cultures

When pasteurized milk is used to make cheese, you get a microbiologically safer product but one that is tasteless and more susceptible to contamination after pasteurization. To avoid these problems, lactic acid bacteria are used. Lactic acid bacteria are mixtures of nonpathogenic bacteria that produce lactic acid, and flavor compounds such as diacetyl and volatile acids that come from the fermentation of the lactose and citric acid found in milk. Without the presence of lactic acid bacteria, the product is not going to produce the typical aromas and flavors that occur in cheese made with raw milk.

Milk coagulation
 
Coagulation is basically produced by the action of renin, LAB (lactic acid bacteria) or rennet, ferments or enzymes in the type of proteases present in gastric secretion in mammals. This acts on the milk casein (soluble protein), transforming, in the presence of calcium salts, into insoluble precipitates which form the coagulation. 

Low temperatures inactivate the rennet and above 45 º C destroy it. The ideal temperature for the coagulation of milk is between 28 and 37 º C. 

Cutting the Curd and Whey 

The time required for the curd to form, and to have the characteristics adequate for cutting, depends on factors such as pH, calcium concentration, enzyme concentration and temperature. 

The division of the curd must be carried out slowly and carefully, in a gentle manner without haste. The cuts have to be clear and complete; it is important not to tear the curd since the curd pieces have to preserve the form that the maker wants to give them: cubic, spherical, etc.

After the cut, it is normal to gently agitate the curd to decrease the whey retained and thus gain more compact and evenly moist cheese. 

After agitation, the curd is allowed to stand for several minutes to settle (i.e., 10 to 20 minutes). The whey separates during this time. In some cases, warm water is used to help the draining process. 

Salting

By adding salt, three different effects are achieved: turning the whey, improving fermentation and seasoning the cheese. 

The first is due to the absorption capacity that salt has for moisture, and the second by salt’s ability to inhibit the development of certain unwanted microbes or mold. 

The salt may be added to the whey, to the curd, during maturation, or in the brine.

Molding and Pressing 

After salting, the curd is placed in wooden, plastic or stainless steel molds. This operation helps the draining, forms the cheese and gives it the necessary consistency.