Cheese

Introduction

When fresh milk is left to become sour, the casein aggregates. If souring occurs at not too low a temperature and without any stirring or shaking of the milk, a gel is formed. Some whey separation generally occurs when the gelled or clotted milk is kept for some time. This can be enhanced by heating and stirring; the mass then separates into curd grains and whey. By allowing more of the whey to drain out from the curd — for instance, by hanging the curd in a cloth — a primitive fresh

cheese is obtained (baker’s cheese, quarg, or simply ‘curds’).

Cheese may be defined as the curd of milk separated from the whey and pressed into a solid mass‘.

Definition

According to the FSSR (2011), cheese means the ripened or unripened soft or semihard, hard and extra hard product, which may be coated with food grade waxes or polyfilm, and in which the whey protein/casein ratio does not exceed that of milk. Cheese is obtained by coagulating wholly or partly milk and/or products obtained from milk through the action of non-animal rennet or other suitable coagulating agents and by partially draining the whey resulting from such coagulation and/or processing techniques involving coagulation of milk and/or products obtained from milk which give a final product with similar physical, chemical and organoleptic characteristics. The product may contain starter cultures of harmless lactic acid and/or flavor producing bacteria and cultures of other harmless microorganisms, safe and suitable enzymes and sodium chloride. It may be in the form of blocks, slices, cut, shredded or grated cheese

Classification of cheese

These can also be classified on the basis of their rheology, and according to the manner of ripening as shown below:

1) Very hard (grating) - Moisture < 35% on matured cheese and ripened by bacteria, e.g.

                                 Parmesan

                                                                                                                                Romano

2) Hard - Moisture < 40% 

a) Ripened by bacteria, without eyes:

                                                                                                                           Cheddar 

b) Ripened by bacteria, with eyes:

                                                                                                                                  Swiss 

3) Semi-hard - Moisture 40-47% 

a) Ripened principally by bacteria:

                                                                                                                              Brick

b) Ripened by bacteria and surface microorganisms:

                                                                                                                           Limburger 

c) Ripened principally by blue mould: i) External –

                                                                                                                        Camembert

ii) Internal –
                                                                                                                           Gorgonzola

                                                        
                                                                                                                          Blue

                                                                      
                                                                                                                          Roquefort

4) Soft - Moisture > 47% 

a) Unripened –
                                                                                                                        Cottage 

b) Ripened –
                                                                                                                            Neufchatel

FSSR (2011) has also defined cheese on the basis of ripening as follows:

(i) Ripened cheese is cheese which is not ready for consumption shortly after manufacture but which must be held for some time at such temperature and under such other conditions as will result in necessary biochemical and physical changes characterizing the cheese in question.
(ii) Mould ripened cheese is a ripened cheese in which the ripening has been accomplished primarily by the development of characteristic mould growth through the interior and/ or on the surface of the cheese.
(iii) Unripened cheese including fresh cheese is cheese which is ready for consumption shortly after manufacture.

Manufacturing of cheese

Cheeses, irrespective of country of origin and method of manufacture possess certain common characteristic steps as follow: 

1. They are made from the milk (or derivatives of milk) of certain mammals derivatives 

2. Souring 

3. Clotting by rennet or a similar enzyme preparations 

4. Cutting or breaking up of the coagulum to release the whey 

5. Consolidation or matting of the curd 

6. Maturing

Essential Process steps

1) Pasteurization of the cheese milk: This destroys microorganisms and enzymes that can be detrimental to ripening. It may also serve to kill any pathogens because some of these can survive for some time, especially in soft-type cheeses. To avoid recontamination after pasteurization, strict hygienic measures have to be taken.
2) Addition of cultures of microorganisms to the cheese milk, especially starters of lactic acid bacteria: The addition is essential if the cheese milk has been pasteurized but is also desirable for cheese made of raw milk. The composition of the starter depends on the type of cheese to be made. For some varieties, cultures of other specific microorganisms are also added.
3) Regulation of composition, i.e., water, fat, salt content, and pH of the cheese: The advantages are obvious but it calls for a detailed understanding of the various processes occurring during cheese making.
4) Clotting of the milk: This is accomplished by means of enzymes or acid (or both). As discussed earlier, the enzymes involved remove the caseinomacropeptide ‘hairs’ from κ-casein; the resulting paracasein micelles will then aggregate. Acid, generally formed from lactose by lactic acid bacteria, dissolves the colloidal calcium phosphate of the micelles and neutralizes the electric charge on the resulting particles, which will then aggregate. The aggregation causes formation of a space-filling network, which encloses the milk serum and the fat globules.
5) Removal of the whey: The gel formed is prone to spontaneous syneresis, i.e., expulsion of whey. Whey expulsion is generally enhanced by cutting the gel into pieces and by stirring the curd–whey mixture that is thus formed. The curd obtained makes up 10 to 30% of the original volume of milk. The drier the curd, the firmer and the more durable the cheese will become.
6) Acid production in the cheese during its manufacture: This is due to the conversion of lactose into lactic acid by lactic acid bacteria. The resulting pH of curd and cheese affects such parameters as syneresis, consistency, and ripening of the cheese.
7) Salting: Cheese contains added NaCl, generally 1 to 4%. This does not apply to some fresh-type cheeses such as quarg. The salt affects durability, flavor, and consistency of the cheese, both directly and by its effect on ripening.
8) Fusion of curd grains into a coherent loaf that is easy to handle. Moreover, the cheese can acquire a rind, which protects the interior. Pressing enhances curd fusion and the formation of a closed rind.
9) Curing: That is, ensuring that conditions during storage and handling of the cheeses are such that ripening proceeds as desired. Ripening is the main factor determining the typical flavor and texture of a given cheese variety. To achieve this, the cheese is kept for a variable time under suitable conditions. The storage conditions vary widely with the type of cheese involved.