Whey

Whey is the milk serum that is obtained during the manufacture of cheese after sepa­ration of casein and fat during milk coagulation. Generally citric acid and some times rennet and few times lactase is used for co­agulation.

Depending upon the raw material used in the coagulation of milk, i.e. enzymatic rennet coagulation or by acid coagulation, it is broadly classified into sweet whey, otherwise known as rennet whey and acid whey or quark whey. The composition of the whey differs depending upon the coagulant used. Generally in pure acid co­agulation, calcium is removed from the calcium-casein complex, and calcium lactate is formed jointly with milk. Casein has the tendency to precipitate when the calcium is removed. The acid whey or quark whey is milk serum obtained during an acidic coagulation and has calcium lactate. Enzymatic coagulation entails splitting of milk protein resulting in the formation of calcium para-caseinate, In this, the calcium remains bound in the coagulated protein. Beta lactoglobulin, alpha lactalbumin, immunoglobulin and serum albumin (the non casein fractions) are not generally precipitated and they remain in solution in the form of whey or serum proteins.

Sweet whey or rennet whey is a milk serum obtained during enzymatic coagulation of casein and is generally free from calcium. Hence, no calcium lactate can be formed with lactic acid. Sweet whey and acid whey are individually distinct. The former cannot be converted into the latter even with post-acidification.

Another type of whey, which is not described earlier is industrial-grade whey, wherein, coagulation of the protein is done with acids other than lactic acid, e.g. hydrochloric acid, acetic acid or sulfuric acid.

General Composition of fresh Whey

S.No Constituent Unit Sweet whey Acid whey
1 Water % 93-94 94-95
2 Dry matter % 6-6.5 5-6
3 Lactose % 4.5-5 3.8-4.3
4 Lactic acid % traces up to 0.8
5 Total protein % 0.8-1.0 0.8-1.0
6 Whey protein % 0.6-0.65 0.6-0.65
7 Citric acid % 0.1 0.1
8 Minerals % 0.5-0.7 0.5-0.7
9 pH 6.4-6.2 5.0-4.6
10 SH Value about 4 20-25

The fat content of the whey depends mainly on the fat content of the cheese milk A high fat content in the cheese milk leads to a more fat content in whey, more so, when the cheese milk has not been homogenized. When the fat content of the whey exceeds 0.1%, it is usually decreased or fat removed. The cream thus obtained is either processed into whey butter or utilized back in the standardization of fat of the cheese milk. Whey contains vitamins B and C, vitamin B2 and lacto flavin which are responsible for the green yellow color of whey.

Whey
Goodness of Whey