Whey protein of milk

Whey is the fluid remaining following precipitation of casein micelles. Whey is typically a by-product formed after the fat and casein have been removed from the milk in cheese and casein production.

Whey protein makes up approximately 20% of milk protein and includes the alpha-lactalbumins and beta-lactoglobulins A and B. Other components are bovine serum albumin BSA, immunoglobulin and protease peptones.

Beta-lactoglobulins and alpha-lactalbumins are primarily responsible for the physiochemical properties of whey proteins.

Whey proteins are more hydrated than casein and are denatured and precipitated by heat rather than by acid.

Because alpha-lactalbumins has low solubility but good water absorption characteristics after heating, it is used widely in bakery products, meats, yoghurts and processed cheese.

High level of denatured whey proteins in cheese milk may exploited as a means on improving the texture of low-fat cheeses, which tend to be too firm and rubbery, compared with their full-fat equivalents.
Whey protein of milk

Proteins in Milk

Proteins in Milk
The protein content of milk is influenced significantly by the feeding and varies between 3.0 and 3.6%. For cheese making this has a special significance, as the yield in cheese making is controlled by the protein content.

The protein content of the milk is not uniform, but consists of two fractions, i.e., the casein and the whey proteins (serum proteins). These fractions can be further split into components and are different in chemical composition.

Milk proteins not only are important for the manufacturer of traditional dairy products but also have a multitude of functional characteristics and high nutritional values, e.g. casein is the major component of cheese and contributes its physical consistency to acidified products,. Individual specific protein fractions such as caseinate, whey protein concentrates or coprecipitates have wide significance in the spectrum of foods such as in infant formula and even some pharmaceutical products.

Casein, which is 80% of the milk protein, is arranged in milk in precisely formed micelle (clusters of individual molecules). Apart from casein, micelles contain a fairly high percentage of colloidal calcium phosphate. Within the range of normal technical processing conditions, they are stable when it comes to thermal and mechanical processing. The casein micelle is sensitive to changes in charge. When milk turns sour, structural change can be observed at PH <5.0, a gel is formed and minimal stability is reached.

The whey proteins are groups of compounds, called albumin and globulin. The thermal modenaturation of whey proteins plays a role, as it is linked with desirable and undesirable modifications:

• A firmer gel structure in acidified products, especially in yoghurt
• An improved water retention capability
• A reduced whey excretion with acidified gels
• Yield increase in fresh cheese products
• Cooked taste
• Soiling of surfaces in heat exchangers
• Reduced lab precipitation of milk
• Change of functional properties in milk powders

During cheese manufacturing, the whey proteins go into the whey; processes for a whey utilization where the protein can be recovered completely have gained significant interest. Apart form casein, albumin and globulin milk contains traces if proteases and peptones and whey contains enzymatically produces glycomacropeptides.
Proteins in Milk