Whey proteins are a group of globular proteins found in whey, the liquid byproduct produced during the cheese-making process when milk is curdled and strained. Most of the protein in milk is casein, but these proteins form curds when the milk is curdled and the curds are strained out. The whey proteins are water soluble so they stay in the whey. These proteins are valued for their nutritional quality, functional properties, and are in widespread use in both food production and dietary supplements.
Whey proteins are a mixture of several key proteins:
Beta-lactoglobulin: This is the most abundant whey protein, making up about 50-60% of the total whey protein content. Beta-lactoglobulin is rich in branched-chain amino acids (BCAAs), particularly leucine, which is used in muscle protein synthesis.
Alpha-lactalbumin: Comprising about 20% of whey protein, alpha-lactalbumin is notable for its high content of essential amino acids, including tryptophan. It plays a role in lactose synthesis in the mammary gland.
Immunoglobulins: These proteins are involved in immune functions and are present in smaller amounts in whey. They are particularly concentrated in colostrum, the first milk produced after birth, which is rich in antibodies.
Serum Albumin: Although present in lower quantities, serum albumin contributes to the overall protein profile of whey and plays a role in maintaining osmotic pressure in the bloodstream.
Lactoferrin and Lactoperoxidase: These are minor components of whey but are important for their antimicrobial and immune-supporting properties.