Whey is the fluid portion of milk that is obtained by coagulating and removing the curd (casein) during cheese production. After its separation from milk, whey contains almost all of the vitamins and minerals, 50% of the milk solids, and 20-24% of the milk proteins. The main protein fractions of whey are a-lactalbumin and ß-lactalbumin, which comprise between 70-80% of whey Additional protein fractions include glycomacropeptides, bovine serum albumin, lactoferrin, immunoglobulins, phospho­lipoproteins, and other bioactive factors and enzymes. Although the nutritional value of this protein was recognized and applied to animal nutrition, its application to human nutrition was delayed. Initially, the major limitation was because whey was available only in a heat­denatured form. Morr et al. reviewed a variety of techniques that were developed to produce undenatured whey in commercial quantities. The results after generations of developing whey separation techniques include a whey protein concentrate (WPC) with a high protein concentration and low levels of minerals, fat, and lactose.

In most protein foods the limiting amino acid is either lysine or methionine plus cystine. Whey proteins are unique in that they contain high levels of essential amino acids (EAAs), which include lysine, methionine, cystine, and the branched-chain amino acids (leucine, isoleucine, and valine). The excellent amino acid profile led to the application of whey protein to medical disorders. WPCs were exposed to different types of hydrolysis (enzymatic and pH) to create whey protein hydrolysates (WPH). The use of acid and alkali media to hydrolyze whey can cause denaturation of essential amino acids, so enzymatic hydrolysis became the method of choice. However, this method can result in incomplete hydrolysis and bitter-tasting hydrolysates. The use of different enzymatic methods (i.e., papain) can result in hydrolysates that are far less bitter tasting. The final products are high quality (providing undenatured amino acids and peptides) and have received tremendous attention from not only the scientific community, but life extensionists, athletes, and health! fitness enthusiasts as well.

Animal Studies

To understand the mechanism by which whey protein can exert its effects on protein synthesis, several areas must be investigated. These areas include the impact of whey on growth during development and recovery from stress or injury. Studies in vitro and in animals have investigated the effects of whey protein on growth and development recovery from severe burns and repair of gastric mucosa. In general, WPC is better for calf growth and development than dried skim milk (DSM) when supplied as 67% or 100% of the major protein source. However, if a starter formula is added to both the WPC and DSM diets, then growth rates between the two diets are similar. When studied as a replacement for colostrum in calves, WPC resulted in similar weight gain and a lower immune status for calves. From this brief summary it may be concluded that whey protein concentrate is better than dried skin milk, but not colostrum, in terms of the growth and development of calves.

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