Production

Whey is left over when milk coagulates and contains everything that is soluble from milk. It is a 5% solution of lactose in water, with some minerals and lactalbumin. It is removed after cheese is processed. The fat is removed and then is processed for human foods.Processing can be done by simple drying, or the protein content can be increased by removing lipids and other non-protein materials.For example, spray drying after membrane filtration separates the proteins from whey.

Whey can be denatured by heat. High heat (such as the sustained high temperatures above 72 °C associated with the pasteurization process) denatures whey proteins. While native whey protein does not aggregate upon renneting or acidification of milk, denaturing the whey protein triggers hydrophobic interactions with other proteins, and the formation of a protein gel. Heat-denatured whey can still cause allergies in some people.

Composition

Whey protein is the collection of globular proteins isolated from whey, a by-product of cheese manufactured from cow’s milk. The protein in cow’s milk is 20% whey protein and 80% casein protein, whereas the protein in human milk is 60% whey and 40% casein.Whey protein is typically a mixture of beta-lactoglobulin (~65%), alpha-lactalbumin (~25%), and serum albumin (~8%), which are soluble in their native forms, independent of pH. The protein fraction in whey (approximately 10% of the total dry solids within whey) comprises four major protein fractions and six minor protein fractions. The major protein fractions in whey are beta-lactoglobulin, alpha-lactalbumin, bovine serum albumin, and immunoglobulins.

Major forms

Whey protein typically comes in three major forms: concentrate (WPC), isolate (WPI), and hydrolysate (WPH).

• Concentrates have typically a low (but still significant) level of fat and cholesterol but, in general, have higher levels of bioactive compounds, and carbohydrates in the form of lactose — they are 29%–89% protein by weight.
• Isolates are processed to remove the fat, and lactose, but are usually lower in bioactivated compounds as well — they are 90%+ protein by weight. Both WPC and WPI are mild to slightly milky in taste.
• Hydrolysates are whey proteins that are predigested and partially hydrolyzed for the purpose of easier metabolizing, but their cost is generally higher.Highly-hydrolysed whey may be less allergenic than other forms of whey.

Benefits for muscle building

Research indicates that the use of supplementary whey or soy protein combined with resistance training offers minimal benefit over no protein supplementation. The authors of this research concluded that “young adults who supplement with protein during a structured resistance training program experience minimal beneficial effects in lean tissue mass and strength.” Another study of elderly men found supplementation with whey protein before and after exercise to not have any significant effect on skeletal muscle hypertrophy compared to placebo.The timing of protein supplement ingestion may not have any significant effects on strength, power, or body-composition.

Health effects

The use of whey protein as a source of amino acids and its effect on reducing the risks of diseases such as heart disease and cancer is the focus of ongoing research.Whey is an abundant source of branched-chain amino acids (BCAAs),which are used to fuel working muscles and stimulate protein synthesis.In particular, leucine plays a key role in initiating the transcription of protein synthesis.When leucine is ingested in high amounts, such as with whey protein supplementation, there is greater stimulation of protein synthesis, which may speed recovery and adaptation to stress (exercise).

Whey protein contains the amino acid cysteine, which can be used to make glutathione. However, this amino acid is not essential for the synthesis of glutathione, and some studies have suggested that the amount of cysteine in the diet may have little effect on glutathione synthesis.However, another study suggested that large amounts of whey protein can increase cellular glutathione levels. Glutathione is an antioxidant that defends the body against free radical damage and some toxins, and studies in animals have suggested that milk proteins might reduce the risk of cancer.

Digestive Issues

A significant portion of the population experiences severe digestive issues following consumption of whey protein powder.These may include gas, bloating, cramps, tiredness, weakness, fatigue, headaches, and irritability. The cause of these digestive problems has not yet been determined but is reported frequently on strength training forums.One assumption is that these digestive issues are caused by consumers’ lactose intolerance after they ingest whey concentrate.However, these digestive issues are most likely attributable to the fact that the human body can only properly process 4 grams to 9 grams of protein per hour, and some of the large amounts of protein (regardless of the type of protein, e.g. whey, casein, egg, soy, meat, et cetera) that bodybuilders typically ingest are left undigested in the intestinal tract. Undigested protein in the colon will undergo bacterial fermentation which leads to the production of, among other things, gas and fatty acids.

Similar symptoms can be caused by ingredients found in lower quality protein powders such as lactose in whey protein concentrate or artificial sweeteners in most commercial protein powders.The effects of these substances can be distinguished from the effects of whey alone by switching to an unsweetened whey isolate or hydrolysate. If symptoms are not eliminated by switching to a purer form of whey protein, using alternative protein sources such as pea protein or rice protein may reduce symptoms.