Therapeutic applications of whey protein

Alternative Medicine Review, June, 2004 by Keri Marshall

Abstract

Whey, a protein complex derived from milk, is being touted as a functional food with a number of health benefits. The biological components of whey, including lactoferrin, beta-lactoglobulin, alpha-lactalbumin, glycomacropeptide, and immunoglobulins, demonstrate a range of immune-enhancing properties. In addition, whey has the ability to act as an antioxidant, antihypertensive, antitumor, hypolipidemic, antiviral, antibacterial, and chelating agent. The primary mechanism by which whey is thought to exert its effects is by intracellular conversion of the amino acid cysteine to glutathione, a potent intracellular antioxidant. A number of clinical trials have successfully been performed using whey in the treatment of cancer, HIV, hepatitis B, cardiovascular disease, osteoporosis, and as an antimicrobial agent. Whey protein has also exhibited benefit in the arena of exercise performance and enhancement.

Introduction

In recent years, milk constituents have become recognized as functional foods, suggesting their use has a direct and measurable effect on health outcomes. (1) Whey, a by-product of cheese and curd manufacturing, was once considered a waste product. The discovery of whey as a functional food with nutritional applications elevated whey to a co-product in the manufacturing of cheese. (2) Milk contains two primary sources of protein, the caseins and whey. After processing occurs, the caseins are the proteins responsible for making curds, while whey remains in an aqueous environment. The components of whey include beta-lactoglobulin, alpha-lactalbumin, bovine serum albumin, lactoferrin, immunoglobulins, lactoperoxidase enzymes, glycomacropeptides, lactose, and minerals. (2) In additional, whey derived from buttermilk versus cheese contains the lipid sphingomyelin.

Several cultures consider fermented foods part of a healthful diet. Historically, whey was considered a cure-all used to heal ailments ranging from gastrointestinal complaints to joint and ligament problems. Nanna Rognvaldardottir, an Icelandic food expert, describes how whey, called syra by the Icelandic people, is fermented and stored in barrels. Syra is diluted with water and ingested or used as a marinade or preservative for meat and other food. Syra was the most common beverage of Icelandic people and is thought to have replaced ale, due to lack of grains in the region. (3)

Today, whey is a popular dietary protein supplement purported to provide antimicrobial activity, immune modulation, improved muscle strength and body composition, and to prevent cardiovascular disease and osteoporosis. Advances in processing technology, including ultrafiltration, microfiltration, reverse osmosis, and ion-exchange have resulted in development of several different finished whey products. Whey protein concentrates (ranging from 80-95 percent protein), reduced lactose whey, whey protein isolate, demineralized whey, and hydrolyzed whey are now available commercially. Each whey product varies in the amount of protein, carbohydrates, immunoglobulins, lactose, minerals, and fat in the finished product. These variables are important factors in the selection of whey fractions for specific nutritional applications. Table 1 describes the various whey protein products available.

Whey Protein Manufacturing

Protein from bovine whole milk consists of approximately 20-percent whey protein. When casein is removed from whole milk, liquid whey remains, having a protein concentration of about 65 percent. The following is a summary of the Ohio State University method of manufacturing whey protein powder. Milk is high-temperature, short-time pasteurized (163 degrees F for 30 seconds) and held overnight at 40 degrees C. The following morning the mixture is cooled to 30 degrees C, inoculated with a lactic acid culture, and incubated for 30 minutes. Rennet extract is added and the mixture is stirred, resulting in coagulation of curd.

Rennet is derived from the abomasum (fourth stomach) of newly born calves. Chymosin, the active enzyme ingredient of rennet, aids in the coagulation of milk by separating it into curds and whey. In a newly born calf, chymosin aides in the digestion and absorption of milk. Adult cows do not have this enzyme.

The liquid whey is drained through a stainless steel screen and the remaining curd is cut and cooked at 30 degrees C. Whey liquid is then filtered at 45 degrees C and brought to a pH of 3 by adding citric acid. The liquid is filtered to one-fifth its original volume, resulting in whey concentrate that is approximately 80-percent protein. This can be additionally micro-filtered to increase protein concentration to as high as 95 percent.

The final whey protein concentrate is warmed and spray-dried to achieve whey protein powder. Whey protein concentrates can then be put through an ion-exchange process to remove fat and lactose. In addition, some manufacturers hydrolyze (cleaving peptide bonds via enzymes or heat) the whey to provide more peptides and free amino acids in the final product. (4)