The Power of Whey

Whey is coming into its own. As consumer demand for health-and-wellness food products continues to increase, manufacturers are turning to whey as a reliable, easy-to-use source of biologically active proteins, carbohydrates and minerals. It not only can boost a food’s nutritional value and contribute to a consumer-friendly clean label, its versatile functional and sensory properties make it useful in a multitude of products.

Whey to go

Whey is the serum, or liquid, part of milk that remains after curd coagulation during cheese manufacturing. Liquid whey is 6.5% total solids, 0.8% protein; the majority of the solids in whey are lactose (4.9%). Fluid milk, which contains both caseins and whey proteins, is made into cheese by adding starter cultures of selected bacteria and enzymes. These cultures cause the casein proteins to denature and coagulate, creating a soft gel. During this process, the whey proteins remain in their native state, but are trapped within the casein matrix, or gel. The gel is cut, releasing the liquid whey that is then removed and processed into a variety of ingredients.

Due to high transportation costs and its perishable nature, liquid whey is rarely used in food products. Normally, it is dried into whey powder, or concentrated by evaporation, reverse osmosis or ultrafiltration into whey protein concentrate (WPC) or whey protein isolate (WPI).

Dry whey is manufactured by removing a substantial portion of water from the whey, which is then pasteurized and dried. Except for moisture, all the constituents of fluid whey are retained in the same relative proportion in dry whey.

Whey protein concentrates are available in various protein concentration levels, such as 35% (WPC35), 50% (WPC50) or 80% (WPC80). These products contain some lactose, fat and minerals. As protein levels increase, the level of lactose in WPC decreases.

WPI, which is more specialized than WPC, contains at least 90% protein on a dry-weight basis and little, if any, lactose or fat.

In the United States, two major types of whey are available as whey protein sources: Acid whey, with a pH of less than 5.1, is produced from cottage or ricotta cheese; and sweet whey, with a pH of more than 5.6, which results from manufacturing rennet-coagulated cheese, such as Cheddar-style and mozzarella-style. The vast majority of whey ingredients manufactured in the United States are made from sweet whey, so the remainder of this article will focus on sweet whey-derived ingredients.

Whey functional

Whey ingredients offer foods a wide range of functionality, with potential use in beverages, confections, baked goods, meat products, salad dressings, sauces and soups. WPCs can modify some or all of the taste, texture, smell, appearance and structural properties of food, resulting in high consumer acceptance.

A number of factors influence whey’s functional properties, including whey source, protein content, heat treatment, and lipid and mineral content. In general, WPCs with lower protein content have more-limited functionality than those with higher protein content.