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.

Emulsification. In many dairy foods, whey can help create a stable emulsion. This aids in efficient dispersion of milkfat, which can reduce fat levels in some formulas and prevent defects such as creaming, coalescence and oiling off. Whey ingredients can act as a component of a fat-mimetic system, a result of whey protein’s exceptional gel-forming abilities and water-holding capacities.

Solubility. Whey proteins in their native state are highly soluble in beverage systems. Many whey ingredients remain soluble below pH 4.5, where other proteins become insoluble. This makes whey the protein-fortifying ingredient of choice in acidic beverages. Many specialized whey ingredients are available, allowing formulators to choose those that maintain solubility during processing, minimize sedimentation and impart a smooth mouthfeel.

Water-binding. Whey ingredients enhance water-binding in viscous food products such as beverages, soups and custards. The ability of a food product to retain water reduces its overall cost. Additionally, water-binding properties are beneficial in the development of reduced-fat formulations.

Flavor profile. In general, dry whey has a clean, neutral flavor. Some whey protein ingredients, especially the higher concentrated proteins, deliver a slightly sweet flavor to baked goods and beverages that enable other flavors, such as chocolate and fruit, to develop to their full potential.

The whey to nutritional benefits

High-quality proteins, such as those found in whey, are not merely complete proteins, they are also highly digestible. Whey is also rich in vitamins and minerals, including calcium, magnesium, phosphorous and zinc. Lipids are present in whey ingredients, but in very small quantities compared to the protein content.

With growing consumer demand for health-and-wellness products, whey ingredients show great promise in meeting those needs. In addition to increasing the nutritional benefits of foods, there is a solid body of research showing that whey protein has a positive effect on muscle building and maintenance (“Effect of Whey and Soy Protein Supplementation Combined With Resistance Training in Young Adults,” [International Journal of Sport Nutrition and Exercise Metabolism], 2006; 16:233-244). There is also emerging research that whey protein promotes satiety, the sense of fullness, which may help people eat less for weight management (“Whey Proteins in the Regulation of Food Intake and Satiety,” Journal of the American College of Nutrition, 2007; 26(6):704S–712S). New research is uncovering ways to expand whey functionality, such as enhancing flavor, water-binding capabilities, solubility, heat stability and optical clarity over a wider pH range, so that it can be used more easily in almost any food formulation imaginable.

Shannon Koski, a consultant to the food industry, works with companies to encourage dairy-ingredient use. She spent six years in commercial whey-protein R&D. Koski is on the Executive Committee of the Rocky Mountain Section of the Institute for Food Technologists and is a member of the Research Chefs Association. Contact her at [email protected].