Whey proteins have microencapsulating potential.

To better control food quality and functional presentation in an application, product developers often seek ways to isolate, protect or control the release of key elements, such as aroma and flavor compounds, oils, fats, essential oils, oleoresins, minerals and vitamins.

One way to do this is to microencapsulate elements in a variety of materials, including natural gums, carbohydrates, waxes, gelatin and some chemically modified natural polymers. Microencapsulation enables us to protect sensitive ingredients from deteriorating before they are consumed in foods. The technique also allows us to deliver bioactive compounds, nutrients and nutraceuticals. However, many of those encapsulating materials are less than consumer-friendly, inconsistent, perform poorly or are unsuitable for specific applications.

There's a need to introduce new, highly functional GRAS microencapsulating agents into the market place. During the last decade, scientists have determined that the functionality of whey proteins makes them ideal microencapsulating agents for both water-soluble and water-insoluble microcapsules used in food and pharmaceutical applications. The physico-chemical properties and the microencapsulating properties of whey proteins allow us to consider these milk constituents as functional compounds for value-added applications.

University of California-Davis researchers have succeeded in developing a process using whey protein to produce a wall material. Whey proteins exhibit unique functionality as wall materials that can be used to encapsulate lipids (up to 75% w/w). The layer of whey proteins adsorbed at the oil-water interface creates sensitive lipids with long-term oxidative stability. Researchers have developed highly functional composite microcapsules containing whey protein-coated lipid droplets embedded in wall systems consisting of wall solids with poor encapsulating properties.

Wall systems that contain whey proteins or blends of proteins with carbohydrates are able to retain volatiles during the microencapsulation process. This makes it possible to prepare water-soluble capsules that contain a high load of flavor and aroma compounds.

By harnessing the emulsification and heat-induced gelation properties of whey proteins, it is possible to produce an array of different water-insoluble microcapsules and microspheres, intended for controlled or sustained core release applications. The rate of core release from these capsules is diffusion-controlled and can be modulated by adjusting the cross-linking density and composition of the wall matrices.

The end result: improved product quality and longer shelf life. Whey protein-based microencapsulation offers a safe, natural, label-friendly technique for controlling the behavior of key functional elements in a variety of applications. Further information. Moshe Rosenberg, Department of Food Science and Technology, University of California, Davis, 1 Shields Ave., 250-A Cruess Hall, Davis, CA 95616; phone: [phone]; fax: [phone]; email: [e-mail].