Opportunities with whey proteins as microencapsulating agents.

Microencapsulation is a unique way of protecting sensitive ingredients against deterioration or loss before they are consumed. It also is a novel approach for delivering bio-active compounds, nutrients and nutraceuticals. The physico-chemical properties and especially the microencapsulating properties of whey proteins allow us to position these milk constituents as functional compounds in food and pharmaceutical value-added applications.

A need to introduce new, highly functional GRAS, microencapsulating agents exists. During the last decade, scientists at the University of California investigated and determined the functionality of whey proteins as microencapsulating agents for both water-soluble and water- insoluble microcapsules designed for food and pharmaceutical applications. They indicate that the physico-chemical properties of whey proteins provide unique opportunities for developing micro- porous microcapsules for the entrapment of bio-active compounds and microorganisms.

Whey proteins exhibit unique functionality as wall materials for encapsulating lipids--up to 75% w/w. The layer of whey proteins adsorbed at the oil-water interface gives sensitive lipids long-term oxidative stability. This type of functionality has been further extended in developing highly functional composite microcapsules containing whey protein-coated lipid droplets. These are embedded in wall systems consisting of wall solids that have poor encapsulating properties.

Wall systems consisting of whey proteins or blends of the latter with carbohydrates allow foods to retain a lot of volatiles during the microencapsulation process by spray-drying the products. This makes it possible to prepare water-soluble capsules that contain a high load of flavor and aroma compounds. To take advantage of the emulsification and heat-induced gelation properties of whey proteins, an array of different water-insoluble microcapsules and microspheres, for controlled or sustained core release applications, can be prepared.

Additionally, for pharmaceutical applications, whey proteins can be used in preparing chemically-cross-linked microcapsules containing water-soluble or water-insoluble pharmaceuticals. The rate of core release from these capsules, into either gastric or intestinal fluid, is diffusion controlled, and can be modulated by adjusting the cross-linking density and composition of the wall matrices.

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].