ABSTRACT
Foods are complex mixtures of a wide variety of different components. It is important to understand how these various components interact with each other to be able (1) to make cost-efficient use of functional ingredients and (2) to control, predict, and improve textural properties of fabricated foods. Globular proteins (whey proteins, egg white, etc.) and polysaccharides are being increasingly used as functional ingredients in the food industry. Thermally set induced gels can be produced individually from both globular proteins and polysaccharides. Whey protein isolates (WPI) are being used in food products to increase viscosity, to form gels, to stabilize emulsions or foams, or as water-binding agents (Kinsella and Whitehead, 1989). The globular proteins j3-lactoglobulin, a-lactalbumin, and bovine serum albumin are the principal components of whey. The gelation of WPI is usually achieved upon heating above their denaturation temperature. Upon heating, the globular proteins are partly unfolded, and some of the amino acid residues that were originally located in the interior of the protein are exposed. Protein molecules then associate and aggregate because of hydrophobic in-
teractions, disulfite bond formation, or hydrogen bonding between exposed amino acid residues on different molecules (Clark and Lee-Tuffnell, 1986).
