SURFACE-ACTIVITY AND RELATED FUNCTIONAL-PROPERTIES OF PEPTIDES OBTAINED FROM WHEY PROTEINS

Whey proteins are less surface-active than caseins, mainly because of their globular structure. Although their solubility characteristics are good, their ability to stabilize emulsions and foams are poor, and this limits their use as food ingredients. Applications of enzymatic hydrolysis to improve surface properties of whey proteins are reviewed. The peptides produced by proteolysis are smaller, have less secondary structure than proteins, and are expected to have different behavior at oil-water or air-water interfaces. Recent advances in the understanding of the factors controlling surface properties of peptides are given. A two-step UF process is described that allows the production of a whey peptide fraction with improved interfacial and emulsifying properties. This peptide fraction was obtained from whey protein concentrate by the combination of heat treatment under acidic conditions, trypsin hydrolysis, and UF of the hydrolysates. Large molecular weight and intact hydrophobic areas of whey peptides are presumed to be associated with the improvement of functionality of hydrolysates. Results concerning food applications of this fraction are presented.