Ultraviolet Absorption and Fluorescence Properties of Whey-Potato and Whey-Pea Protein Composites

Abstract

Several whey-potato and whey-pea protein composites were prepared by wet-blending and their ultraviolet (UV) absorption and fluorescence properties were measured at pH 4 to 8. A significant (p<0.05) interaction between the effects of pH and the proportion of vegetable proteins combined with acid whey proteins was observed for all UV absorption variables. In general, however, a blue shift and reduction of intensity of both UV absorption and fluorescence emission spectra occurred as pH decreased and the proportion of vegetable protein increased. Extrinsic fluorescence of proteins, measured at pH 6 to 8, also decreased with increasing proportions of vegetable protein. Increased protein-protein interaction and/or changes in protein conformation are implicated as proportions of vegetable protein in composites increased, and as pH decreased to near the pi of parent source proteins.