RHEOLOGICAL ANALYSIS OF ANION-INDUCED MATRIX TRANSFORMATIONS IN THERMALLY-INDUCED WHEY-PROTEIN ISOLATE GELS

The formation of thermally induced whey protein isolate (WPI) gels exh ibiting fine-stranded, mixed and particulate matrices was investigated . Various concentrations of stabilizing salts (sodium sulfate and sodi um phosphate) or a chaotropic salt (sodium thiocyanate) were used to f orm the different types of thermally induced gel matrices. Gelation un der all conditions showed similar trends in small-strain viscoelastic properties. Storage modulus (G') increased during heating to and hold at 80 degrees C followed by an additional increase in cooling to 25 de grees C. Mixed matrix gels had proportionately more hydrophobic intera ctions (large Delta G'(heat)/Delta G'(cool)) and had greater initial g elation rates than fine-stranded and particulate matrix gels. The prop ortion of hydrophobic interactions in the gels correlated with the ani ons' influences on the hydrophobic effect as indicated by their positi ons in the Hofmeister series.