Kinetic Analysis of Soy-protein Denaturation by a Temperature-programmed Heat-denaturation Technique

The soy-protein denaturation rates of defatted soy flour and isolated soy protein of varying moisture content were analyzed by a temperature-programmed heat-denaturation (TPHD) technique with a hand-press reactor. The degree of protein denaturation of the soy proteins, which is defined as the solubility in 0.1 m phosphate buffer (pH 8.0) containing 1% SDS and 1% 2-ME, could be estimated with the TPHD model as a first-order heat-denaturation process. A kinetic compensation effect was observed for the protein denaturation of both soy proteins, the activation energy of the denaturation rate decreasing linearly with a moisture content below 0.4.