Effects of simultaneous heat and reducing treatments on some structural characteristics of soy isolates obtained at pilot plant scale

摘要

The influence of simultaneous heat and reducing treatment on some structural soy isolate characteristics such as protein denaturation enthalpy, free sulphhydryl groups and disulphide bonds contents were studied through the surface response methodology. The model obtained showed that denaturation enthalpy was mainly affected by treatment temperature and that sulphite effect depended on the temperature. At low temperature, sulphite stimulated the denaturation process by reducing the temperature at which denaturation began, while at high temperature a stabilisation effect was observed. A maximum sulphitolysis activity was observed in the temperature range of 67-75degreesC and between 0.35 and 0.5% sulphite concentration, in which the reaction efficiency is improved. These results showed the existence of a critical temperature above which the rupture of disulphide bonds would increase the molecular flexibility. The occurrence of new disulphide bonds could favor the formation of aggregates by the production of new disulphide bonds, others reactions, such as the interaction between the polypeptide B of glycinin and the subunits beta of the beta-conglycinin could also play an important role.