Heating of an ovalbumin solution at neutral pH and high temperature

Abstract

The thermal denaturation, aggregation, and degradation of hen egg white ovalbumin dissolved in distilled and deionized water (60 mg/ml, pH 7.5) was investigated by differential scanning calorimetry (DSC), polyacrylamide gel electrophoresis (PAGE), and viscosity measurement. Two independent endothermic peaks were observed up to 180°C by the DSC analysis. The first peak appeared at around 80°C, corresponding to the denaturation temperature of ovalbumin. The second peak occurred around 140°C due to the degradation of protein molecules as judged from the analysis by SDS-PAGE. The viscosity of the ovalbumin solution increased dramatically above 88°C and maintained almost the same value up until heating to 140°C. The increase in viscosity after heating to 88°C was due to the denaturation and subsequent aggregation of ovalbumin molecules as observed by SDS-PAGE. The decrease in viscosity of the samples heated above 150°C appears to have been the result of degradation of the ovalbumin molecules. © 2002 by Japan Society for Bioscience, Biotechnology, and Agrochemistry.