Heating of β-Lactoglobulin A Solution in a Closed System at High Temperatures

Authors


  • This work was supported by a grant-in-aid for the “Research for the Future” Program from the Japan Society for the Promotion of Science, and by a grant from the Hitachi Scholars hip Foundation to S.P.

Inquiries should be directed to Naofumi Kitabatake, Research Institute for Food Science, Kyoto University, Uji, Kyoto 611-0011, Japan. (E-mail: kitabata@food2.food.kyoto-u.ac.jp)

Abstract

ABSTRACT β-Lactoglobulin A solution at pH 6.4 was heated to 180 °C at the rate of 6 °C/min. By differential scanning calorimetry two independent endothermic peaks were observed. The first peak appeared below 100 °C is corresponded to the thermal denaturation of protein. This conformational change led to the aggregation and polymerization of molecules through disulfide linkage, particularly observed above 100 °C. The second endothermic peak appeared around 150 °C, which was brought by the decomposition of molecules as judged from electrophoresis. Up to 100 °C the viscosity of β-lactoglobulin A solution increased by heating, while the viscosity was reduced beyond 113 °C, due to change in the size of aggregate and decomposition of β-lactoglobulin A molecules.

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