Sweetness of Sweet Protein Thaumatin Is More Thermoresistant under Acid Conditions Than under Neutral or Alkaline Conditions

概要

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Thermostability of thaumatin and mechanisms of thermoinactivation were examined at 80℃ for in the pH range from 2 to 10. The sweetness of thaumatin disappeared on heating at pH above 7for 15min, but the sweetness remained even after heating at 80℃ for 4h at pH2. This indicated that the sweet protein thaumatin is more thermoresistant under acid conditions than under neutral or alkaline conditions. Prolonged heating of thaumatin under acid conditions slowly reduced sweetness, and produced a heterogeneous population of molecules, all of which was soluble and monomeric. The resultant molecules were clearly distinct from those generated by heating at pH above 7. Hydrolysis of peptide bonds and other irreversible chemical reactions slowly took place in the molecule heated under acid conditions, and it would be, in part, a cause of thermoinactivation of thaumatin under acid conditions. The thermostability of thaumatin and the mechanism of thermoinactivation were largely dependent on pH.
社団法人日本農芸化学会の論文
2001-02-23