Enzymatic Modification of Soy Proteins: Effects of Functional Properties of Soy Isolate upon Proteolytic Hydrolysis

대두단백질(大豆蛋白質)의 효소적(酵素的) 변형(變形) : 분리대두단백질(分離大豆蛋白質)의 기능성(機能性)에 미치는 단백질가수분해(蛋白質加水分解)의 영향(影響)

  • Kang, Yeung-Joo (Department of Food Science and Technology, Cheju National University)
  • 강영주 (제주대학교 식품공학과)
  • Published : 1984.06.30

Abstract

To study affinity of proteolytic enzymes to soy proteins, the physicochemical and functional properties of enzymatically modified protein products, kinetic parameters and degree of hydrolysis were measured using trypsin, alcalase (serine type protease) and pronase. Bacterial alcalase and pronase showed much greater affinity to soy protein than animal intestinal trypsin. This effect was very significant when unheated soy isolate was used as a substrate. Specific activities of these enzymes decreased with the increment of substrate concentration (over 2.0%, w/v) when heat denatured soy protein was used as a substrate. However, the decrease in specific activity was negligible at substrate concentrations lower than 2.0%. Polyacrylamide gel electrophoretic results showed that the pattern of 2S protein band changed distinctly in alcalase hydrolysis as compared with those of trypsin and pronase. Protein solubilities of alcalase and pronase hydrolyzates increased by 25-30%, at their pI (pH 5.0) over the control. Virtually no change was observed in solubility by trypsin hydrolysis. Heat coagulability and calcium-tolerance of the protein increased by enzymatic hydrolysis. No clear tendency, however, was observed for emulsion properties, foam expansion and the amount of free -SH groups. The enzyme treatment considerably decreased foam stability.

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