Hydrolysis of ${\beta}-glycosidic$ Bonds of Isoflavone Conjugates in the Lactic Acid Fermentation of Soy Milk

대두 요구르트 제조에서 이소플라본 배당체의 가수분해

  • Choi, Yeon-Bae (Department of Health Food Science, Chungkang College of Cultural Industries) ;
  • Woo, Je-Gu (Department of Food Science and Technology, Dongguk University) ;
  • Noh, Wan-Seob (Department of Food Science and Technology, Dongguk University)
  • 최연배 (청강문화산업대학 건강식품과학과) ;
  • 우제구 (동국대학교 식품공학과) ;
  • 노완섭 (동국대학교 식품공학과)
  • Published : 1999.02.28

Abstract

Isoflavones of soy milk were mainly present as sugar conjugates such as genistin and daidzin which a glucosyl residue was attached to their aglycones, genistein and daidzein through ${\beta}-glycosidic$ bond, respectively. When soy milk containing sucrose as a sugar source was fermented with lactic acid bacteria, small amount of lactic acid $(0.16{\sim}0.29%)$ was produced but isoflavone conjugates were fully hydrolyzed. Supplementation of glucose or lactose was required for normal lactic acid production and affected the hydrolysis of isoflavone conjugates in some lactic acid bacteria. In the case of Lactobacillus delbrueckii subsp. delbrueckii KCTC 1047, glycosidic bond of isoflavone was fully hydrolyzed regardless of glucose supplementation. But only $25{\sim}40%$ of daidzin and $65{\sim}80%$ of genistin was hydrolyzed when glucose was added into soy milk in the other lactic acid bacteria, Lactobacillus bulgaricus KCTC 3188, Lactobacillus casei KCTC 3109, Lactobacillus delbrueckii subsp lactis KCTC 1058, Lactobacillus lactis KCTC 2181. The hydrolyzing enzyme, ${\beta}-glucosidase$ produced by lactic acid bacteria except Lactobacillus delbrueckii subsp. delbrueckii KCTC 1047 could be considered as inducible in the fermentation of soy milk and its production was decreased when glucose was added.

Keywords

isoflavone;genistein;soy yoghurt;lactic acid bacteria