Growth Characteristics of Bifidobacteria and Quality Characteristics of Soy Yogurt Prepared with Different Proteolytic Enzymes and Starter Culture

단백분해효소와 배양방법의 종류에 따른 비피더스균의 생육특성 및 soy yogurt의 품질특성

  • Lee, Jung-Eun (Department of Food & Nutrition, Chung Ang University) ;
  • Lee, Sook-Young (Department of Food & Nutrition, Chung Ang University)
  • 이정은 (중앙대학교 식품영양학과) ;
  • 이숙영 (중앙대학교 식품영양학과)
  • Published : 2001.10.01

Abstract

The quality characteristics of soy yogurt prepared with different proteolytic enzymes and starter culture were evaluated. In order to facilitate the growth of lactic acid bacteria and subsequent production of lactic acid, soy protein isolate(SPI) was hydrolyzed using three kinds of proteases; one extracted from Aspergillus oryzae, bromelain and ${\alpha}-chymotrypsin$. The cultural systems employed thereafter for lactic fermentations were: 1) Bifidobacterium bifidum, 2) B. bifidum and Lactobacillus acidophilus, 3) B. bifidum and Lactobacillus bulgaricus. In soy yogurt, pH was more decreased by mixed culture method than single culture method with the accumulation of lactic acid. Viable cells of lactic acid bacteria in soy yogurts were measured $10^8$ CFU/g by the single culture method while $10^9$ CFU/g by the mixed culture method except ${\alpha}-chymotrypsin$ treatment. The amount of free amino acids in soy yogurts were substaintially increased by enzyme treatment. Viscosity was decreased by enzyme treatment, resulting in higher viscosity by ${\alpha}-chymotrypsin$ treatment. Water holding capacity was found to be higher in the single culture method in case of enzyme treatment. Among the various volatile flavor components isolated and identified after enzyme hydrolysis, acetaldehyde, ethanol, diacetyl, butyl alcohol contents tended to increase by lactic fermentation.