Pysicochemical and Bacteriological Properties of Yogurt made by Single or Mixed Cultures of L. bulgaricus and S. thermophilus

L. bulgaricus 와 S. thermophilus 의 단독 및 혼합배양에 의한 요구르트의 이화학적 미생물학적 특성

  • 이신호 (효성여자대학교 식품가공학과) ;
  • 구영조 (농수산물 유통공사 종합식품연구원) ;
  • 신동화 (농수산물 유통공사 종합식품연구원)
  • Published : 1988.04.01

Abstract

The pysicochemical and bacteriological properties of yogurts made by single or mixed cultures of L. bulgaricus FRI025 and S. thermophilus CHI were investigated. L. bulgaricus FRI025 which was isolated from raw milk was selected as starter culture among 22 strains of lactic culture by measuring viscosity, flavor, growth and acid production ability. The acid production and number of viable cell were increased by using L. bulgaricus FRI025 and S. thermophilus CHI together in ratio of apporximately 1:1. The pH, titratable acidity, viable cell number and viscosity of yogurt were 4.08, 1.14%, $2.5{\times}10^{10}/ml$ and 2100 cp after 9 hours incubation at $40^{\circ}C$, respectively. The pH and viable cell number were decreased on the other hand titratable acidity and viscosity were increased after 7 days of storage at $4^{\circ}C$. The changes of quality did not show significantly after storage. The selected starter was much higher than commercial yogurt starter in the acid production and growth of starter. The yogurt nanufactured with selected starter was better than with commercial yogurt in sensory evalution such as taste, texture, flavor and overall acceptability.

Keywords

yogurt;mixed culture;physicochemical properties of yogurt;bacteriological properties of yogurt