Lactic Acid Fermentation in Soymilk by Single and Mixed Cultures of Lactobacillus Casei and Kluyveromyces fragilis

Lactobacillus casei IFO 3012 와 Kluyveromyces fragilis KFCC 35458의 혼합배양에 의한 두유의 젖산발효

  • Yu, Ju-Hyun (Department of Food Engineering, Yonsei University) ;
  • Lew, In-Deok (Department of Food Engineering, Yonsei University) ;
  • Park, Chung-Kil (Department of Food Technology, Chung Ju National Technical College) ;
  • Lim, Hong-Chul (Department of Biochemical Engineering, University of California)
  • 유주현 (연세대학교 식품공학과) ;
  • 류인덕 (연세대학교 식품공학과) ;
  • 박정길 (충주공업전문대학 식품공업과) ;
  • 임홍철 (캘리포니아대학교 생물공학과)
  • Published : 1988.08.01

Abstract

Lactobacillus casei IFO 3012 and Kluyveromyces fragilis(KFCC 35458) were cultured together in Soymilk to investigate the growth characteristics and the conditions suitable for acid Production. L. casei produced more amount of acid rapidly when cultured with K. fragilis in soymilk than when cultured singly. The optimum conditions for acid production by the mixed cultures of L. casei and K. fragilis were achieved with a temperature of $35-37^{\circ}C$, a 1:5-1:9(O.D 660) ratio of L. casei to K. fragilis at inoculum, a 1.0 level of sucrose fortification or a 2.0% level of skim milk powder fortification and a culture time of 24hr. Under these conditions the amounts of acid produced by the single culture of L. casei and the mixed cultures with K. fragilis were 0.31% and 0.44% in soymilk, 0.43% and 0.97%, respectively, in soymilk fortified with 1.0% level of sucrose. These indicate that the amount of acid produced by mixed cultures is about 1.42 fold greater in soymilk and about 2.26 fold greater in soymilk fortified with 1.0% level of sucrose than that produced by the single culture of L. casei. The amount of acid produced in soymilk fortified with 2.0% level of skim milk powder was 1.0 level for both of the single culture of L. casei and the mixed cultures of L. casei and K. fragilis after 24hr incubation. In soymilk fortified with skim milk power less than 1.5 the mixed culture with K. fragilis showed higher content of acid than the single culture of L. casei only.

두유를 L. casei로 젖산발효시킬 때 L. casei 단독발효와 효모인 K. fragilis와의 혼합발효에 대하여 검토하였다. 그 결과두유를 L. casei로 단독발효한 경우 보다 K. fragilis와 혼합발효한 경우 산생성량이 많고 산생성속도가 빨랐다. 이 두균을 혼합배양하여 산생성을 높이기 위한 발효조건은 두유에 sucrose를 1.0% 또는 skim milk를 2.0%첨가하고 L. casei와 K. fragilis를 O.D 660값으로 $1\;:\;5{\sim}1\;:\;9$되게 접종하여 $35{\sim}37^{\circ}C$의 온도에서 24시간 발효하는 것이 효과적이었다. 두유를 L. casei로 단독발효 한 경우와 L. casei와 K. fragilis로 혼합발효한 경우의 산도는 각각 0.31%와 0.44%로서 혼합발효한 경우가 1.42배 높았다. sucrose를 1.0% 첨가한 두유를 사용하였을 경우는 각각 0.43%와 0.97%로서 혼합발효한 경우가 2.26배 높았다. 그리고 skim milk를 2.0% 첨가한 두유를 사용하였을 경우는 각각 1.05%와 0.99%로서 L. casei로 단독발효한 것과 K. fragilis와 혼합발효한 것 사이에 차이가 없이 같은 수준을 나타내었다. 단지 skim milk를 1.5%이하로 첨가했을 때만 L. casei로 단독발효한 것보다 K. fragilis와 혼합발효 한 것이 산생성량이 많았다.

Keywords