The effects of low temperature storage and aging of Jeot-kal on the microbial counts and microflora

젓갈의 숙성 및 저온 저장이 미생물 균수 및 균총에 미치는 영향

  • Hong, Yeun (Food Chemistry and Biotechnology Division, Korea Food Research Institute) ;
  • Kim, Jeong-Hee (Food Chemistry and Biotechnology Division, Korea Food Research Institute) ;
  • Ahn, Byung-Hak (Food Chemistry and Biotechnology Division, Korea Food Research Institute) ;
  • Cha, Seong-Kwan (Food Chemistry and Biotechnology Division, Korea Food Research Institute)
  • 홍연 (한국식품개발연구원 생물공학연구본부) ;
  • 김정희 (한국식품개발연구원 생물공학연구본부) ;
  • 안병학 (한국식품개발연구원 생물공학연구본부) ;
  • 차성관 (한국식품개발연구원 생물공학연구본부)
  • Published : 2000.12.30

Abstract

The addition of 5% NaCI to standard plate count (SPC) and bromcresol purple (BCP) agar showed the highest viable cell counts for Jeot-kal samples. The use of 15% glycerol as cryoprotectant showed the highest microbial survival rate at both temperatures, $-20^{\circ}C$ and $-170^{\circ}C$, and on both colony count media, SPC and BCP. During the aging, the pH of Bajirak Jogae-Jeot (fermented clam) decreased from 6.8 to 5.0. Crude protein content was 10% for Bajirak Jogae-Jeot and $6{\sim}7%$ for Myeolchi-Jeot (fermented anchovy). Microbial population of Bajirak Jogae-Jeot was $10^9\;CFU/g$ after 4 weeks of aging, but was only $10^{3-5}\;CFU/g$ in the case of Myeolchi-Jeot. The proportion of Gram positive and catalase negative bacteria in Bajirak Jogae-Jeot increased drastically during the 4 weeks of aging, which showed typical lactic bacterial fermentation. After 2 years' storage of Jeot-kal in liquid nitrogen tank, the cell counts of total aerobic or lactic bacteria were decreased, resulting in about 10% survival rate. Microbial floral change of Jeot-kal was also investigated. In the case of Bajirak Jogae-jeot, the ratio of rod to cocci and that of Gram negative to positive increased after liquid nitrogen storage. But, rod to cocci ratio of Myeolchi-jeot decreased after liquid nitrogen storage. The ratio of yeasts decreased in both cases after storage.

Keywords

microflora;liquid nitrogen storage;fermented fish;cell viability