김치의 저장 온도에 따른 유산균총의 변화와 김치 쓴 맛 원인균 규명

Abstract

To investigate effect of temperature on growth of lactic acid bacteria (LAB), mixture of LAB (Weissella spp., Leuconostoc spp., and Lactobacillus spp.) was cultivated at -2℃ for 12 weeks, -1℃ for 12 weeks, 4℃ for 4 weeks, 6.5℃ for 12 weeks 15℃ for 1 week, and 30℃ for 48 hr in MRS broth as well as kimchi filtrate. The LAB analysis was monitored by cell counting and PCR-DGGE. When mixture of LAB was cultivated in MRS broth, W. koreensis predominated at –2℃ from 4 weeks, at -1℃ from 2 weeks, at 4℃ from 4 weeks and at 6.5℃ from 5 days, and then reached its counts upto 7.5∼8.6 log CFU/mL. Lb. sakei was the second dominance with 6.0∼7.7 log CFU/mL of cell counts from 2 weeks at –2∼6.5℃. At 6.5℃, Leu. mesenteroides reached its counts upto 6.3 log CFU/mL on 3 days of storage and was maintained for up to 4 weeks. Lactobaillus spp. predominated at 15℃ from 3 days. Leuconostoc spp. predominated from 12 hr and then Lactobacillus spp. became predominance after 24 hr. In cultivation of LAB mixture in kimchi filtrate, W. koreensis grew most rapidly from 1∼2 weeks at -1∼-2℃ and 4℃. Cell counts of Weissella spp. and Leuconostoc spp. were reached to 8 log CFU/mL at 15℃ for 24 hr, thereafter Weissella spp. were not detected anymore in the kimchi filtrate. However, counts of Lactobacillus spp. were reached to 8 log CFU/mL at 15℃ for 72 hr cultivation. By using PCR-DGGE, W. koreensis and Lb. sakei were detected throughout the storage period in MRS broth and kimchi filtrate. Leuconostoc spp. were detected at –2∼15℃ in initial fermentation. Major lactic acid bacteria in MRS broth at 30℃ were appeared W. cibaria, Lb. sakei and Lb. plantarum. In kimchi filtrate, Leu. gelium or Leu. inhae was detected at all temperature. Lactobacillus spp. showed more rapid growth at high temperature than low temperature. W. koreensis and Lb. sakei were dominant at low temperture and were presumed to be a cause of bitter taste in kimchi storage. When these strains were respectively applied to kimchi, W. koreensis was dominant when it reached 8.2∼8.7 log CFU/mL. Sensory evaluation showed that kimchi filtrate inoculated with W. koreensis was the largest. The aboce results suggested that W. koreensis has the most psychrophilic property among the tested 6 specise of LAB and was a cause of bitter taste in kimchi storage at low temperature.