한국식품저장유통학회지 (Korean J. Food Preserv.) 제22권 제6호 (p.920-925)

온도를 달리한 누룩 발효 기간별 배양 유산균 변화 및 분리 유산균들의 효소 활성

Change in the composition and enzyme activity of culturable lactic acid bacteria in Nuruk during fermentation at different temperatures
키워드 :
Nuruk,fermentation,lactic acid bacteria,enzyme activity,microbial succession

초록

The microbial composition in Nuruk, a Korean cereal fermentation starter, is a critical factor for the quality and organoleptic properties of traditional alcoholic beverages. This study was aimed at monitoring the compositional change and enzyme activity of culturable lactic acid bacteria (LAB) in two types of Nuruk fermented at different temperatures. All culturable LAB were isolated at various time points (0, 3, 6, 10, 20, and 30 days) and identified by 16S rRNA sequencing. In traditional Nuruk type A (TN-A), which was fermented at 36℃, the population of total culturable LAB during the fermentation period was between 104 and 105 log CFU/mL. On the other hand, the LAB population in traditional Nuruk type B (TN-B) fermented at 45℃ (primary fermentation for 10 days) and 35℃ (secondary fermentation for 20 days) was 102 log CFU/mL; however, these bacteria could not be detected after 6 days. Major LAB strains were identified in both Nuruk types: (1) from the MRS-culture of TN-A, Pediococcus pentosaceus at 3-30 days; (2) from MRS-culture of TN-B, P. pentosaceus at 3 days and Enterococcus hirae at 6 days. The protease activities of the dominant LAB isolated from the TN-A and TN-B cultures were within the ranges of 0.64~1.03 mg/mL and 0.74~0.81 mg/mL (tyrosine content), respectively, whereas the α-amylase activities were 0.75~0.98 mg/mL and 0.78~0.79 mg/mL (amylose content), respectively.