Analyses of microbial community and quality characteristics of nuruk

Abstract

Nuruk is a traditional Korean fermentation starter containing various microbes; it is utilized for the synthesis of alcoholic beverage. In this study, the changes in the quality characteristics and microbial community during the cultivation period of nuruk were analyzed. The results indicated that the fungal richness, expressed as Chao 1, from 70.0 to 19.3 on day 10 and subsequently increased to 35.0 on day 30 of cultivation. The content ratio of Aspergillus sp., Rhizopus sp. and Saccharomycopsis sp. increased with the progress of cultivation. Among the fungi, the content of the Aspergillus genus increased from 0.01% before cultivation to 70.4 %. Among the bacteria, the content of the Pantoea genus increased to 69.76% on day 7 and decreased to 44.80% on day 14. Considering the enzyme activity, saccharogenic power, α-amylase and carboxy peptidase exhibited the highest activity on day 7 while lipase exhibited the highest activity on day 14. Considering only the enzyme activity, the results indicated that it would be appropriate to terminate cultivation before day 14. The traditional cultivation period of nuruk is approximately 14 days; However, it is necessary to determine a suitable cultivation period for the application of nuruk as enzyme source.

Analysis of Flavor Characteristics of Commercial makgeolli

“…이처 럼 전자코를 사용한 식품의 향기성분 분석을 통해서 원산지 Isoamyl acetate는 발효과정에서 Saccharomyces cerevisiae 에 의해 생성되어 주류에 바나나향을 부여하는 향미성분으 로 보고되었으며 [34], 약주나 사케에 비해 막걸리에 높은 함 량으로 함유되어 막걸리에 특성을 부여하는 주요한 향미성 분이다 [6,33]. 누룩에는 S. cerevisiae 외에 비전통(non-Saccharomyces) 효모, 고초균, 젖산균 등 다양한 미생물이 포함되어 있어 막걸리 발효과정에서 S. cerevisiae에 의한 isoamyl acetate 생산 효율이 감소되고 효모 및 혼합 종균 막 걸리와 비교하여 누룩 막걸리의 isoamyl acetate 함량이 낮 은 것으로 판단된다 [39,40]. 부분 최소제곱 판별분석(PLS-DA) 을 통하여 살균 여부와 사용한 발효제 종류에 따라 향미의 차이를 나타내는 성분을 선발하였다 [32].…”