Abstract
In order to improve the sensory preference and to mitigate the bitter taste of green tea extract products, 100 microorganisms isolated from Korean traditional fermented foods were used to ferment green tea extract and the analysis of catechins and sensory evaluation of the fermented green tea extract products were undertaken. When the isolates were cultured into 2, 4, 6, 8, and 10% green tea extract, the highest growth rates were observed when 2 and 4% of green tea extract were used as growth medium. When the contents of catechin components of non-fermented and fermented green tea extracts were analyzed by HPLC, there was a significant decrease in content of epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin (EC) (EGCG: $125.45{\rightarrow}65.42\;{\mu}g/mg$, EGC: $85.96{\rightarrow}38.03\;{\mu}g/mg$, EC: $25.64{\rightarrow}13.84\;{\mu}g/mg$), whereas there was a significant increase in content of gallocatechin gallate (GCG) and gallocatechin (GC) (GCG: $7.79{\rightarrow}85.22\;{\mu}g/mg$, GC: $9.46{\rightarrow}64.59\;{\mu}g/mg$). Eleven strains of lactic acid bacteria, which showed relatively small content of gallate-type catechins (EGCG, ECG, GCG, CG) in their fermented green tea extracts, were selected and used for sensory test. As a result of sensory evaluation, Lactobacillus plantarum 62901 and Leuconostoc pseudomesenterioides K200132 showed the best score in overall preference. Their fermented products also showed strong roasted flavor while decreased grass flavor and bitter taste were observed.
미생물 발효에 의한 녹차 추출물의 쓴맛 감소와 관능성 개선을 위하여 식품으로부터 분리된 미생물을 이용하여 녹차 추출물을 발효시킨 후 catechin 성분 분석과 관능검사를 실시하였다. 다양한 발효식품으로부터 분리된 100종의 미생물을 2, 4, 6, 8, 10%(w/v) 녹차 추출물에 배양하였을 때 2%와 4% 녹차 배지에서 최대 생육도을 나타내었다. 녹차 추출물 발효액의 HPLC에 의한 catechin 종류별 분석 결과 epigallocatechin gallate(EGCG), epigallocatechin (EGC), epicatechin(EC)는 발효에 의해 함량이 급격히 감소하였고(EGCG : $125.45{\rightarrow}65.42\;{\mu}g/mg$, EGC : $85.96{\rightarrow}38.03\;{\mu}g/mg$, EC : $25.64{\rightarrow}13.84\;{\mu}g/mg$), gallocatechin gallate (GCG)와 gallocatechin(GC)의 함량은 급격하게 증가하였다 (GCG : $7.79{\rightarrow}85.22\;{\mu}g/mg$, GC : $9.46{\rightarrow}64.59\;{\mu}g/mg$). 발효 후 galloyl residue를 가지는 cathechin(EGCG, ECG, GCG, CG)의 함량이 상대적으로 작은 값을 나타낸 유산균 11주를 선정하여 녹차 추출물을 발효시킨 후 관능검사를 실시한 결과 Lactobacillus plantarum 62901과 Leuconostoc pseudomesenteroides K200132가 전체 기호도 조사에서 가장 우수한 결과를 보여주었다. 기호도가 좋게 나타난 샘플의 맛 패턴 특성을 살펴보면 구수한 향미는 강해지고 상대적으로 풀 비린 향미와 쓴맛이 낮아졌음을 확인할 수 있었다.
