Natto의 향미 개선 및 품질 개선을 위한 기초연구를 목적으로 증자대두에 Bacillus natto(NN-1)를 접종하고 마늘(2%)과 고추 oleoresin (0.2%)을 첨가하여 40℃에서 24시간 발효시켜 향기성분, 지방산, 유기산, pH 및 적정산도의 변화를 측정하였다. 발효 중에 생성되는 휘발성 물질을 연속 증류 장치로 추출하여 GC 및 GC-MSD로 향기성분을 분석 동정한 결과, 무첨가 Natto에서는 62종류의 휘발성 성분이 검출되었으며 그중 2,5-dimethylpyrazine, trimethylpyrazine, 2,6-bis(1, 1-dimethylethyl)phenol 등의 함량이 높게 나타났고, 마늘 첨가에 의한 Natto 제조시 71종의 휘발성 성분이 검출되었는데 2,6-bis(1,1-dimethylethyl)phenol, 2,5-dimethylpyrazine의 높은 함량과 아울러 2-methoxyphenol, 1,2-benzenedicarboxylic acid 등의 함량은 증가되었고 1,2-propanediol, 1-hexanol, 2-dimethylpyrazine 등의 함량은 크게 감소되었다. 또한 고추 oleoresin 첨가 Natto에서는 70종의 화합물이 분리 동정되었고 그 성분 중에서 4,5-dihydroxy-5-propyl-1H-pyrazole, 1,1,3-trime- thylcyclopentane 성분이 검출되었으며 trimethylpyrazine, 3-ethyl-2,5-dimethylpyrazine, hexadecanoic acid 등의 함량은 증가되었지만 1,2-propanediol, 1-hexanol, 2,5-dimethylpyrazine 등의 함량은 감소되었다. 지방산의 조성은 마늘 및 고추 oleoresin 첨가에 의한 변화가 없었으며 전 시험구에서 myristic, palmitic, stearic, oleic, linoleic, linolenic, arachidic acid의 지방산이 검출되었다. 유기산은 전 시험구에서 citric acid, pyroglutamic acid가 검출되었고, citric acid는 24시간 발효시켰을 때 무첨가구와 마늘첨가구는 44~45% 감소, 고추 oleoresin 첨가구는 24~28% 감소하였다. pH는 전 시험구에서 발효 초기 6.4~6.5 범위에서 24시간 발효했을 때 7.52~7.78 범위로 중성에서 약 알카리화 되었고, 적정산도는 전 시험구에서 대체적으로 발효 12시간에서 크게 증가 하다가 그 후에 점차 감소하는 경향이었다.
Natto is a Japanese traditional food made from whole soybeans by the fermentation of Bacillus natto. This study was attempted to improve the taste of Natto, garlic(2%) and red pepper oleoresin(0.2%) were added. Conventional Natto(N-1), garlic Natto(N-2), red pepper oleoresin Natto(N-3), garlic and red pepper oleoresin Natto(N-4) were prepared. Volatile flavor components, fatty acid, organic acid, pH and titratable acidity in all samples were investigated. The experimental results revealed the presence of 62 volatile components in conventional Natto. Among there, the major flavor compounds were identified to be 2,5-dimethylpyrazine, trimethyl-pyrazine, 2,6-bis(1,1-dimethylethyl)phenol. Seventy-one volatile compounds were detected in N-2, and major compounds were identified to be methyl-2-propenyl disulfide, 2,6-bis(1,1-dimethylethyl)phenol and 2,5-dimethylpyrazine. The amounts of volatile compounds, 2-methoxyphenol and 1,2-benzenedicarboxylic acid increased by addition of garlic, where as, 1,2-propanediol, 1-hexanol and 2,5-dimethylpyrazine decreased. The compounds, 4,5-dihydroxy-5-propyl-1H-pyrazole, 1,1,3-trimethylcyclopentane were identified in N-3. The compounds, such as trimethylpyrazine, 3-ethyl-2,5-dimethylpyrazine increased by addition of red pepper oleoresin, whereas 1,2-propanediol, 1-hexanol and 2,5-dimethylpyrazine decreased. Fatty acid compositions were mainly consisted of linoleic acid (43.66~55.89%) and followed by oleic, palmitic, linolenic, stearic, arachidic, myristic acid. The organic acids were identified to be citric (28.2~30.6), acetic (50.0~73.3) and pyroglutamic acid (2.1~3.7).