밀, 쌀 및 녹두를 분쇄 후 밀기울을 첨가하여 일정 비율(15:1:1:3)로 혼합한 곡물에 양조용 곰팡이의 균종을 달리하여 제조한 누룩의 품질 특성을 알아보고자 발효 시기별 일반성분 및 효소활성과 유기산 분석을 하였다. 누룩의 pH는 발효 시기별 큰 차이는 보이지 않았으며, 산도와 아미노산도는 두균을 혼합하여 제조한 누룩(AO-AK)이 가장 높게 나타났다. 전반적으로 두 균을 혼합한 누룩이 단일 균을 접종한 누룩보다 ${alpha}$-amylase 및 acidic protease의 효소활성이 높게 나타났다. 누룩의 유기산은 acetic, citric, formic, fumaric, lactic, malic 및 oxalic acid 등이 확인되었다. 전체 유기산 총량은 혼용누룩(2,116.3 mg%), A. kawachii SC60 단용누룩(1,608.5 mg%), A. oryzae RIB1353 단용누룩(1,146.7 mg%) 순으로 혼용누룩의 유기산 생성량이 가장 높게 나타났다. 따라서 두 균주를 혼용하여 제조한 누룩이 단일균주를 사용한 누룩보다 유기산 함량, 효소활성 등 품질 특성이 우수한 것으로 여겨진다.
Nuruk is a fermented ingredient used for production of traditional Korean rice wine. In this study, quality characteristics of mixed-grain nuruk was made by brewing with different fungal strains was analyzed. Quality elements including enzyme activity and organic acids constituents were measured. The fermentation time of the nuruk did not make a significant difference in terms of its pH, but the acidity and amino acid content for nuruk made from a mixture of two fungal strains was higher than that seen with a single fungal strain. Overall, the enzyme activity for two fungal strain nuruk was higher than that observed for single fungal strain nuruk, with ${alpha}$-amylase and acidic protease activity in the mixed strain nuruk observed to be more than twice that of the single strain. The major organic acids observed in the manufactured nuruk were identified as acetic, citric, formic, fumaric, lactic, malic and oxalic acids. The total amount of organic acids contained in the nuruk made with the two fungal strain was (2,116.3 mg%). The fungal strains used were A. kawachii SC60 nuruk (1,608.5 mg%) and A. oryzae RIB1353 nuruk (1,146.7 mg%).
