摘要 该研究首先构建对酱油风味有重要贡献的吡嗪化合物的定性定量方法。其次,筛选得到1株可合成7种烷基吡嗪的微生物,命名为枯草芽孢杆菌Nr. 5。在前期解析多种烷基吡嗪微生物合成机制的基础上,提出了生物法提升酱油中吡嗪化合物种类及质量浓度的策略。构建酱油模拟发酵体系,在发酵初期分别或联合添加发酵剂-枯草芽孢杆菌Nr. 5及发酵底物-L-苏氨酸及D-葡萄糖。研究表明,相比于无添加的酱油发酵样品,只添加枯草芽孢杆菌 Nr. 5的酱油样品中2,5-二甲基吡嗪及2,3,5-三甲基吡嗪质量浓度分别提高了18和3倍,其他吡嗪质量浓度未增加。同时添加枯草芽孢杆菌 Nr. 5、L-苏氨酸及D-葡萄糖的样品,7种吡嗪化合物质量浓度均有效提升,吡嗪化合物总质量浓度提高了12.5倍。该研究首次提出生物法提升酱油发酵过程风味吡嗪合成策略,对酱油中吡嗪化合物合成途径解析及工业酱油生产中吡嗪浓度提升有借鉴意义。
Abstract: Qualitative and quantitative methods of pyrazines, a compound that contributes to the soy sauce flavor, were constructed. Bacillus subtilis Nr. 5 capable of producing 7 alkylpyrazines was selected. Based on previous work revealing the biosynthesis mechanisms of alkylpyrazine, a biological method was proposed to enhance the production of pyrazines by adding starter and fermentative substrates during soy sauce fermentation. A stimulate soy sauce fermentation system was constructed by adding starter-B. subtilis Nr. 5 and/or substrates L-threonine and D-glucose at the early stage of fermentation. After 30 days fermentation, the addition of B. subtilis Nr. 5 improved the production of 2,5-dimethylpyrazine by 18 folds and 2,3,5-trimethylpyrazine by 3 folds, while the concentrations of other 5 pyrazines had no significant difference. After the addition of B. subtilis Nr. 5, L-threonine and D-glucose, the production of all 7 pyrazines improved significantly and their total concentration increased by 12.5 folds. It is the first time that a bio-strategy of pyrazines improvement was proposed for soy sauce fermentation. This study provides reference for the synthesis pathway analysis and concentration increase of pyrazines during soy sauce fermentation.
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