Luo Shuai, Zhang Qiaoling, Yang Fan, Lu Jianjun, Peng Zheng, Pu Xiuxin, Zhang Juan, Wang Li
Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China.
Science Center for Future Foods, Jiangnan University, Wuxi, China.
Front Microbiol. 2022 Mar 24;13:857966. doi: 10.3389/fmicb.2022.857966. eCollection 2022.
Sauce-flavored Daqu exhibits different colors after being stacked and fermented at high temperatures. Heiqu (black Daqu, BQ) with outstanding functions is difficult to obtain because its formation mechanism is unclear. In this study, we compared the metabolites in different types of Daqu using ultra-high-performance liquid chromatography triple quadrupole mass spectrometry to explore the formation process of BQ. We found that 251 differential metabolites were upregulated in BQ. Metabolic pathway analysis showed that "tyrosine metabolism" was enriched, and most metabolites in this pathway were differential metabolites upregulated in BQ. The tyrosine metabolic pathway is related to enzymatic browning and melanin production. In addition, the high-temperature and high-humidity fermentation environment of sauce-flavored Daqu promoted an increase in the melanoidin content a typical Maillard reaction; thus, the melanoidin content in BQ was much higher than that in Huangqu and Baiqu. By strengthening the Maillard reaction precursor substances, amino acids, and reducing sugars, the content of Daqu melanoidin increased significantly after simulated fermentation. Therefore, the enzymatic browning product melanin and Maillard reaction product melanoidin are responsible for BQ formation. This study revealed the difference between BQ and other types of Daqu and provides theoretical guidance for controlling the formation of BQ and improving the quality of liquor.
酱香型大曲在高温堆积发酵后呈现出不同颜色。功能优异的黑曲（黑大曲，BQ）难以获得，因为其形成机制尚不清楚。在本研究中，我们使用超高效液相色谱三重四极杆质谱法比较了不同类型大曲中的代谢产物，以探究黑曲的形成过程。我们发现黑曲中有251种差异代谢产物上调。代谢途径分析表明，“酪氨酸代谢”被富集，该途径中的大多数代谢产物是黑曲中上调的差异代谢产物。酪氨酸代谢途径与酶促褐变和黑色素生成有关。此外，酱香型大曲的高温高湿发酵环境促进了类黑素含量的增加——这是典型的美拉德反应；因此，黑曲中的类黑素含量远高于黄曲和白曲。通过强化美拉德反应前体物质、氨基酸和还原糖，模拟发酵后大曲类黑素含量显著增加。因此，酶促褐变产物黑色素和美拉德反应产物类黑素是黑曲形成的原因。本研究揭示了黑曲与其他类型大曲的差异，并为控制黑曲的形成和提高白酒品质提供了理论指导。
