Screening and mutagenesis breeding of B. A salt YB13 for high producing tetramethylpyrazine and the application of its fortified Daqu for improving the quality of mixed-flavor baijiu.

This study isolated B. halotolerans YB13 from high-temperature Daqu and enhanced its tetramethylpyrazine (TTMP) yield to 2.98 g/kg through screening and plasma mutagenesis. The fortified Daqu containing YB13 was used in Mixed-flavor Baijiu fermentation. Compared to the control, the experimental group showed higher microbial diversity and more flavor compounds. Starch and acid protease were key physicochemical factors affecting flavor formation, with acid protease positively correlating with major flavors like ethyl palmitate, acetic acid, and octanoic acid. Dominant microbes (Lactobacillus, Thermoascus, Aspergillus) in the experimental group were strongly correlated with esters, acids, and alcohols. TTMP content and sensory scores were significantly higher in the experimental group, demonstrating the potential of microbial enhancement to improve baijiu quality.