Application of fortified Daqu to optimize the core fermentation microbial flora and improve the ester profile of Nongxiangxingbaijiu

Nongxiangxing baijiu , a traditional fermented alcoholic beverage, undergoes a complex microbial succession and metabolic process. Recently, many baijiu producers have been manufacturing Nongxiangxing baijiu with elevated levels of ethyl acetate and reduced levels of ethyl hexanoate, which disrupts the flavor equilibrium of the baijiu . This study employed fortified Daqu to enhance the quality of raw baijiu . The findings indicated a significant reduction in fungal diversity and a decrease in Lactobacillus abundance. Specifically, the ethyl hexanoate content in the top, middle, and bottom layers of the experimental group's raw baijiu increased by 15.9 %, 15.5 %, and 27.2 %, respectively, while the ethyl acetate content decreased by 5.4 %, 11.1 %, and 26.6 % correspondingly. Spearman correlation analysis revealed a positive association between the relative abundance of Lactobacillus and both ethyl acetate and 2,4-di-tert-butylphenol. Therefore, using fortified Daqu in baijiu production not only boosted the ethyl hexanoate content and lowered the ethyl acetate content in raw baijiu but also adjusted the proportions of other favorable flavors. This established a theoretical foundation for enhancing the quality of Nongxiangxing baijiu. • The raw baijiu achieved the goal of "increasing hexyl and reducing ethyl". • Esters in raw baijiu increased after the application of fortified Daqu fermentation. • The quality of raw baijiu was improved by fortified Daqu. • The use of fortified Daqu for fermentation simplified the fungal community structure.