Exploring the Enhancement of Guaiacol Compounds in Sesame-Flavored Baijiu via Inoculation with Pseudomonas azotoformans YF-58

Guaiacol, 4-vinylguaiacol, 4-methylguaiacol and 4-ethylguaiacol, being guaiacol compounds characterized by spicy and smoky flavor, are important functional factors and key aroma components in sesame flavore Baijiu. In this study, to enhance the content of guaiacol compounds in this product, a strain of Pseudomonas azotoformans YF-58 which produced guaiacol compounds was added to the Zaopei (fermented grains) in the form of bacterial Fuqu. Subsequently, the effect of YF-58 strain on the fermentation system was explored from multiple perspectives, including microbial community composition, volatile flavor substance content and the expression levels of functional enzymes. The results showed that the addition of YF-58 strain altered the relative abundance of microorganisms such as Lactobacillus, Aspergillus, Pseudomonas, Staphylococcus, Weiniella, Bacillus and Corynebacterium in Zaopei. Moreover, the contents of acids, esters, alcohols and guaiacol compounds in Zaopei increased. Additionally, key enzymes associated with guaiacol compounds formation, such as 4-hydroxy-3-polyprenylbenzoate decarboxylase (EC 4.1.1.98), cellulase (EC 3.2.1.4) and catechol O-methyltransferase (EC2.1.1.6), were up-regulated. As a result, the contents of guaiacol, 4-methyl guaiacol, 4-ethylguaiacol and 4-vinylguaiacol in sesame flavor Baijiu were significantly increased by 193.1, 11.6, 95.4 and 105.2%, respectively. The research findings provided some theoretical guidance for enhancing the content of volatile flavor substances in Baijiu.