The first application of biological pretreatment in Chinese spirits, utilizing cellulose-degrading probiotics from Jiangshui to improve the quality of Highland Barely Liquor

Highland barley liquor is a distilled spirit made from highland barley on the Tibetan Plateau, but its alcohol yield is limited by the high fiber content of the raw material. In the field of biomass resources, functional microorganisms are commonly used in pretreatment to degrade cellulose and other substances, improving fermentation output. In this study, we isolated the cellulose-degrading probiotic Lactobacillus delbrueckii GR-8 (CMCase 6.21 U/mL) from the traditional vegetable-based fermented food "Jiangshui" and applied biological pretreatment to the fermentation of highland barley liquor. During pretreatment, probiotics enhanced cellulase and amylase activities in the fermented grains, resulting in a 25% reduction in cellulose content and a 112% increase in free reducing sugar content. The pretreatment significantly altered the microbial community structure, enhancing microbial diversity. After distillation, alcohol yield increased by 3.5%, and total acid and ester contents rose by 25% and 23%, respectively. Pyrazine compounds increased by 1290%, while higher alcohols like nonanol, phenylethanol, and hexanol decreased. The treated liquor caused less harm to mice, who showed improved memory, motor skills, and lower oxidative liver damage. This study demonstrates that biological pretreatment enhances both fermentation and the quality of Chinese spirits. Probiotics Lactobacillus delbrueckii were used for pretreatment before highland barely liquor fermentation, and fermented grain samples were collected on the first day of fermentation, the third and seventh days of pretreatment, and the 1st, 4th, 13th, and 26th days of formal fermentation, and the bacterial and fungal communities were determined by the method of measuring the bacterial V3V4 region, and the fungi were determined by measuring the ITS sequence. In addition, the mice were given fermented and distilled barley liquor by gavage, and the bacterial flora structure of the cecal contents was determined after three days of feeding.