Innovative use of unhulled rice in Baijiu brewing: impact on flavor and microbial composition

The quality of light-flavor Baijiu (LFB), a traditional Chinese liquor, is strongly influenced by fermentation raw materials. Traditional Baijiu brewing uses rice husk as an excipient, requiring energy-intensive steaming to remove off-flavors—a process that increases production time and costs. This study introduces an innovative co-fermentation technique using unhulled rice (Jingkangyou/Pinxiangyou varieties) with sorghum, improving LFB quality while reducing expenses. Metagenomic and flavoromic analyses compared three groups: a rice husk control and two experimental groups with varying proportions of unhulled rice. Results showed significant flavor differences, with D-lactic acid, leucinic acid, and putrescine levels correlating significantly positively to unhulled rice content. Experimental groups exhibited altered microbial diversity, flavor profiles, and physicochemical properties compared to the control. Key metabolic pathways, including galactose, phenylalanine, and lysine metabolism, were significantly modified, indicating unhulled rice reshaped biochemical reactions. These findings advance understanding of LFB fermentation dynamics and offer strategies for raw material optimization. • Novel brewing method using unhulled rice enhances Baijiu quality and reduces costs. • Key flavors in Baijiu positively correlate with unhulled rice proportion. • Unhulled rice alters microbial diversity and metabolic pathways during fermentation. • Current findings guide raw material optimization for improved Baijiu flavor and sustainability.