Upcycling of Chinese Nong-Flavor Baijiu Distiller’s Grains Through Solid-State Fermentation by Microbial-Enzyme Synergy

Chinese Baijiu distiller’s grains are by-products of the Chinese Baijiu brewing process, characterized by high water content, high acidity, and high fiber content, which make them unsuitable for animal feed, especially for monogastric animals. This study investigated the possibility of increasing the feed value of Nong-flavor Baijiu distiller’s grains (NFBDGs) for monogastric animals via solid-state fermentation by microbial-enzyme synergy. Experiments evaluated microbial growth, pH variation, improvement of crude protein (CP), true protein (TP), and acid-soluble protein (ASP), degradation of crude fiber (CF), acid detergent fiber (ADF), and neutral detergent fiber (NDF). The results indicated that Ligilactobacillus salivarius CRS23, Bacillus subtilis YLZ7, Saccharomyces cerevisiae CJM26, and xylanase were identified for the fermentation of NFBDGs. When the initial moisture content of NFBDGs was 60% and the initial pH was 3.4, under the conditions of aerobic fermentation at 37 °C for 4 days, the pH of NFBDGs increased from 3.49 to 6.04, the contents of CP and TP increased by 33.59% and 31.21%,,, respectively, while the contents of CF, ADF, and NDF decrease by 35.44%, 20.53%, and 25.02% respectively. The nutritional value of NFBDGs was significantly improved after microbial-enzyme synergistic fermentation, providing a new approach for their application as feed.