New approach for the reuse of Chinese rice wine lees and Hyriopsis cumingii wastes: multistarter solid‐state fermentation

Chinese rice wine lees are the main by‐products in wine industry, with a great many of bioavailable constituents, such as amino acid, reducing sugars, short chain fatty acid and organic acids. Normally, most of the Chinese rice wine lees are made to animal feeds, therefore some effective approaches are needed to improve its nutritional and economy value. Hyriopsis cumingii is widely cultivated in China as a member of freshwater pearl mussels, by which over 95% of Chinese freshwater pearls are produced. After producing freshwater pearls, Hyriopsis cumingii flesh becomes food industry waste and are used mainly as animal feeds and fertilizer. However, Hyriopsis cumingii waste, rich in bioactive polysaccharides and polypeptides, has been reported to possess the ability of the anti‐tumor, immunity‐enhancement, anti‐inflammation and anti‐aging function. In our study, Chinese rice wine lees and Hyriopsis cumingii waste were utilized to obtain their residual value via solid‐state fermentation. Through solid‐state fermentation processes, agro‐industrial wastes are not only used for manufacturing of animal feed, but also for producing enzymes, antioxidants, chemicals and other bio‐based products like bio‐energy and biofertilizers. A variety of microorganisms participating in biotransformation are capable of secreting extracellular enzymes resulting in biomacromolecules decomposition. The strong symbiotic effect was observed in multistarter fermentation with natural yeast‐fungus mixed culture; meanwhile the mixture of Chinese rice wine lees and Hyriopsis cumingii waste at a ratio of 1:10 (w/w) was determined via series of adaptive optimization. Besides this, some chemical properties of the fermented production in Chinese rice wine lees and Hyriopsis cumingii waste was examined, including the ethanol levels, pH, total acids, total soluble proteins and sugars content. A soluble protein content of 26.1 ± 1.2% and a reducing sugar content of 17.8 ± 0.9% were achieved at the optimized condition. The digestibility of crude protein was increased, and the efficiency of nitrogen utilization was improved significantly after fermentation. The physicochemical properties of the crude protein were examined, covering the improved solubility, emulsifying properties and foaming properties in a pH range of 2.0‐12.0 and a sodium chloride concentration of 0‐1.0 M. The results showed a good solubility, oil absorption capacity, emulsifying property and foaming property of the fermented production. We found that the purified crude proteins and polysaccharides showed higher capabilities of reducing power, chelating capability of oxidative metal ions and scavenging free radicals. Therefore, the application of solid‐state fermentation with multistarter technology provides a new opportunity for improving the contents of nutritional protein and functional polysaccharides.