Abstract: [Objective] Aiming at the problem that fresh soybean residues are difficult to ferment directly due to excessively high moisture content,this study was conducted to explore the effects of types and mixing ratios of dry auxiliary materials on the fermentation parameters of soybean residues,and to screen out suitable fermentation processes.[Method] Cassava distillers' grains,corn cob powder and rice straw powder were selected as moisture-regulating auxiliary materials.Three mixing ratios （92∶8,84∶16 and 76∶24） were set,with pure soybean residues as the high-moisture control group.All groups were inoculated with Lactobacillus plantarum at 1×10⁷ CFU/g,and related indexes were determined after 30 days of fermentation.[Result] Corn cob powder and rice straw powder could effectively reduce the moisture content of materials and improve fermentation quality.Among them,the corn cob powder group had the highest lactic acid content and excellent sensory quality at the mixing ratio of 84:16.However,local mould growth occurred in the corn cob powder group at the high auxiliary material ratio of 76∶24,indicating a critical equilibrium point between material compaction and moisture.Due to the strong buffering capacity caused by high ash content and the lack of water-soluble carbohydrates,the pH value of the cassava distillers' grains group was significantly higher than that of other groups.[Conclusion] Mixing soybean residues with corn cob powder at a ratio of 84∶16 is the optimal process for optimizing soybean residue fermentation and nutrient retention.

Key words: soybean residue, fermentation technology, fermentation parameters, nutritional value