Optimization of solid-state fermentation process of highland barley for 1-deoxynojirimycin production and its in vitro hypoglycemic ability

Using highland barley as the raw material and Bacillus amyloliquefaciens B-14 as the fermentation strain, 1-deoxynojirimycin (DNJ) was produced with solid-state fermentation. The optimal process parameters for the solid-state fermentation of DNJ were optimized through single-factor and response surface experiments. The in vitro hypoglycemic activity was investigated by measuring α-glucosidase, α-amylase, and conducting in vitro digestion experiments. The results indicated that the optimal process parameters for DNJ production by solid-state fermentation of highland barley with B. amyloliquefaciens were fermentation time 3 d, cooking time 41 min, temperature 37 ℃, and inoculum 5.5%. Under these optimized conditions, the DNJ content reached 6.13 mg/g. The half-maximal inhibitory concentration (IC₅₀) values for α-glucosidase and α-amylase were 0.29 mg/ml and 2.89 mg/ml, respectively. In the in vitro digestion experiments, as the addition of the solid-state fermented highland barley product increased, the starch hydrolysis rate showed significantly inhibitory effect. When the addition was 20%, simulated intestinal digestion time was 180 min, the starch hydrolysis rate was 35.13%, indicating that the highland barley fermentation products had a significant effect on reducing blood sugar levels, which provided a reference for the research and development of functional foods based on barley.