Effect of Enzymatic Hydrolysis Combined with Fermentation Treatment on Reducing Sugar Content and Antioxidant Performance of Auricularia auricula

In order to improve the reducing sugar content and antioxidant capacity of Auricularia auricula, thus providing new insight into the development and utilization of Auricularia auricula-based products, in this paper, the Auriculari aauricula pulp was subjected to the joint treatment of enzymatic hydrolysis and fermentation. Cellulase, pectinase or the combination of the two enzymes were used to hydrolyze the Auricularia auricula pulp, which was then co-fermented by Lactobacillus plantarum and Lactobacillus fermentum alone or in combination. Single-factor experiments involving the material to liquid ratio, the amount of enzyme used, zymolysis time, temperature and pH were optimized using reducing sugar content as criteria. And the effects of inoculum amount, the fermentation temperature and time of the fungus zymolysis liquid on the 1,1-Diphenyl-2-trinitrophenylhydrazine (DPPH) radical scavenge rate were optimized, and finally the response surface experiment was used to determine the optimal parameters for Auricularia auricula fermentation. The results showed that the maximal reducing sugar content reached (6.94±0.24) mg/mL when 3.2% (w/w on Auricularia auricula pulp base) of pectinase and cellulase was added, and the mass ratio of pectinase and cellulase was 2:3 (w/w) under the following enzymatic hydrolysis conditions: Temperature of 50 ℃, pH5.50 for 3.5 h. Under the conditions of L. plantarum and L. fermentum ratio of 1:1, fermentation temperature at 37 ℃, inoculation amount at 3%, and fermentation time for 8 h, the DPPH free radical scavenging rate of the fermentation broth reached 92.46%±3.22%. The reducing sugar content and antioxidant capacity of the Auricularia auricula pulp treated by enzymatic hydrolysis and fermentation had been significantly improved.