Response Surface Methodology to Optimize the Process of Fermentation Powder of Cyclocarya paliurus with High Antioxidant Activity by Using Enzyme-Microorganisms Synergy Method

The dried leaves of Cyclocarya paliurus were enzymatically hydrolyzed with complex enzymes (cellulase and hemicellulase). The fermentation solution was fermented by mixed bacteria (Lactobacillus plantarum and Saccharomyces cerevisiae) and then freeze-dried to prepare Cyclocarya paliurus fermentation powder with high antioxidant activity. Single factor experiment was conducted to study the effects of material-liquid ratio, compound enzyme content, compound enzyme mass ratio, enzymolysis time, sucrose addition, mixed bacteria content, mixed bacteria mass ratio and fermentation time on DPPH free radical scavenging effect of Cyclocarya paliurus fermentation powder. On this basis, Plackett-Burnman (PB) experimental design and response surface methodology were used to optimize the co-fermentation process of cyclocarinase. The results showed that the optimal technological parameters were as follows: Material-liquid ratio 1:12 g/mL, compound enzyme content 0.80%, compound enzyme mass ratio 2.20:1 g/g, enzymolysis time 2.5 h, sucrose addition 8.0%, mixed bacteria content 5.80%, mixed bacteria mass ratio 2:1 g/g, fermentation time 42 h. Under these conditions, the DPPH free radical scavenging rate of Cyclocarya paliurus fermentative powder was 82.17%. The DPPH free radical scavenging rate of Cyclocarya paliurus was increased by 159.9%, the polysaccharide content was increased by 194.0%, and the flavonoids content was increased by 72.0%, the content of triterpene in Cyclocarya paliurus increased by 52.6% .This paper has laid a foundation for Intensive processing of Cyclocarya paliurus leaves and industrialization of instant tea powder.