Abstract:Dendrobium officinale is a medicinal and food homologous plant, ranking first among the "Nine magic herbs of China". To investigate the changes in active ingredients of Dendrobium officinale during microbial transformation, the most suitable strain for fermentation using Dendrobium officinale as the fermentation substrate was screened out. Based on single factor experiments, the changes in comprehensive score of the polysaccharide, flavones and total phenolics were used as evaluation indicators, the optimal fermentation process was obtained by orthogonal experiments , and the antioxidant capacities of Dendrobium officinale before and after fermentation were measured. Using Dendrobium officinale as the fermentation substrate, the most suitable strain was Aspergillus niger. The optimal fermentation process was as follows: ratio of material to liquid, 1:3; initial pH, 8; inoculation amount, 10%; fermentation temperature, 34 ℃; fermentation time, 9 days. The validation test results showed that the polysaccharide content was 72.65 mg/g, the flavonoid content was 6.67 mg/g, the polyphenol content was 11.32 mg/g, and the comprehensive score Pi was 0.945 5. Taking Vitamin C as the control, the IC50 of DPPH free radical scavenging ability of fermented Dendrobium officinale was 0.67 mg/g, IC50 of ABTS free radical scavenging ability was 0.41 mg/g, and IC50 of reducing ability was 16.50 mg/g. The screened strains could increase the content of active substances in Dendrobium officinale, optimize the fermentation process, increase the antioxidant capacity of Dendrobium officinale, which allowed achieving the goal of economy, safety, and efficiency, thereby improving greatly the application value of Dendrobium officinale.
