Abstract:Objective This study aimed to solve the issue of poor nutritional and sensory quality of Gastrodia elata fermented by single strains, this study explored the improving effects of mixed strain fermentation on the nutritional quality and flavor of Gastrodia elata. Method Strains that could improve the flavor of Gastrodia elata liquid were screened, and the mixed strain fermentation process was optimized. The nutritional and flavor quality were compared between the Gastrodia elata liquids fermented by mixed strains and single strains.Result The optimized process was as follows: eight suitable strains (Weissella halotolerans, Lactobacillus farciminis, Lactiplantibacillus plantarum, Lactobacillus brevis, Lactobacillus mucosae reuteri, Pediococcus pentosaceus, Lactococcus acidophilus, and Enterococcus faecalis) were mixed in equal proportions, fermentation for 3 d, an inoculation volume fraction of 2.25%, and a fermentation temperature of 37 ℃. The red-yellow degree of the Gastrodia elata liquid fermented by mixed strains increased, the mass concentration of total acids was (4.81±0.39) g/mL and the mixed strain fermentation group showed the mass concentration of flavonoids (1.28±0.03) mg/mL. Compared with the control group, the DPPH free radical scavenging rate increasing by 47.96%, being significantly better than single strain fermentation. The mass concentrations of gastrodin and p-hydroxybenzyl alcohol were (434.53±14.11) μg/mL and (289.94±0.11) μg/mL, respectively. The mass concentration of polyphenols decreased by 6.70%, and that of soluble solids also decreased. The data indicated that mixed strain fermentation outperformed single strain fermentation. The analysis of the fermented Gastrodia elata liquid by an electronic nose showed that the response values of the W1W and W5S sensors decreased. The main off-flavor components were sulfides, terpenes, and nitrogen oxides, and the coordination effect of mixed strain fermentation on off-flavors was better, which was consistent with the results of sensory evaluation.Conclusion The mixed strain fermentation has a synergistic acid production effect, producing the Gastrodia elata liquid with a relatively high retention rate of polyphenols and flavonoids, an enhanced antioxidant activity, and improved flavor quality and demonstrating the value of popularization and application.
