Screening of Fermentation Strains of Quinoa and Lonicera caerulea and Optimization of Complex Fermentation Process

In order to improve the variety of multigrain beneficial fermented foods and address the sour flavor and strong seasonality of tiny berries, research was conducted on the best processing method for the quinoa-Lonicera caerulea complex fermentation liquid. Using quinoa and Lonicera caerulea as raw materials, a synergistic fermentation process involving a combination of yeast and lactic acid bacteria was employed. By comparing the superoxide dismutase (SOD) activity and viable bacteria number of the quinoa-Lonicera caerulea complex fermentation solution following fermentation of different strains, the most appropriate fermentation strains were chosen, and the fermentation conditions were improved. SOD activity and γ-aminobutyric acid (GABA) concentration were used as optimization indices to further enhance the fermentation process of the quinoa-Lonicera caerulea complex fermentation solution by combining single component and response surface testing. Results showed that BA, LP, and LA were the best strains for fermentation. During the Saccharomyces fermentation stage, the inoculum amount was 0.30%, the bottling amount was 40 mL/100 mL, and the incubation was carried out in a shaker at 30 ℃ for 16 h, the SOD activity of quinoa-Lonicera caerulea complex fermentation liquid was measured at (139.740±0.485) U/mL, and the amount of live bacteria was (4.667±0.450)×10⁶ CFU/mL during the yeast fermentation stage. During the Lactobacillus fermentation stage, the inoculum amount was 2%, with a 1:1 ratio of Lactobacillus plantarum and Lactobacillus acidophilus, and the culture was incubated at 37 ℃ for 24 hours, the SOD activity of quinoa-Lonicera caerulea complex fermentation solution was (174.000±3.055) U/mL, and the number of live bacteria was (27.250±1.05)×10⁸ CFU/mL. During the composite fermentation stage, the optimal fermentation conditions for the quinoa-Lonicera caerulea complex fermentation were as follows: Initial pH was 5.0, mixing ratio was 1:3, sugar addition was 10%, fermentation temperature was 37°C, and under these optimal conditions, the SOD activity of quinoa-Lonicera caerulea complex fermentation was (318.245±3.245) U/mL, and the GABA content was (0.647±0.018) mg/g. The resultant quinoa-Lonicera caerulea complex fermentation solution was dark purple in color and rich in both SOD and GABA. It would provide the theoretical framework for creating functional fermented foods using tiny berries and grains as the primary ingredients.