Optimization of fermentation process and quality analysis of Pueraria lobate lactic acid bacteria beverage

In this study, using Pueraria lobata as raw material, and the enzymatic hydrolysis rate and isoflavone content as the evaluation indexes, the enzymatic hydrolysis conditions of P. lobata treated by compound enzymatic method were optimized by single factor tests and orthogonal tests. Using the enzymatic hydrolysate as the fermentation substrate, and Lactiplantibacillus plantarum STDA5 as the fermentation strain, the P. lobata beverage with lactic acid bacteria was prepared, the fermentation process conditions were optimized by single factor tests and response surface tests, and its quality indexes were determined. The results showed that the optimal enzymatic hydrolysis conditions of P. lobata were as follows: compound enzyme addition 1.2%, enzymatic hydrolysis pH 6.5, temperature 65 ℃, and time 240 min. The optimal fermentation conditions of P. lobata lactic acid bacteria beverage were as follows: inoculum 1×10⁵ CFU/ml, fermentation temperature 38 ℃, time 12 h, and sucrose addition 10%. Under the optimal conditions, the number of viable bacteria in P. lobata lactic acid bacteria beverage was 6.89×10⁸ CFU/ml, the reducing sugar content was 17.37 g/L, the total acid content was 43.50 g/L, the soluble solids content was 14.10%, the isoflavone content was 0.71 g/L, and the puerarin content was 27.60 μg/ml.