Process Optimization and Analysis of Product Quality of Blueberry and Corn Peptide Fermented by Mixed Lactic Acid Bacteria

To study the mixed fermentation technology of blueberry and corn peptide by Lacticaseibacillus rhamnosus ZYN-0417 and Lactiplantibacillus plantarum ZYN-0221 and its effect on fermentation quality, fermentation conditions were optimized using a single-factor test and a Plackett–Burman design combined with a Box–Behnken response surface methodology, with blueberry juice and corn peptide as raw materials and L. rhamnosus ZYN-0417 and Lp. plantarum ZYN-0221 as the starter. The results showed that the optimum fermentation conditions were as follows: the volume ratio of ZYN-0417 and ZYN-0221 was 1:1, the amount of blueberry juice was 20%, the amount of corn peptide was 22%, the amount of glucose was 2%, the amount of inoculation was 5%, the fermentation time was 40 h, and the fermentation temperature was 37 °C. Under optimum conditions, the viable count of lactic acid bacteria in fermented blueberry and corn peptide was 16.28 log CFU/mL, the pH value was 4.86, the total acid content was 14.00 g/L, the total sugar content was 39.98 g/100 g, the protein content was 48.34 g/100 g, the scavenging ability of the DPPH, ABTS+ and ·OH− radicals increased by 10.14%, 10.98% and 25.02%, respectively, the chelating ability of Fe2+ increased by 14.92%, the content of total phenol increased by 1.43 mg/L, the content of total flavonoids increased by 0.38 mg/L, the activity of superoxide dismutase increased by 122.10 U/mL, and the activation rate of alcohol dehydrogenase increased by 5.74%. The results showed that mixed lactic acid bacteria could be used as a starter of blueberry and corn peptide and effectively improve the nutritional value of the product.