Screening and Properties of Functional Probiotics for Apple Fermentation

[Objectives] To screen functional probiotics for apple fermentation and study their probiotic properties. [Methods] A total of 35 strains were screened from traditional fermented foods in different regions. After primary screening, re-screening and research on growth characteristics, two characteristic strains, CTCF-LC1 (LC1, with strong acid production ability) and CTCF-LT1 (LT1, with strong adaptability), were obtained. [Results] The results of physiological and biochemical identification and 16sDNA-based identification show that LC1 is Lactobacillus casei and LT1 is Lactobacillus reuteri. Their fermentation performance in apple juice was tested, and it was found that the two strains grew well in the fermentation broth, and the total number of colonies could reach 109 cfu/mL. The final pH value of LC1 fermentation broth dropped below 3.5, and the total acid content exceeded 12 g/L. The pH of LT1 fermentation broth dropped to 3.9, and the total acid content also exceeded 6 g/L. In the study on the antioxidation property of apple juice, it was found that after high temperature and high pressure steam sterilization, the DPPH free radical scavenging rate of apple juice extract increased by 35.8%, and potassium ferricyanide reduction capability increased by 68%. After fermentation by LC1 and LT1, the potassium ferricyanide reducing power of apple juice was increased by 42.9%. [Conclusions] This has a good application prospect in the development of fruit and vegetable juice fermented beverages.