Abstract: In this study, two acid-tolerant, salt-tolerant and high glucose-tolerant strains were isolated from naturally fermented apple puree samples from the apple-producing area of Yiyuan Mountain in Shandong province through primary screening using MRS medium at pH 2.0 and secondary screening using MRS medium supplemented with 10% sodium chloride and 30% glucose. They were identified to be Lactobacillus plantarum S3-10 and L. casei R10 by physiological, biochemical and molecular biology characterization. The fermentation performances of the strains in MRS medium and fruit and vegetable puree were studied by measuring the dry cell mass, viable cell count, pH value and acidity. Results showed that the two strains had the characteristics of vigorous growth and rapid acid production. The growth and acid production of L. plantarum S3-10 were significantly higher than those of L. casei R10. Both strains display excellent fermentation performance, and have broad application prospects in fermenting fruit and vegetable juices and and developing functional probiotic products.

Key words: lactic acid bacteria, fruit and vegetable fermentation, screening, identification, fermentation characteristics