Isolation and Identification of Lactic Acid Bacteria from Naturally Fermented Pickles from Ningxia and Its Application in Goji Berry Juice Fermentation

Abstract

Using 3 home-made fermented pickles from Yinchuan city of Ningxia as material, lactic acid bacteria with high acid production were selected,and identified through morphological observation, physiological and biochemical tests and molecular biology techniques, and their acid resistance, bile salt resistance,salt tolerance and fermentation ability were determined.The lactic acid bacteria with excellent performance were screened and finally applied to fermented Goji berry juice. The results showed that 5 strains of lactic acid bacteria with high acid production were obtained,one strains was identified as Lactobacillus plantarum NXU_ 19010, one strain was identified as Lactobacillus rhamnosus NXU_ 19023, one strain was identified as Lactobacillus pentosus NXU_ 19006, one strain was identified as Lactobacillus helveticus NXU_ 19022, one strain was identified as Lactobacillus paracasei NXU_ 19004.Among them, Lactobacillus helveticus NXU_ 19022 had good acid resistance, bile salt resistance and growth performance, at about 6 h, it began to be logarithmic growth phase, thesurvival rate was about 92% at pH2 and the survival rate was about 18% when the bile salt content was 0.9%. the polysaccharide content of fermented Goji berry juice by NXU_ 19022 increased by 29%, and the polyphenol content fermented Goji berry juice decreased to 91%, the sensory score was the best and could significantly improve the free radical scavenging rate and flavor quality of fermented Goji berry juice. Analyzed the volatile components of unfermented and fermentad Goji berry juice by the non-targeted metabonomics analysis technology, a total of 20 metabolites were identified as differential metabolites. The content of lipids, aroma and sweet substances increased. The results showed that the strain had good fermentation characteristics and could be further developed and utilized as a production strain of fermentation products.