Screening And Identification Of Lactic Acid Bacteria In Guizhou Pickles And Its Application In Red Jujube Puree

Jujube is the mature fruit of prickly Rhamnaceae plants,and there are few deep-processed products of jujube.In this project,11 self-made kimchi samples were taken from Zunhua City,Guizhou Province,and lactic acid bacteria were isolated and purified from them,and some of their properties were tested.A strain with multiple excellent properties was screened and a sterilization method suitable for red jujube puree was optimized.;Ferment the red jujube puree with lactic acid bacteria and yeast,optimize the fermentation process,and measure some physical and chemical indexes of the fermented red jujube puree.The results are as follows:(1)Using 11 fermented kimchi products collected in Guizhou as materials,11strains of acid-producing bacteria were selected,and 5 strains were identified as Lactobacillus plantarum and 6 strains were Lactobacillus paraplantarum.(2)The acid resistance,bile salt tolerance,salt tolerance and antibacterial properties of 11 strains were tested,and the lactic acid bacteria A50f7 with a variety of excellent properties was screened.After A50f7 is treated in acid solution with p H 2 and0.3%bile salt solution for 2 h,the survival rates were 99%and 85%.A50f7 has a strong inhibitory effect on Escherichia coli and Staphylococcus aureus.The growth rate of A50f7 in the MRS medium containing 8%Na Cl was significantly higher than that of other strains.The strain began to enter the logarithmic phase when it was cultured for 10h,and grew into a stable phase at 26 h.Based on the above performance test results,A50f7 is determined to be an excellent lactic acid bacteria.(3)Take the bactericidal effect as an indicator,compare pasteurization,microwave sterilization,ultra-high pressure sterilization,heat-assisted ultrasonic sterilization,choose the combination of microwave sterilization and heat-assisted ultrasonic sterilization with better sterilization effect and optimize sterilization conditions.The best parameters for sterilization are ultrasonic power of 1000 W,ultrasonic time of 50s,microwave power of 700 W,microwave time of 45 s,and temperature of 90°C.(4)By optimizing the fermentation process of red jujube puree,it is determined that the optimal fermentation process of red jujube puree is 3%inoculation amount of lactic acid bacteria,0.3%inoculation amount of yeast,24 h of lactic acid bacteria fermentation time,and 48 h of yeast fermentation time.The total acid and total phenol content of the fermented red jujube puree increased by 105.16%and 127.59%,the total sugar and Vc content decreased by 70.26%and 5.01%.The red jujube puree can be stored at room temperature for 28 days,and it can still maintain the number of viable lactic acid bacteria above 10~6 CFU/mL.