Screening And Application Of Lactic Acid Bacteria For Lightly Fermented Jujube Drink

The lactic acid bacteria mildly fermented jujube beverage is a fruit and vegetable beverage beverage that uses jujube as raw material,combines the physiological functions of lactic acid bacteria and the nutrients obtained after fermentation,and can retain the flavor and nutrients of jujube to a great extent.In this study,natural fermented kimchi juice and red dates were used as samples to isolate and screen out lactic acid bacteria with excellent acid production,tolerance,and antibacterial properties,which were applied to fermentation of red date juice for fermentation after the optimization of the extraction process.The strains suitable for fermenting jujube beverages were screened out by fermentation performance,and the jujube beverages were fermented with this strain,the optimal fermentation process conditions were determined,and the process of mild jujube fermentation beverages was optimized.The components of the lightly fermented jujube beverage under the optimal technological conditions were analyzed and compared with the normal fermented jujube beverage and the original jujube juice to explore the advantages and disadvantages of the lightly fermented jujube beverage.Finally,a lactic acid bacteria suitable for fermented jujube beverages was screened out,and a reliable theoretical basis was provided for the best production process of lightly fermented jujube beverages.The results show:(1)10 strains of acid-producing bacteria isolated from the surface of red dates and pickle juice were identified as Lactobacillus paraplantarum,and 4 strains were screened for relatively high acid production,with an acid-tolerant survival rate of over 96%,and bile salt-tolerant survival Strains PC2,PC4,HZ2,HZ3,which have a rate of more than 77%,excellent sugar-tolerant survival rate,and good inhibition of Escherichia coli,Staphylococcus aureus,and Bacillus subtilis.(2)Through single-factor experiment and response surface optimization,the best extraction process of red jujube juice for fermentation is as follows: red jujube is added with pure water at a ratio of material to liquid of 1:7,pre-cooked at 100°C for 12 min,and with 0.25% pectinase dosage and enzymatic hydrolysis at 50°C for 2.5 h,the extraction rate of fermented jujube juice prepared by this process was 51.61%.(3)The selected excellent strains were gradually domesticated and fermented in red jujube juice for fermentation.The results are as follows: Lactobacillus plantarum PC2,PC4,HZ2,HZ3 were domesticated with domestication medium to gradually adapt to the growth environment of red jujube juice for fermentation.The number of bacteria increased by 35.20%,42.06%,28.72%,30.87%,and the acidity value increased by 24.52%,24.28%,23.46%,27.55%,respectively.Combined with the viable cell count,p H,acidity value and sensory evaluation of 4 excellent strains fermented in 100% jujube juice,the strain HZ2 was determined as the strain for fermenting jujube juice.(4)Through the single factor experiment of jujube fermented beverage strain inoculation amount,fermentation time,and fermentation temperature,the optimal fermentation process for jujube fermented beverage is determined as follows: strain inoculation amount is 3%,fermentation time is 25 h,and fermentation temperature is 37?,and found The red jujube mildly fermented beverage has the highest fermentation sensory score under other conditions,and the temperature is 20°C.Compared with the non-lightly fermented beverage,the acidity value is reduced by 64.19%,the p H value is increased by 52.99%,and the reducing sugar content is increased by 31.29%.The sensory score increased by 5.74%.