Development Of Shelf Life Pprediction Of Fermented Cloudy Apple Juice By Probiotics

Probiotics ferment cloudy apple juice,which can preserve the original nutrients and attractive color of cloudy apple juice,and contain the unique flavor of probiotic fermentation.At the same time,it can inhibit the spoilage of fermented products,prolong the shelf life,regulate the physiological functions of human body.In addition,it in line with the concept of people pursuit food green,natural and healthy nutrition,and has broad prospects for development.In this paper,the probiotics of fermented cloudy apple juice were screened by the acid and bile salt resistance and fermentation characteristics of the strain,and head-space solid phase micro-extraction(HS-SPME)combined with gas chromatography-mass GC-MS)was used to identify the aroma components of nine varieties of apple turbid juice before and after fermentation.And the compounding ratio of apple varieties was determined by combining the mixture design.On this basis,the stability and kinetics of fermented cloudy apple juice of probiotics were studied,and the fermentation kinetics model was constructed.The changes of various indexes of fermented cloudy apple juice during storge were analysed.The main results are as follows:(1)The suitable combination of strains selected from 10 probiotic strains for fermented apple juice was Lactobacillus acidophilus 6005,Lactobacillus plantarum 21805,and Lactobacillus fermentum 21828.According to the sensory evaluation and the number of viable cell counts,the ratio of three strains was 1:1:1,the taste of fermented apple juice was the best and the number of viable cell counts could reach(8.5±2)×10~8 CFU/mL was the highest.(2)The aroma components of nine varieties of cloudy apple juice were mainly composed of esters,alcohols and aldehydes and ketones.There were significant differences in the types and contents of aroma components between different varieties(p < 0.05).The aroma was significantly improved after fermentation,alcohol content increased,ketones and acids increased,ester and aldehyde content decreased,and methyl ketone 2-undecanone,2-nonanone,2-heptanone,2-Octanone,acetic acid,hexanoic acid and 2-methyl-butanoic acid were newly formed.(3)Chang Fu: Qin Guan = 3:2,the experimental value is in good agreement with the predicted value of the regression equation,the number of viable bacteria is 5.3 × 10~8 CFU /m L,the sensory score is higher.After centrifugation of apple turbid juice at 2500 r/min,after 20 MPa homogenization,the suspension stability coefficient reached 0.4,and the total color difference ΔE changed little,which effectively solved the problem of precipitation and browning during fermentation.The fermentation kinetics model of the fermented apple turbid juice was established.The variance analysis of the model was extremely significant(P<0.01).The theoretical and experimental values of the model were less than 10%,indicating that the model reflected the fermentation process well.Dynamic changes in the middle.(4)Using the number of viable bacteria as the shelf-predicting index,establish a shelf-life model of fermented cloudy apple juice at 4 ℃ and 25 ℃.The relative error between the predicted and measured values of the model is less than 10%,indicating that the model is reliable and reasonable,and can be quickly and accurate predict the shelf life of fermented cloudy apple juice well.