Study On Fermentation Technology And Active Ingredients Of Apple Juice By Compound Lactic Acid Bacteria

In this paper,Apple was used as the experimental raw material to prepare compound starter with Lactobacillus plantarum,Streptococcus thermophilus,Lactobacillus acidophilus and Lactobacillus rhamnosus.The fermentation process of apple juice by compound lactobacillus was optimized by single factor and response surface methodology,and the fermented apple juice was prepared by the optimized process.The changes of Polyphenol content in the fermentation process and the antioxidant activity of polyphenols before and after fermentation and during digestion were detected.The research contents and results are as follows:1.Using Lactobacillus plantarum,Streptococcus thermophilus,Lactobacillus acidophilus and Lactobacillus rhamnosus 1:1:1 to prepare starter to ferment apple juice.The results showed that the product quality was better when the addition of sucrose was 3%,the addition of apple juice was 30%,the fermentation temperature was 35?,the inoculation amount of starter was 2%,and the fermentation time was 35 H.The sensory evaluation was 82.44 points and the number of viable bacteria was 6.64×10~8CFU/m L?After fermentation,the sugar content and acidity of the product increase,and this fermentation method is feasible.Therefore,the apple juice prepared under this fermentation condition can be used for subsequent fermentation experiments.2.The change of total phenol in apple juice fermentation was determined by Foling-Shawka method.The results showed that the total phenol content of apple juice increased first and then decreased,and reached the maximum value at 60 h,with the polyphenol content of 18.31 mg/L,35.3%higher than that before fermentation.The scavenging rates of DPPH free radical and OH free radical and iron reduction colorimetry were used to determine its antioxidant activity.The results showed that the scavenging rate of DPPH on fermented apple juice increased gradually with the decrease of dilution ratio of apple juice,and the maximum scavenging rate of DPPH free radical was 89.1%.The OH free radical clearance rate increased gradually with the decrease of dilution ratio,and the maximum OH free radical clearance rate was 91%.The effect of fermentation apple juice on FRAP increased gradually with the decrease of fermentation dilution ratio,and the maximum FRAP value was 4.3?mo L Trolox/mg.3.Prepare gastric juice simulant(SGF)and intestinal juice simulant(SIF).The changes of polyphenol content at different times were studied by dynamically simulating the digestive system of rats in vitro,and the changes of antioxidant capacity of polyphenols at different digestion times were studied by DPPH radical and OH radical scavenging rate and iron reduction colorimetry.The results showed that the content of polyphenols decreased gradually during digestion,from 18.31 mg/L to 3.93 mg/L before fermentation;During the digestion of fermented apple juice,the scavenging rates of DPPH and OH radicals decreased gradually.After digestion,the scavenging rates of DPPH and OH radicals decreased to 18.1%and 10.3%respectively.The reduction ability of iron ions also decreased gradually,and decreased to 0.97after digestion?mo L Trolox/mg?...