Lactic Acid Fermentation Of Apple Juice And Analysis Of Its Functional Components

Apple is rich in dietary fiber,which has the effects of lowering blood lipids and preventing obesity.The fermentation of lactic acid bacteria increases the content of phenols in apple juice and improves the antioxidant capacity.But in the production process of apple juice,it will be accompanied by the appearance of spoilage bacteria Alicyclobacillus.The bacteria will cause the spoilage of apple juice.The suitable fermentation of lactic acid bacteria can not only increase the nutrient content in apple juice,but also inhibit the growth of spoilage bacteria.This paper studies the most suitable lactic acid bacteria for fermentation in apple juice The composition changes during fermentation and its influence on nutrients such as apple juice aroma substances,amino acids,organic acids,etc.,to explore the changes in antioxidant capacity during fermentation,in order to develop nutritious functional drinks.The main results of the test are as follows:1.According to the growth of five test strains of Lactobacillus plantarum,Lactobacillus brevis,Lactobacillus fermentum,Leuconostoc mesenteri,and Lactobacillus casei in apple juice,LP was selected as the most suitable strain.2.A single factor test combined with the Plackett-Burman test design was used to screen the composite carbon source that affected the growth and acid production capacity of the strain Lactobacillus plantarum:glucose;the composite nitrogen source:peptone;and the buffer salt combination:KH2PO4.And determine the optimal concentration of each.3.Lactobacillus plantarum was inserted into the apple juice for fermentation.Through the single factor test and response surface optimization test,the best process conditions for fermenting apple juice were obtained.The strain inoculation amount was 8%,the fermentation temperature was 36? and the fermentation time was 72 h.Through fermentation under this condition,the number of lactic acid bacteria reached 2.97 × 109 cfu/mL,the total acid content was 2.61 g/100mL,and the reducing sugar was 5.027 g/100mL.4.The amino acid content and aroma components of apple juice before and after fermentation were compared.The amino acid content in apple juice after fermentation was 11.29 mg/mL,an increase of 8.87 mg/mL compared to before fermentation.Among them,sweet amino acids and umami amino acids increased significantly.The content of aroma substances in apple juice was mainly lipid and alcohol.The content of esters increased from 4825.16±28.50?g/L to 12502.79±89.96?g/L,accounting for the total aroma The content increased from 39.15%to 54.36%.5.By measuring the content of total phenol and total flavonoids,comparing the DPPH and ABTS free radical scavenging ability of apple juice before and after fermentation,the DPPH scavenging rate of apple juice after fermentation reached 80.06%,and the ABTS scavenging rate was 78.06%,and the antioxidant activity was significantly improved.At the same time,the addition of Lactobacillus plantarum plays an inhibitory role on the growth of Alicyclobacillus bacilli and has good bacteriostatic properties.6.After sensory evaluation of the fermented apple juice,the color,acidity,aroma,and overall acceptability of the juice before and after fermentation were determined,and it was concluded that the fermentation of lactic acid bacteria can improve the sensory quality of apple juice to a certain extent,making the apple juice taste better.More popular.