Study On Fermentation Of Apple Juice By Lactic Acid Bacteria

Lactobacillus fermented fruit and vegetable juice as a new generation of health drinks,both the nutritional value of fruit and vegetable juices and the health benefits of lactic acid bacteria,is gradually becoming a research hotspot in the beverage industry.In this study,strain 717,strain 176 and Lactobacillus paracasei,which have excellent fermentation performance,were isolated from traditional fermented foods.By optimizing the fermentation process,an apple juice lactic acid bacteria fermentation broth was prepared and its in vitro antioxidant capacity was studied.Research.In order to meet the needs of consumers,we have conducted experiments on the preparation of apple juice fermentation broth to develop two different flavors of fermented apple juice beverages.The main research contents and results of this paper are as follows:(1)Strains ?L1 and ?L25 with excellent fermentation performance were isolated from traditional fermented foods and identified as Lactobacillus paracasei and Lactobacillus plantarum,respectively.(2)A single factor experiment was conducted on the fermentation conditions of apple juice,and further optimized by orthogonal test.Finally,the optimum technological parameters for lactic acid bacteria fermentation of apple juice were determined.The optimum conditions were as follows:Lactobacillus paracasei:strain 717:strain 176 was 4:1:1,the inoculum size was 8%(v/v),the fermentation temperature was 37?,and the fermentation time was 72 hours.The lactic acid bacteria fermented apple juice under this condition has a good taste and is full and delicate.(3)Further explored the changes in the quality of apple juice during fermentation.The types and contents of organic acids and flavor compounds in the samples before and after fermentation of apple juice lactic acid bacteria were analyzed by HPLC and GC/MS.The results showed that the content of lactic acid in apple juice after fermentation was significantly increased,the content of malic acid and formic acid was reduced,and the overall acidity of the product was softer.The flavors of apple juice before and after fermentation are mainly alcohols,aldehydes,ketones,esters and other compounds.After fermentation,the flavor of apple juice increased,the alcohol content increased significantly,and the fermentation of lactic acid bacteria improved the apple juice flavor.Apple juice also showed good in vitro antioxidant capacity after fermentation.(4)According to the beverage market survey,two fermented apple juice beverages,No.1(near-water light)and No.II(high-end quality),were formulated.The formula was optimized through single-factor tests and response surfaces.The results showed that the optimum formula for the No.1 near-water light fermentation apple juice beverage was:10%(v/v)fermented apple juice,9%(w/v)granulated sugar,0.15%(w/v)citric acid,0.15%(w/v)malic acid,0.025%(v/v)apple essence BJF-36,0.03%(v/v)apple essence ZWO1023.The best formula for high-quality fermented apple juice beverage No.? is:30%(v/v)fermented apple juice,6.6%(w/v)granulated sugar,0.1%(w/v)citric acid,0.08%(w/v)malic acid.