Study On The Fermentation Technology Of The Mixed Juice Drink Of Bitter Melon Juice And Wort

In order to develop a mixed juice drink,in this paper,the mixed juice of bitter melon juice and wort were prepared through fermentation by Lactobacilus or two step fermentation by yeast and Lactobacilus.Test results are as follows:1.Study on mixed juice of Lactobacilus fermentation:The excellent strains were selected as fermentation strains,from 7 Lactobacilus strains.And the strain Pr5 was identified by morphological and molecular identification.The growth and acid production of A and Pr5 in different proportion of bitter gourd mixed juice were studied.The optimum growth conditions of mixed lactic acid bacteria in the mixed juice of bitter gourd and wort were determined by single factor experiment and orthogonal experiment.The results showed that:(1)The fermentation performance and flavor of the Lactobacilus strains A and Pr5 were better than others.Pr5 was Lactobacillus plantarum.(2)The Lactobacillus plantarum and Lactobacillus bulgaricus were able to grow well in the wort,however,the growth and acid production in the mixed juice were greatly inhibited.The growth and acid production of Lactobacillus plantarum and Lactobacillus bulgaricus were better in 1:9-3:7 of bitter malt mixed juice,and the highest acid in the 1:9 of bitter malt mixed juic e was 105.430 T,87.560 T,respectively.(3)Not only cell growth and acid production of mixed bacteria fermentation had both the advantages of single strain fermentation,but also the mixed strains fermentation could produce more organic acids and give the f ermentation broth more abundant in the flavor substances than single strain fermentation.The optimum conditions of mixed lactic acid bacteria growth in the bitter malt mixed juice were determined:the fermentation temperature was 37 ?,the inoculum concentration was 3%,the fermentation initial p H was 5.5.2.Study on mixed juice of two step fermentation by yeast and Lactobacilus:The conditions of yeast and lactic acid bacteria fermentation in the mixed juice were discussed.The fermentation conditions of mixed juice beverage were optimized by single factor experiment and response surface experiment.Preliminarily,the content of total esters and acidity of fermented liquid were studied under different conditions.The results showed that:(1)Yeast fermentation did not improve the bitterness of the fermentation broth,significantly,but it can partly remove grass smell.Lactobacilus fermentation could remove some of the bitterness and the grass smell in the fermentation broth.The first fermentation with yeast,and then secondary fermentation with Lactobacilus,was much better than yeast or lactic acid bacteria single fermentation.(2)The optimum fermentation conditions in the bitter malt mixed juice was that:2.5 Bx bitter gourd juice and 12 Bx wort mixed juice(bitter gourd juice and wort volume ratio of 1:9)were fermented for 12 h at 28 ? with 4%(m L/m L)inoculation quantity by Saccharomyces cerevisiae,then inactivated and was fermented for 23 h at 36 ? with 3%(m L/m L)inoculation quantity by the mixed lactobacillus of Lactobacillus bulgaricus and Lactobacillus plantarum,the fermented juice taste soft and the flavor was abundant and full body.(3)Sterilization of fermentation liquid and refrigerate for 1 week,the flavor of the fermented broth was obviously enh anced,presenting similar sweet and sour flavor of hawthorn and total ester content reached the highest of 39.79g/ L.