Study On The Technology And Antioxidant Activity Of Lactobacillus Fermented Jujube Juice

As an edible fruit, Jujube is loved by the people due to its rich nutritional value and health benefits. Jujube resources in China is very rich. But jujube products is mainly primary processing products with low added value. In recent years, the market has gradually emerged deep processing products like jujube wine, jujube vinegar, jujube powder. To increase the variety of jujube, dried jujube was chosed as the research object. The factors include ratio of material to liquids, pre-cook time, mixed enzyme proportions and the enzyme solutions conditions, lactic acid fermentation strains and the ratio, lactic acid fermentation conditions, nutrition components changes after fermentation and anti-oxidation activity. The results showed that: 1. This test chose the sensory quality of jujube juice as the evaluation indicators. The best material to liquids was 1:6, which can both guarantee convenient and retain flavor. 2. The sensory quality of jujube juice was scored under different precooking time, and the optimum boiling time was 9min. On this basis, evaluation of reducing sugar content in jujube, the optimum jujube extraction was 80℃, 90 min. 3. Cellulase and pectinase enzyme was chosed and different ratio of jujube juice yield was contrasted, then the enzyme ratio of pectic enzymes to cellulase was 2:1. Chose jujube juice yield as indicators, the optimum time was 1.5~2.5h, enzymatic hydrolysis temperature was 40~60℃, enzyme concentration was 0.1%~0.2%. Using response surface methodology to optimize the results, the test obtained the regression model were as follows: Y=87.06+0.31*A+0.41*B-0.033*C+0.075*A*B-0.090*A*C-0.030 *B*C-1.08*A2-0.88*B2-1.35*C2 The best enzymatic hydrolysis conditions were enzyme 0.16%, enzyme time 2.1h, enzymatic hydrolysis temperature 50℃, and the jujube juice yield under the condition was 87.17%. 4. Viable count and lactic acid content was chosed as indicators, then selected Lactobacillus acidophilus(NCFM), Lactobacillus casei(D400), lactobacillus plantarum(121) and Streptococcus thermophilus(St). Mix design optimization was used to determine the strain ratio, and the regression mathematical models of the factors on lactic acid contents R1 and viable count R2 were built as follows: R1 =1.189E+008*A+3.604 E+008*B+5.771 E+008*C+2.170 E+008*D+2.108 E+009*A*B+3.421E+009*A*C+2.238E+009*A*D+4.996E+009*B*C+4.785E+009*B*D+2.828 E+009*C*D; R2=4.46*A+4.69*B+4.87*C+4.58*D+2.23*A*B+4.16*A*C+2.47*A*D+5.29*B*C+5.32*B*D+3.35*C*D The optimum ratio were D400: NCFM: 121 =1:1:2, and the viable count at this condition was 1.81E+009cfu/m L, Lactic acid content was 6.31g/L. 5. The test chose lactic acid content for evaluation, and the optimum time(C) were 24~31h, fermentation temperature(A) were 34~41℃, inoculation(B) were 3~5%. using response surface method, the lactic acid content regression model was built. Y=6.45-0.41*A+0.14*B-0.25*C-0.24*A*B-0.050*A*C+0.093*B* C-1.31*A2-0.60*B2-0.51*C2 The optimum fermentation conditions were fermentation temperature 36.5℃, inoculation 4.2%, time 27 h. Under this condition,the lactic acid content was 6.51g/L. 6. This paper studied the initial date syrup, date syrup after enzymatic hydrolysis and the changes of some main nutritional components in date syrup after fermentation. The results showed that the reduced sugar content in jujube first increased and then decreased throughout the processing stages, Vc content decreased during the entire process. Total sugars, total phenolics and flavonoids content in the process consistent and gradually increased. 7. The test compared vitro antioxidant activities of five substances, that was jujube juice, jujube juice lactic fermentation broth, fig juice, fig juice lactic fermentation broth and fig vinegar. The results showed that antioxidant capacity of jujube fermentation fluid and jujube juice were significantly higher than those of the other three substances. Jujube juice and jujube juice fermentation broth of DPPH free radical scavenging rate had significance at P<0.05, that was 98.213% and 96.622% respectively, ?OH clearance rate had no significance at P<0.05,that was 92.623% and 92.34% respectively, the O2?- clearance rate had significance at P<0.05, that was 78.881% and 75.361% respectively, the T-AOC value had significance at P < 0.05, that was 19.102 units/m L and 18.173 units/m L respectively. Therefore, the jujube vitro antioxidant activities increased through lactic acid fermentation.