| In this study,Ficus carica L. was chosen as the test materials.The lactic acid bacteriawhich was suitable for fig juice fermentation was selected and identified preliminarily. Thequantity of added water in fig juice, the selection and proportion of fermentation strains, theparameters of fermentation and the antioxidant activity of fermentation broth were alsostudied in this paper. The test results showed that：1. The strain Yj which had excellent characteristics in acid production was isolated fromnatural fermented fig juice and identified as Lactobacillus plantarum through physiologyand biochemical tests.2. The optimum amount of added water was1~2times mass of figs through thefermentation test using the strain Yj.The fermentation broth had the largest number ofviable bacterials and it was also easy to juicing in this condition.3. This study chose the viable count and pH value of fermentation broth as the testindicators.Lactobacillus acidophilus(NCFM),Lactobacillus plantarum(Yj),Streptoco-ccus thermophilus(St) and Lactobacillus casei(Y5-2b) were selected as the fermenta-tion strains from12strains which were tested.4. The effects on the viable count and the acid yield by the proportion of fermentation strainswere studied through using mixture design,and the regression mathematical models of themain influential factors on the viable count Y1and the acid yield Y2were built.Y1=1.921E+008*A+3.747E+008*B+1.033E+009*C+1.275E+009*D+3.181E+009*AB+2.763E+009*AC+4.267E+009*AD+1.847E+009*BC+2.310E+009*BD+1.858E+009*CDY2=6.63*A+6.77*B+7.05*C+7.15*D+1.44*AB+1.38*AC+1.97*AD+0.73*BC+1.01*BD+0.77*CDBy predictive analysis,the optimal proportion of fermentation strains were that Lacto-bacillus casei(Y5-2b):Lactobacillus plantarum(Yj):Lactobacillus acidophilus(NCFM)=1:1:2,and the viable count was1.86E+009cfu/mL,the acid yield was7.41g/l.5. The acid yield was chosen as the test indicator,and the results showed that thefermentation temperature of30~40℃,the fermentation time of18~30h and the in-oculation quantity of1.5%~2.5%were tested to be suitable.The regression mathema-tical model of the main influential factors above on the acid yield was built byBox-Behnken experimental design.Y=-87.25706+4.27170*A+1.16804*B+8.47711*C-9.08100E-003*AB-0.021794*AC+0.034811*BC-0.058572*A2-0.018603*B2-2.27933*C2By response surface analysis，the optimal parameter conditions were that the fermen-tation temperature was34.19℃,the fermentation time was25h,and the inoculation was1.89%.According to the actual situation,the parameters were chosen to be thatthe fermentation temperature was34℃,the fermentation time was25h,and the ino-culation was1.9%,in this condition,the acid yield was8.20g/l.6. As the antioxidant tests showed,the O2·-clearance rate of all samples was that figvinegar>lactic fermentation broth of figs>lactic fermentation broth of apples>fig jui-ce,the clearance rate of fig lactic fermentation broth was32.56%,and it was thesame to that of Vc at concentration of52.10ug/mL.The·OH clearance rate of allsamples was that lactic fermentation broth of figs>fig vinegar>fig juice>lactic fer-mentation broth of apples, the clearance rate of the fig lactic fermentation broth fivefold diluted was68.50%,and it was the same to that of Vc at concentration of200ug/mL. The DPPH clearance rate of all samples was that lactic fermentation broth of figs>fig juice>fig vinegar>lactic fermentation broth of apples,the clearance rate ofthe fig lactic fermenta-tion broth tenfold diluted was69.49%,and it was the same to that of Vc at concentration of14.14ug/mL.The total antioxidant capacity ofall samples was that fig juice>lactic fermentation broth of figs>fig vinegar>lactic fermentation broth of apples, the T-AOC value of fig lactic fermentation broth was14.53units/mL,and it was the same to that of Vc at concentration of62.36ug/mL. |
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