Study On The Preparation Of Blackcurrant Enzyme And Its Antioxidant Activity

Blackcurrant has a variety of nutritious ingredients and health benefits.Therefore,it is an effective way to ferment and develop it into jiaosu products.In this experiment,the fermentation technology of blackcurrant jiaosu made by three kinds of lactobacillus and yeast was optimized,nutritious ingredients,flavor substances and antioxidant activities of the jiaosus were compared.The experiment results are as follows:1.The total antioxidant capacity and superoxide dismutase(SOD)activity were used as comprehensive evaluation indicators,the optimal fermentation process of fermentation time,inoculum size,initial sugar content and fermentation temperature was determined by single factor and orthogonal experiment.The results are as follows:(1)The optimal fermentation conditions of blackcurrant jiaosu fermented by Lactobacillus plantarum are as follows: fermentation time 24 h,inoculum size 1%,initial sugar content 20%,fermentation temperature 39 °C.Under the optimal fermentation conditions,the total antioxidant capacity of the blackcurrant jiaosu is 935.02 U/mL,and the SOD activity is 6172.72 U/mL.(2)The optimal fermentation conditions of blackcurrant jiaosu fermented by Lactobacillus casei are as follows: fermentation time 72 h,Lactobacillus casei inoculation 5%,initial sugar content 18% and the fermentation temperature 37 °C.Under the optimal fermentation conditions,the total antioxidant capacity of the blackcurrant jiaosu is 779.88 U/mL,and the SOD activity is5957.57 U/mL.(3)The optimal fermentation conditions of blackcurrant jiaosu fermented by Lactobacillus helveticus are as follows: fermentation time 36 h,inoculum size 3%,initial sugar content 18%,fermentation temperature 35 °C.Under the optimal conditions,the total antioxidant capacity of the blackcurrant jiaosu is 757.92 U/mL,and the SOD activity is 5672.36 U/mL.(4)The optimal fermentation conditions of blackcurrant jiaosu fermented by yeast are as follows: fermentation time 96 h,inoculum size 0.07%,initial sugar content 20%,fermentation temperature 28 °C.Under the optimal conditions,the total antioxidant capacity of the jiaosu is880.60 U/mL,and the SOD activity is 4873.13 U/mL.2.The changes of main active components and flavor substances in the blackcurrant jiaosu fermented by different strains are compared.The results indicate that the activity of SOD,typesand contents of free amino acids and organic acids in the blackcurrant jiaosu made by different strains,are much higher than those of the natural fermentation group.The activity of SOD,types and contents of free amino acids and organic acids in the blackcurrant jiaosu by lactobacillus,are all higher than those of the group by yeast.During the fermentation process,the contents of total phenols in the blackcurrant jiaosus by lactobacillus plantarum,Lactobacillus helveticus and yeast all show the change of rising first and then going down,and the contents of total phenols are obviously higher than that before fermentation,however,it is the converse by Lactobacillus casei.The contents of anthocyanin in blackcurrant jiaosu made by these four different strains are decreased obviously during the fermentation process.The flavor substances of blackcurrant jiaosu fermented by lactobacillus plantarum and yeast are better,which reach 22 species and 20 species respectively,accounting for 54.62% and 66.63% of the total flavor components,and the other flavor substances of the jiaosu made by other strains are low.Comparing the above nutrients and wind substances,the blackcurrant jiaosu fermented by Lactobacillus plantarum is superior to the jiaosus fermented by the other three bacteria.3.The scavenging ability of blackcurrant jiaosus prepared under the optimum fermentation condition,on hydroxyl free radical,DPPH free radical,superoxide anion free radical,reducing power and ABTS free radical are determined,the antioxidant activities of blackcurrant jiaosus fermented by different strains,blackcurrant juice and natural fermentation jiaosu are compared,and 4 mg/mL Vc solution is used as control.The results show that the hydroxyl free radical scavenging ability of blackcurrant jiaosu fermented by yeast and natural fermentation group is higher than the others,DPPH free radical scavenging rate and reducing power of blackcurrant jiaosu fermented by the four strains are higher than that of the natural fermentation group.The blackcurrant jiaosus fermented by yeast and Lactobacillus plantarum have better effect on superoxide anion free radical.ABTS free radical scavenging rate of blackcurrant jiaosu fermented by Lactobacillus is higher than that of the yeast fermentation group.In summary,the blackcurrant jiaosus fermented by different strains have better antioxidant activity.