Preparation Of Chinese Bayberry Pomace Jiaosu And Study On Its Antioxidant Function

Chinese bayberry（Myrica rubra Sieb.et Zucc.）is one of the characteristic fruits in our country.The cultivation area in China accounts for more than 99%of the world.The bayberry pomace is a by-product of bayberry juice processing,which is mostly discarded as waste and not fully utilized.In this paper,the by-product of bayberry juice produced by the factory was used as raw material,the selection of bacteria and process optimization of the Jiaosu fermentation of bayberry pomace were carried out.The fermentation kinetics of the bayberry pomace Jiaosu was studied.The nutrients and in vitro antioxidant activities of Jiaosu were analyzed,and the effective components of antioxidants were identified.Then the effects of storage and simulated digestion on phenolic substances and antioxidant activities of Jiaosu were studied.The antioxidant function of Jiaosu were studied using cell models and Drosophila models.The main conclusions of the experiment ware as follows:（1）The selection of probiotics and process optimization of Jiaosu fermentationThe nutrient components in bayberry pomace were analyzed,the probiotics combination for preparing bayberry pomace Jiaosu was selected,and finally the process optimization of bayberry pomace Jiaosu fermentation was carried out.The bayberry pomace contained 77.41%moisture,0.39%ash,2.38%protein,6.46%total sugar,0.49%fat,total phenols 2.57 mg/g,total flavonoids 0.72 mg/g,and anthocyanins 0.23 mg/g,citric acid 13.85 mg/g,malic acid 2.18 mg/g,succinic acid 1.07 mg/g,1.42 lactic acid mg/g and acetic acid 0.88 mg/g.The combination of probiotics for preparing bayberry pomace Jiaosu was yeast,lactic acid bacteria and acetic acid bacteria.The optimal process conditions for Jiaosu fermentation of bayberry pomace were the ratio of fermentation material to liquid was 3:5（w/w）,initial sugar content was 20°Bx,yeast inoculum was 0.02%（w/w）,temperature was 25°C,and fermentation time was 24 h.Then inoculated with 0.6%（w/w）lactic acid bacteria,and fermented at 30°C for 72 h.Finally,0.1%（w/w）acetic acid bacteria were inoculated,and the fermentation was carried out at 30°C for 48 h.（2）Study on the interaction of probiotics and fermentation kinetics of bayberry pomace JiaosuThe interaction between probiotics has been studied and it can be seen that there is no antagonistic effect between yeast,lactic acid bacteria and acetic acid bacteria,but there is a synergistic effect between yeast and lactic acid bacteria.On the basis of the previous process optimization,the change law of main substances in the process of Jiaosu fermentation of bayberry pomace was discussed.Based on the Logistic equation,DoseResp equation,SGompertz equation,Boltzmann equation and SGompertz equation,the models of bacterial growth kinetics,alcohol production kinetics,lactic acid production kinetics and substrate consumption kinetics models in the process of Jiaosu fermentation were simulated.The results showed that the final cell OD 600 nm value of bayberry pomace Jiaosu was 3.08,the alcohol content was 9.1%,the lactic acid content was 61.66 mg/m L and the sugar content was 9.34 mg/m L.The coefficients of determination R² of the respective kinetic models were:0.99591,0.99591,0.99594,and0.99962,respectively.The obtained models were as follows:Cell growth:Logistic model y=3.4431-3.0009/(1+（x/1.18058）^1.27446)Alcohol production:DoseResp model y=-1.24914+10.06227/(1+10^{（1.72473-x）*0.61559})Lactic acid production:Logistic model y=72.03311-67.97837/(1+（x/3.13416）^2.7392)Total sugar consumption:Logistic model y=72.1992+1394.2538/(1+（x/1.96665）^4.08659)The measured value and the fitted curve fit well,indicating that the kinetic model could better reflect the kinetic characteristics of the fermentation process of bayberry pomace Jiaosu.And compared with bayberry pomace wine and lactic acid bacteria fermented bayberry pomace,the fermentation rate of Jiaosu was fast,the number of probiotics was large,and contained alcohol and lactic acid.The comprehensive benefit of Jiaosu was high.（3）Research on nutrients and antioxidant activity of bayberry pomace JiaosuThe nutrients and antioxidant activities of the bayberry pomace Jiaosu were studied by unfermented bayberry pomace and bayberry pomace wine as controls.The red color of bayberry pomace Jiaosu fermented by yeast,lactic acid bacteria and acetic acid bacteria was stronger,the color saturation was higher,and the glossiness was stronger.Bayberry pomace Jiaosu contained 1.56 mg/m L citric acid,1.88 mg/m L malic acid,0.42 mg/m L succinic acid,1.11 mg/m L acetic acid and 7.59 mg/m L lactic acid.The SOD activity and protease activity of bayberry pomace Jiaosu were 50.59 U/m L and86.25 U/m L.Polysaccharides from bayberry pomace Jiaosu had the special structure of general polysaccharides and had antioxidant activity.The total phenol content,total flavone content and anthocyanin content of bayberry pomace Jiaosu were 2092.75mg/L,566.41 mg/L and 50.18 mg/L.Phenolic acids and flavonoids in the Jiaosu were determined by HPLC,including gallic acid,protocatechuic acid,myricetin,quercetin,myricetin,quercetin and anthocyanin cyanidin-3-O-glucoside.The DPPH clearance rate of bayberry pomace Jiaosu was 54.37%,ABTS clearance rate was 59.09%,FRAP antioxidant activity was 6.67 m M and the hydroxyl radical clearance rate was 28.75%.Gallic acid,protocatechuic acid,quercetin,myricetin and cyanidin-3-O-glucoside in the Jiaosu all had the ability to scavenge DPPH free radicals,while myricetin did not.With the extension of storage time,the color of the Jiaosu became lighter,the content of polyphenols decreased and the antioxidant activity weakened.In the simulated digestion process,the phenolic substances in the Jiaosu were relatively stable,and the antioxidant activity was gradually weakened.（4）Study on the antioxidant function and action mechanism of bayberry pomace Jiaosu the cellular levelThe HepG2 cell model of H₂O₂ oxidative stress injury was established to study the antioxidant function and mechanism of bayberry pomace Jiaosu.Jiaosu could increase the survival rate of cells treated with H₂O₂ from 46.49%to 55.26%-87.85%.Bayberry pomace Jiaosu could reduce ROS in H₂O₂-damaged HepG2 cells,and play a role in protecting HepG2 from oxidative damage by ROS.Bayberry pomace Jiaosu could protect HepG2 cell membrane from damage by H₂O₂.Bayberry pomace Jiaosu could increase the content of SOD and CAT in HepG2 cells when they were damaged by H₂O₂,and reduce the content of MDA.Bayberry pomace Jiaosu could increase the activity of intracellular GR,increased the content of GSH,reduced the content of GSSG,and maintain the balance of GSH/GSSG.By regulating the antioxidant defense signaling pathway Keap1/Nrf2,the Bayberry pomace Jiaosu increases the content of SOD,CAT,HO-1,NQO1,GSH-Px,GCLC and other antioxidant defense enzymes in HepG2 cells,thereby improving the ability of cells to resist oxidative damage.（5）Drosophila model to study the antioxidant function and mechanism of bayberry pomace JiaosuIn order to study the effect of Jiaosu on anti-aging,a Drosophila melanogaster model was established.It was found that bayberry pomace Jiaosu could prolong the life span of Drosophila melanogaster and increase the food intake of male fruit flies and significantly reduce the food intake of female fruit flies.Jiaosu would reduce the reproductive capacity of fruit flies.When Drosophila was acutely injured by SDS and H₂O₂,Jiaosu could enhance the proliferation of Drosophila intestinal epithelial cells,increase the expression of antimicrobial peptide gene and improve the survival rate.Jiaosu could increase the activities of SOD and CAT in Drosophila and reduce the content of MDA.Jiaosu could activate the expression of CuZn-SOD,Mn-SOD and CAT genes in Drosophila,but had no significant effect on the expression of MTH,TOR and S6K genes.