Study On The Fermentation Technology And Antioxidant Properties Of Quinoa In Kombucha

In this paper,quinoa was selected as the fermentation raw material to optimize the fermentation process of Kombucha and to analyze the dynamic change process of the total amount of microorganisms,pH,total acid content,total phenol content and flavone content in the fermentation process.On this basis,the antioxidant activity of Kombucha fermentation liquid was studied.The purpose of this study is to provide theoretical reference for enriching the varieties of Kombucha fermented products in China,and to improve the utilization and economic value of quinoa.The conclusion were as follows:(1)In this paper,the pH,total phenol content,flavonoid content and microorganism quantity of fermentation broth were used as evaluation indexes to optimize the fermentation conditions of quinoa in Kombucha.The results showed that the best way to add quinoa was quinoa grinding liquor.On this basis,the fermentation process was optimized by single factor and orthogonal experiments,the optimal fermentation condition were the ratio of material to water was 10:100,the amount of sugar added was 8%,the inoculum size was 8%and the culture temperature was 25?.(2)The changes of pH,total acid,total phenol content,flavone content,microbial quantity and nutrient composition in the fermentation process of quinoa based and traditional Kombucha fermentation broth(TFB)were measured.The results showed that the pH of TFB was always higher than that of QFB during the whole fermentation process.The pH values of QFB and TFB were 2.63±0.08 and 3.30±0.01 at 5 days,respectively.On the contrary,the total acid content reached the highest value at 5d of fermentation,which the content were18.25±0.15 mg/m L and 6.45±0.10 mg/m L,respectively,and the content was 2.83 times of TFB.Compared with TFB,the change trend of Acetobacter,yeast and Lactobacillus in different fermentation time of QFB were similar,that the number of Acetobacter,Lactobacillus and yeast reached the highest value when cultured 2 days,the number of Acetobacter>Lactobacillus>yeast,and the number of microorganisms in QFB was higher than TFB.The content of total phenols and flavonoids in QFB and TFB reached the highest value in 2 days of fermentation.The content of total phenols and flavonoids in QFB were0.584±0.009 mg/m L and 0.340±0.009 mg/m L,respectively,which the content phenols and flavonoids were 1.72 and 1.93 times of TFB.(3)In order to investigate the antioxidant activity of the fermentation broth of Kombucha,the DPPH free radical(·DPPH),hydroxyl free radical(·OH),superoxide anion free radical(·O^2-)scavenging rate and iron ion reducing ability of the fermentation broth of Kombucha(QFB)and the traditional fermentation broth of Kombucha(TFB)with different fermentation time were determined.With the prolongation of fermentation time,the scavenging rate of·DPPH,·OH and·O^2-and the reducing ability of iron ions of the two kinds of fermentation broth increased first and then decreased within 1-5 days,and the in vitro antioxidant ability of QFB was higher than TFB.At 2 days,the scavenging rate of·DPPH,·OH and·O^2-and the reducing ability of iron ions were 76.52±0.08%,52.96±0.22%,33.93±0.28%,0.68±0.017,respectively.(4)On this basis,the model of UV damage and H₂O₂oxidation damage of yeast cells was established,and the survival rate of Saccharomyces cerevisiae treated by UV radiation and hydrogen peroxide solution were used as the index to evaluate the anti-radiation and anti-oxidation ability of the fermentation liquor of Kombucha.Saccharomyces cerevisiae cultured to logarithmic stage were selected.The time of ultraviolet irradiation was 150s,and the optimal incubation time was 20 min.Under this condition,the survival rate of Saccharomyces cerevisiae was 6.99%in the control group(i.e.without adding the fermentation liquid of Kombucha),which the the survival rate of Saccharomyces cerevisiae were 12.53%-16.84%and 9.57%-11.05%with added the QFB and TFB for 1-5 days.Furthmore,when adding the fermentation liquid of Kombucha for 2 days,the survival rate of Saccharomyces cerevisiae was the highest 25.4±0.73%(QFB)and 20.62±1.2%(TFB).Compared with Saccharomyces cerevisiae cultured by ultraviolet radiation,the change trend of Saccharomyces cerevisiae protection was similar.When adding 2 days of fermentation liquid,the survival rate of Saccharomyces cerevisiae was the highest that the survival rate of Saccharomyces cerevisiae was 5.10%±0.35%,19.39±0.57%and 15.45±0.86%in the control group,QFB and TFB.It could be concluded that the Kombucha fermentation liquid has a strong protective ability to Saccharomyces cerevisiae,and the protective ability of QFB is better than the TFB.