Change Of Bacterial Diversity And Antioxidant Active Compounds During The Traditional Fermented Of Chopped Pepper

Pepper is a kind of vegetable with high medicinal and nutritional value.It contains many kinds of bioactive components such as polyphenols,flavonoids and capsaicin.Therefore,pepper has strong anti-oxidation effect.Chopped pepper is a kind of traditional fermented vegetable by spontaneous fermentation,which is deeply loved by consumers.At present,the research on chopped pepper is mainly focused on the improvement of the processing technology,but lacks research on its internal fermentation mechanism and substances transformation.In order to further clarify the changes of microbial flora in the fermentation process of chopped pepper,the change of antioxidant capacity of chopped pepper was explored.In this study,pepper was used as raw material,chopped pepper was made according to the traditional process,and high-throughput sequencing technology was used to analyse the bacterial diversity.The antioxidative activity of chopped pepper was studied by using in vitro antioxidant test.The active substances such as polyphenols,flavonoids and capsaicin in chopped pepper were determined by high performance liquid chromatography.The results are as follows:(1)During the fermentation process of the chopped pepper,the pH value is continuously decreased,and the acidity of the titration is continuously increased.At 6 days before fermentation,the lactic acid bacteria increased obviously,and the increase was flat after the sixth day of fermentation.After 12 days of fermentation,the number decreased.The results of high-throughput sequencing indicated that the main bacteria in the chopped pepper were mainly Tatumella,Lactobacillus and Weissella.As the fermentation progressed,the genus Tatumella decreased and the Weissella genus became the dominant bacteria in the first 6 days of the fermentation stage.In the subsequent fermentation stage,Weissella was overtaken by Lactobacillus,and Lactobacillus became the dominant bacteria.Some of the spoilage bacteria of the genus Rosenbergiella,Pantoea,Pseudomonas and Pectobacterium,which existed at the beginning of the fermentation,were present in very low amounts during the late fermentation.(2)The pepper exhibited good antioxidant capacity during the whole fermentation process.Its DPPH free radical scavenging ability showed an upward trend.The uptrend trend was the most obvious in the first nine days during the fermentation(P?0.01)and turned to be gradual since the ninth day during the fermentation(P?0.05).The hydroxyl radical scavenging rate of showed a significant downward trend in the first six days during the fermentation(P?0.01),and then began to rise until reaching the same level as the initial stage of the fermentation at the end of the fermentation(91.633±0.906%).The total antioxidant capacity also showed an upward trend during the fermentation process(P?0.01).In addition,the contents of total phenols and total flavonoids also showed a certain upward trend,and their contents reached the highest value at the end of fermentation.The DPPH free radical scavenging ability and total antioxidant capacity may be related to the changes in the contents of hpolyphenol flavonoids in the chopped pepper.(3)The content of benzoic acid increased significantly in the first nine days during the fermentation process of chopped pepper(P?0.01),and the salicylic acid showed an obvious upward trend during the fermentation(P?0.01).In terms of phenolic acid,the content of gallic acid increased continuously during the fermentation process(P?0.01),the caffeic acid showed a very significant upward trend in the first six days during the fermentation(P?0.01),and the chlorogenic acid and protocatechuic acid showed a continuous downward trend during the fermentation of chopped pepper(P?0.01).In terms of flavonoids,the content of rutin increased gradually(P?0.01),the content of quercetin and luteolin decreased gradually(P?0.01),and luteolin reached only 1.512±0.016 ?g/g at the initial stage of fermentation and was no longer detected since the eighteenth day of fermentation.The content of capsaicinoids was high and showed a certain upward trend during the fermentation process(P?0.05).The content of benzoic acid,salicylic acid,protocatechuic acid,rutin and gallic acid in the fermentation process of chopped pepper showed a significant correlation with its DPPH scavenging ability and total antioxidant capacity(P?0.01).