Abstract
Kombucha is a symbiotic culture of bacteria and yeast which produces a high-end fruity fitness beverage by fermentation of normal tea for approximately two weeks. In addition to the advantage of being a low-sugar probiotic-rich drink, kombucha also offers the benefits of the tea used for its preparation, especially its high antioxidant content. In this research, kombucha tea was prepared by using three different tea types: green, black, and pu’er tea, and the chemical profiles and antioxidant activity were analyzed during the fermentation process (up to 20 days). The results showed that the tea type has an obvious influence on the factors associated with the antioxidant potential. The fermentation process caused a marked increase in polyphenol content and antioxidant activity initially, but this slowed progressively over time. In contrast, the fermentation of black tea contributed to the degradation of flavonoids but showed no significant effect on the other tea types. Therefore, we conclude that the tea type selected to make kombucha affects the end product as well as the fermentation time.
Highlights
Fermentation is a process that involves the breakdown of sugars by bacteria and yeast and helps to enhance food preservation
Glucose and fructose are fermented by yeasts into ethanol, carbon dioxide, and glycerol, and the ethanol produced by yeasts is used by the AAB for the production of acetic acid, which can further stimulate the production of ethanol by yeasts. e acetic acid bacteria produce a Journal of Food Quality cellulose pellicle which leads to biofilm formation on the surface of the fermenting liquor. us, because of the consumption of oxygen by the microorganisms in the zoogleal mat and the liquor, a more anaerobic environment might arise with low substrate concentrations and a high enough acidity to inhibit pathogen growth
Despite that polyphenols could be consumed during these processes, we found that the Total polyphenol content (TPC) increased progressively with the duration of fermentation in all types of kombucha. e highest concentration was observed in the green tea, which showed the highest radical scavenging activity as indicated by the diphenyl-1-picrylhydrazyl radical (DPPH) values. is TPC increase could be explained by acid hydrolysis and the microbial biotransformation of condensed phenolic components [23, 24]
Summary
Fermentation is a process that involves the breakdown of sugars by bacteria and yeast and helps to enhance food preservation. Kombucha (tea mushroom or tea fungus) is a beverage traditionally produced using a home-scale fermentation technique, made by adding a symbiotic culture of bacteria and yeast (SCOBY) to a solution of tea and sugar, a process referred to as backslopping. E most characteristic microbes in kombucha fermentations are yeasts and acetic acid bacteria (AAB). E acetic acid bacteria produce a Journal of Food Quality cellulose pellicle which leads to biofilm formation on the surface of the fermenting liquor. It is apparent that the fermentative process will exert a considerable influence on the final microbial community and on the metabolite composition of kombucha. Few studies have investigated the influence of tea types on the dynamics of the kombucha microbial ecosystem throughout the fermentation process as well as on the final metabolite concentrations, and further research is needed
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