Arabic coffee infusion based kombucha: Characterization and biological activity during fermentation, and in vivo toxicity

In this study, arabic coffee infusion was used to produce a fermented beverage known as kombucha. The physicochemical, antioxidant and antimicrobial activities, as well as in vivo toxicity were evaluate throughout 21 days of fermentation. Reduction in pH and sugar levels were observed throughout the fermentation period. There was no significant difference in the content of total phenolic compounds between the unfermented and fermented beverage, nor between the fermentation times, as well as in the antioxidant activity. The 5-caffeoylquinic acid was identified at all fermentation times evaluated, and no significant difference was observed regarding its concentration. It showed antibacterial and antifungal activity against all strains tested. No toxic effect of the beverages was observed in the in vivo model (Galleria mellonella) studied. These results demonstrated that coffee infusion is a possible alternative for kombucha production since the physicochemical changes prove the metabolic activity of Symbiotic Culture of Bacteria and Yeast.

Kombucha: A review of substrates, regulations, composition, and biological properties

Kombucha has been gaining prominence around the world and becoming popular due to its good health benefits. This beverage is historically obtained by the tea fermentation of Camellia sinensis and by a biofilm of cellulose containing the symbiotic culture of bacteria and yeast (SCOBY). The other substrates added to the C. sinensis tea have also been reported to help kombucha production. The type as well as the amount of sugar substrate, which is the origin of SCOBY, in addition to time and temperature of fermentation influence the content of organic acids, vitamins, total phenolics, and alcoholic content of kombucha. The route involved in the metabolite biotransformation identified in kombucha so far and the microorganisms involved in the process need to be further studied. Some nutritional properties and benefits related to the beverage have already been reported. Antioxidant and antimicrobial activities and antidiabetic and anticarcinogenic effects are some of the beneficial effects attributed to kombucha. Nevertheless, scientific literature needs clinical studies to evaluate these benefits in human beings. The toxic effects associated with the consumption of kombucha are still unclear, but due to the possibility of adverse reactions occurring, its consumption is contraindicated in infants and pregnant women, children under 4-years-old, patients with kidney failure, and patients with HIV. The regulations in place for kombucha address a number of criteria, mainly for the pH and alcohol content, in order to guarantee the quality and safety of the beverage as well as to ensure transparency of information for consumers.