A Review on Kombucha Tea—Microbiology, Composition, Fermentation, Beneficial Effects, Toxicity, and Tea Fungus

Abstract

Fermentation of sugared tea with a symbiotic culture of acetic acid bacteria and yeast (tea fungus) yields kombucha tea which is consumed worldwide for its refreshing and beneficial properties on human health. Important progress has been made in the past decade concerning research findings on kombucha tea and reports claiming that drinking kombucha can prevent various types of cancer and cardiovascular diseases, promote liver functions, and stimulate the immune system. Considering the widespread reports on kombucha, we recognized the need to review and update the research conducted in relation to kombucha tea, its products and tea fungus. Existing reports have suggested that the protective effects of kombucha tea are as good as those of black tea, however, more studies on kombucha tea and its composition are needed before final conclusions can be made.

Effect of medicinal plant type and concentration on physicochemical, antioxidant, antimicrobial, and sensorial properties of kombucha

“…However, IC 50 values of all samples decreased significantly ( p  <   0.05) during fermentation, which denotes increasing antioxidant activity. The increase in antioxidant activity of kombucha samples is mainly due to the low molecular weights of the produced polyphenols and is also accompanied by various changes to the structures of polyphenols (Jayabalan, Malbaša, Lončar, Vitas, & Sathishkumar, 2014). In another experiment, kombucha tea was produced by the integration of green tea, black tea, and waste tea.…”

A review on health benefits of kombucha nutritional compounds and metabolites

“…This beverage is prepared by fermenting sugared tea with a SCOBY (Jayabalan, Malbaša, Lončar, Vitas, & Sathishkumar, 2014). Its flavour is slightly sweet and sour at the same time, plus it may contain traces of carbon dioxide (Nummer, 2013).…”

“…In kombucha beverage, "the most abundant prokaryotes in the symbiotic culture belong to the Acetobacter and Gluconobacter bacteria genus" (Jayabalan et al, 2014). These genus belong to the Acetobacteraceae family (Table 1), the bacteria are Gramnegative aerobic bacilli (Stasiak & Blazejak, 2009).…”

“…The enzyme invertase, derived from yeasts, catalyses the hydrolysis of sucrose to glucose and fructose, producing ethanol through the glycolysis pathway. On the other hand, Gluconobacter and Acetobacter bacteria use glucose to produce gluconic acid and ethanol to produce acetic acid (Jayabalan et al, 2014). The production of ethanol and acetic acid inhibits the growth of pathogenic bacteria in the kombucha (Dufrense & Farnworth, 1999).…”

“…Using sucrose as a carbon source, the acetic acid bacteria of the tea produce a network of cellulose as a secondary metabolite of fermentation, mainly the bacteria Acetobacter xylinum. The symbiotic mass of bacteria and yeast adheres to the biofilm, forming a thick jelly-like membrane also called zooglea biofilm (Jayabalan et al, 2014).…”