Kombucha is a fermented beverage that is traditionally made by fermenting sweetened black or green tea. It is also another name for the symbiotic consortium of bacteria and yeast also known as tea fungus. The purpose of thesis is to study the scientific literature to determine what other substrates can be fermented with natural culture of kombucha, what happens during fermentation, what compounds fermented beverages contain, and how the biological activities of these beverages differ. Since kombucha is made from a large number of different substrates, only a few substrates will be presented in the thesis, namely yarrow tea, red grape juice, date syrup, soy whey, coconut water, and coffee. Fermentation with natural culture of kombucha is a combination of alcoholic, acetic acid and lactic acid fermentation. In addition to the type of substrate, the duration and temperature also affect the fermentation and the chemical composition of the fermented beverage. The pH is one of the most important parameters monitored during fermentation. Organic acids and phenolic compounds are predominant in fermented beverage, which also contain ethanol, carbon dioxide, amino acids, some vitamins and minerals, and many other compounds that have not yet been explored. At the end of the thesis, some biological activities are presented such as antioxidant activity, antimicrobial activity, antiproliferative activity and starch hydrolase inhibitory activity. Kombucha is also a popular drink because many other positive effects on health and well-being.
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