Kombucha tea: A promising fermented functional beverage

Abstract

Kombucha tea is produced by fermenting sweetened tea with mixture of symbiotic colony of bacteria (Acetobacter xylinum) and yeast (Brettanomyces, Zygosaccharomyces, Saccharomyces, Pichia). It is a popular traditional fermented drink with health-promoting attributes. The duration of fermentation could differ from 5 to 10 days under aerobic conditions. An ideal fermentation period (7-12 days) is necessary for kombucha with fine taste and flavor. Eventually, sugar is converted to organic acids and ethanol. It is reported that this beverage could improve resistance against different types of cancers (breast, lung, and prostate), promote digestion, boost the immune system, and reduce inflammation. Also, kombucha tea has antihypercholesterolemic effect (reducing levels of total cholesterol and LDL-Ch, increasing the level of HDL-Ch). The therapeutic effects of this probiotic beverage are accepted to be derived from active compounds mainly the polyphenols that possesses antioxidant activity, minerals (K, Mg, Ca, Fe), and vitamins (C, B1, B6, B9, B12). Secondary metabolites particularly gluconic, glucuronic, usnic, and lactic acids make this functional beverage attractive. Scientific evidences also indicate d-saccharic acid-1,4-lactone (DSL), a substantial constituent of kombucha tea, restrain the activity of glucuronidase enzyme which is mediately related to cancer. The objective of this chapter is to discuss beneficial health effects and enrichment of kombucha tea with several medicinal herbal extracts as well as potential risk factors that may exist.