Review of the Efficacy of Fermented Tea

Microbial fermentation is an important process in food production. It not only transforms the structure of the food, but also changes its composition and efficacy. In the case of tea, microbial fermentation increases the soluble sugar content, changes the amino acid contents and the pH value, makes the flavor more appealing, and forms compounds such as theaflavins and thearubigen. The microbial content in the beverage can be increased by using appropriate strains and conditions.

Fermented tea is said to improve digestion, boost energy levels, aid weight loss, lower cholesterol and triglyceride levels, reduce high blood pressure, and prevent cancer, among other health benefits. It is also alleged to be an excellent source of probiotics, which can help with digestive problems like diarrhea and irritable bowel syndrome. The bacterium in fermented tea can even fight bad bacteria in the gut.

The bioconversion and transformation of tea polyphenols during microbial fermentation have been studied in recent years. However, the research has been mainly focused on kombucha tea. This article aims to review the current state of knowledge about the efficacy of fermented tea, and to offer suggestions for future studies.

A wide variety of microbial species can be used to make teas undergo microbial fermentation, and the types of microorganisms and time periods for the microbial fermentation vary. The time period can be short such as in sencha or pu-erh tea, or long such as with black tea in China.

During the fermentation, many nutrients in the tea are transformed by the microorganisms, including vitamins and minerals. The most well-known is vitamin B12, which helps keep nerves and blood cells healthy, as well as folate, an antioxidant that protects against cell damage. Several studies have found that microbial fermentation increases the level of these nutrients in the finished tea.

Some nutrients are also lost during the fermentation process. Copper, for example, is an essential mineral that influences enzymatic reactions and plays a role in the decomposition of free radicals. It is required for a number of cellular processes, such as synthesis of collagen and neurotransmitters. During the fermentation, the content of copper in the finished tea decreases.

The content of iron in the finished tea can also be changed during microbial fermentation. Iron is an essential mineral for the synthesis of hemoglobin in erythrocytes, which carries oxygen molecules to the tissues and blood cells. It is recommended to consume a daily amount of iron, ranging from 10 to 18 mg for both men and women, to maintain good health. The level of iron in the finished tea will increase during microbial fermentation, especially on day 14 of fermentation, when it reached 0.46 mg/L.