Organic certification for tea

Courtesy: Organic certification for tea

Physically speaking, tea has properties of both a solution and a suspension. It is a solution of all the water-soluble compounds that have been extracted from the tea leaves, such as the polyphenols and amino acids, but is a suspension when all of the insoluble components are considered, such as the cellulose in the tea leaves.  Tea infusions are among most consumed beverages globally.

Caffeine constitutes about 3% of tea’s dry weight, translating to between 30 and 90 milligrams per 250-millilitre (8+¹⁄₂ US fl oz) cup depending on the type, brand, and brewing method. A study found that the caffeine content of one gram of black tea ranged from 22 to 28 mg, while the caffeine content of one gram of green tea ranged from 11 to 20 mg, reflecting a significant difference. Tea also contains small amounts of theobromine and theophylline, which are stimulants, and xanthines similar to caffeine.

Fresh tea leaves in various stages of growth

The astringency in tea can be attributed to the presence of polyphenols. These are the most abundant compounds in tea leaves, making up 30–40% of their composition. Polyphenols include flavonoids, epigallocatechin gallate (EGCG), and other catechins. Although there has been preliminary clinical research on whether green or black teas may protect against various human diseases, there is no evidence that tea polyphenols have any effect on health or lowering disease risk

Although health benefits have been assumed throughout the history of Camellia sinensis‘s consumption, there is no high-quality evidence showing that tea consumption gives significant benefits other than possibly increasing alertness, an effect caused by caffeine in the tea leaves. In clinical research conducted in the early 21st century, it was found there is no scientific evidence to indicate that consuming tea affects any disease or improves health.

Black and green teas contain no essential nutrients in significant amounts, with the exception of the dietary mineral manganese, at 0.5 mg per cup or 26% of the Reference Daily Intake (RDI). Fluoride is sometimes present in tea; certain types of “brick tea”, made from old leaves and stems, have the highest levels, enough to pose a health risk if much tea is drunk, which has been attributed to high levels of fluoride in soils, acidic soils, and long brewing.