The Chemical Components of Tea

"The act of drinking tea must be appreciated for its own sake, without seeking any other justification, for only thus con the tea drinker taste the sunlight the wind and the clouds."

J. Blofeld, The et tao

When you pour simmering water over tea leaves and feel transported by the magical aromas they release, the soluble elements that make up the tea leaf are gently transferred to the liquid. During infusion, some chemical elements, such as vitamin C, are destroyed, whereas others are more easily dissolved into the liquid. Roughly speaking, a cup of tea is composed of several hundred active substances. While tea leaves contain the components found in every living organism (proteins, carbohydrates, amino acids and the like) and those characteristic of plant species (such as chlorophyll and cellulose), it is the presence of polyphenols and alkaloids that gives an infusion of tea leaves such astonishing properties.


Polyphenols, as their name suggests, are a combination of several groups of phenols that make up a family of organic molecules present throughout the plant kingdom. In tea, these phenols are found in the catechins, of which epigallocatechin gallate (EGCG) is the main component Commonly known as "tannins" and having astringent properties that make living tissues contract, these polyphenols give tea its astringency, strength and thickness.


Alkaloids are naturally occurring heterocyclic organic molecules that contain nitrogen and are found in amino acids. Three kinds of alkaloids are found in tea, the main one being caffeine.


Theine and caffeine are the same alkaloid. Recognized in 1838 as being identical to the caffeine in coffee, the caffeine in tea is, nonetheless, distinguished from the caffeine in coffee because it forms different bonds with other substances, which changes how it affects the body. When tea leaves are infused, the caffeine combines with tannins, which attenuate and stabilize its effect. Tannins prevent caffeine from being released rapidly, so it is absorbed over a longer period of time. The effect, therefore, lasts longer and is more regular.

In tea, caffeine stimulates the central nervous system and the cardiovascular system by enlarging the diameter of the vessels in the cerebral cortex. When ingested in coffee, caffeine has a direct effect on blood circulation through the coronary system, stimulating an acceleration of the heart rate. In other words, tea is a more of a stimulant than an excitant It sharpens the mind, increases concentration, eliminates fatigue and enhances intellectual acuity.


Tea leaves are 20 percent proteins, but only 4 percent of those proteins, present in the form of albumin, are water soluble. In addition, just like the proteins, only a small percentage of the carbohydrates in tea are soluble in water: Just one carbohydrate, monosaccharide, is soluble, making tea a low-calorie drink that contains only one or two calories per cup. Tea also contains some 20 amino acids, including theanine, which accounts for 50 to 60 percent of these amino acids. Tea also contains many vitamins (including A, B complex, E, K and flavonoids), about 30 minerals (including potassium, phosphorus, iron, magnesium and calcium), chlorophyll and hundreds of aromatic components.

WATER QUALITY Since 99 percent of a cup of tea consists of water, the quality of the water used is extremely important Ancient Chinese masters used to amuse themselves by trying to guess the source of the water used to infuse their tea, and the choice of water is still critically important today. Lu Yu claimed that "the most suitable water is from the same region as the tea," as when in contact with the water that the tree drank all its life, the leaves will reveal their true nature. A rather utopian ideal today, yet the use of high-quality water is strongly advised. Hard, limestone-rich water should be avoided, as should water laden with calcium oxide, magnesium, lead or chlorine (which can cause a bleach aftertaste). The ideal water is pH neutral and contains few minerals.