Compounds which contribute to characteristic tea taste are poly‐phenolic compounds, amino acids, caffeine, etc. Very complicated mixtures of volatile compounds, such as terpenoids, alcohols, carbonyl compounds, etc., contribute to characteristic tea aromas.
Taste of food is mainly composed of five basic sensations; that is, sweetness, astringency, sourness, bitterness and umami . A delicious cup of tea infusion is an ingenious balance of various taste sensations.
*Astringency is a drying, puckering sensation in the mouth that affects the whole of the tongue more or less uniformly. Tannin has a strong astringent or pungent taste. Tea has high tannin content. It congeals proteins on the top of the mucous membrane layer of one’s mouth and makes the tissues contract.
* Bitterness is usually unpleasant, but sometimes desirable in moderate amounts, and is perceived predominantly at the back of, and sometimes along side of, the tongue. Caffeine is the stimulant in green tea. Caffeine possesses a bitter taste, and the detection threshold is 3 ppm in water, which is 0.0003% .It, is important in tea flavor and briskness.
* The umami is a Japanese term, it is similar to the “meaty” taste or “brothy” taste.
Besides catechins and caffeine, some amino acids (such as arginine, alanine, etc) also contribute to the bitterness of green tea infusion. The amino acids in green tea area major factor in its quality, with about 20 different amino acids contributing to the overall content. Theanine accounts for more than 60% of the amino acids; theanine, glutamic acid, asparagines, arginine, and serine account for about 90% of total amino acids. Amino acids are mainly responsible for brothy taste. The umami taste of green tea infusion was shown to be due to some amino acids such as theanine, serine, etc and the sweetness to sugars.
Bioactive compounds that contribute to the taste of tea
