The aroma, taste, color and bioactive constituents of tea

The genus Camellia sinensis belongs to the family of Theaceae of the flowering plants. The leaves and leaf buds of C. sinensis are used to produce tea. The chemical composition of tea leaves has been thoroughly studied and the main constituents belong to the polyphenol group accounting for 25 to 35% on a dry weight basis. C. sinensis also contains various chemical constituents including methylxanthines, amino acids, chlorophyll, carotenoids, lipids, carbohydrates, vitamins, and more than 600 volatile compounds. Literature reports indicated that consumption of tea protects from various physiological and pharmacological effects which could be because of the presence of crucial therapeutic compounds which are more bio-stable and direct acting than those present in other medicinal plants. The activities of the compounds from tea are so pervading that they are virtually broad spectrum in their actions. This article provides a critical review of different phytochemicals isolated from tea and their associated medicinal properties as well as the chemical constituents responsible for aroma, taste and color.   Key words: Tea, Camellia sinensis, chemical constituents, biological activity, aroma, taste, color.