Abstract: Black tea, featured with a strong aroma and sweet flavor as well as ‘red infusion and red leaves’, is made from fresh buds, leaves and tender stems through a series of procedures including withering, rolling (kneading and cutting), fermentation and drying. As the international demand for black tea has continued to increase recently, a variety of black tea products with distinctive sensory flavor characteristics have emerged in many regions. In order to gain insights into the characteristics of black tea and the underlying biochemical basis, this paper summarizes recent studies in the chemistry of black tea quality and specifies the chemical factors related to the color, aroma, taste and other key sensory attributes of black tea, including theaflavins, thearubigins, theabrownines, aromatic substances, polyphenols, caffeine and amino acids, with the aim of providing a theoretical basis for the innovation and quality improvement of black tea.

Key words: black tea, quality, chemical factors