A research group led by Associate Professor Takashi Shirai of the Graduate School of Nagoya Institute of Technology discovered that catechins contained in green tea are selectively oxidized by the catalytic action of the glaze surface of ceramics, and are abundant in fermented teas such as black tea and oolong tea. It was discovered for the first time in the world that polyphenols produced by
Tea is made by drying and fermenting fresh leaves of the tea tree of the Camellia family.Depending on the degree of fermentation, it becomes various types of tea such as green tea, oolong tea, and black tea.Catechins, which are abundant in green tea, are considered protective substances against cardiovascular disease and cancer.Common pottery and porcelain teacups are made by coating the surface of a molded clay vessel with a glaze (a glassy material) [glazing].The glaze provides water resistance and a variety of colors.
The research group glazed ceramic pieces with commercially available glazes (Oribe, sea cucumber, Irabo, and Toumei) with different metal oxides, and prepared glaze phase samples by firing at 1250°C.Green tea extracted from tea leaves and each glaze phase sample were mixed and kept at 80℃ for 6 hours.
As a result, various catechins contained in green tea are selectively oxidized by the catalytic action of the glaze surface of ceramics, and polyphenols (theaflavin and its oxides, and polymers such as ) was found to produceThis means that the same reaction as the oxidation of catechins by oxidase in the fermentation process of tea leaves was caused by the catalytic action of the glaze surface.
In the future, we can expect the creation of new functions for tea and ceramics that have been enjoyed all over the world since ancient times, such as the synthesis of catechins that contribute to the improvement of human health (in-situ synthesis) and the development of tea utensils that allow you to enjoy changing flavors. and
Paper information:[Scientific Reports] Glazes-induced degradation of tea catechins
