Effect of Ca2+ concentration on the tastes from the main chemicals in green tea infusions

The effects of Ca2 + on the taste of green tea infusions and solutions of the main taste compounds were studied. Increasing the Ca2 + concentration influenced the appearance and the taste of the tea infusions prepared from instant green tea by weakening the bitter, umami and sweet tastes and by strengthening the astringent taste. Ca2 + enhanced the astringent taste of EGCG, caffeine and theanine solutions and weakened the bitter taste of EGCG and caffeine solutions, the umami taste of the theanine solution and the sweet taste of theanine and sucrose solutions. Synergistic or countervailing actions were found among the taste substances: EGCG and caffeine could strengthen each other's astringent and bitter tastes; theanine could weaken the astringent taste of the EGCG solution, and caffeine could strengthen the umami taste of the theanine solution. The results suggest that green tea infusion prepared from instant green tea should use water with low Ca2 + concentration.