Kinetics and equilibria of tea infusion. Part 13. Further studies on tea scum: the effects of calcium carbonate, lemon juice and sugar

Experiments carried out on tea infusions with blown-over films of calcium carbonate (CaCO3) have shown that it is the presence of calcium and bicarbonate ions in the water, and not the concomitantly produced CaCO3, which mediates the formation of tea scum. Other experiments have refuted Lewinʹs (1993) theory that tea scum is mainly composed of epidermal waxes loosened from the tea leaves by hot water. on of fresh lemon juice greatly decreased the amount of tea scum formed in temporary hard water. This effect was explained by the resulting drop in pH and by complexation of calcium ions by the citric acid contained in the juice. Addition of sucrose equivalent to two cubes of sugar per cup significantly reduced the mass of scum, far more than could be accounted for by the increase in solution viscosity.