Effects of natural spring water on the sensory attributes and physicochemical properties of tea infusions.

The sensory quality of tea is influenced by water quality, with natural spring water (NSW) gaining much attention for its natural and healthy qualities. The effects of NSW on the sensory attributes, physicochemical composition, and antioxidant capacity of Chinese tea were investigated. Tea brewed with pure water was the most resistant to oxidation and darkening. NSW with low total dissolved solids (TDS) was most suitable for brewing unfermented or mildly fermented teas, improving their sensory quality. The simulated green tea infusion system was used to investigate further the dramatic darkening of tea infusions in NSW. Exposure of infusions to air promoted the degradation, epimerization, and oxidative polymerization of catechins, and further formed theabrownins which darkened the tea infusions. These findings enabled tea consumers to choose the most suitable NSW for brewing Chinese teas and illustrated the darkening mechanism of tea infusion in high pH/TDS water.