Effect of Hydrogen Carbonate in Brewing Water on the Aroma of Tea Infusions

Abstract

Tea aroma is significantly influenced by hydrogen carbonate (HCO3-) in brewing water. This study investigated the impact of HCO3- in water on the aroma of brewed tea infusions using sensory evaluation, headspace solid-phase microextraction, and gas chromatography-mass spectrometry techniques. As the concentration of HCO3- in water increased, the purity of tea aroma diminished, while attributes related to cooked flavors and sweetness intensified; this effect is particularly pronounced at high temperatures and prolonged brewing times. HCO3- altered both the concentration and ratio of volatiles, leading to a significant reduction in concentration of dimethyl sulfide, β-ionone, and others. Furthermore, the presence of HCO3- markedly decreased EGCG content while increasing GCG content in tea infusion; these variations in catechin concentrations were correlated with changes in dimethyl sulfide and β-ionone concentrations. These findings enhance the understanding of flavor chemistry concerning tea and water, provide valuable insights for the scientific selection of tea brewing water.

Keywords: tea brewing water, tea aroma, hydrogen carbonate, water chemistry