Effect of Ferrous Ion on Heat-Induced Aroma Deterioration of Green Tea Infusion

Aroma deterioration is one of the biggest problems in processing tea beverages. The aroma of tea infusion deteriorates fast during heat sterilization and the presence of ferrous ion (Fe²⁺) aggravates it. The underlying mechanism remains unveiled. In this study, Fe²⁺ was verified to deteriorate the aroma quality of green tea infusion with heat treatment. Catechins were necessary for Fe²⁺-mediated aroma deterioration. By enhancing the degradation of catechins, Fe²⁺ dramatically increased the production of hydrogen peroxide (H₂O₂). Fe²⁺ and H₂O₂ together exacerbated the aroma of green tea infusion with heat treatment. GC-MS analysis revealed that the presence of Fe²⁺ enhanced the loss of green/grassy volatiles and promoted the formation of new volatiles with diversified aroma characteristics, resulting in a dull scent of green tea infusion. Our results revealed how Fe²⁺ induced aroma deterioration of green tea infusion with heat treatment and could help guide tea producers in attenuating the aroma deterioration of tea infusion during processing.