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

Ying Gao,Gen-Sheng Chen,Jun-Feng Yin,Jian-Xin Chen,Fang Wang,Yong-Quan Xu,Jie-Qiong Wang

doi:10.3390/molecules26144255

Abstract

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.

Highlights

Green tea has been traditionally and widely used as a beverage in China
Aroma deterioration is positively correlated to the degradation of unoxidized catechins and the accumulation of hydrogen peroxide (H2O2) [4], suggesting catechins might be vital in the aroma deterioration
Green tea was purchased from Jiangsu Xinpin Tea Co., Ltd (Changzhou, China). (−)Epigallocatechin gallate (EGCG), (−)-gallocatechin gallate (GCG), (−)-epicatechin (EC), (+)catechin (C), (−)-epicatechin gallate (ECG), (−)-catechin gallate (CG), (−)-epigallocatechin (EGC), (−)-gallocatechin (GC), and gallic acid (GA) were obtained from Sigma-Aldrich Co

Summary

Introduction

Green tea has been traditionally and widely used as a beverage in China. Readyto-drink tea is preferable in modern society because of its convenience. Compared with freshly-brewed tea, the aroma of ready-to-drink tea is less fresh, sometimes even dull, impairing its sensory quality. The aroma of tea infusion deteriorates fast during heat sterilization [1,2]. Green tea infusion, which contains a higher level of unoxidized catechins (Figure 1), tends to experience more severe aroma deterioration than black tea and dark tea infusions during heat treatment [3]. Aroma deterioration is positively correlated to the degradation of unoxidized catechins and the accumulation of hydrogen peroxide (H2O2) [4], suggesting catechins might be vital in the aroma deterioration.

Methods

Results

Conclusion