Formation of Nε-(carboxymethyl)lysine and Nε-(carboxyethyl)lysine during black tea processing

Ye Jiao; Jialiang He; Zhiyong He; Daming Gao; Fang Qin; Mingyong Xie; Maomao Zeng; Jie Chen

doi:10.1016/j.foodres.2018.12.051

Formation of N^ε-(carboxymethyl)lysine and N^ε-(carboxyethyl)lysine during black tea processing

Food Res Int. 2019 Jul:121:738-745. doi: 10.1016/j.foodres.2018.12.051. Epub 2018 Dec 24.

Authors

Ye Jiao¹, Jialiang He², Zhiyong He¹, Daming Gao¹, Fang Qin¹, Mingyong Xie³, Maomao Zeng⁴, Jie Chen⁵

Affiliations

¹ State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; International Joint Laboratory on Food Safety, Jiangnan University, Wuxi 214122, China.
² State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; School of Food and Bioengineering, Henan University of Science and Technology, Luoyang 471023, China.
³ State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330031, China.
⁴ State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; International Joint Laboratory on Food Safety, Jiangnan University, Wuxi 214122, China. Electronic address: mmzeng@jiangnan.edu.cn.
⁵ State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; International Joint Laboratory on Food Safety, Jiangnan University, Wuxi 214122, China. Electronic address: chenjie@jiangnan.edu.cn.

PMID: 31108804
DOI: 10.1016/j.foodres.2018.12.051

Abstract

This study selected common processing methods for orthodox black tea and investigated changes in the levels of N^ε-(carboxymethyl)lysine (CML), N^ε-(carboxyethyl)lysine (CEL), lysine, and polyphenols during each processing stage and using different parameters of each processing step. The effects of epicatechin gallate, epigallocatechin, epigallocatechin gallate, and gallic acid on the levels of CML, CEL, fructoselysine, glyoxal, and methylglyoxal were investigated by chemical model systems study under black tea processing conditions. In tea samples, CML and CEL levels significantly increased during drying (could reach 51.8 and 8.7 μg/g tea, respectively), while natural withering and extensive rolling and fermentation times facilitated the formation of CML and CEL by altering the substrate concentrations and the cellular structure of tea leaves to be dried. The results of model systems (containing lysine, glucose, and fructose) indicated that polyphenols were able to enhance the production of CML and CEL, and the levels of CML and CEL increased 1.2-3.2- and 1.6-3.5-fold, respectively. Furthermore, the main pathways responsible for CML and CEL formation during black tea processing likely involve fructoselysine and others but not glyoxal or methylglyoxal.

Keywords: Black tea; Dietary advanced glycation end products; Intermediate compounds; N(ε)-(carboxyethyl)lysine; N(ε)-(carboxymethyl)lysine; Polyphenols; Tea processing.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Camellia sinensis
Catechin / analogs & derivatives
Catechin / analysis
Food Analysis
Food Handling*
Gallic Acid / analysis
Glyoxal / analysis
Lysine / analogs & derivatives
Lysine / analysis*
Plant Leaves / chemistry
Polyphenols / analysis
Pyruvaldehyde / analysis
Tea / chemistry*

Substances

N(6)-carboxyethyllysine
Polyphenols
Tea
fructosyl-lysine
Glyoxal
Gallic Acid
N(6)-carboxymethyllysine
Pyruvaldehyde
Catechin
epicatechin gallate
epigallocatechin gallate
gallocatechol
Lysine