Nε-(carboxymethyl)lysine and Nε-(carboxyethyl)lysine in tea and the factors affecting their formation

Ye Jiao; Jialiang He; Fengli Li; Guanjun Tao; Shuang Zhang; Shikang Zhang; Fang Qin; Maomao Zeng; Jie Chen

doi:10.1016/j.foodchem.2017.04.059

N^ε-(carboxymethyl)lysine and N^ε-(carboxyethyl)lysine in tea and the factors affecting their formation

Food Chem. 2017 Oct 1:232:683-688. doi: 10.1016/j.foodchem.2017.04.059. Epub 2017 Apr 12.

Authors

Ye Jiao¹, Jialiang He², Fengli Li¹, Guanjun Tao¹, Shuang Zhang¹, Shikang Zhang³, Fang Qin¹, Maomao Zeng⁴, Jie Chen⁵

Affiliations

¹ State Key Laboratory of Food Science and Technology, 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 Hangzhou Tea Research Institute, China Coop., Hangzhou 310016, China.
⁴ State Key Laboratory of Food Science and Technology, 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; Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi 214122, China. Electronic address: chenjie@jiangnan.edu.cn.

PMID: 28490128
DOI: 10.1016/j.foodchem.2017.04.059

Abstract

The levels of N^ε-(carboxymethyl)lysine (CML) and N^ε-(carboxyethyl)lysine (CEL) in 99 tea samples from 14 geographic regions, including 44 green, 7 oolong, 41 black, and 7 dark teas were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The CML and CEL contents varied from 11.0 to 1701μg/g tea and 4.6 to 133μg/g tea, respectively. Dark tea presented the highest levels of CML and CEL, whereas green and oolong teas presented the lowest levels. Five kinds of catechins in the tea were also analyzed, and spearman's correlation coefficients showed that all the catechins negatively correlated with CML and CEL. The results suggested that withering, fermentation and pile fermentation may facilitate the formation of CML and CEL. Catechins might inhibit the formation of CML and CEL, but their inhibitory effects may be affected by tea processing. The results of this study are useful for the production of healthier tea.

Keywords: Catechins; LC–MS/MS; N(ε)-(carboxyethyl)lysine; N(ε)-(carboxymethyl)lysine; Tea.

MeSH terms

Glycation End Products, Advanced
Lysine / analogs & derivatives
Tandem Mass Spectrometry
Tea*

Substances

Glycation End Products, Advanced
Tea
N(6)-(1-carboxyethyl)lysine
Lysine