N^ε -carboxymethyllysine and N^ε -carboxyethyllysine kinetics and water loss analysis during chicken braising

Braised chicken is one of the well-known traditional processed meat products in China. However, reports are scarce with respect to the formation of N^ɛ -carboxymethyllysine (CML) and N^ɛ -carboxyethyllysine (CEL) during chicken braising. Furthermore, braising for a long time and using high-temperature process will result in water loss. However, the relationship between water loss and advanced glycation end products (AGEs) kinetics is limited. The present study aimed to investigate the relationship between water loss and kinetics of free and protein-bound CML and CEL in braised chicken under different braising conditions (60-100 °C for 5-60 min).

Levels of free and protein-bound CML and CEL were found to increase with heating time and temperature. The correlation coefficient (r² ) was largest at zero-order reaction (free CML: r² = 0.908-0.954, protein-bound CML: r² = 0.901-0.958, free CEL: r² = 0.952-0.973, protein-bound CEL: r² = 0.959-0.965). The activation energy was 44.158 ± 3.638 kJ mol^-1 for free CML, 40.041 ± 3.438 kJ mol^-1 for protein-bound CML, 40.971 ± 0.334 kJ mol^-1 for free CEL and 40.247 ± 0.553 kJ mol^-1 for protein-bound CEL. Furthermore, with the increase of braising time and temperature, the drip loss and cooking loss also became aggravated. A significant positive correlation between water loss and AGEs levels during braising was observed by Pearson's correlation analysis (P < 0.05).

We conclude that the levels of free and protein-bound CML and CEL during braising were different, although they all met zero-order reaction kinetics. Water loss was probably one of the main reasons for the formation of AGEs during chicken braising. © 2020 Society of Chemical Industry.