Original research articleFormation of advanced glycation end-products in fish muscle during heating: Relationship with fish freshness

- AGEs levels in raw and heated fish muscle as affected by freshness were studied.
- Ice storage (0-21 days) did not significantly affect AGEs levels in raw fish muscle.
- More AGEs were formed upon heating in fish muscle stored at 0 °C for longer time.
- As much as 0.95 to 4.5-folds more AGEs could be formed in less fresh fish muscle.

The purpose of this study was to investigate the formation of advanced glycation end-products in raw and heat-treated fish muscle as affected by fish freshness. The amounts of free and protein-bound Nε-carboxymethyllysine (CML) and Nε-carboxyethyllysine (CEL) in raw and heat-treated (100 °C, 5, 30 min) white muscle from cultivated grass carp (Ctenopharyngodon idellus) (n = 12) and catfish (Clarias leather) (n = 24) steaks previously stored at 0 °C for 0-21 days were quantified with an HPLC-MS/MS method. The levels of free and protein-bound CML and CEL in raw fish muscle did not change significantly during 21 days of ice storage. However, the longer the fish muscle was stored at 0 °C, the more protein-bound CML and CEL were formed upon heating. The heat-induced formation of protein-bound CML in catfish muscle previously stored at 0 °C for 21 days increased by 107% (5 min heating) or 172% (30 min heating), and CEL increased by 448% (5 min heating) or 191% (30 min heating), as compared with that in heat-treated freshly killed catfish muscle. In grass carp muscle, the increases were from 144% (5 min) to 131% (30 min) for protein-bound CML, and 135% (5 min) to 95% (30 min) for protein-bound CEL.