Formation kinetics of MeIQx in a threonine-glucose-creatinine system under oxidative conditions and its regulation in aquatic product thermal processing

2-amino-3,8-dimethylimidazo[4,5-f] quinoxaline (MeIQx) generated during the thermal treatment of aquatic products, presents potential health hazards. However, the formation kinetics under the combined influence of multiple factors and species differences are still unclear. A threonine-glucose-creatinine simulation system was built by incorporating in vitro kinetic analysis (spanning 105 to 255 °C, with a time span of 0–12 min) and in vivo verification across four aquatic species (shrimp, squid, tilapia, and oyster). Ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS) was utilized for the precise quantification of MeIQx, together with thiobarbituric acid reactive substances (TBARS) tests and Arrhenius equation analysis to link lipid oxidation with reaction thermodynamics. The outcomes showed that the formation of MeIQx had dual thresholds with peaking at 10.13 ng/mL at 165 °C and stabilizing at temperatures over 165 °C. A three-stage kinetic pattern was found that featuring an accumulation stage from 0 to 8 min and a degradation stage from 8 to 12 min, which was in sync with TBARS. Squid had the highest MeIQx content, while oyster had the lowest. This study created an initiation-acceleration-stabilization kinetic model, where the acceleration stage (105–165 °C) was propelled by temperature-dependent activation energy. The results revised the idea of unrestricted MeIQx accumulation at high temperatures and revealed the species-specific molecular basis in aquatic products. Furthermore, it provided theoretical support for limiting the frying time of aquatic products to 8 min to attain low MeIQx levels in industrial production.