Abstract: In this study, we developed a rapid method to determine the amount of polar compounds generated from lipid oxidation in fish based on thin layer chromatography (TLC) and image analysis in order to identify the extent of lipid oxidation in fish. The chromatographic separation of yellowfin tuna (Thunnus albacores) oil (0.5 μL) was performed on TLC plates using hexane-diethyl ether-acetic acid (30:70:1, V/V) as a mobile phase for 12 min. Color development was carried out by spaying the plates with 3% copper acetate in phosphoric acid and heating them at 150 ℃ for 15 min. The polar compounds derived from lipid oxidation during the heating process were semiquantitatively determined by area calculation with a special software. It was indicated that the amount of polar compounds measured by TLC was highly correlated with two common lipid oxidation parameters of peroxide value (POV) and carbonyl value (CV) with a correlation coefficient (R2) of 0.993 8 and 0.972 5, respectively. Furthermore, a good positive correlation between the measured amount of polar compounds and POV with a correlation coefficient of 0.962 5 was observed for salted Pleurogrammus azonus stored at 4 ℃, while salted sockeye salmon (Oncorhynchus nerka) stored at ?5 ℃ showed a good negative correlation between this measured parameter and color parameter a* value with a correlation coefficient of ?0.822 9. These results strongly suggest that TLC image analysis has the advantages of simplicity, rapidity, microscale quantitation and easy visualization without the need for expensive equipment.

Key words: TLC-i analysis, lipid oxidation, polar compounds, rapid detection