Effects of Coconut Exocarp Flavonoid and EDTA-2Na on Aldehyde Generation During Pan-Frying Processing of Squid (Dsidicus gigas)

Squid is rich in polyunsaturated fatty acids (PUFAs), especially docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which exert various human health benefits. Pan-fried squid is a popular processed product beloved by consumers. However, the PUFAs of squid can be severely oxidized during thermal processing, which will result in the reduction in nutritional value and generation of harmful compounds like aldehydes. In this study, flavonoids extracted from coconut exocarp (CEF) and the metal ion chelating agent disodium ethylenediaminetetraacetate (EDTA-2Na) were used to inhibit lipid oxidation during the frying of squid, with the lipid oxidation level, the changes in fatty acid composition, and aldehyde concentrations being examined by gas chromatography mass spectrometry and high-performance liquid chromatography mass spectrometry. Results indicated that during pan-frying, the peroxide value, thiobarbituric acid value, and total oxidation value increased significantly, while the contents of EPA and DHA decreased significantly, and the concentrations of most aldehydes increased in a time- and temperature-dependent pattern. Both CEF and EDTA-2Na treatments inhibited these changes; comparatively, the CEF treatment was significantly better than that of EDTA-2Na. For instance, the CEF treatment inhibited the generation of HHE by 31.90%, 33.24%, and 19.73%, respectively, after pan-frying of squid at 180 °C for 6, 8, and 10 min, while the corresponding values for HNE were 22.65%, 18.96%, and 17.28% respectively. These results suggested that CEF can improve the oxidative stability of squid lipids during pan-frying and reduce the generation and accumulation of aldehydes and improve the security of processed squid products.