Mitigation of malondialdehyde and eight α,β-unsaturated aldehydes in flaxseed oil systems by gallates: Matrix-dependent formation patterns and inhibitory mechanisms

The accumulation of toxic α,β-unsaturated aldehydes in lipid-rich foods poses significant safety risks. This study elucidated the formation patterns of nine aldehydes in bulk flaxseed oil versus oil-in-water (O/W) emulsions, while evaluating the inhibitory mechanisms of gallates. In simulated systems, acrolein-trapping capacity declined with increasing alkyl chain length due to steric hindrance. Crucially, in simulated lipid models, gallates failed to scavenge acrolein, proving their inhibitory effect in bulk oil relied solely on upstream antioxidant activity, with octyl gallate being most effective. Conversely, emulsions promoted a catastrophic 519-fold aldehyde surge and favored accumulation of toxic hydroxy-alkenals. The superior performance (85.5% inhibition) and rapid depletion of propyl gallate in emulsions suggested a more complex mechanism involving both interfacial antioxidant activity and potential carbonyl scavenging. These findings highlight that simply increasing lipophilicity of polyphenols does not guarantee the enhancement of their inhibitory effect on aldehydes accumulation, necessitating matrix-specific strategies.