Synthesis and Occurrence of Oxoaldehydes in Used Frying Oils

As part of our efforts to identify volatile decomposition products in used frying oils, a series of 4- and 5-oxoaldehydes were synthesized, purified, and characterized by gas chromatography, gas chromatography-mass spectrometry, gas chromatography-Fourier transform infrared spectrometry, and nuclear magnetic resonance spectrometry. Oxoaldehydes have been proposed as possible precursors of alkylfurans, which have potential anticancer effects. In a model reaction 4-oxononanal was refluxed in hexane for 40 days and only trace amounts of 2-pentylfwan were produced, suggesting that it is not a major precursor of the furan. The volatile constituents of used frying oils obtained from commercial food processors were studied, and 4-oxohexanal, 4-oxooctanal, 4-oxononanal, and 4-oxodecanal were identified