Effect of Oleic and Linoleic Acids on the Production of Deep-Fried Odor in Heated Triolein and Trilinolein

To determine sources of desirable deep-fried flavor in frying oils, degradation products from heated triolein and trilinolein with 5−31% polar compounds representing low to high deterioration were evaluated by purge−trap gas chromatography−mass spectrometry−olfactometry. (E,E)-2,4-Decadienal, 2-heptenal, 2-octenal, 2,4-nonadienal, and 2,4-octadienal produced deep-fried odor at moderate−strong intensities in heated trilinolein. However, unexpected aldehydes2,4-decadienal, 2,4-undecadienal, 2,4-nonadienal, and 2-octenal (all <15 ppm)were produced in triolein heated for 6 h. These dienals possibly were produced by hydroperoxidation and/or hydroxylation followed by dehydration of 2-alkenals. The 2-alkenals were produced from thermal decomposition of hydroperoxides, epoxides, and keto and dimeric compounds produced during the heating of triolein. These aldehydes produced low intensities of deep-fried odor in triolein. This information helps to explain sources of the deep-fried flavor that is characteristic of high linoleic frying oils but which is only at low intensity levels in high oleic frying oils. Keywords: Fried odor; frying oil; mass spectrometry; nonvolatile; odor; olfactometry; oxidation; trilinolein; triolein; volatile compound