Changes in organic acid formation in volatile degradation products during oxidation of oils treated with antioxidant

The effects of antioxidant (tert-butylhydroquinone, TBHQ) and a peroxide decomposer (thiodipropionic acid, TDPA and thiourea, TU) on the rancid point (induction time, I.T.) and organic acid content of volatile degradation products during oxidation of oil were investigated by the Rancimat method. Organic acids in volatile degradation products collected in distilled water were analyzed by HPLC. The I.T. of the tested oils was prolonged, and the suppression of formation of organic acids (formic, propionic and isovaleric acids etc.) was also noted upon addition of TBHQ, TDPA and TU. In particular, TBHQ showed a greater preventive effect on both oxidation of oil and formation of organic acids than those of TDPA and TU. The amounts of organic acids produced from rancid oil (POV 98 and 224 meq/kg) were markedly higher than in peroxide-free rancid oils