Development of a method predicting the oxidative stability of edible oils using 2,2-diphenyl-1-picrylhydrazyl (DPPH)

The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to predict the oxidative stability of edible oils. The principle of DPPH method is to measure the free radicals generated from oxidized oils directly. The absorbance of DPPH from oils before thermal oxidation decreased proportionally to the concentration of free radical scavenging compounds such as butylated hydroxytoluene (BHT). Oxidized oils with high polyunsaturated fatty acid (PUFA) contents showed high changes in DPPH absorbance or free radical formation rates than those with low PUFA. Oxidized oils with high BHT content were more stable and showed slower pattern change of DPPH absorbance from positive to negative slopes than those with low BHT content. Oxidative stability of oils could be predicted considering the initial values of DPPH absorbance, the free radical formation rates, and the oxidation period for pattern changes. The results from DPPH method on the oxidative stability of vegetable oils agreed with conventional methods such as p-anisidine value (p-AV), conjugated dienoic acids (CDA), or total polar matter (TPM).