Comparing antioxidant effectiveness of natural and synthetic free radical scavengers in thermally-oxidized lard using DPPH method.

Antioxidant effectiveness of free radical scavengers (FRSs) of alpha-tocopherol, sesamol, butylated hydroxytoluene (BHT), and tert-butylhydroquinone (TBHQ) were evaluated in thermally-oxidized lard using methods of 2,2-diphenyl-1-picrylhydrazyl (DPPH), conjugated dienoic acid (CDA), and p-anisidine value (p-AV). Absorbance of DPPH with lard containing 2.5 micromol/g FRSs were low before oxidation while those with control lard was high due to the hydrogen atom donating ability of FRSs. During oxidation, DPPH absorbance with lard containing FRSs increased differently up to the certain point depending on the types of FRSs. DPPH absorbance of lard without FRSs started to decrease upon oxidation, which indicates that free radical scavenging compounds were generated from oxidized lipids. Results of CDA and p-AV showed that the highest antioxidant capacity was in the order of TBHQ = sesamol, BHT, and alpha-tocopherol. Antioxidant effectiveness of FRS should consider the hydrogen atom donating rates of FRS, the reactivity and stability of FRS at treatment temperature, and characteristics of radicals from FRSs, which may be predicted by the results of DPPH method.