Abstract: Petroleum ether, methanol and ethanol were used to explore the effect of different solvents on the acid-catalyzed degradation of sesamolin. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay was used to evaluate the antioxidant ability of sesamolin as well as its degradation products. Phosphotungstic heteropoly acid (HPW) was used to catalyze the sesamolin in sesame oil with the aim of investigating the effect of this catalysis on the oxidative stability of cold pressed sesame oil. The results indicated that different products were generated from the catalytic reaction in three different solvents. Sesamol was produced in all three solvents, while semin and sesaminol were detected only in petroleum ether and two unknown substances were found in both methanol and ethanol. The DPPH radical scavenging capacity of sesamolin and sesamin was much weaker than that of sesamol, tertiary butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT); however, the DPPH radical scavenging capacity of sesamolin was markedly increased after being catalyzed by HPW in petroleum ether, which would provide a theoretical basis for enhancing the oxidative stability of cold pressed sesame oil by catalysis of sesamolin with HPW. The content of sesamolin in cold pressed sesame oil was gradually decreased with increasing addition of HPW, whereas the contents of sesamol and sesaminol were increased. Meanwhile, the oxidation induction time (OIT) of sesame oil was increased, which suggested enhanced oxidative stability.

Key words: sesamolin, acid catalysis, DPPH radical scavenging capacity, oxidative stability of cold pressed sesame oil