Effect of Black and White Sesame Cake Extracts on Retarding Lipid Oxidation in Catfish Fat

Abstract

The aim of this research was to study the possibility for preservation of catfish fat by using sesame cake extracts (SCE) as a source of natural antioxidants. The SCEs were obtained by extraction of black and white sesame cakes with methanol. Catfish (Pangasius hypophthalmus) fat was mixed with the black and white SCE at different concentrations and stored at room temperature (RT) and 60oC, in comparison with the synthetic antioxidant –BHT at concentration of 200 ppm. The results showed that the total phenolic content (TPC) in black SCE was 1386.3 ± 89.6 mgGAE/100g dw (dry weight) and in white SCE 1318.5 ± 68.7 mgGAE/100g dw. The free-radical scavenging capacity, determined by the 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free-radical scavenging assay, of the black and white SCE were significantly lower than that of BHT and ascorbic acid. The IC50 values of the black, white SCE samples, BHT and ascorbic acid were 817, 833, 31 and 7 mg/L, respectively. However, both the white and black SCE showed a strong effect on retarding lipid oxidation in catfish fat, which was comparable to that of BHT at 200 ppm. The free fatty acid values (FFA) and peroxide values (PV) of the catfish fat samples treated with the black and white SCEs at a concentration of 400 ppm, were lower than 6.0 mg KOH/g fat and 16 meq/kg fat, respectively, when stored at both room temperature and 60oC up to 42 days.