Comparing antioxidant efficiency of curcumin with natural and artificial antioxidants in food model system (Soybean oil)

Nowadays, increasing demand for developing natural component in food products besides the potential risks of artificial antioxidant for human health has cause many researchers to substitute natural antioxidant in food stuffs. Turmeric is one of those plants which owns unique functional properties and has several applications in traditional food and drug industries. In this study, in order to introduce a natural antioxidant for food industry, the active substance in turmeric rhizome (curcumin) was extracted by maceration method and identified with thin layer chromatography (TLC) and nuclear magnetic resonance (NMR).To evaluate the antioxidant efficiency of curcumin, the soybean oil with no antioxidant was used as a food model and its fatty acids profile was determined by gas chromatography (GC). Then the effect of various concentration of curcumin (0.012,0.016,0.02%) was compared with TBHQ (0.012%), α- tocopherol (0.02%) and blank (oil without antioxidant) in two temperatures (25 and 55 ºC) under dark and light conditions, during 90 days. The result of TLC analysis showed that the extracted curcumin contained bisdemethoxycurcumin, demethoxycurcumin. In addition, NMR spectra corroborated the chemical structure of curcumin. GC analysis showed that linoleic acid was the major fatty acid of soy bean oil and the other fatty acids were in the standard range. The results showed that increasing curcumin concentration significantly leads to decreasing oxidation rate. Peroxide value in treatment with 0/02% curcumin was the same as treatments contain 0/02% α- tocopherol and 0.012% TBHQ in 25 ºC. Data obtained from study of light effect in oil samples showed that in oil contain 0/02% curcumin, Oxidation rate in dark were the same as Oxidation rate in0/02% α-tocopherol and 0.012% TBHQ. Also in all samples, peroxide values increased in light and high temperature but light did not show any effect on acidity of samples (p 0/05) and iodide value of all samples were constant.