Effect of Added Black Cumin Seed (Nigella sativa L) Oil on Oxidative Stability of Flaxseed Oil

Abstract

Background: Lipid oxidation has adverse effect on food deterioration and human health. Oxidative reactions limit the shelf-life of fresh and processed foodstuffs which are of great concern in the vegetable oil and fat industry. Aim: The antioxidant activity of Black Cumin (Nigella sativa L) Oil (BCO) as a source of natural antioxidants was compared against a synthetic antioxidant (BHA). Its oxidative stability was evaluated in Flaxseed oil (as the most sensitive oil against oxidation) in concentrations of BHA (200ppm). Study Design: Oils were analyzed for the composition of fatty acids, tocopherols and for some physicochemical properties [Peroxide (PV), P-Anisidine (AV),TOTOX values, Thiobarbituric acid, Iodine value, Oxidative stability (OS)and Refractive index]to assess the extent of oil deterioration during 30th days of storage. Place and Duration of Study: Islamic Azad University of Varamin and Tehran University, Tehran, Iran, From March 2018 to April 2018. Methodology: Optimal condition was investigated to protect edible oil like flaxseed oil from oxidative reaction. Black cumin seeds and flaxseeds were pressed separately by cold press. Then BCO was prepared at five concentration levels of 5, 10, 15, 20 and 25% (w/w) and added to Flaxseed oil. In terms of antioxidant activity, they were analyzed by Gas Chromatography and compared with sample containing 200 ppm of synthetic antioxidant (BHA) during 30thdays at ambient temperature (22-25° C). Results and Conclusion: The results showed that different levels of BCO were able to slow down the lipid oxidation well, but the effect of sample contained 5% BCO was higher than other levels and has potential source of natural antioxidant for the application in food industry to prevent lipid oxidation.