The Effect of Microwave Pretreatment on the Oxidative Stability and Some Quantity and Quality of Extracted Oil from Rapeseeds

Canola or rapeseeds oil, comparing to sunflower oil, corn oil and soybean oil, is more qualified because of existence of unsaturated fatty acids and lack of cholesterol in its ingredients. In this study, the effect of the microwave time (0, 30, 60, 90, 120, 150, 180, 210, 240 and 270 seconds) on the phenolic compounds, oxidative stability and physicochemical properties of rapeseed oil such as oil extraction yield, density, refractive index and acidity of the oil using a completely randomized design with three replications. The results showed that by increasing the microwave time, density and color index increased. By increasing the microwave time at first to increase the oil extraction yield, acidity, oxidative stability and total phenol were then reduced For example, by increasing the microwave time to 240 seconds, the oil extraction yield increased, but further increase in microwave time led oil extraction yield reduction. The analysis of variance results showed that the studied microwave time had no effect on the refractive index (P>0.05). According to the information obtained from this study, it can be concluded that the microwave time (for 150 seconds) for pretreatment of rapeseeds to extract oil via screw press was effective in improving the quantitative and qualitative characteristics of the oil achieved.