Effects of the microwave of treatment of rapeseed on the extracted oil quality

Nowadays, oil extracted by cold press is getting more demand in the market. Important issues in the application of this method are the low oil extraction yield, and the low amount of minor compounds (phytosterols, tocopherols) present in the extracted oil compared with the extracted oil by the solvents. Many efforts have been made to improve the extraction efficiency of the cold press. The aim of this study was to evaluate the effect of microwave treatment on the extracted oil quality from rapeseed. Rapeseeds were treated with microwave (2450 MHz) in three different times (0, 2 and 4 min) and their oils were then extracted by press. The oil samples were then evaluated for physical and chemical properties, and fatty acids composition. There was a significant difference (p<0.05) among samples on the oil extraction yield, chlorophyll content, oxidative stability. It was found that microwave treatment had no significant effect (p<0.05) on the refractive index and the fatty acids profile of the extracted oil samples. The oil extracted from the treated rapeseed samples had significant differences (p<0.05) in the acid value. The oil extracted by using the solvent and microwave for 4 min had the highest and lowest peroxide values, respectively. Microwave treatment of rapeseeds for 4 min increased the oil extraction yield (by 10%), chlorophyll content (by 5.3%), oxidative stability (7h), and reduced the acid and peroxide values. According to the obtained results, it can be concluded that microwave treatment of rapeseeds before oil extraction by the cold press can improve oil extraction yield and quality and enhance its minor compounds level.