Effect of pretreatment with microwaves on oxidative stability and nutraceuticals content of oil from rapeseed

Demand for oil extracted by cold press, such as rapeseed oil, is increasing, but oil extraction yield, and nutraceuticals content are lower for cold pressed oil, compared with oil extracted by solvent. In this study, rapeseed was treated with microwaves, to investigate the possibility of enhancing oil extraction yield, oxidative stability and nutraceuticals content. Rapeseed was pretreated with microwaves for two different times (2 min and 4 min) and oil was then extracted with a press. To compare the results, oil was also extracted from untreated rapeseed by solvent and press. Results showed that solvent-extracted oil had the highest phytosterol content. Microwave pretreatment of rapeseed can increase the oil extraction yield (by 10%), phytosterols (by 15%) and tocopherols (by 55%) of the oil extracted by press. Oil extracted from untreated rapeseed by press had the lowest oxidative stability (1 h); this was increased to 8 h by pretreatment of rapeseed with microwaves. Therefore, from the obtained results, it is advisable to treat rapeseed with microwaves before extraction by oil press, because it gives a relatively good recovery of oil, with a high amount of nutraceuticals, and can produce oil with a longer shelf life and enhanced value. (C) 2010 Elsevier Ltd. All rights reserved.