Abstract
In the extraction of vegetable oils, the idea of using ethanol as a solvent, allowing solvent recycling without distillation, can be attested as early as 1948 (Beckel), yet it is now seldom envisaged. The development of organic farming and a growing demand for a more natural diet prompted us to revisit this approach, which takes advantage of the relatively low affinity of ethanol for lipids to produce pure crude oils and meal with higher protein content. This method is based on the change of oil solubility in ethanol with temperature. Rapeseed oil extraction was carried out by hot pressurized ethanol (subcritical extraction condition). Oil was then recovered by cooling the miscella and demixing of two phases, an oil-rich phase and a solvent-rich phase. This study, after verifying the kinetics of extraction, focused on the optimization of the demixing temperature based on the amount and quality of recovered oil. The results show that ethanol extraction followed by cold demixing of the miscella makes it possible to obtain a high quality oil, free of free fatty acids and phospholipids.
Highlights
The currently used oilseed crushing process includes a solvent extraction step, which removes the oil remaining in the press cake
The use of hot pressurized ethanol-water azeotrope resulted in fast and efficient removal of oil from kernels: practically complete oil extraction yield was reached in only 10 min of the process (Fig. 3)
Owing to the high extraction temperature (95 °C), the observed oil content in miscella was substantially higher than the miscibility threshold of vegetable oil in ethanol-water azeotrope at room temperature (< 2 g/100 g of miscella according to Rao and Arnold, 1956)
Summary
The currently used oilseed crushing process includes a solvent extraction step, which removes the oil remaining in the press cake. Hexane is commonly used for this extraction, in. Compared with other “green” solvents, it is less toxic, already authorized for food extraction by the European Directive 2009/32/EC, readily available and bio-based (Perrier et al, 2017). Ethanol extraction concentrates proteins in the meal and detoxifies it
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