Freeze assisted-aqueous extraction of rapeseed oil using Tween 20

The traditional oil extraction methods often rely on organic solvents, raising environmental and health concerns, while aqueous extraction offers a potentially greener alternative. Therefore, the present study attempted to investigate the feasibility of the aqueous extraction of oil from rapeseed (canola) using a food-grade surfactant (Tween 20). The physicochemical properties of the rapeseed (moisture, ash, protein, and oil content) were first determined. The effects of key parameters, including seed-to-water ratio, Tween 20 concentration, pH, and pre-treatment temperature and time, were evaluated using a one-factor-at-a-time approach. According to our findings, the optimal oil extraction conditions were as follows: seed-to-water ratio 1:10, Tween 20 concentration 1.4 wt%, pH 12.0, pre-treatment temperature/time combination 190°C/30 min. Under the optimal conditions, an oil extraction yield of 50.5% was achieved. The impact of the pre-treatment step (before or after grinding the seeds) also showed that thermal treatment (190°C/30 min) prior to grinding was much more efficient. Additionally, freezing and rapid defrosting treatments yielded comparable results to the optimized aqueous extraction. The results suggest that aqueous extraction with Tween 20, particularly with optimized pre-treatment, offers a viable alternative to solvent-based methods, although further optimization is needed to match the higher yield of the solvent extraction method.