Aqueous Extended‐Surfactant Based Method for Vegetable Oil Extraction: Proof of Concept

Abstract

The use of hexane to extract vegetable oil from oilseeds is of growing concern due to hexane's environmental impact and because of worker exposure concerns. The goal of our work is to demonstrate that the aqueous extended-surfactant-based method is a viable alternative for vegetable oil extraction. In our method, ground oilseeds were dispersed in the aqueous surfactant solution, allowing the oil to be liberated from the seeds as a separate phase from the aqueous phase. The impact of pH, shaking intensity, shaking time and seed to liquid ratio on oil yield are presented. Extended-surfactants are a new type of surfactant with propoxylate (PO) and/or ethoxylate (EO) groups inserted between the hydrophilic head and the hydrophobic alkyl chain of the surfactant molecule. This unique structure of extended-surfactants enables them to produce ultralow interfacial tension with vegetable oils. We have found that at low aqueous concentrations (less than 0.3 wt%), extended-surfactant solutions are able to produce ultralow interfacial tension between aqueous extraction and vegetable oil phases. At optimum condition (seed to liquid ratio of 1-5, 30 min extraction at 150 shakes/min and 30 min centrifugation at 2,1709g) we achieved 93-95% extraction efficiency for peanut and canola oils at 25°C. The oil quality produced from the aqueous extended-surfactant-based method was found to be comparable or even superior to that obtained from hexanebased extraction, further demonstrating the viability of aqueous extended-surfactant based extraction.

Characterisation of crude palm oil O/W emulsion produced with Tween 80 and potential in residual oil recovery of palm pressed mesocarp fibre

“…The importance of increasing temperature in non-ionic surfactant is similar to the addition of electrolyte in anionic surfactant which has been proven to cause significant reduction in IFT between some vegetable oils and water in previous literatures [2,3]. Observation of the phase behaviour of CPO/Tween 80 solution at increasing temperature and different concentration of Tween 80 was conducted to investigate the existence of a phase inversion temperature (PIT).…”

“…The solid was dried and the residual oil after SAAEP was extracted using hexane via Soxhlet apparatus. The residual oil was weighed and subtracted from the reference total oil of PPF to obtain the oil extraction efficiency [2]. Referring to Figure 1, Tween 80 concentration was varied in order to observe its effect on the reduction of IFT.…”

“…Surfactant-assisted aqueous extraction process (SAAEP) has been proposed as an environmentally friendly alternative to hexane extraction for the recovery of oil from plant materials such as corn germ and canola seeds [2]. The surfactant reduces the high interfacial tension (IFT), the surface energy exerted by intermolecular interactions, between two immiscible phases of oil and water [2]. An efficient aqueous surfactant extraction system usually has the ability to reduce the IFT value to an ultralow level (10 -3 mN/m) [3].…”

“…An efficient aqueous surfactant extraction system usually has the ability to reduce the IFT value to an ultralow level (10 -3 mN/m) [3]. Previous researches have shown that ultralow value of IFT contributed to significantly high extraction efficiency and free oil recovery [2,3]. Formulating microemulsion between surfactant and vegetable oils in the form of triglycerides is quite challenging compared to hydrocarbons.…”

“…Extended surfactant, a special surfactant with unique structure of having groups of intermediate polarity in between hydrophilic and lipophilic group of the surfactant, acts like a linker or a bridge that will provide stronger interaction between the hydrophobic group of the surfactant and the hydrophobic oil as well as between hydrophilic group of surfactant and water. This strong interaction will contribute to IFT reduction to the ultralow level [2,3]. However, the health and safety aspects of extended surfactant in food processing application is uncertain.…”