Surfactant aqueous-based for vegetable oil extraction using microemulsion system

Abstract

Vegetable oil extraction is a crucial process for achieving high yield of oil from vegetable seeds. The conventional practice for the vegetable oil extraction is using hexane as solvent. The impact of this method is a leak of hexane which is considered a hazardous air pollutant (HAPs) to the atmosphere. So, the main objective of this study aimed to find the cleaner process for vegetable oil extraction process by introducing the surfactant aqueous-based using microemulsion system as extraction solution. Microemulsion system is able to reduce interfacial tension (IFT) between oil seed solid surface and the liquid oil. Hence, the vegetable oil can be extracted from their seeds due to the reducing IFT at the oil seed surface. However, high solubilization of oil in micelles often occurred with low IFT. Thus, to design a microemulsion system for oil extraction, one needs to minimize IFT as well as to minimize solubilization. To obtain this target, an investigation on a microemulsion system has been carried out. Then, the selected system will be used for extraction study. Soybean and palm kernel oil seeds were selected for this study. However, for soybean oil, this work emphasized only on oil quality study of the extracted oil obtained from the condition recommended from the previous study. It found that the soybean oil extracted from this work contains very low surfactant and very low concentration of protein loss from seed meal to the aqueous solution. For palm kernel oil, the phase study showed that the mix surfactant systems of 3% Comperlan KD and 0.1% Alfoterra145-5PO and of 3% Comperlan KD and 0.1% Alfoterra5-8PO achieved the ultra low IFT in the range of 10¯¹ – 10¯² mN/m. The optimum condition which achieved the extraction efficiency higher than 85% for palm kernel oil was at grain size 0.212-0.425 millimeter, 1 g of palm kernel load and 30 minutes contact time. The extraction efficiency of our surfactant aqueous-based system is almost as good as the one from hexane in conventional extraction process. In comparison for the quality of extracted oil, the oil from our technique is almost the same quality or even better than the hexane extraction in term of water content in oil phase, fatty acid composition of extracted oil and surfactant partitioning into oil phase. In conclusion, surfactant aqueous-based system can be considered as a promising alternative approach for oil extraction industry in the future.