Preliminary formulation development for aqueous surfactant-based soybean oil extraction

Soybean oils are increasingly being used for a range of non-food applications, including production of biofuels and oleochemicals. While most soybean oil is produced by hexane-based extraction methods, concern about environmental and health effects from hexane extraction has led to increased interest in development of aqueous extraction methods. Among aqueous methods, surfactant-based aqueous extraction of vegetable oils has shown particular promise as an alternative to hexane-based extraction methods. The objectives of this work were to explore the use of surfactant-based methods for the extraction of soybean oils, and to test whether the use of mixed anionic–cationic and anionic–cationic–nonionic surfactant mixtures could successfully be used to reduce the salinity requirements for surfactant-based extraction. All three formulations tested were capable of producing ultra-low (<0.01 mN/m) interfacial tensions with soybean oil. One of the formulations, a four-component (three surfactant, one hydrotrope) mixture, was able to reduce the salinity requirement from 5% down to 0.75%. A range of experiments was conducted to better understand the factors influencing extraction yield for surfactant-based extraction of soybean oil. Extraction experiments were conducted with a single extended surfactant system which has been used previously for extraction of other oilseeds. Extraction yields as high as 88.6% were observed for the conditions tested. Extraction yield was strongly dependent on salinity, and was found to increase with increasing shaker agitation rate, decreasing solid to liquid ratio, and decreasing particle size.