Optimisation of supercritical carbon dioxide derived soybean oil

Abstract

The objective of the study was to extract soybean oil [Glycine max (L.) Merrill] from seed by supercritical carbon dioxide (sc-C02) and to optimise the yield and composition of the oil by varying relevant process parameters. Extraction runs were conducted with a commercially available laboratory size supercritical fluid extractor (LECO TFE 2000) capable of operating in a static, dynamic or combined static/dynamic mode. Density was shown to playa major role in extraction efficiency as it determines solvent strength of sc-C02. It was found to be optimum at liquid-like densities (0.8 - 1 g/mL), with an almost exponential increase in extracted oil yield on changing from gas-like to liquid-like densities. The solubility of soybean oil in sc-C02 was measured utilising the static mode of the supercritical extractor and found to be 0.00198 g oil / 1 g of CO2 at 300 atm and 40 °C. The oil content of the seed was established by utilising the dynamic extraction mode and found to be 18.7%, in agreement with a corresponding value in the literature.

The sc-C02 extracted soybean oil was analysed by several chromatographic techniques including GC-MS, GCxGC/TOF-MS and GC-FID. The extracts were found to be' component-rich and up to 113 compounds could be successfully identified by GCxGC/TOF-MS. The results compare favourably to those of oil extracted by other methods (soxhlet, cold press). The quality of the sc-C02 extracted oil was benchmarked against a commercially available standard.