Enrichment of stearidonic acid in modified soybean oil by low temperature crystallisation

The main objective of the present work was to increase the stearidonic acid (SDA, 18:4 ω-3) content of modified soybean oil (initial SDA content, ∼23%). Low temperature crystallisations of soybean oil triacylglycerols (TAG) were carried out to effectively concentrate SDA. Several variables, such as winterisation time, type of solvent, and the oil:solvent ratio were evaluated until optimisation of the process was achieved. In the second study, some changes in the winterisation procedure were introduced and the SDA concentration of the final products was remarkably improved. Best relationship between SDA concentration (44.5%) and SDA yield (35.1%) was attained by performing winterisation of TAG with hexane:acetone (10:90, v/v) at 10% oil:solvent ratio for 24 h. Remarkably improved SDA yields (57.4%) were obtained when the lowest oil:solvent ratio (2.5%, w/v) was used. However, the SDA concentration decreased to 39.4% under these conditions. Scaled-up processes were also performed to obtain 33 g of TAG (concentration 45.2%; yield 34.8%) enriched in SDA. The products obtained can be used as starting materials for the production of functional lipids and for clinical trials.