Separation of diacylglycerols from enzymatically hydrolyzed soybean oil by molecular distillation

Soybean oil was partially hydrolyzed by phospholipase A1 (Lecitase Ultra) to produce a mixture of water, diacylglycerols, free fatty acids and unreacted triacylglycerols. The non-polar upper layer (NPUL) composed of acylglycerols and free fatty acids, was treated with a two-step molecular distillation (MD) to separate and purify diacylglycerols. The free fatty acids in the NPUL were removed by the first-step MD at 150 °C to obtain the diacylglycerols-enriched soybean oil (DESO) with diacylglycerols purity of 42.64 wt%. Soybean diacylglycerols oil (SDO) with purity more than 80 wt% diacylglycerols was obtained when the DESO from the first-step MD was molecularly distilled at the evaporate temperature of over 220 °C at the second-step MD. The changes of antioxidants content in the oils have been investigated and acyl migration of 1,2-DAG to 1,3-DAG during MD has been observed during MD.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights▶ Phospholipase A1 rather than lipases used as a catalyst for partial hydrolysis of soybean oil to obtain diacylglycerols. ▶ A two-step molecular distillation process developed for production of soybean diacylglycerol oil with a high purity. ▶ Acyl migration of 1,2-DAG into 1,3-DAG occurring during the distillation. ▶ Enrichment of tocopherols in the distillate in the second-step molecular distillation.