Efficient preparation of diglycerides from rapeseed oil sediment using phospholipase C in a solvent-free phospholipid hydrolysis system

Diacylglycerols (DAGs), which are involved in rapid energy supply and fat reduction, are typically produced from triglycerides, glycerol and fatty acids through lipase-catalysis. This study introduces a novel method for preparing DAGs in a solvent-free system by using phospholipase C (PLC) hydrolysis of rapeseed oil sediment, which is a byproduct of the rapeseed oil water degumming. The optimisation of DAGs production by PLC hydrolysis using Response Surface Methodology (RMS) and Box-Behnken design. Under optimal conditions of 0.6% enzyme concentration, 51 °C reaction temperature, 56% water content and 2.2 h reaction time, phosphatidylcholine (PC) and phosphatidylethanolamine in the oil sediment were almost entirely converted into DAGs. This reaction yielded an oil product containing 27.1% DAGs, with 1,2-DAGs at 24.88% ± 0.01% and 1,3-DAGs at 2.22% ± 0.01%, which is favoured in drug delivery systems, and the fatty acid composition of DAGs oil was almost consistent with rapeseed oil. Moreover, the residual phospholipids were primarily phosphatidylinositol (PI), with an amount of 69.73%, suggesting the potential for high-purity PI production. In this study, rapeseed oil sediment achieved comprehensive utilization through hydrolysis by PLC, which not only enhanced the value of the oil sediment but also provided a new approach for the synthesis of DAGs.