Preparation of polyunsaturated phospholipids by lipase-catalyzed transesterification

Transesterifications were investigated to determine a means for preparing polyunsaturated phospholipids simply from soy phospholipid, sardine oil, and two kinds of microbial lipases originating fromCandida cylindracea andRhizopus delemar. The optimum reaction conditions forCandida cylindracea lipase were: 4 g of sardine oil, 10 mL of water, 0.7 g of lipase, 10 mL of hexane, 48 hr of reaction time at 37°C for 3 g of soy phospholipid, for which the transesterification ratio reached approximately 45%. Recovery of phospholipid was low, because hydrolysis also occurred under these reaction conditions. However, hydrolysis could be suppressed by using glycerine instead of water, and the recovery of phospholipid increased to 47%, although the transesterification ratio was reduced to 32%. Rhizopus delemar lipase has 1,3-specificity for triglycerides, and the transesterification ratio was approximately 37% in the 1-position of phospholipid. The resulting phospholipid was rich in polyunsaturated fatty acids and linoleic acid, while the total percentage of polyunsaturated fatty acids incorporated was 18.4%. Therefore, polyunsaturated phospholipids can be prepared easily by transesterification of soy phospholipid with fish oil by means of commercial lipases.