ENZYMATIC AND NONENZYMATIC ESTERIFICATION OF LONG POLYUNSATURATED FATTY-ACIDS AND LYSOPHOSPHATIDYLCHOLINE IN ISOOCTANE

Phosphatidylcholine containing large amounts of long polyunsaturated fatty acid, eicosapentaenoic acid (C20:5) and docosahexaenoic acid (C22:6), was synthesized in isooctane. Immobilized phospholipase A(2) was used as a catalyst. A parallel non-enzymatic esterification reaction was investigated in separate experiments. The concentrations of lyso-phosphatidylcholine, polyunsaturated fatty acids, water and the enzyme were varied over wide ranges as were the temperature and the reaction time. The type of enzyme, carrier and immobilization procedure were held constant. The yield of phosphatidylcholine was relatively high (about 21%) when the concentration of polyunsaturated fatty acids was high (300 mg/g of reaction mixture) and the water content was low (below 30% of the dry immobilized enzyme). The highest yield of phosphatidylcholine was found at 80 hours and 75 degrees C. However, at this temperature an extensive non-enzymatic reaction between polyunsaturated fatty acids and lyso-phosphatidylcholine occurred. At 80 degrees C the polyunsaturated fatty acids were partly oxidized. Therefore, a temperature of 45 degrees C to 65 degrees C is probably the optimum temperature for the reaction.