Abstract
The transesterification of soybean lecithin with ethyl esters of polyunsaturated fatty acids (eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) using immobilized lipase from Rhizomucor miehei was tested in the presence or absence of organic solvent (hexane) and additives (urea with Ca2+ or Mg2+). The reaction was carried out at a water concentration of 4 % and ethyl ester to phospholipid mass ratio of 3:1. After 24 h of reaction without solvent or additive, fatty acid incorporation reached 29.1 % and thereafter increased only slightly. After 48 h, incorporation was highest in the presence of Mg2+, urea, and solvent. After 72 h, it was highest with Mg2+ and urea in the presence or absence of solvent (56.8 and 45.7 %, respectively). Incorporation of EPA and DHA was thus initially fast without solvent and additive, but was increased after prolonged reaction in the presence of Mg2+ and urea with or without solvent. These results are innovative and promising since they show that immobilized Rhizomucor miehei lipase has potential as a biocatalyst for interesterification reactions without solvent.