Production of structured lipids containing essential fatty acids by immobilized Rhizopus delemar lipase

An attempt was made to produce structured lipids containing essential fatty acid by acidolysis with 1,3-positional specific Rhizopus delemar lipase. The lipase was immobilized on a ceramic carrier by coprecipitation with acetone and then was activated by shaking for 2 d at 30 degrees C in a mixture of 5 g safflower or linseed oil, 10 g caprylic acid, 0.3 g water and 0.6 g of the immobilized enzyme. The activated enzyme was transferred into the same amount of oil/caprylic acid mixture without water, and the mixture was shaken under the same conditions as for the activation. By this reaction, 45-50 mol% of the fatty acids in oils were exchanged for caprylic acid, and the immobilized enzyme could be reused 45 and 55 times for safflower and linseed oils, respectively, without any significant loss of activity. The triglycerides were extracted with n-hexane after the acidolysis and then were allowed to react again with caprylic acid under the same conditions as mentioned above. When acidolysis was repeated three times with safflower oil as a starting material, the only products obtained were 1,3-capryloyl 2-linoleoylglycerol and 1,3-capryloyl-2-oleoyl-glycerol, with a ratio of 86:14 (w/w). Equally, the products from linseed oil were 1,3-capryloyl-2-alpha-linolenoyl-glycerol, 1,3-capryloyl-2-linoleoyl-glycerol, and 1,3-capryloyl-2- oleoyl-glycerol (60:22:18, w/w/w). All fatty acids at the 1,3-positions in the original oils were exchanged for caprylic acid by the repeated acidolyses, and the positional specificity of Rhizopus lipase was also confirmed to be strict.