Immobilized lipase-mediated acidolysis of butteroil with conjugated linoleic acid: batch reactor and packed bed reactor studies

Abstract

Six commercial lipases, in either free or immobilized forms, were screened for their ability to catalyze acyl exchange between the triacylglycerols of butteroil (milkfat) and conjugated linoleic acid (CLA) in an organic solvent-free medium. Immobilized lipase preparations from Candida antarctica and Mucor miehei demonstrated the ability to increase the CLA content of the milk fat acylglycerols from the native value of 0.6 g/100 g fat to values which were at least an order of magnitude higher. Comparable increases were also obtained with a free enzyme from Candida rugosa.In addition to the screening studies, the effects of the weight ratio of milkfat to CLA on the product distribution and of the water content on the kinetics and maximum extent of this acidolysis reaction were systematically investigated in a batch reactor: The fatty acids liberated from the butteroil triacylglycerols were primarily short chain fatty acids, especially butyric and caproic acids.Modified butteroils were also produced via acidolysis of butteroil with CLA in a packed bed reactor containing an immobilized lipase preparation from C. antarctica. Significant enrichment of the butteroil in CLA residues was accomplished at reactor space times (fluid residence times) of 2–4 h at 40–60°C. Under these conditions, approximately 80–90% of the free CLA fed to the reactor is (inter)esterified.