ENRICHMENT IN GAMMA-LINOLENIC ACID OF ACYLGLYCEROLS BY THE SELECTIVE HYDROLYSIS OF BORAGE OIL

Selective hydrolysis of borage oil by Candida rugosa lipase immobilize d on microporous polypropylene was carried out in an iso-octane-water two-phase system in order to obtain glycerides rich in gamma-linolenic acid (GLA). Lipase was immobilized on hydrophobic microporous polypro pylene supports by physical adsorption. gamma-linolenic acid content i n the unhydrolyzed acylglycerols could be raised to 51.7 mol% from an initial content of 23.6 mol% in borage oil with a yield of 59%. A simp lified kinetic model was proposed for this selective hydrolysis. The M ichaelis constant K-M and the maximal-rate constant V-max are 0.107 M and 393.9 U/mg-protein, respectively. Product inhibition with a dissoc iation constant of the enzyme-product complex K-I = 25 mM was confirme d. Some properties of the immobilized lipase were also examined.