(528h) Selective Esterification of Tuna Free Fatty Acids With Immobilized Pseudomonas Cepacia and Thermomyces Lanuginosus Lipases to Produce Esters Rich in Docosahexaenoic Acid

In the present work, selective esterification of DHA from Tuna fish oil free fatty acids (TFFAs), using immobilized lipases from Pseudomonas cepacia (PCL) and Thermomyces lanuginosus (TLL) have been studied. The suitable reaction conditions have been determined as lauryl alcohol to FFAs ratio, 2:1 (wt/wt), pH 7.0, buffer to FFAs ratio,1:1 (wt/wt), temperature 50 ºC and agitation speed 800 rpm. At the suitable reaction conditions, 47% and 41% esterification have been obtained in 6 h for immobilized PCL and TLL, respectively. Reusability of both the immobilized lipases for esterification has also been carried out and the activity retention was stabilized around 29% and 21% after 5 cycles of repeated use of immobilized PCL and TLL, respectively. Kinetic study of esterification has also been carried out using four different substrate concentrations and conducting the reaction for 56 h. Kinetic parameters using Oliveira model has been obtained by fitting in the MATLAB program, such as K_cat = 488.2 (h^-1), K_B = 105 (µmoles of DHA esters/ml); K_m(B) = 20.5 (µmoles of DHA esters/ml); K_m(A) = 6.1 (µmoles of DHA esters/ml)for immobilized PCL and K_cat = 267.17 (h^-1), K_B = 777.3 (µmoles of DHA esters/ml); K_m(B) = 211.1 (µmoles of DHA esters/ml); K_m(A) = 118.75 (µmoles of DHA esters/ml)for immobilized TLL. Regression coefficient (R²) such as 0.99 and 0.98have been obtained for immobilized PCL and TLL respectively, indicating a good fitting of the modelfor both the lipases.