Optimization of structured diacylglycerols production containing ω-3 fatty acids via enzyme-catalysed glycerolysis of fish oil

The main objective of the present work was the production of structured diacylglycerols (DAG) by Novozym 435-catalysed glycerolysis of n-3 PUFA rich fish oil. Different enzyme loads (5, 7, 10, 13 and 15 %, with respect to the total weight of substrates), temperatures (40, 44, 50, 56 and 60 °C) and molar ratios of substrates (1, 1.4, 2, 2.6 and 3, oil/glycerol) were explored by the response surface methodology in order to optimize the reaction system. Temperature showed the highest significant effect (P < 0.05) on the glycerolysis reaction. Good agreement on the experimental data and the second-order polynomial regression was obtained (R2 = 0.85). Optimal conditions for the production of DAG were established by the model using 15 % enzyme load at 60 °C for a 2:1 (oil/glycerol) substrates molar ratio, reaching a 50 % yield, with 89.37 % n-3 PUFA content, namely, EPA (11.32 %), DPA (8.34 %) and DHA (69.71 %).