Physicoenzymatic Production of Monoacylglycerols Enriched with Very Long Chain Polyunsaturated Fatty Acids

The aim of this study was to develop an efficient enzymatic glycerolysis system together with physical fractionation operation for the production of monoacylglycerols (MAG) containing polyunsaturated fatty acids (PUFA), especially, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from tuna oil. The enzymatic glycerolysis system at 40-70 °C is unfortunately a multiple-phase system, which leads to lower reaction efficiency. A solvent system targeting on highly efficient reactions was therefore the focus. Based on previous progress, tertiary alcohols were selected. Therefore, a further screening of solvent mixtures involving tertiary alcohols was made and a number of mixtures gave a good performance. Novozym 435 was employed as a catalyst in glycerolysis following enzyme screening. Basic reaction parameters were thoroughly studied. In the batch reaction system with tert-Butanol (TB) as solvent, the following conditions for MAG production was recommended as: mole ratio of glycerol to tuna oil 4.0:1.0, the weight ratio of TB to tuna oil 2.0:1.0, 15 wt% Novozym 435 (based on glycerol and tuna oil), and no additional water. The temperature was controlled at 40 ° C. Under these conditions, the yield of MAG was up to 90% after 3 h incubation. Crude MAG from glycerolysis of fish oil was fractionated with acetone and hexane as solvent to produce MAG with higher EPA and DHA content. Using acetone at 0 °C was the suitable condition for the fractionation. Under these conditions, the yield of MAG was about 50% but contained EPA and DHA up to 71% in comparison with around 30% in tuna oil.