Integrated Green and Enzymatic Process to Produce Omega-3 Acylglycerols from Echium plantagineum Using Immobilized Lipases

This work presents an original approach to develop an integrated process to improve the nutritional characteristics of natural oils, starting with the extraction from raw material by ecofriendly methods, followed by the production of novel acylglycerols using immobilized lipases. Specifically, 2-monoacylglycerols (2-MAG) enriched in omega-3 stearidonic acid (SDA) were synthesized by selective ethanolysis of extracted Echium plantagineum oil using the lipase from Thermomyces lanuginosus (TLL). Different reaction conditions were investigated to minimize acyl migration and to ensure the purity of final products. The biocatalyst produced in our laboratory by the immobilization of TLL on Sepabeads C-18 reached the maximum theoretical amount of 2-MAG (33%) in only 2 hour at mild reaction conditions (25 degrees C), achieving a product enriched in omega-3 SDA (up to 25%). Moreover, the produced biocatalyst exhibited higher stability than commercial lipases. The average activity after five cycles was 71%, allowing several reutilization cycles and developing a feasible enzymatic process. Finally, 2-MAG were used as starting material to synthesize structured triacyclglycerols (STAG) through transesterification with caprylic acid ethyl esters using the lipase from Rhizomucor miehei (RML) in solvent-free systems. The use of molecular sieves in combination with RML immobilized on Sepabeads C-18 was demonstrated to be an extraordinarily fast strategy to produce pure STAG (100% in 1 hour), four times higher than the activity showed by commercial biocatalyst. Thus, the enzymatic processes developed in this study open a range of possibilities to synthesize omega-3 acylglycerols with improved characteristics, proving the usefulness of immobilized lipases to produce novel lipids.