New immobilized biocatalysts for the synthesis of dietary structured licuri oil enriched with caprylic acid

Abstract: Medium-chain saturated fatty acids (C6 to C12) show high benefits against diabetes, and have also been included in formulations for parenteral nutrition. Licuri oil is extracted from the seeds of Syagrus coronata, a native palm tree known as licuri, from the Brazilian Caatinga biome. Lauric acid is the major fatty acid (c.a. 50 %) in licuri oil. Therefore, medium chain triacylglycerols (TAG) containing lauric acid account for approximately half of all TAG in this oil. The objective of this study was to produce dietetic functional structured lipids by acidolysis of licuri oil and caprylic acid (C8:0) using sn-1,3 regioselective Rhizopus oryzae lipase containing 28 C-terminal amino acids of the prosequence fused to the N-terminal mature sequence (proROL) immobilized in novel carriers. New biocatalysts were proROL immobilized by physical adsorption in lignocellulosic waste of licuri fruit (WLO), hybrid system (SiO₂–WLO) or inorganic material (silica-SiO₂) used as standard. Reactions were performed batchwise using these new biocatalysts, in solvent-free systems for 72 h. The highest productions of dietary structured lipids (new TAG) were achieved at 40 ^◦C, molar ratio TAG:C8:0 of 1:2, after 3 h. New TAG yields obtained with proROL immobilized on WLO or SiO₂–WLO (16.3 and 17.2%, respectively) were more than 6-fold the values obtained with proROL immobilized on silica-SiO₂ (2.7%). Therefore, using lignocellulosic Licuri waste to prepare biocatalyst carriers is a sustainable route to contribute for reducing the environmental impacts in the Brazilian Caatinga protected biome.

Funding: This work was funded by FCT –Fundação para a Ciência e a Tecnologia, I.P., Portugal, under the scope of the project Linking Landscape, Environment, Agriculture and Food Research Centre (UIDP/04129/2020; UIDB/04129/2020), and National Council CNPq (Process: 200222/2020-1,Type: Post-Doctorate Abroad – PDE Call: Postdoctoral Abroad - PDE 2019), Brazil.