Production of MLM type Structured Lipids from Grapeseed Oil Catalyzed by Non-Commercial Lipases

Abstract

Low calorie triacylglycerols (TAG) presenting medium-chain fatty acids (M) at positions sn-1,3 and long-chain fatty acids (L) at position sn-2, are known as MLM. This study aimed at the production of MLM by acidolysis of grapeseed oil with medium-chain caprylic (C8:0) or capric (C10:0) acids. Grapeseed oil was used as source of long-chain polyunsaturated fatty acids, especially linoleic acid, at sn-2 position in TAG. Reactions were performed in batch, in solvent-free systems, during 48 h. Novel non-commercial sn-1,3 regioselective lipases were used as alternative to high cost commercial biocatalysts, namely: the heterologous lipase from Rhizopus oryzae (rROL) immobilized in Amberlite^™ IRA 96 and Carica papaya lipase (CPL) self-immobilized in papaya latex. The highest productions of new TAG were achieved at 40 °C, molar ratio TAG:M of 1:2, after 48 h, with both biocatalysts, with yields varying between 38 and 69 %. rROL immobilized in Amberlite IRA 96 showed a preference towards caprylic acid while CPL showed no preference towards caprylic or capric acid. First-order deactivation kinetics was observed for both biocatalysts. Half-lives at 40 °C were 166 and 118 h for rROL and 96 and 81 h for CPL, in the acidolysis of grapeseed oil with C8:0 or C10:0, respectively.

Practical applications: Grapeseeds of Vitis vinifera L. are a by-product of the wine industry. Using grapeseed oil to produce added-value functional oils rich in linoleic acid (essential fatty acid) may be a way of improving the revenues of the enological and oil sectors.

Both lipases, and mainly Carica papaya lipase self-immobilized in papaya latex, due to its low-cost production and easy preparation, are promising non-commercial biocatalysts for the synthesis of MLM in solvent-free media. The use of a solvent-free system, in addition of being a green option, is also preferred for economic reasons, avoiding the costs with solvent and solvent recovery. Also, the use of the stoichiometric molar ratio TAG:M of 1:2 will (i) decrease costs related with the recovery and reutilization of medium chain fatty acids in excess, product recovery and purification, and (ii) avoid biocatalyst deactivation by high amounts of free fatty acids in reaction media.

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