Synthesis of trans-10,cis-12 conjugated linoleic acid-enriched triacylglycerols via two-step lipase-catalyzed esterification

Abstract

This study aimed to synthesize trans-10,cis-12 conjugated linoleic acid (t10,c12-CLA)-enriched triacylglycerols (TAGs) with potential anti-obesity effects via a two-step lipase-catalyzed reaction. Commercial CLA isomer mixtures, containing 33.3 g/100 g t10,c12-CLA, were esterified with dodecan-1-ol to selectively enrich the t10,c12-CLA in a free fatty acid (FFA) fraction. The reaction was performed in a recirculating packed bed reactor using Candida rugosa lipase (immobilized on Immobead 150) as the biocatalyst. An FFA fraction containing 54.7 g/100 g t10,c12-CLA was produced in a yield of 21.8 g/100 g initial t10,c12-CLA under the optimal conditions, i.e., temperature, 20 °C; CLA mixtures-to-dodecan-1-ol molar ratio, 1:1; water content, zero (no added water); reaction time, 36 h. A t10,c12-CLA-enriched FFA fraction was esterified with glycerol to prepare t10,c12-CLA-enriched TAGs. The reaction was performed in a stirred batch reactor using Candida antarctica lipase B (immobilized on macroporous acrylic resin) as the biocatalyst. The optimal combination of temperature, glycerol-to-FFA fraction molar ratio, enzyme loading, reaction time, and vacuum level was 60 °C, 1:3, 10 g/100 g (based on total substrates), 12 h, and 0.4 kPa, respectively. Under these conditions, the TAG content reached 93.7 g/100 g and t10,c12-CLA was evenly distributed throughout the glycerol backbone of the TAG.