Preparation of phytosteryl ester and simultaneous enrichment of stearidonic acid via lipase-catalyzed esterification

The simultaneous synthesis of a phytosteryl ester and enrichment of stearidonic acid (SDA) were performed via a one-step lipase-catalyzed esterification of fatty acids from Ahiflower™ seed oil with phytosterol. A commercial lipase (Lipase OF) from Candida rugosa was employed as a biocatalyst. Three solvents were screened and cyclohexane was selected as a suitable reaction medium. The effects of enzyme loading, temperature, and solvent amount were investigated. The conversion as well as the SDA content were significantly improved by adding molecular sieves after 1 h of reaction. The optimum conditions were the enzyme loading of 10% (based on the total substrate weight), the temperature of 30 °C, and the solvent amount of 4 mL (based on a substrate weight of 2 g), respectively. The maximum conversion and SDA content in the residual fatty acid were 81 mol% and 58 mol%, respectively, under the optimum conditions. The SDA content increased a 3.4-fold from 17 mol% in Ahiflower™ seed oil to 58 mol%.

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