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2025 AOCS Posters

Biotechnology

Biotechnology Poster Session

Lipase-catalyzed synthesis of phytosterol esters in a deep eutectic solvent

Monday, April 28, 2025
5:00 PM – 6:00 PM PST
Room: Expo Hall
Abstract:

This work explores the efficiency of the synthesis of phytosterol esters by the lipase-catalysis transesterification of a blend of free phytosterols with vinyl laurate in the deep eutectic solvent comprised by choline chloride/urea at molar ratio 1:2.

25 mg of a blend of three phytosterols (51% b-sitosterol, 39% campesterol, 10% brassicasterol) were incubated for different periods with 65 mg vinyl laurate, 30 mg of a commercial Candida rugosa lipase and 4 g of DES 4. Incubations were performed at 45 ºC for different periods under orbital stirring at 200 rpm. Alternatively, water was added to the system at molar ratios “R” water/choline chloride equal to 1, 2 or 3. GC was used to analyze samples collected at different periods, and the conversions were determined by comparing the areas of the chromatogram peaks corresponding to esterified and free sterols.

Results showed that after 24 h of incubation, no products were detected when the reaction was performed in the anhydrous system. The addition of water to the reaction media enhanced the efficiency of the reaction, and 12 % conversion was achieved with water added at R = 3. Despite the favorable effect of the addition of water on the efficiency of the transesterification, its high concentration also enhanced the hydrolysis of vinyl laurate, an undesirable effect.

Thus, to maintain a high concentration of the reactive during the whole incubation period, stepwise additions of vinyl laurate (2 x 65 mg) were performed. This procedure permitted achieving a total conversion to phytosterol ester of 53%.

Results also showed that the proportion of the different phytosterols in the product was identical to that of the free sterols; thus, the process did not show any selectivity.

Work has shown promising results concerning a green alternative to the traditional chemical-catalyzed technology for the synthesis of phytosterol esters.