Lipase-catalyzed synthesis of phytostanyl esters in non-aqueous media

Stanols are more effective and safer than sterols in lowering plasma total cholesterol, while stanol esters are advantageous since this compound has a better solubility than the free stanols, which contribute to the practical application in foods. The current work focuses on the synthesis of phytostanyl esters from plant stanols and fatty acid such as lauric acid, including screening of various source lipases and selecting solvents of different Log P values. Among lipases from different origins, the immobilized Novozym 435 lipase from microorganism was found to be the best biocatalyst, while plant lipase from Carica papaya and animal lipase from Porcine pancreas are quite ineffective as biocatalyst for the esterification of plant stanols with fatty acid. The highest phytostanyl laurate esterification degree of 79.3% was obtained under the selected conditions: 25 μmol/mL plant stanols, 100 μmol/mL lauric acid, 80 mg/mL 3 Å molecular sieves and 40 mg/mL Novozym 435 at 150 rpm and 55 °C for 96 h in 10 mL of n-hexane. The chemical structure of sitostanyl laurate was confirmed by FT-IR, MS and NMR. The comparison of solubility of plant stanols and phytostanyl laurate in plant oil was done.