acyltransferase activity of lipase CAL‐A allows efficient fatty acid esters formation from plant oil even in an aqueous environment

• Published in: European journal of lipid science and technology 2015-12, Vol.117 (12), p.1903-1907
• Main Authors: Müller, Janett, Sowa, Miriam A, Dörr, Mark, Bornscheuer, Uwe T
• Format: Article
• Language: English
• Subjects: Acyltransferase; Alcohol; CAL-A; carboxylic ester hydrolases; cost effectiveness; ethanol; fatty acid esters; Fatty acids; free fatty acids; industrial applications; methanol; palm kernel oil; Pseudozyma antarctica; solvents; Transesterification; Water content; water temperature
• ISSN: 1438-7697; 1438-9312
• DOI: 10.1002/ejlt.201500292

The enzymatic synthesis of fatty acid esters (FAE) can be performed by lipases in reaction systems in the absence of bulk water. However, some lipases such as Candida antarctica lipase A (CAL‐A) have an acyltransferase activity, which enables FAE synthesis from natural oils and suitable alcohols even in the presence of water. The ability to generate these compounds in an aqueous system would be interesting for an industrial application, because this could lead to a more cost‐efficient and environmentally friendly process as the alcohol donor also serves as solvent. Using refined palm kernel oil (PKO) the CAL‐A‐catalyzed ester synthesis was studied with methanol or ethanol in the presence of 5–10% (w/w) water. Optimizing reaction parameters (e.g., temperature and water content) resulted in up to 95% ester formation after 24 h. In addition, methanol allowed higher ester formation than ethanol. Practical applications: The enzymatic synthesis of fatty acid esters from plant oils using standard lipases is hampered by the fact that the presence of water leads to undesired formation of free fatty acids. The use of CAL‐A with its unique acyltransferase activity overcomes this limitation and hence makes the industrial scale synthesis of these esters more feasible. The identification of important parameters influencing the ester formation is crucial to establish such processes. Optimization of reaction conditions leads to protocols suitable to use lipase CAL‐A in a water containing system for the synthesis of fatty acid methyl or ethyl esters in up to 95% concentration.