Journal of Oil Palm Research Vol. 26 (4) December 2014, p. 355-365

RECENT PROGRESS FOR LIPASE-CATALYSED SYNTHESIS OF SUGAR FATTY ACID ESTERS

RAN YE* and DOUGLAS G HAYES*

ABSTRACT

Sugar fatty acid esters, important biobased value-added emulsifiers in foods, cosmetics, pharmaceuticals, and personal care products, are typically prepared using high temperatures (>100oC) and in the presence of organic solvents. A more environmental sustainable approach is to employ biocatalysis, particularly lipases, for their preparation, leading to reduced solvent usage, lower temperatures, and lower generation of waste products. In order for lipase-catalysed synthesis to be a robust alternative to chemical synthesis, several technical barriers need to be overcome, particularly the difficulty in co-solubilising acyl donor and acceptor, leading to a lower reaction rate. This article reviews two recent approaches to overcome the latter barrier via formation of suspensions of saccharide particles, in ionic liquids for one case and in solvent-free reaction media in another. The former provides 10-100-fold higher saccharide concentration, hence more rapid enzyme kinetics; but, both suspension types yield similar values for productivity (moles of product per mass of enzyme per time). The solvent-free approach offers improved enzyme activity retention, minimal requirements for downstream purification, and the absence of costs associated with solvent usage and recovery. Other recent trends for the enzymatic synthesis of sugar esters are also reviewed, particularly the utilisation of oligomeric acyl acceptors and new biocatalysts.

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* Department of Biosystems Engineering and Soil Science, University of Tennessee, Knoxville, TN 37996-4531, USA.
E-mail: dhayes@utk.edu