ENZYMATIC-SYNTHESIS OF MONOGLYCERIDES IN A MEMBRANE BIOREACTOR WITH AN IN-LINE ADSORPTION COLUMN

The chemical synthesis of monoglycerides requires high temperatures, which may lead to the polymerization of unsaturated fatty acids. The enzymatic synthesis of these esters is performed at moderate temperatures and, hence, polymerization is avoided. However, enzymatic processes often end up with a mixture of the product, by-product, substrate and enzyme. An alternative process is an immobilized enzyme membrane reactor equipped with an in-line adsorption column to adsorb the monoglycerides, preferentially onto the adsorbate. A silica 60 column has shown preferential adsorption of monocaprinate. The adsorption of a mixture of decanoic acid, mono- and diglycerides is based on two different mechanisms. The decanoic acid will interact with hydroxyl groups at the silica gel surface, which results in a noncompetitive decanoic acid adsorption onto 25% of the silica gel surface. On the remaining part of the silica gel surface, mono- and diglycerides adsorb competitively. When a mild eluant is used, such as 5% ethanol in hexane, only the competitively adsorbed molecules are desorbed. This results in a purification factor of approximately 90% after desorption. The column can be desorbed off-line in a continuous membrane/repeated batch column process. This results in an estimated production of monoglycerides of 60 mol (15 kg) of monoester per gram enzyme.