Fatty acid sugar esters are a type of nonionic glycolipid surfactants and can be made from renewable biomaterials (saccharides and fatty acids). These biosurfactants are non-toxic, tasteless, odorless, nonirritant, and biodegradable with broad applications in pharmaceuticals, detergents and cleaners, cosmetics, and the food industry. Compared to harsh chemical methods (high temperature and alkaline catalysts), enzymatic preparation of sugar esters has advantages of mild conditions and regioselective synthesis (i.e., only certain hydroxy groups in sugars are esterified under enzymatic conditions, resulting in desired biosurfactant properties). However, enzymatic synthesis of sugar fatty acid esters is challenged by the lack of a suitable reaction system that can dissolve both polar sugars and non-polar fatty acids, while maintaining high enzyme activity. Our group developed new functionalized ionic liquids that are lipase-compatible and can dissolve sugars and fatty acids/fatty acid esters. Using these novel ionic solvents, we successfully prepared biosurfactants by reacting mono- and disaccharides with different fatty acids (or their esters) via regioselective (trans)esterification reactions catalyzed by immobilized
Candida antarctica lipase B (CALB). We examined the effect of various ionic liquids, sugars and fatty acids on the outcome of the enzymatic reaction. Our study demonstrated that novel enzymatic reaction systems enabled an effective conversion of renewable biomaterials into valuable chemicals.
