Abstract
The enzymatic transglycosylation to monoacylglycerol (MG) to synthesize a more hydrophilic emulsifier was investigated using various α-glucosidases. Among the α-glucosidases examined, rice α-glucosidase had the highest transglucosylating activity to MG. The formation of the glucosylated MG was more effective in the presence of acetone because of higher solubility of MG. The structure of the purified glucosylated MG was identified as a mixture of (2R)-1-monoacyl-3-O-α-D-glucopyranosyl-sn-glycerol and (2S)-1-monoacyl-3-O-α-D-glucopyranosyl-sn-glycerol by FAB-MS, 1H-, 13C-NMR analyses and α-, β-glucosidase treatments. The solubilities of monocaprylin [MG(C8:0)], monocaprin [MG(C10:0)] and monolaurin [MG(C12:0)] were increased by glucosylation. The surface tensions of the aqueous monocaprylin monoglucoside [MG(C8:0)-G], monocaprin monoglucoside [MG(C10:0)-G] and monolaurin monoglucoside [MG(C12:0)-G] solutions significantly decreased with up to 0.01% concentration of emulsifiers, and then decreased slightly at concentrations above that. The foamability increased with the MG(C8:0)-G, MG(C10:0)-G and MG(C12:0)-G contents. The foamability and the foaming stability of MG(C8:0)-G, MG(C10:0)-G and MG(C12:0)-G were superior to those of the original MG and the other commercial emulsifiers.
