Comparative study of some surface active properties of fructose esters and commercial sucrose esters

Surface active properties (i.e. oil–water interfacial tension γo/w, air–water surface tension γa/w, critical micelle concentration (CMC), foaming and emulsion stability) of different enzymatically synthesized pure monoesters and blends of mono- and difructose esters were investigated and compared with those of some sucrose esters (P1670, S1670, SP30, SP70). The results show that fructose esters exhibited interesting surface properties. Indeed, fructose esters with low chain lengths led to the lowest values of surface tension whereas for high chain lengths of fatty acids, γa/w values were similar to those obtained with sucrose esters. However, fructose esters exhibited higher interfacial tension values compared with commercial sucrose esters. The results also show that depending on the carbon chain length and the monoester/diester ratio, fructose esters may be more advantageous than sucrose esters. Actually, the highest oil–water emulsion stability was reached with pure fructose monocaprate and blend of mono- and dicaprate. Moreover, the best initial foaming power was reached with fructose monocaprate and was comparable to that of P1670 after 45 min.