CHARACTERIZATION OF ENZYMATICALLY PREPARED BIOSURFACTANTS

Various fatty monoesters of sugars and sugar alcohols were prepared en zymatically in organic solvent. Water produced during esterification w as removed by refluxing through a dessicant under reduced pressure. Su rface properties of these esters such as surface and interfacial tensi ons and their ability to stabilize emulsions at 30 degrees C were eval uated: oleate esters of glucose, fructose, and sorbitol show similar b ehavior in reduction of surface and interfacial tensions, and values f or the critical micelle concentration are about 8 . 10(-5) M. It was a lso observed with sorbitol esters that the shorter the alkyl chain, th e higher the critical micelle concentration. Generally, emulsions prep ared with the emulsifier dissolved in the water or in the oil phase le ad to oil-in-water or water-in-oil emulsions, respectively. Sorbitol m onolaurate significantly increased the stability of oil-in-water emuls ions, with only 5% separation of the phases after 48 h at 30 degrees C , compared to 10% for chemically prepared sorbitan monolaurate under t he same conditions. Sorbitol monoerucate was very efficient in stabili zing water-in-oil emulsions, with only 1% separation of the phases.