Enzymatic modification and characterization of xylo-oligosaccharide esters as potential emulsifiers

Hydrophobically modified xylo-oligosaccharides were prepared by enzymatic esterification of xylo-oligosaccharide and three fatty acids: decanoic acid (C-10), lauric acid (C-12) and palmitic acid (C-16). Lipase obtained from Thermomyces lanuginosus was used as a biocatalyst in the reaction. The degree of substitution (DS) of esterified xylo-oligosaccharide, prepared at a reaction temperature of 60oC for 4 h, ranged between 0.042 and 0.066. Esterified xylo-oligosaccharides were investigated for physicochemical properties. The esterified xylooligosaccharides reduced the interfacial tension and exhibited emulsifying properties. Esterified samples did not completely dissolve in water, showed higher viscosity, and changed thermal properties compared with native samples. At a concentration of 25% (w/w), esterified xylooligosaccharides exhibited Newtonian flow behavior similar to that of native one, except for palmitate derivatives which exhibited shear-thinning behavior. Esterified xylo-oligosaccharides were then used as emulsifiers to make n-hexadecane O/W emulsions. The emulsions were characterized according to their oil droplet characteristics, emulsification index, and centrifugal force-induced oil separation. Xylo laurate has potential in emulsifying activity and in preserving the stability of emulsions after centrifugal acceleration.