Abstract:

Galactomannans are considered to be predominantly hydrophilic carbohydrate polymers (gums) with a rigid backbone. The gums are not expected to have significant surface activity nor to form primary absorbed layers on oil-water interfaces. However, it was found that com., native BLG and guar gum reduce surface tension of water to ∼55 mN/m, and absorb/ppt. on oil-water interfaces, reducing their interfacial tensions. The surface activity of purified guar, where levels of proteins were reduced to a min. of 0.8% wt. was not inferior to that of the crude gum, unlike gum arabic. Oil-in-water emulsions of various oils with LBG or guar were prepd. The oil droplets were covered with pptd. gum layers exhibiting strong birefringency, indicating formation of organized gum layers on the interface. The adsorption capacity and surface load were evaluated. Coalescence and flocculation were minimized by establishing the best gum/oil ratios for full droplets coverage. [on SciFinder(R)]