Abstract:

A new water-sol. anionic low-mol. wt. polysaccharide (gum) with surface, interfacial and emulsification properties was extd. from leaves of the legume Portulaca oleracea (POG). Vegetable oil-in-water emulsions with small droplets (2-5 $μ$m), stable to flocculation and coalescence (for a few months) can be formed in the presence of 0.1-0.8 wt% POG. The gum adsorbs onto the oil-water interface. The nature of this adsorption was tested by evaluating the competitive adsorption of Tweens (ethoxylated sorbitan esters) and the POG in oil-in-water emulsions. It was demonstrated that Tweens form weak assocs. with the POG at the interface at certain emulsifier/gum binary mixts., but any excess concns. of the Tween will cause a gradual displacement of the gum from the interface. The POG and/or the gum-Tween assocs. (complex) have weak anchoring capabilities at the interface. [on SciFinder(R)]