Abstract:

The properties of a new gum extd. from the leaves of an edible herb (Portulaca oleracea) were studied. The biopolymer is a relatively small mol. wt. polysaccharide and exhibits significant charge d. at pH \textgreater 2. The extd. gum has surface and interfacial properties derived from its chem. compn. and structure. The Portulaca oleracea gum (POG) adsorbs onto the oil (n-tetradecane or soya) interfaces and stabilizes oil-in-water emulsions. Emulsions (5 wt% oil and 0.7 wt% gum) are stable to flocculation and coalescence at room temp. (for a year) but upon heating the gum desorbs and the emulsion coalesces. Mechanistic considerations regarding its adsorption isotherms, the role of the residual proteinaceous matter contaminating the polysaccharide and the charge are discussed. POG is a good example of a new gum that can be considered as a food emulsifier. [on SciFinder(R)]