Surface and emulsification properties of a new gum extracted from Portulaca oleracea L.

Hydrocolloids are water-soluble polysaccharides used mainly as food stabili zers. We are searching for a new surface active gums as an alternative to t he gum Arabic. Efforts are being made to extract some new water-soluble pol ysaccharides from selected plants, preferably free of proteineous matter an d exhibiting low viscosity and to examine their surface, interfacial and em ulsification properties. The present study explores the properties of a new gum extracted from the leaves of an edible herb of the Portulaca family. T he biopolymer is relatively small molecular weight polysaccharide and exhib its significant charge density at pH > 2. The extracted gum has surface and interfacial properties derived from its chemical composition and structure . The Portulaca oleracea gum (POG) adsorbs onto the oil (n-tetradecane or soy a) interfaces and stabilizes oil-in-water emulsions. Emulsions (5 wt% oil a nd 0.7 wt% gum) are stable to flocculation and coalescence at room temperat ure (for a year) but upon heating the gum desorbs and the emulsion coalesce s. Mechanistic considerations regarding its adsorption isotherms, the role of the residual proteineous matter contaminating the polysaccharide and the ch arge are discussed. FOG is a good example of a new gum that can be consider ed as a food emulsifier. (C) 1999 Elsevier Science Ltd. All rights reserved .