Influence of pH and ionic strength on formation and stability of emulsions containing oil droplets coated by beta-lactoglobulin-alginate interfaces.
Emulsions of 0.1 wt % corn oil-in-water containing oil droplets coated by beta-lactoglobulin (0.009 wt % beta-Lg, 5 mM phosphate buffer, pH 7.0) were prepared in the absence and presence of sodium alginate (0 or 0.004 wt %). The pH (3-7) and ionic strength (0-250 mM NaCl) of these emulsions were adjusted, and the particle charge, particle size, and creaming stability were measured. Alginate adsorbed to the beta-Lg-coated droplets from pH 3 to 6, which was attributed to electrostatic attraction between the anionic polymer and cationic patches on the droplet surfaces. Droplets coated by beta-Lg-alginate had better stability to flocculation than those coated by beta-Lg alone, especially around the isoelectric point of the adsorbed proteins and at low ionic strengths (< 100 mM NaCl). At pH 5, alginate molecules desorbed from the droplet surfaces at high salt concentrations due to weakening of the electrostatic attraction.
Harnsilawat
Thepkunya
T
Department of Product Development, Faculty of Agro-Industry, Kasetsart University, Bangkok, Thailand, 10900.
Pongsawatmanit
Rungnaphar
R
McClements
David J
DJ
D000464:Alginates / Q000737:chemistry*; D003314:Corn Oil / Q000737:chemistry*; D004655:Emulsions; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007782:Lactoglobulins / Q000737:chemistry*; D009994:Osmolar Concentration; D055672:Static Electricity; D013499:Surface Properties; D014867:Water / Q000737:chemistry
D000464:Alginates; D004655:Emulsions; D006603:Hexuronic Acids; D007782:Lactoglobulins; D014867:Water; D003314:Corn Oil; D020723:Glucuronic Acid