title: Charge modifications to improve the emulsifying properties of whey protein isolate.
abstract: Whey protein isolate was modified by ethylene diamine in order to shift its isoelectric point to an alkaline pH. The extent of the modification was studied using SDS-PAGE and MALDI-TOF mass spectrometry. The modified whey proteins were used as an emulsifier to stabilize oil-in-water emulsions at acidic and neutral pH ranges, and their emulsifying properties were compared with that of the unmodified whey proteins and with the previously studied ethylene diamine modified sodium caseinate. The emulsifying activity of the modified whey proteins was similar to that of the unmodified ones, but the stability of an emulsion at pH 5 was significantly improved after the modification. Charge and coverage of droplet surface and the displacement of the interfacial proteins by surfactant Tween 20 were further studied as a function of pH. As compared with the unmodified whey proteins, the modified ones were proven to cover the interface more efficiently with extensive surface charge at pH 5, although the interfacial layer was less resistant to the surfactant displacement.
authors: VTT Technical Research Centre of Finland, PO Box 1000, FI-02044 VTT, Finland.
authors: Hairan
authors: H
authors: Ma
authors: Pirkko
authors: P
authors: Forssell
authors: Riitta
authors: R
authors: Partanen
authors: Johanna
authors: J
authors: Buchert
authors: Harry
authors: H
authors: Boer
mesh_terms: D004355:Drug Stability; D004591:Electrophoresis, Polyacrylamide Gel; D045703:Emulsifying Agents / Q000737:chemistry*; D004655:Emulsions / Q000737:chemistry; D005029:Ethylenediamines / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D008894:Milk Proteins / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D000067816:Whey Proteins
chemical_list: D045703:Emulsifying Agents; D004655:Emulsions; D005029:Ethylenediamines; D008894:Milk Proteins; D000067816:Whey Proteins; C031234:ethylenediamine