Charge modifications to improve the emulsifying properties of whey protein isolate

Hairan Ma, Pirkko Forssell, Riitta Partanen, Johanna Buchert, Harry Boer (Corresponding Author)

    Research output: Contribution to journalArticleScientificpeer-review

    21 Citations (Scopus)


    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.
    Original languageEnglish
    Pages (from-to)13246-13253
    Number of pages8
    JournalJournal of Agricultural and Food Chemistry
    Issue number24
    Publication statusPublished - 2011
    MoE publication typeA1 Journal article-refereed


    • emulsifying acitivity
    • emulsion stability
    • ethylene diamine modification
    • whey protein isolate


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