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Comparative emulsifying properties of sodium caseinate and whey protein isolate in 18% oil in aqueous systems

Published online by Cambridge University Press:  01 June 2009

John Foley  and
Catherine O'Connell
John Foley
Affiliation:
Department of Food Technology, University College, Cork, Irish Republic
Catherine O'Connell
Affiliation:
Department of Food Technology, University College, Cork, Irish Republic
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Summary

Both whey protein isolate (WPI) and Na caseinate gave similar emulsion capacity-concentration profiles at pH 7. The emulsion capacity of aqueous solutions of WPI was relatively independent of pH while the values for caseinate fell in the isoelectric region. Saline (7·59 g/1) compared with aqueous solutions improved emulsion capacity, particularly above pH 7. At low concentration, WPI had greater emulsifying capacity and gave finer globule dispersion than sodium caseinate. Increase in emulsifier concentration, within a certain range, increased stability, improved dispersion and reduced capacity. Ethanol up to about 20% w/w improved the emulsion capacity of both proteins while at 50% the phases separated. Heat treatment (> 65 °C) of WPI solution before emulsion formation impaired capacity and stability. Heat treatment of preformed WPI emulsions did not have the same effect. Na caseinate and WPI each formed a thin continuous layer of relatively uniform thickness over the oil globule surfaces while denatured WPI appeared aggregated and relatively unevenly distributed at the oil-aqueous interface.

Type
Original Articles
Information
Journal of Dairy Research , Volume 57 , Issue 3 , August 1990 , pp. 377 - 391
Copyright
Copyright © Proprietors of Journal of Dairy Research 1990

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References

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