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Influence of EDTA and citrate on physicochemical properties of whey protein-stabilized oil-in-water emulsions containing CaCl2

J Agric Food Chem. 2002 Nov 20;50(24):7145-53. doi: 10.1021/jf020489a.

Abstract

The influence of chelating agents (disodium ethylenediaminetetraacetate (EDTA) and sodium citrate) on the physicochemical properties of whey protein isolate (WPI)-stabilized oil-in-water emulsions containing calcium chloride was determined. The calcium-binding characteristics of EDTA and citrate at 30 degrees C were characterized in aqueous solutions (20 mM Tris buffer, pH 7.0) by isothermal titration calorimetry (ITC). EDTA and citrate both bound calcium ions in a 1:1 ratio, but EDTA had a much higher binding constant. Oil-in-water emulsions (pH 7.0) were prepared containing 6.94% (w/v) soybean oil, 0.35% (w/v) WPI, 0.02% (w/v) sodium azide, 20 mM Tris buffer, 10 mM CaCl(2), and 0-40 mM chelating agent. The particle size, apparent viscosity, creaming stability, free calcium concentration, and particle surface potential of the emulsions were measured. The chelating agents reduced or prevented droplet aggregation in the emulsions. When they were present above a certain concentration (>3.5 mM EDTA or >5 mM citrate), droplet aggregation was prevented. The reduction of aggregation was indicated by decreases in particle size, shear-thinning behavior, apparent viscosity, and creaming. Emulsions containing chelating agents had lower free calcium concentrations and more negatively charged droplets, indicating that the chelating agents improved emulsion stability by binding calcium ions. EDTA could be used at lower concentrations than citrate because of its higher calcium ion binding constant.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Calcium Chloride / chemistry*
  • Chelating Agents / pharmacology*
  • Chemical Phenomena
  • Chemistry, Physical
  • Citric Acid / pharmacology*
  • Drug Stability
  • Edetic Acid / pharmacology*
  • Electrochemistry
  • Emulsions / chemistry*
  • Hydrogen-Ion Concentration
  • Milk Proteins / chemistry*
  • Particle Size
  • Rheology
  • Sodium Azide
  • Solutions
  • Soybean Oil / chemistry
  • Viscosity
  • Water
  • Whey Proteins

Substances

  • Chelating Agents
  • Emulsions
  • Milk Proteins
  • Solutions
  • Whey Proteins
  • Water
  • Citric Acid
  • Soybean Oil
  • Sodium Azide
  • Edetic Acid
  • Calcium Chloride