Calcium‐Induced Destabilization of Oil‐in‐Water Emulsions Stabilized by Caseinate or by β‐Lactoglobulin

Abstract

The stability to aggregation of 20% soya oil-in-water emulsions stabilized by 0.3 to 2% sodium caseinate or P-lactoglobulin in the presence of calcium chloride solutions was studied using light scattering and electron microscopy. Stability increased with the amount of protein in the emulsion, and decreased with the concentration of added calcium. Growth of particle size with concentration of Ca2+ was more in emulsions containing lower concentrations of protein. Sodium chloride at 50 and 100 mM stabilized both systems to the'presence of calcium ions. Microstructure and light scattering showed caseinate emulsions formed clusters even at low concentrations of Ca*+ while P-lactoglobulin emulsions formed extensive strands.

The Composition of the Milk Fat Globule Surface Alters the Structural Characteristics of the Coagulum

“…But our results are in agreement with previous studies showing that the particle size decreases as the concentration of protein increases (36). As the same homogenizing conditions were applied, the limiting factor for the mean droplet size of the emulsion formed was the protein concentration (37).…”

Flocculation of protein-stabilized oil-in-water emulsions

“…As sodium caseinate is mainly composed of calcium-sensitive proteins, it can be no surprise to learn that caseinate-stabilized emulsions are readily flocculated by calcium ions [58,[88][89][90][91]. Depending on the calcium/caseinate ratio and the hydrodynamic conditions, this flocculation may be partially reversed by dilution, and it may be enhanced or disrupted shearing [89][90][91][92].…”

“…Emulsions based on ␤-lactoglobulin are readily flocculated in the presence of calcium ions [88] and other multivalent counterions. The mechanism involves both the screening of interdroplet electrostatic repulsion forces and the reduction in surface charge density arising from direct ion binding to adsorbed protein.…”

Kinetics of the Calcium-Induced Instability of Oil-in-Water Emulsions: Studies Under Quiescent and Shearing Conditions

“…In many cases, however, aggregation is much slower than the collision frequency because of interparticle repulsive forces, and a stability ratio (W) or collision efficiency factor (α = 1/W) is usually incorporated into the Smoluchowski Eqn [1], so that if all collisions lead to aggregation, α = W = 1. For food emulsions, however, α is always less than 1.…”