Many food-grade proteins and polysaccharides will aggregate together when acidified or
heated, due to electrostatic and hydrophobic interactions. At low concentrations, aggregates
are soluble and colloidally stable, and they have potential applications as Pickering emulsifiers
and nutrient carriers. Sodium caseinate (SC) and gum arabic (GA) at pH 7 will form colloidal
aggregates when heated, but aggregation is largely reversed on cooling. Whey proteins (in
the form of whey protein isolate, WPI) will aggregate irreversibly with GA when they are
heated together, but aggregation is often so rapid and extensive that aggregates precipitate.
Here we sought to overcome those limitations, and to develop an in situ method for
quantifying heat-induced aggregation. Aggregation was measured using temperature controlled
dynamic light scattering equipment and transmission electron microscopy.
Combinations of SC, WPI and GA were heated at either pH 7 or 3.5, and the weight ratio of
protein to polysaccharide was held at 1:5 for simplicity. Heat-induced colloidally stable
aggregates of SC + WPI + GA did not dissociate on cooling. Aggregation was measured in situ,
both in temperature ramps and with isothermal experiments. In situ measurement allowed us
to avoid potential artefacts stemming from the temperature changes and measurement
delays associated with ex situ measurements. This work demonstrated how the size and heat stability
of colloidal protein-polysaccharide aggregates can be tailored by judicious selection
of proteins, pH and heat treatment.
Loveday, S. M., Ye, A., Anema, S. G., & Singh, H. (2013). Heat-induced colloidal interactions of whey proteins, sodium caseinate and gum arabic in binary and ternary mixtures. Food Research International, 54(1), 111-117. doi: 10.1016/j.foodres.2013.06.013
NOTICE: this is the author’s version of a work that was accepted for publication in Food Research International. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Food Research International, 54, 1, (2013) 10.1016/j.foodres.2013.06.013