Kinetics of droplet aggregation in heated whey protein-stabilized emulsions: effect of polysaccharides

The kinetics of heat-induced destabilization of whey protein emulsions was studied in the presence of varied concentrations of the polysacchride stabilizer xanthan, carrageenan or propylene glycol alginate (PGA). Both xanthan and carrageenan increased the rate of emulsion droplet aggregation in heated whey protein emulsions, whilst PGA had no observable effect. The maximum effect for xanthan was a 3.5-fold increase in the rate of destabilization for concentrations of 0.05 wt% and above. For carrageenan the increase in aggregation rate was smaller, with a 2.7 times increase observed at a carrageenan concentration of 0.1 wt%. For xanthan gum the decrease in heat stability was explained in terms of the known tendency for xanthan to cause depletion flocculation in emulsions. For carrageenan the effect was related to evidence that the polysaccharide can interact with denatured whey protein, but not with the native molecule.