Influence of hydrolysed lecithin addition on protein adsorption and heat stability of a sterilised coffee cream simulant

Within an overall goal to enhance the stability of coffee cream, the influence of hydrolysed soybean lecithin addition was investigated. To avoid the seasonal variations in milk composition a model system was used containing 5% (w/w) soybean oil and 12% (w/w) skimmed milk powder with and without lecithin addition before a two-step high-pressure homogenisation. Addition of 20% (w/v) caesium chloride enabled a nearly complete recovery of the fat in the cream layer upon centrifugation of casein-stabilised emulsions. From the fat and protein content of this cream layer, it was concluded that lecithin addition did not significantly affect the protein content of the cream layer after emulsion preparation, but significantly reduced the additional milk protein adsorption at the oil/water interface upon sterilisation. The experimental data suggest that the enhanced heat stability of the lecithin-supplemented coffee cream simulant may be explained by the fact that hydrolysed lecithin largely reduces attractive protein-protein interactions during sterilisation.