MSc Student Toronto Metropolitan University Toronto, Ontario, Canada
Abstract: Emulsifiers are used in confectionery production to control the viscosity and yield value of molten chocolate. Most research on confectionery suspensions has been conducted on model systems of sugar suspended in oil. To develop a deeper understanding of the structure-function relationship of surfactants in confectionery particle suspensions, the Casson plastic viscosity, Casson yield value, aggregation behaviour, and emulsifier adsorption efficiency of an industry standard milk chocolate were investigated in the presence of up to 1.5 wt% commercial soy lecithin, polyglycerol polyricinoleate (PGPR), citric acid esters of mono- and diacylglycerols (CITREM) or ammonium phosphatides (AMP). The molecular structure, polar head group, and concentration of the surfactant all played crucial roles in shaping these properties of the chocolate. Despite the similarities in molecular structure among lecithin, AMP, and CITREM, each exhibited a distinct capacity to impact viscosity and mean aggregate size. Notably, lecithin demonstrates pronounced adverse effects on viscosity when used beyond its critical concentration. This investigation shows the effect of subtle variations in polar head group properties on particle-particle aggregation and viscosity, while more substantial structural differences, as observed with PGPR, result in an entirely different behaviour. The reduction in the plastic viscosity of chocolate samples was more dependent on the emulsifier's capability to decrease the surface tension of the dispersed particles, while the impact on yield stress and aggregation behavior was contingent on the emulsifier's ability to hinder particle interactions through steric repulsion.
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