Flow behaviors of multiple molten chocolate matrices: Appropriate curve fitting models and impact of different types of surfactants

In this study, flow behaviors of different types of molten chocolates with extremely broader consistency and composition were investigated to identify the most appropriate curve fitting models that could be used for evaluating accurately the yield character of any molten chocolate-types. Additionally, a particular attention was devoted on better understanding the mechanisms behind the best identified fitting models as well as the role of surfactants as single ingredient or in mixture at variable proportions (0-1.5 wt%) in considered chocolate matrices. Experiments with multiple molten chocolate samples at 40 degrees C with viscosity values ranging from similar to 1 to 22 Pa s at 50 s(-1), revealed that Casson model fits the best the flow curves obtained for the molten dark and milk chocolates, whereas those of the molten white chocolate samples appeared well-described by the Herschel-Bulkley model. It was also shown that in presence of PGPR alone or mixed with lecithin or ammonium phosphatide, a drastic change of the fitting model from Casson model to Herschel-Bulkley model was evidenced only for the dark and milk chocolates, whereas no change was noticed for the white chocolates whatever their composition and consistency. Finally, modelling approaches have been developed to better understand structure/flow properties relationships of the chocolate matrices upon varying surfactant content. Using these approaches, it appeared that while increasing surfactant content from 0 to 0.6 wt% in all chocolate-types, the yield character can be lowered for at least 2-fold for the systems containing lecithin or ammonium phosphatide, and 50-fold for the PGPR-based systems.