Rheological properties of a comercial food glaze material and their effect on the film thickness obtained by dip coating

Abstract

Glazing refers to the application of a coating material onto the surface of foods to enhance their shine and appearance. The objective of this work was to analyse the rheological properties of a commercial food glaze material and to study their effect on the film thickness obtained by dip coating. Glazing suspension (83.33% total solids content) was obtained using a commercial powder product. Apparent viscosity was determined (shear rate 0.6-50 s^-1) and yield stress was estimated with a creep test (0.5-10 Pa during 5 s). Experimental data were analysed applying the generalised Herschel -Bulkley model. A comparison between average thickness values obtained by dip coating and using a phenomenological mathematical model was carried out. All determinations were done at 20, 30, 40, and 50 °C. Rheological parameters were obtained with satisfactory root mean squared errors. Good agreement between experimental and theoretical film thickness as affected by temperature was obtained.