Rheological Properties of a Commercial 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 objectives of this work were to analyze 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) and yield stress was estimated with a creep test (0.5-10 Pa for 5 s). Experimental data were analyzed by applying the generalized 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 carried out at 20, 30, 40 and 50C. Rheological parameters were obtained with satisfactory root mean square errors. Good agreement between experimental and theoretical film thickness as affected by temperature was obtained. Practical Applications Glazing refers to the application of a coating glaze material onto the surface of foods to enhance their shine and appearance, contributing to extend the shelf life of foods (like in bakery and confectionery products). In the present paper, the rheological properties of a commercial food glaze material were analyzed and their effect on the film thickness obtained by dip coating was evaluated. This study provides new experimental data to validate the mathematical modeling of the dip-coating process developed in our research group. The general approach proposed to face the food glazing process will be of great significance for industry mainly to improve the control of film thickness of glazes.