Evaluation of the effect of maltodextrin and hydroxyethyl cellulose solution containing ZnO and Fe2O3 nanoparticles on the CO2 release in sodium bicarbonate coating process

Abstract

Coating is a rapidly extending technology; especially in food and pharmaceutical industries. The coating process of sodium bicarbonate using ZnO and Fe2O3 nanoparticles (NPs) in aqueous solutions of maltodextrin (MD) and hydroxyethylcellulose (HEC) as wall materials has been studied in this work. The best operating conditions obtained by factorial design were the fluidization air flow rate of 100 m3/h, spraying pressure of 4 bars, drying air temperature of 60 °C, MD concentration of 30 % and HEC concentration of 0.1 %. The introduction of the NPs into the coating solution provides a heterogeneous surface, which enforces the wall material to a more uniform and faster crystallization. The applied conditions have been shown to be efficient for the coating process investigated in this study since they improve the coating characteristics such as CO2 release reduction, which is the most important one. CO2 release was reduced from 4 % for coated powders with no NPs in the coating solution to 2.4 % and 3.5 % for coated powders with Fe2O3 and ZnO NPs in the coating solution, repectively. The adsorption–desorption of N2 gas implies that the pore sizes of the coating layer surface have been significantly decreased by adding NPs to the coating solution.