Effect of foaming and drying temperature on the physical, chemical, and functional properties of egg white powders produced using refractance window drying

This study investigated the effect of drying form (natural and foamed) and temperature (50–100 °C) on the physical, chemical, and functional properties of egg white powder produced using refractance window drying. The egg whites were dried in 4-55 min, depending on the drying conditions. On the one hand, the drying form was effective on the color properties, densities (bulk, tapped, or particle), Carr index, Hausner ratio, porosity, hygroscopicity, solubility, and foaming capacity of egg white powders. On the other hand, the drying temperature was effective for all analyzed properties except hygroscopicity, moisture content, and water activity of samples. The study demonstrated that foaming before refractance window drying enhances the color of the egg white powders and provides better solubility and foaming capacity. However, it has a detrimental effect on the flow properties of the powders evaluated according to the Carr index and Hausner ratio. Increasing the drying temperature until a certain extent (80 °C) generally provided better color, protein content, surface hydrophobicity, and functional properties. The study shows that egg powders suitable for different purposes (better foaming, low protein denaturation, better gelling, etc.) can be obtained if the drying form and temperature conditions are fine-tuned.