Composed of dried egg whites, sugar and gum, meringue powder provides an alternative to egg whites in many bakery items. Commonly used in royal icing as well as meringues, the pasteurised powder makes a safe substitution for raw egg whites. It is not used on a frequent basis in most homes, so if a recipe calls for meringue powder it can easily be substituted for by using a mixture of egg whites, either raw or powdered, and sugar.
Determine the amount of meringue powder called for in the recipe. Use 1 egg white for every 1 tbsp meringue called for in the recipe.
Use powdered egg whites if you do not want to chance the risk of salmonella poisoning. Whatever amount of powdered meringue the recipe requires, substitute an equal amount of powdered egg white.
Add 1 tsp cream of tartar when making royal icing or frosting when using either substitute above for meringue powder. This replaces the gum thickening agent present in the meringue powder.