How Mousse Is Made

• Although the exact instructions vary from recipe to recipe, the concept behind chocolate mousse is simple. You melt dark chocolate, then mix it with egg yolks. A common ratio might be one egg yolk and 1 ounce of chocolate per person, though some recipes use more eggs. Whip egg whites until they are foamy and firm, then add them to the yolk and chocolate mixture. The beaten egg whites add volume and body to the mousse. Some recipes also call for cream or for additional flavors, such as coffee, vanilla or rum.

Meringue Powder

• Meringue powder acts as a substitute for egg whites. It consists of powdered, pasteurized egg whites, sugar, cornstarch and silicon dioxide, which helps keep the powder from becoming moist and from clumping. Meringue powder usually has a higher sugar content than egg content. The powder is often used to make royal icing or other meringue-based frostings. Since it's pasteurized, there is no risk of bacterial contamination. There is a small chance of salmonella contamination when a recipe uses raw eggs and egg whites.

Swapping Powder for Eggs

• It's not a good idea to trade meringue powder for eggs when you make a chocolate mousse. For one thing, the powder is only designed to replace egg whites. It can't replace egg yolks, which are high in fat and contain lecithin, which allows the ingredients in the recipe to emulsify. "Cook's Illustrated" magazine advises against using the powder as an egg white replacement in any recipe. Their testers noted that the powder made the finished product of recipes overly sweet or gave the dishes a gritty texture.

Pasteurizing Egg Whites

• If you are concerned about using raw egg whites in a mousse recipe, there are ways to make the whites safe without resorting to meringue powder. You can use a pasteurized, liquid egg white product instead of raw whites. Test the product before you start to assemble the mousse, as some don't whip up or form a foam. You can also pasteurize the whites yourself, according to the "Chicago Tribune." Combine egg whites with 1 teaspoon of water per white and 1/8 teaspoon cream of tartar for every two whites on the stove, in a double boiler. Heat until the mixture reaches 160 degrees Fahrenheit, then whip as directed. Most chocolate mousse recipes heat the egg yolks to a safe temperature, so you don't have to worry about them.