A well-made chocolate mousse gives an intensely chocolatey flavor, partly because it contains so few other ingredients. Many recipes call for little more than chocolate, beaten egg whites and perhaps small quantities of butter or vanilla. This poses a dilemma for modern cooks because of the potential food safety issues associated with uncooked egg whites. One way around that issue is to use meringue powder, which relies on pasteurized dried eggs, instead of egg whites.
Just Add Water
Meringue powder is designed to be a convenience product for bakers, a shelf-stable pantry item that can be converted into a light, fluffy meringue in minutes. Its main ingredient is powdered egg whites, mixed with a small amount of cornstarch to keep the eggs from absorbing moisture and forming lumps. Most brands incorporate a few gums or other stabilizers to keep the meringue light and fluffy, and a few are presweetened or flavored with vanilla. Read the label closely to determine the adjustments you need to make in the mousse recipe.
Mixing It Up
Meringue powder is easy to use, requiring just 2 teaspoons of powder and 2 tablespoons of water to replace each egg white. Whisk these ingredients together in a bowl, and then beat them on high speed to make a meringue. If your brand isn't sweetened, add sugar when the meringue begins to form soft peaks. To finish the mousse, melt your chocolate and stir in any other ingredients, such as vanilla or softened butter. Cool the chocolate until it thickens slightly and is just warm to the touch. Stir 1/3 of your meringue into the mousse to lighten it, and then gently fold in the remaining 2/3 until there aren't any visible streaks of meringue. Portion the mousse, and chill it until it's firm.
Meringue powder provides a convenient and food-safe way to make mousse at the drop of a hat -- or a hint -- but that convenience has a price tag. The meringue powder is never cooked, so its cornstarch gives the finished mousse a faintly starch taste and gritty feel in your mouth. It's not obvious, but it's there. Using meringue powder also means putting a range of additives and stabilizers into a dessert that should be free of them. If that doesn't appeal to you, there are other alternatives.
One obvious substitution for plain egg whites in your mousse is pasteurized egg whites. They can be found in the cooler section of most supermarkets, and once you open the package, the remainder can be portioned and frozen for later use. They whip and act like regular egg whites but are heat treated to make them food safe. Powdered egg whites are the same ingredient that's used in meringue powders, but without the added ingredients. They're also pasteurized and food safe, but they require careful storage. They readily absorb moisture from the air, so keep them in a sealed airtight container or vacuum-sealed bag.