The Science of Dark Chocolate Mousse

If you are a fan of quick and easy recipes with a delicious result, then this mousse recipe is perfect for you! I had never made chocolate mousse before I tried this recipe, and the simplicity amazed me.  All you need to know how to do is whip up a good foam!

But how exactly do you whip up a good foam?  Well, the answer to that is a little more complicated than you might expect.

A dairy foam is formed using a cream of no less than 30 percent fat (any lower and the cream will not foam) (Wolke, 2005).  Whipping creams are able to form stable foams thanks to the unique properties of the proteins found in milk.  These proteins are able to stick to that air-water interface found on the surface of a bubble and form a layer (Vega et al., 2012).  Once this layer is formed on the surface of an air bubble, the proteins create a flexible network across bubbles that stabilizes and holds the foam in its shape (Vega et al., 2012).

Dairy foam will be combined with another foam, an egg white foam, to produce an end result that is as light and airy as possible. Eggs whites can be beaten into a foam that can expand the egg whites 6-8 times in volume (“Foam”). The hydrophic regions of egg whites facilitate the incorporation of air bubbles by coating the air and allowing them to become incorporated in the protein interface as it denatures (Lomakina & Míková, 2011). There are some important factors to keep in mind that will inhibit the foaming. Fat is the most common of these. The properties of fat conflict with the delicate structure of the protein interface (“Foam”). To avoid the interruption of fat on the foaming process, make sure to exclude any egg yolk and to thoroughly clean baking materials.

And how to we generate the air bubbles in the first place?  In the case of our recipe, we used mechanical agitation, which is when you use a whisk or a hand mixer to whip the air into the cream, creating whipped cream and whipped egg whites (Vega et al., 2012).  In both cases, we want to whip the cream and the egg whites until they form stiff peaks so that our foam is as full of air as we can get it.  This creates the desired mouth feel of the mousse: creamy, airy, and light.

If you are making the dairy-free version of this mousse, then you will be using coconut cream instead of dairy cream.  Coconut cream will be harder to whip into those nice, stiff peaks because it only contains between 20 and 29 percent fat, which is lower than the percent fat necessary to get a good whipped cream going (“The Chemistry of Coconut Milk and Cream,” 2017).  We tried to make the recipe with coconut cream, and our first attempt did not turn out successfully. Using some tips we included in the notes of this recipe, the second attempt turned out nicely.

Another question you might be asking yourself is if you can substitute cocoa powder for chocolate in this recipe.  For flavor, yes, you probably could.  Cocoa powder actually has a stronger initial chocolate flavor than chocolate because it is almost entirely cocoa solids and is therefore lacking the cocoa butter fats that weaken the burst of chocolate flavor (Rees, 2017).  However, we would not suggest completely substituting chocolate for cocoa powder because the fats found in cocoa butter really lend this recipe the creamy, silky mouthfeel that is so desirable in a mousse.  We did experiment by adding in a tablespoon of cocoa powder to the 5 ¼ oz chocolate, and this did give the recipe a little extra chocolate flavor.  If you are looking for a way to deepen that chocolatey punch, definitely try adding a tablespoon of cocoa powder to the chocolate as it is melting!

For an easy-to-follow recipe card, please check here.