How to make a chocolate mousse without eggs.
THE WORDS CHANTILLY CREAM conjure up images of fresh strawberries, ice cream, and airy desserts. Chantilly is a kind of foam, or mousse, made by whipping cream in a chilled bowl. When the whisk is guided in a circular motion, through a vertical plane, its wire loops steadily introduce air bubbles in the cream that are stabilized by the molecules of the casein (a protein) and by the crystallization of the fatty droplets. This crystallization takes place at a low temperature, which is why the cream and the bowl must be chilled beforehand. This cooling process also prevents the cream from turning into butter. To obtain the best results, stop whipping the cream once strands begin to form inside the loops of the whisk.
Can the fundamental principle of Chantilly cream be applied to fatty matter other than milk? Because chocolate contains cocoa butter, for example, it ought to be possible to make Chantilly chocolate.
A Chocolate Emulsion
Our chances of obtaining such a foam will increase if we begin by creating a physicochemical system similar to cream but with a chocolate base. Physical chemists know that cream is an emulsion, a dispersion of fatty droplets in water (in this case the water contained in milk, which also dissolves sugars, such as lactose, and mineral salts, but these ingredients, although they contribute to the taste of Chantilly cream, are unimportant for our purposes here).
The fatty droplets in an oil-in-water emulsion such as cream do not combine with one another, for they are stabilized by casein micelles and calcium phosphate. The casein molecules are bound together by the calcium phosphate into tensioactive structures, or structures with a hydrophobic tail immersed in the fatty droplet phase and a hydrophilic head immersed in the water phase.
The emulsion we need to make Chantilly chocolate can be formed in an analogous manner by mixing together water, tensioactive molecules, and cocoa butter. One simply pours a little water into a pan (which will be improved from the gastronomic point of view if it is flavored with orange juice, for example, or cassis purée) and adds some tensioactive molecules, either proteins from the yolk or white of an egg or gelatin (often used to thicken butter and cream sauces, which are also emulsions). One could rely simply on the lecithin already present in chocolate, but let’s use gelatin instead and dissolve it in the water by heating. Then whisk in the chocolate. The result is a homogeneous sauce—precisely the chocolate emulsion we were looking to create.
From Emulsion to Foam
With this emulsion we can make a foam. Put the pan in a bowl partly filled with ice cubes to crystallize the chocolate around the air bubbles that we will next introduce by whisking the chilled sauce, either manually or with an electric mixer. The procedure is then exactly the same one followed in the case of Chantilly cream. Whisking creates large air bubbles in the sauce, which steadily thickens. Once the crystallization temperature is reached, the volume of the sauce suddenly expands, and its color changes from dark to blond chestnut.
This lighter color results from the air bubbles, which can be seen under a microscope. They also gradually change the texture of the sauce: After a while strands of chocolate form inside the loops of the whisk, just as in the case of Chantilly cream. In this way one obtains a foam that, unlike classic versions, is unadulterated by crème fraîche or stiffly whipped egg white. It is a purely chocolate mousse!
Want to try? Melt a half pound of chocolate with about 6 ounces of water. Three things can go wrong. If your chocolate doesn’t contain enough fat, melt the mixture again, add some more chocolate, and then whisk it again. If the mousse is not light enough, melt the mixture again, add some water, and whisk it once more. If you whisk it too much, so that it becomes grainy, this means that the foam has turned into an emulsion. In that case simply melt the mixture and whisk it again, adding nothing.