All About Thickening
For custardy desserts that do not rely on heating eggs to build structure, we’ve found these ingredients (and techniques) effective at producing thickened, creamy, luxurious textures.
Gelatin
How it Works: Gelatin has long been used to impart a silken, delicate texture to desserts such as panna cotta and some mousses. In contrast to other thickening agents, gelatin begins to melt at body temperature, contributing to a luxuriously smooth, soft-yet-set consistency. A pure protein, gelatin changes a liquid into a semisolid state by trapping water and slowing its movement; essentially, it has a stabilizing effect. Because gelatin is extracted from animal bones and connective tissue, it may not be appropriate for all diets. Agar agar is often used as a replacement, although it cannot be used as a 1:1 substitute in recipes.
Aeration
How it Works: Whipping egg whites or whipped cream to soft peaks introduces air bubbles into the mixture. When folded into a densely flavored base, the elements come together to form a light and creamy mousse. Some mousses just use cream, while others use whipped egg whites as well as whipped cream. Either way, the result is delicious.
Freezing
How it Works: Freezing contributes to the thick set of semifreddo, but without the proper technique, you can end up with a solid block of ice. We begin with a custard base using whole eggs instead of just yolks, adding a little water to the cream in the base, and whipping cream to soft peaks then folding that into the base. The aeration in the mixture keeps this dessert from freezing too hard and yields a creamy and sliceable dessert.
