At its core, a foam is simply a collection of gas bubbles trapped in a liquid or semisolid. When it comes to food, foams are a creative way for cooks to enhance the textures and flavors of dishes. But not all foams are created equal. Their texture, stability, and taste depend on how those bubbles are formed, what gas is used, and what kind of liquid they’re suspended in.
Whisks, Blenders, and Whipping Siphons
The classic tool for making a foam is the humble whisk. As you whip a liquid, the wires pull in air and create bubbles. The more wires, the more air gets incorporated. Whisks also shear the liquid—breaking larger bubbles into smaller ones, which creates a finer texture and a more stable foam.
While whisks work wonders, other tools are hit-or-miss. A countertop blender, for example, isn’t great at making foams because its blades sit at the bottom of the container, where there’s no air to work into the liquid. Unless you find a way to blow air in at the same time (which is not easy), it won’t give you the fluffy result you’re after.
Immersion blenders, however, are a different story. Because you control how deep the blade goes, you can hold it near the surface to suck in air and create bubbles. Swap out the cutting blade for a flat disc attachment and you’ll get even better foaming results.
One of the best tools for making foams is the whipping siphon. These use gas cartridges—usually filled with nitrous oxide—to force gas into a liquid, creating a stable foam with a beautiful texture. They’re especially great for cream-based foams, thanks to how well nitrous oxide dissolves in fat.
Foams Made with Steam, CO2, and N2O
Air is the most common gas used in foams because it’s free and easy to access. But it has one drawback: oxygen can oxidize food and cause spoilage. That’s why nitrogen is often used in packaged baked goods—it’s inert and won’t affect flavor or shelf life.
Steam is another surprisingly common foaming gas. When water turns into steam, it expands by a factor of 1,700. Foods like puffed snacks, chicharrones, prawn crackers, and puffed potato chips all rely on this effect. In each case, residual water inside a gel or dough suddenly vaporizes during frying, puffing up the food into a crisp, airy foam.
Even in baking, steam plays an important role. Bubbles created by air, yeast, or baking powder expand further as the batter or dough heats and releases water vapor. This helps set the final texture of breads, muffins, and meringues.
Carbon dioxide is another common foaming gas, especially in baked goods. Yeast and chemical leaveners produce CO2 that inflates bubbles before the structure sets. You’ll also find CO2 in fizzy beverages like beer and soda. In beer, the gas comes out of solution when the pressure drops, creating foam. Most beers contain natural or added foaming agents that help trap the gas and create that satisfying head.
But we consider nitrous oxide to be the go-to gas for whipping siphons. It dissolves easily in both water and fat, doesn’t oxidize food, and even helps prevent bacterial growth. One charger typically holds about 8 grams of gas—enough for a small batch of foam. Because cream is high in fat, it’s especially easy to foam with N2O, which is why whipped cream dispensers work so well.
If you’re experimenting with a whipping siphon, you might need multiple chargers, depending on your recipe. The key is to chill your mixture and shake the siphon well to help the gas dissolve before dispensing.
Ways to Incorporate Foams into Your Dishes
Foams are a playful, visually striking way to add new textures and layers of flavor to your food. They can transform familiar ingredients into something unexpected. In Modernist Cuisine at Home, we share several creative ways to use foams to enhance both sweet and savory dishes.
For example, try the Refried Bean Foam shown above (p. 223). This twist on a Mexican classic uses pressure-cooked beans and a whipping siphon to create a creamy, cloudlike foam that melts in your mouth. It’s best served right away, as the foam holds for about 10 minutes.
We also have a Strawberry Juice with Green Apple Foam recipe (p. 161), where tart green apple adds a bright, effervescent contrast to the sweet juice.
Seafood lovers will appreciate Clams in Chowder Sauce (p. 292), a lighter, modern take on chowder. The warm sauce is made foamy using whey protein isolate, adding a rich but airy texture to the dish.
Whether you’re looking to elevate the texture of a dish, add a new visual element, or surprise your guests, foams are a fun and approachable way to modernize your cooking.
FURTHER READING
- Forming Foams with Eggs—Modernist Cuisine Vol. 4:247, 251, 255
- Strawberry Juice with Green Apple Foam—Modernist Cuisine at Home, p. 161
- Refried Bean Foam—Modernist Cuisine at Home, p. 223
- Clams in Chowder Sauce—Modernist Cuisine at Home, p. 292