Foam: An Introduction

Foams, if you’ll pardon the pun, are the whipping boy of avant-garde cuisine. Those who fear “molecular gastronomy” deride them; those who practice it often downplay them. Anthony Bourdain once famously derided the godfather of avant-garde cooking, Ferran Adrià, as “that foam dude.”

So what exactly is a foam? At the highest level, it’s a dispersion of a gas in a liquid or solid, in the form of tiny bubbles. Because these bubbles interfere with the movement of the liquid phase, a foam is, perhaps counterintuitively, thicker in texture than the fluids it’s made up of. Different foams have different levels of stability: some are fleeting, needing to be eaten moments after they’re created, while others will last indefinitely. Foams collapse as the liquid in the bubble walls drains downward due to gravity; you can stabilize them by thickening the liquid, which makes it drain more slowly.

Although the term is currently associated with avant-garde cuisine, foams have been a mainstay of Western cooking since well before Adrià: for example, the steamed milk shown above is a type of foam, as are meringue, sabayon, whipped cream, and even bread. Many foams exhibit a couple of properties that make them useful in culinary applications. Because they have copious amounts of surface area, aroma molecules can easily escape, giving them great flavour release; at the same time, their relative fragility gives them a pleasing light-as-air texture, as they dissipate in your mouth. Foams have been around for a while and, like it or not, they’re here to stay.

Are you pro-foam or anti-foam in your food?

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5 Responses to “Foam: An Introduction”

  1. I am definitely pro-foam. New Year’s at the Oban Inn featured a celeriac and apple soup with apple foam and a coriander cress. The contrast between the richness of the soup and the tartness of what I think was a granny smith foam was amazing.

  2. Being a foam virgin so to speak, I am neither pro or anti.

    Is there any easy one to make with standard home-kitchen equipment? If there is, kindly tell me what to do!

  3. Matthew Kayahara January 12, 2011 at 7:48 am

    Skip, it depends entirely on the kind of foam you want to make! The type that most people think of when they hear “foam” in an avant-garde context requires a whipped cream siphon, but there are several types that can be made with a mixer or an immersion blender. I’ll be going over some of them in some upcoming posts.

  4. Definitely pro-foam. Tons of flavor in a light as air package. I like milk steeped with a bit of cardamom and frothed with a milk frother to put on top of tea. I also like to make savory foams with a flavorful liquid, a bit of soy lecithin and an immersion blender.

  5. Matthew Kayahara January 18, 2011 at 10:15 am

    Thanks, Raza! I’m a fan of soy lecithin foams, too. I’ll be talking about them in a future post.