Fun with Foam

If you're like most of the dining public, edible foam impresses the shit out of you.  When you find the strange, dish-soap-looking substance atop your salmon actually tastes intensely of corn, or saffron, or espresso, your entree becomes memorable. The foam's effervescent, airy mouth feel leaves an indelible impression.  Wow, you think. The guys in this kitchen are unbelievable.  They're aces.  Magicians.  Gods even.  How ever do they do it?

A magician never tells his secrets, but I, dear reader, am no magician.  Just a humble line cook with a humble blog and I'll happily dispel foam's mysterious aura. The secret is soy lecithin.  And the process of making foam is so shockingly simple, you'll wonder why more people don't do it.

Extracted from soy beans, soy lecithin is a friendly little protein that's sold all over the place as a dietary supplement.  It's also commonly used as an emulsifying agent in many processed foods.  But what we in the fine-dining world love about soy lecithin is it's ability to stabilize air bubbles.  All you have to do is make a tasty liquid, add a spoonful of our little foam-making friend, and aerate the mixture with an immersion blender.  The bubbles that form naturally when you aerate something simply don't pop and your left with a palate-amusing froth that can be spooned onto a plate.

The other night we cooked up some nice sea bass with heirloom sweet potatoes, cabbage and onions (all from our CSA of course).  I spiced the veggies with smoked paprika, chipolte powder, and a little cinnamon.  But the dish still needed a sauce, so I broke out my molecular gastronomy kit and made lemon-lime foam.

Foam ingredients:

• 1 lemon, juiced
• 1 lime, juiced 
• 1/2 cup water
• 1 tsp soy lecithin powder

Directions:

• Juice lemon and lime into a small, flat-bottomed container.  I used a deli container.
• Mix in water and soy lecithin
• Aerate, preferably with an immersion blender.  Keep part of the blender's head above the surface of the liquid to maximize the amount of air that gets forced into the mixture.
• Spoon resulting foam onto the plate

Note: I used water for this foam, but you can use anything.  At work we make a buttery Parmesan broth that becomes Parmesan foam. Try blanching garlic in cream and using that to make garlic foam.  Use chicken stock to make chicken foam.  You're limited only by your imagination.