There are a few methods of incorporating airs into a mix to create a foam:
If you are serious about creating and serving culinary foams, we highly recommend purchasing an iSi whipper. This durable stainless steel device is the easiest way to create luxurious foams that can be served at any temperature. The nitrous oxide used by these devices also create the smallest bubbles possible, therefore creating a creamier texture.
Whisk or hand mixer
Hand mixers have long been used by chefs to create whipped creams and meringues. The same techniques can be used to create modernist foams using Versawhip or Methycellulose. For a creamier texture, we recommend thickening the base liquid with xanthan gum or another hydrocolloid.
Whipping wands or immersion blenders
There are good for creating light, frothy foams. To create the foam, combine all ingredients in a tall plastic container, then whip the mixture until small bubbles form at the top of the container. You will then be able to scoop the bubbles off with a spoon or ladle.
Fish tank air pump
And of course, don't forget to try the fish tank bubble technique to create large, airy bubbles that can be spooned on top of any presentation.
Tips for Successful Foams
Troubleshooting foams can be complex, but likely problems include acidity, alcohol, and fat.
Traditional whipped creams and egg meringues both benefit from a slightly acidic environment. That's why many recipes call for the addition of cream of tartar - a weak acid that helps to stabilize the foam. However, make the liquid too acidic and the foam can break.
In addition, foams only work to mix air with polar water. Alcohol, with its dual polar and nonpolar ends, does not foam effectively. In addition, alcohol interferes with the function of many stabilizers. If using alcohol in a foam, try to use a lower-alcohol formulation.
Finally, the presence of fat can weaken a foam. For example, the peaks of an egg-white-only foam will be much taller than the same foam made with egg yolks. If you are specifically making a fat-based foam, know that you may need to add additional emulsifiers or use special emulsifiers (like glycerin) designed for use with fats.
By Kevin Liu