Why Won't My Cocktail Foam?

The silky cap on a whiskey sour or pisco sour comes from proteins in egg white or aquafaba unfolding during a hard shake and trapping air. When the cap comes out thin, bubbly or disappears within a minute, something has stopped those proteins from building a stable film around the bubbles.

The usual suspects are traces of fat, a shake that was too short or too gentle, too much dilution, and aquafaba that is too thin. Each has a simple fix. Because a raw egg white is involved, it is also worth choosing pasteurized whites for anyone at higher risk from foodborne illness.

Fat is the foam killer

Fat interferes with the way egg proteins bond around air. A speck of yolk, an oily shaker tin, a glass rinsed with greasy water or even citrus oils from heavily expressed peel shaken in the tin can flatten the foam. Separate eggs carefully, crack them into a small cup first, and wash tins well with hot water and soap.

Cream liqueurs, coconut cream and other rich ingredients will also suppress foam. Drinks combining them with egg white rarely get a tall cap.

Shake longer and harder

A few lazy seconds is not enough. Shake the ingredients without ice for 10 to 15 seconds to whip the proteins, then add ice and shake hard for another 10 to 12 seconds to chill. You should feel the liquid change from sloshing to a thicker, quieter thud as it foams.

For an even denser cap, try a reverse dry shake: shake with ice first, strain the drink back into the empty tin, discard the ice and shake again without it. Removing the spring from a Hawthorne strainer and dropping it in the tin for the dry shake acts like a whisk and helps too.

• Classic dry shake: no ice, then ice
• Reverse dry shake: ice, strain out ice, then no ice
• Spring trick: add the strainer coil to the dry shake

Too much dilution

Watery drinks foam poorly because there is less protein per milliliter. Shaking with wet, half-melted ice or for too long on ice can dilute the drink enough to thin the cap. Use fresh, dry ice and keep the ice shake to about 10 to 12 seconds.

Using roughly 20 to 30 ml (about ¾ to 1 oz) of egg white per drink gives enough protein. A large egg holds about 30 ml of white.

Getting aquafaba to foam

Aquafaba is the cooking liquid from chickpeas. Liquid from unsalted canned chickpeas works best, and it should be slightly viscous, like a loose egg white. If it is watery, simmer it gently for a few minutes to reduce it, then cool before using. Use about 22.5 to 30 ml (¾ to 1 oz) per drink.

Aquafaba needs a slightly longer dry shake than egg white. It produces a whiter, lighter foam that can fade a little faster, so serve promptly.

Strain and pour correctly

Fine strain the drink through a mesh strainer into a chilled glass to remove ice shards, which can puncture the foam. Pour steadily and let the drink sit for about 20 seconds so the foam rises and settles into a smooth layer before garnishing. Bitters dropped onto the foam work best once it has set.

Egg freshness and pasteurized whites

Fresh egg whites hold together more firmly and give a more stable foam, while older whites are thinner and whip quickly but collapse sooner. Carton pasteurized whites often foam a little less vigorously than fresh-cracked whites; a longer dry shake usually makes up the difference.

Raw egg can carry Salmonella. The FDA recommends using pasteurized shell eggs or pasteurized egg products in recipes served raw or undercooked. Egg-white drinks should be made fresh and served right away, never held at room temperature.

Common questions

Why does my foam disappear after a minute?

Unstable foam usually means fat contamination, too short a dry shake or a very diluted drink. Use clean tins, extend the dry shake and keep the ice shake brief. Aquafaba foam also fades faster than egg white.

Can I use carton egg whites for cocktails?

Yes. Pasteurized liquid egg whites are a safer option for raw-egg drinks. Some brands include additives that slightly reduce foaming, so give them an extra 5 to 10 seconds of dry shaking.

Does citrus help or hurt the foam?

Fresh citrus juice helps stabilize egg-white foam, much as cream of tartar does in meringue. Expressing too much peel oil into the shaker, however, can weaken it.