What Is Cold Foam?

If you’ve hit up Starbucks at any point in the last few years, your curiosity might have been piqued by a novel addition to the menu. We’re talking about cold foam—the mysterious and relatively new beverage garnish that’s been making an appearance on iced lattes and coffees and, well, pretty much anything cold these days. Now that we’ve caught you off-guard and groggy (and wondering whether your bare iced drink is inadequate), let’s get to the question at hand: What is cold foam anyway? Spoiler: it’s just nonfat milk that was frothed without heat.

It’s a major beverage trend right now (yes, that’s a thing), but if you’re late to the party, the ubiquity of cold foam on cafe menus might have you feeling dazed and confused—and not just because you’re under-caffeinated. Well, friends, let’s start from the beginning: The birth of this popular new coffee topping can be explained by the fact that the microfoam found in hot beverages (i.e., the frothed milk used to make pretty pictures and impart a silky, creamy texture to lattes) just doesn’t work well with cold coffee. Obviously, this made the iced drinks feel pretty jealous…until cold foam came along.

So what is cold foam, exactly? Quite simply, cold foam is milk that has been frothed into a firm but oh-so fluffy foam (think: stiff peaks) without the use of steam or any other form of heat. What is this wizardry,” you ask? Well, the science behind cold foam and microfoam is similar in that both involve agitating the proteins that are naturally present in milk, such that they separate and form bubbles. The key difference is that with cold foam, this is done by way of vigorous shaking and results in larger bubbles, whereas microfoam is created by aerating milk with steam until very tiny bubbles form. Needless to say, another distinction is that one is cold and the other hot.

If you’re a fan of frothed milk, a simple experiment will quickly reveal the point of cold foam. Yep, just try adding that beautifully thick and creamy steamed milk to your cold brew and see what happens. (Hint: It’s not latte art.) Indeed, the microfoam of steamed milk will sink right into a cold beverage much like regular milk would, so the layering effect you enjoy in a latte or cappuccino will be completely lost. Cold foam is the workaround that allows for a dollop of foam to sit pretty atop an iced drink. This creamy garnish won’t mix into the coffee, but can be enjoyed on its own—and fans of the stuff will tell you it scores points for aesthetic and textural appeal alike.

Given that there’s no steam or heat involved in creating cold foam, you’ve probably already surmised that you can make this frothy topping for your iced coffee at home. There’s one big caveat, though: Whole milk won’t do. Indeed, you can shake it like a polaroid picture, and still that container of full-fat milk won’t cooperate. The reason for this is that whole milk has a higher ratio of fat to protein and, as previously mentioned, the big bubbles in cold foam are composed solely of milk proteins. In whole milk, the fat molecules will weigh down the protein molecules, preventing them from expanding into the meringue-like froth you desire. As such, non-fat milk has a far more impressive capacity for heat-free frothing, and is thus the milk of choice when it comes to making cold foam.

If you swoon for the decadent creaminess of a perfectly frothed whole-milk latte, cold foam might be a bit of a letdown. For starters, the stuff doesn’t mix into cold beverages well—hence, the layered effect—so it won’t make for a milkier tasting beverage. In fact, you probably won’t enjoy the stuff all that much unless you’re totally cool with nonfat milk, as it is similarly watery and flavorless (despite its sumptuous appearance). Bottom line: If you consider nonfat milk to be an abomination (raises hand), then you’re better off adding a splash of half and half to your cold brew and calling it a day. That said, anyone can enjoy a whole milk iced latte with a dollop of cold foam—namely because the latter simply makes the drink look fancy. As for those of you who prefer their coffee with a non-dairy alternative like soy or almond milk, we’re sorry to say there’s no cold foam for you.