You might know you need steamed milk for lattes, but what does steaming milk do? The way it functions in a quality coffee drink provides structure and stability as well as a unique mouthfeel you simply can’t get without steaming. It can even change the taste itself! We’ll dive into all the science behind it as well as how to handle it when you’re trying out steaming for yourself.
The science behind steaming milk
Every milk steaming technique is going to use a little bit of science to pull it off. But when you consider that in so many ways cooking is science, it’s makes a lot of sense. The way heat affects milk in the steaming process can change a lot about it, but how?
How does steaming change milk’s texture? Is steamed milk just hot milk?
Short answer first: no, steamed milk is not just hot milk! That’s why simply heating it over the stove or in a microwave alone is incapable of producing the same results. The way a steam wand works is with an induction of pressurized steam. That pressure adds air to the milk through powerful jets of steam. These jets act like “tiny, fierce whisks” introducing that air faster and more vigorously than other methods.
The steam is also heating it while introducing air at the same time. Milk is full of proteins like casein and whey, but when milk is cold those proteins are pressed tightly together. But as the milk warm, they loosen and wrap around the air bubbles created by the steam wand. It’s this process that gives the foam that stability.
That’s what sets the microfoam created by steaming apart from any other. Traditional foam simply isn’t capable of being as stable and the creation of that microfoam is essential for making your espresso drinks the best. The way the proteins bind together is what gives those cortados, lattes, and cappuccinos the silky mouthfeel you crave.
Why temperature matters when steaming milk
It’s very easy to overheat your milk and once you do, there’s no turning back. The only option is to toss it and start over! That’s because scalded milk, which means it’s been heated above 160°F, breaks down the proteins that help give the milk in your coffee drinks that delicious flavor. You’ll also want to be careful of milk’s natural sugars, lactose, which can have a tendency to burn when overheated. All of that can leave your coffee drinks dull and bitter.
To heat your milk properly, it should be heated to between 130 and 150°F only. That’s the sweet spot for creating the creamy, silky texture you’re looking for. Beyond that is when it can become dry, foamy, and lacking in structure.
What is the difference between steamed and frothed milk?
Frothed and steamed milk might initially look similar, but they’re actually quite different in form and structure. Milk can be steamed or frothed, but only steaming can create true microfoam. Frothing can be done to milk that’s hot or cold and is simply about incorporating air into the existing drink. That makes the bubbles light, airy, and more delicate. Steaming adds heat and air at the exact same time which gives the air bubbles a structure that can’t be achieved in another way. That’s how you get microfoam.
Steamed milk is best for drinks like lattes, flat whites, and cortados — especially if you want to make latte art. Frothed milk, however, can be used for cappuccinos, macchiatos, and cold coffee drinks. It’s important to keep in mind which type of foam is best for your particular drink in order to achieve the optimal flavor.
Does steaming milk change the way it tastes?
You might notice that steamed milk tastes different than regular milk, and that’s because it does! The heat of the steaming process breaks down the natural sugars in milk into simple sugars that do in fact taste sweeter. This process is also what makes milk taste more bitter once heated beyond the optimal temperature of 140°F — the sugars at that point have broken down completely, which makes the milk taste less sweet.
That’s also why you should use a light hand when you begin adding sugars and syrups to flavored drinks. You’ll want to account for the natural enhanced sweetness of the heated milk to avoid overpowering your coffee.
Is steamed milk good for latte art?
Not only is steamed milk good for latte art, it’s the best option available. The structure that milk’s whey and casein proteins lend the foam is essential not only for microfoam, but for the ability to hold the art you want to create. Airy foam isn’t as capable of holding and maintaining art, especially as you graduate toward making more detailed and complicated art.
Luckily, when you have a quality steam wand you can more easily create the microfoam you need. Once the microfoam is settled, you’ll want a precision milk jug to pour sharp lines in your mug. Just make sure the milk you’re using looks glossy and smooth after it’s steamed, not bubbly.
The bottom line – should you steam milk?
If you’ve gotten all the proper equipment, then there’s no reason not to steam your milk at home. Just make sure you’re using one of Pesado’s quality tamping stations to prep your shot before steaming your milk in a sharp-spouted milk jug so you can draw clear lines and beautiful patterns in your latte art. Shop Pesado’s whole collection to upgrade your entire espresso setup!
