First, science. Chemistry plays a major role in the steaming and frothing of your milk and is almost as important as the way you brew your espresso shots. The idea of “frothing” is actually using hot air or steam to create microbubbles in the milk. There are 3 parts to the milk that determine flavor and texture: lactose, fat and protein. Lactose is also known as “milk sugar” and doesn’t really break down until it is heated. That’s why, when milk is cold, it’s not all that sweet. But once heat enters the conversation, that lactose breaks down and makes the milk have a much sweeter taste. Your fat percentage will determine how rich the milk will taste. A higher percentage will result in a creamier taste which is what we would recommend. Finally, the proteins. Milk contains both whey and casein and, when heated to 160 degrees, they become stable and help create the foam that will top your latte. Beyond 160 degrees, they break down and become unstable which will change the texture of your foam - not something you want.
Now that you know the science behind foam, let’s talk about the process. For our example, we’re going to assume you’re making a 16 oz drink. First, you’ll want to fill a chilled stainless steel container about ⅓ full with cold milk. The stainless steel prevents the milk from picking up any other flavors and besides, heating plastic isn’t a good idea. If possible, you should store your pitcher in the refrigerator so that the milk and the pitcher are the same temperature. This will help everything to heat evenly.
Next, place your steam wand about a half an inch below the surface of the milk at a 45 degree angle and steam for 7 seconds. This allows the wand to pull air under the surface and create the beginnings of the microbubbles. Then, you’ll drop the steam wand further into the milk until it’s about 2 inches from the bottom of the container. This is where the bulk of the heating is done and also when you’ll want to attach your thermometer to the side of the cup. Once the pitcher reaches 140- 160 degrees, turn off the steam wand and remove it from the cup. You’ll want to tap the bottom of the pitcher on a flat surface to release any large air bubbles (remember, we want microbubbles only) and then pour the foam into your latte at an angle. The milk will run out first (as it is heavier) and then the foam will rest on top of the latte.
And that’s it! You’ve officially completed barista training and can now froth milk like a pro! It may take a few times to get it right, but don’t give up. After you’ve mastered the art of making foam, you can always experiment with making latte art. But that’s another skill for another time. And if, no matter how hard you try, you just can’t get your foam to be silky smooth? Come see us at The Meeting Place on Market and we’ll be happy to make your favorite latte, complete with perfectly heated foam.