Cappuccinos are pretty great. They’re creamy, frothy, and delicious—but did you know there’s so much more to them than meets the eye? It turns out that cappuccinos have more in common with snowflakes than you might think. So grab some milk and let’s get started!
Foam is a colloid of air bubbles in a liquid.
Foam is a colloid of air bubbles in a liquid. A colloid is any substance whose components are not dissolved or suspended but are dispersed evenly throughout the solution. In this case, the air bubbles are dispersed throughout your coffee.
The foam on your cup of coffee is a suspension—a dispersion of small particles (the bubbles) in another medium (the liquid). If you look at it under an electron microscope, you’ll also see that there’s no real separation between them; they’re all mixed together like a solution or a mixture, but rather than being homogenous in nature like those other two things, it’s heterogeneous: It has distinct phases (liquid and air), one floating above the other.
Another great thing about foam? It’s not just for cappuccino anymore! Check out how some people have figured out how to use it for everything from shaving cream to bath bombs:
There are two types of foam, stable and unstable.
There are two types of foam: stable and unstable. The type you want depends on what kind of coffee drink you’re making. For example, if you’re making a cappuccino, which is made from high-fat milk with a small amount of espresso (about 2 shots), your goal is for the foam to be thick and long lasting. You can achieve this by using the right kind of milk.
When you add steamed milk to an espresso shot in the cup, there’s a chemical reaction between them and it produces air bubbles that make up your foam.
This is called “stabilisation”.
When people talk about “stabilising” their milk, they mean they’re adding some sort of stabilising agent such as powder or syrup before steaming it–to prevent it from separating into fat and water when heated.
The recipes vary depending on where you look but generally speaking these products contain:
- Sugar – A sweetener that helps keep the proteins in suspension while heating; also provides flavour. * Milk Solids – Protein content gets denatured during heating process; adds viscosity which slows down drainage rate (so not too much air escapes). Unstable Foam: unstable foams have low surface tension so when mixed with hot liquid such as coffee they tend to collapse quickly due to gravity pulling out all those delicious bubbles!
The difference between snow and foam is that the air bubbles are bigger in snow.
Many of us like to refer to foam as a type of snow. However, there is one major difference between the two: the size of air bubbles in foam versus snow. Snow is made up of larger air bubbles than foam, which means that it will melt faster on your tongue when you eat it (and also be easier for you to make).
The best cappuccinos have about 0.8 mm of foam.
The best cappuccinos have about 0.8 mm of foam, which means that the drink is only about 80 percent milk. It’s important to note that this measurement refers only to the thickness of the foam (as in its height), not its overall volume—which is why you can’t see it on top of your cappuccino! If your barista uses too much or too little milk, then they’ll get a different result when pouring over their coffee grounds.
The easiest way to measure how much foam there is on top of your cappuccino is with a spoon—just put it in and lift up gently until it’s covered by milk. Count how many times you had to do this before all your milk was gone (you may need more than one if there’s an especially thick layer). That number indicates how many millimeters tall was left behind from each sip; multiply that number by itself (two times two equals four), and then divide by 100 (eight divided by 100 equals eight thousandths). That gives us our answer: about 0.8 mm!
A cappuccino’s thickness is the result of the ratio of milk to espresso (1 : 1) and the temperature of your milk (about 68°F).
- The thickness of your cappuccino’s foam is determined by three factors: the ratio of milk to espresso, the temperature at which you froth your milk and how long you steam it.
- The more espresso you add, the greater the surface area per volume of liquid becomes—and the faster your foam will dissipate into an unappetizing puddle.
- For best results, use hot but not boiling water when making coffee…
Speaking of foam, if you’ve ever had a root beer float made with real root beer and real ice cream, you’ll know that the root beer foam rises up past the top of the glass.
If you’ve ever had a root beer float made with real root beer and real ice cream, you’ll know that the root beer foam rises up past the top of the glass. It’s not as dense as milk foam or whipped cream. Milk is heavier than water, and whipped cream is lighter than milk. Similarly, ice cream is more dense than frozen root beer but less dense than liquid root beer. That means that when you add all this stuff together (soap suds! crushed ice! sprinkles!), it won’t float—it’ll sink immediately to the bottom of your cup, where it gets trapped under all those layers of dark chocolate chips and caramel sauce (if there are any).
You can make fancy coffee drinks in your own kitchen with nothing more than an espresso machine and some reasonably fresh milk.
You can make fancy coffee drinks in your own kitchen with nothing more than an espresso machine and some reasonably fresh milk. There are a few things you need to know before you get started, though:
- Use a stovetop espresso maker or a home espresso machine.
- Use warm or hot water to steam your milk. If it’s too hot, the foam will dissipate within seconds of being poured over the coffee; if it’s not warm enough, the foam will be dense and heavy—not ideal for cappuccinos!
- Use a frothing pitcher or steam wand (the latter is what we recommend). A home blender works well too if you have one on hand.
- Keep your eye on the temperature of both the water and milk as they heat up together in your pan/jug/container! It should be about 150F when added to the espresso shot for best results.
In the end, foam is just another way to enjoy your coffee. The next time you’re in the mood for something special, try making a cappuccino at home!