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Intro into Frothing Milk at Home

Table of Contents

Table of Contents

how to steam milk at homeHaving trouble steaming milk at home? Scratching your head trying to figure out why you’re not getting a consistent foam for your coffee or espresso?

You’re not alone. This is a comprehensive guide which is all about steaming milk at home. We’ll be discussing the technique first, how to froth milk to get a really fine mousey texture of foam that you can use to pour latte out if you want to or just drink and enjoy.

Once we’ve understood the steaming technique then we’ll dive into a few more bits and pieces.

This is a comprehensive guide which is all about steaming milk at home. We’ll be discussing the technique first, how to steam milk to get a really fine mousey texture of foam that you can use to pour latte out if you want to or just drink and enjoy.

Milk Frothing Topics Covered

The Proper Technique Using a Milk Frother

4 steam hole wandLet’s start right at the beginning with how to steam milk; the technique of it. This is a technique you’d use for any machine that has a traditional steam wand. It generally has a metal tip on the end with 1 to 4 holes where the steam comes out.

Not all machines have traditional steam wand tips. If yours doesn’t have that it might have a weird little plastic wand or some level of automation really the answer is read the instructions and do what the manufacturer tells you to do. However, if you’ve got a traditional steam wand you should be able to create a really beautiful milk texture. 

Where to start? First of all you’re going to start with cold milk so we’re going to be steaming in a stainless steel pitcher. That’s useful because you can touch the side and feel exactly how hot the milk is.

We’ll come back to that in a moment. The size of the jug determines the amount of milk that you’re going to steam. You don’t want to steam in a massive jug just a little bit of milk and you don’t want to steam a lot of milk in a small jug. 

You never really want to fill a jug above where the spout starts on the side. That’s a good max line for most jugs. You’ll add some volume to the milk when you steam it and the motion of the milk and the jug will drive it up the side of the wall, so if you feel above this line you risk a terrible mess. 

We’ll talk more about different kinds of dairy milk and non-dairy milks later on.

Theory of Steaming Milk

For the sort of theory and practical bit of foaming milk you’re trying to do three things when you steam milk.

Firstly, you’re trying to make it hot. As long as steam is going into milk, as long as the process is happening, the milk is getting hot. The milk will heat up in a pretty linear way during the sort of steaming section.

The goal is to heat the milk no hotter than 149 degrees.We’ll explain later on why you want your milk to be 150 degrees. For now there are two other things we want to focus on while steaming milk and we’re going to look at those kinds of one at a time in the process. 

frothing milk techniqueNot all machines have traditional steam wand tips. If yours doesn’t have that it might have a weird little plastic wand or some level of automation really the answer is read the instructions and do what the manufacturer tells you to do.

However, if you’ve got a traditional steam wand you should be able to create a really beautiful milk texture. 

Where to start? First of all you’re going to start with cold milk so we’re going to be steaming in a stainless steel pitcher. That’s useful because you can touch the side and feel exactly how hot the milk is.

The size of the jug determines the amount of milk that you’re going to steam. You don’t want to steam in a massive jug just a little bit of milk and you don’t want to steam a lot of milk in a small jug. 

You never really want to fill a jug above where the spout starts on the side. That’s a good max line for most jugs. You’ll add some volume to the milk when you steam it and the motion of the milk and the jug will drive it up the side of the wall, so if you feel above this line you risk a terrible mess.

Creating Bubbles

The first thing we’re going to do, and we’ll start doing it as soon as we start steaming milk, is blowing bubbles. To make foam we have to inject air into the milk. We can do that using the very tip of the steam wand.

 

When that sits on the surface of the milk then the pressure of the steam coming out of the wand drags in air from around it into the milk. It essentially blows big bubbles and the more bubbles that you blow into the milk the foamier your milk is going to be.

You want to do this part of the process really as quickly as you can. Not so quick that you lose control over it because you you know you want to do this with some purpose. But you want to get it done pretty quickly. 

Creating Texture in Steamed Milk

perfect milk froth textureThat’s because the second thing you want to focus on in the second really two-thirds of the process is texture.

We’re going to use the steam wand like a hot whisk and it’s going to take our big bubbles that we blew at the start and whisk them down smaller and smaller until they’re so small they’re pretty much invisible.

At that point you have what’s called micro-foam you have a foam that feels just marshmallowy and soft and beautiful to drink. You’ve made a great drink. That’s the goal. 

We’re gonna heat milk for the duration. At the start we’re gonna add our air. In the second two thirds we’re gonna texture that foam. We’re gonna whisk it down to the smallest bubbles we can make.

When that sits on the surface of the milk then the pressure of the steam coming out of the wand drags in air from around it into the milk.

It essentially blows big bubbles and the more bubbles that you blow into the milk the foamier your milk is going to be. You want to do this part of the process really as quickly as you can. Not so quick that you lose control over it because you you know you want to do this with some intentionality with some purpose.

But you want to get it done pretty quickly. 

Step-by-Step Guide to Frothing Milk

Now let’s look at how you do that in a more practical sense. Steam wands on most machines have some movement to them and generally you want to have it pulled away from the machine.

Pointing out towards you just away from the machine a little bit. Slide the wand flush with the spout of the jug. The steam wand is going to sit inside that spout. You only want it to go as deep as the tip on the end of the wand. 

You can see there’s always a join, the fatter head of the wand, where that tip meets the rest of the wand. Don’t insert the wand any deeper than that. There’s no point, it doesn’t help you out.

The last thing to do is to add a little bit of an angle to your jug. Tilt your jug slightly to the right, but you can tilt to the left. It depends on the sort of space around your machine. You’re not dead on, slightly angled. 

You’re doing that to help with the second stage, where we’re trying to whisk the milk around. Before you start to steam make sure you purge your steam wand.

In many cases you’ll have a little bit of condensation that you want to get rid of. 

In other cases you may actually have a little bit of air still in the system and you don’t want to accidentally blow a big uncontrolled bubble into the milk. That’s why you purge the wand to get it ready to go. Then get the jug into place.

Now you’ve got your jug in place. At the right angle, the steam wand tip is just under the surface and then you’re going to start to steam. With just about every machine out there you want to go straight to full power. You don’t want to go to half power a little bit. You just go on full steam.

The best machines are those that just let me go straight all the way. As soon as you turn the steam wand on you want to begin to lower the jug to bring the tip right to the surface of the milk.

Not quite above it but just to the surface and you know it’s in the right spot because you’ll begin to see and hear and feel air being blown in. You’ll be able to hear a kind of slurping noise, feel the kind of vibrations of the steam blowing bubbles in the milk. You want to do this to create as much foam as you need for the drink that you’re making.

For example if you’re making a cappuccino I would say you want a good amount of foam you want to have the tip on the surface until you’ve created say an additional 50 to 80% in volume. That will give you lots of foam. If you’re trying to pour fancy latte art you may want to add 20 to 30% volume only so that you have a thinner foam at the end of it. 

Either way, you’re trying to get this done really early in the process. As soon as you’ve added as much air as you need you’re going to raise the jug back up and stop the foaming process. All you want to do is watch the milk roll and spin and churn. That’s why we had our jug at that angle. 

It’s to help create that vortex where the steam is just going to be whisking and swirling all of those bubbles smashing them down to be smaller. If you’re comfortable, use your hand on the side of the jug. When you reach the point of discomfort, you’re probably around 120 to 140 degrees. Going on another 3 or 4 seconds will get you close to 140, which is typically considered a great drinking temperature. Another two three seconds maybe if you want to go to 150 which is where milk tops out. 

That’s the process.

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After Foaming

milk frothAfter you’ve reached the desired volume and temperature of the milk foam you should put the jug down and forget about it for a second. Clean your steam wand, purge it out. 

You want the jug to do nothing at all for a little bit. The reason why is even the most experienced barista can end up with a few slightly larger bubbles than they would want.

The point of pausing here before you tap allows those bubbles to get weak. Then they pop easily and you can begin to swirl the milk and foam together again until you see a gloss finish in the jug. 

At this point you can pour this into coffee and create a beautiful drink. You can pour the milk and foam together because there’s enough liquid in the foam that it’ll pour. If you look in the jug and it has a matte finish when you tilt, just liquid milk will come out. The foam will almost sit as a raft on top and sit back from the edge. This is not good. So really make sure you mix the two together.

It should be a gentle mixing motion. Don’t be too aggressive. You don’t want to make new bubbles, but you just want to make sure that you’ve got the silkiest, glossy looking milk before you pour it into your drink. 

That’s the process, that’s how to steam milk and really all you’re changing for different drinks is how long you’re doing that kind of stretching phase. For that kind of foaming phase at the start of the process.

Everything else, whether it’s kind of thick moussey cappuccino foam, or very thin delicate foam, something for a flat white, it’s the same process. Start cold, add the air, churn it around as much as possible, and stop.

That’s it. Seems pretty simple. But it goes wrong for people in lots of different cases and we should talk about why. 

Science of Foaming Milk

Let’s briefly talk about the science of milk foams. It does become relevant later on when we get into troubleshooting. To quickly recap, it’s proteins in the milk that are involved in the foaming process primarily. The simplified way it works is they are kind of long noodles that are all kind of coiled up and wrapped around each other because parts of it really are repelled by water. They are hydrophobic and they face each other giving it its shape. When you very slightly denature that protein, there are a couple of different ways to do it:

Think about a meringue. That whisking action is actually denaturing some of the proteins in the egg white and forcing the bits that sort of hate water to come away from each other. 

 

At that point the bits of the protein that hate water are trying to find anything that isn’t water. What we’ve done when we foam milk is create a big air bubble that’s very appealing to the bits that hate water. 

 

What happens is that the protein wraps itself around the air bubble on that surface, thus making the bubble strong. It’s called a surface active agent or a surfactant. It’s what makes milk foam stable. In fact, most foams work in this way. 

 

Now what we’re doing when we’re steaming milk is actually mixing those two things. We are whisking with the violence of the steam, going into the milk, as well as heating it up.

So very quickly, very effectively, we can denature these proteins to the extent that they will wrap themselves around air bubbles. 

 

If you’re trying to foam cold milk you’ll notice it can be done, but it takes much more effort. The heat is a really nice kind of shortcut, which is why steaming can happen so effectively and still get such good texture at the end of it. That’s why things foam and anything that has surfactants in it will foam.

Cost Effective way to Practice Frothing

A great way to practice steaming is with dishwashing liquid. This is a super good way to practice with as little waste as possible. Really we’re taking a drop of soap and you would go through the same process you would steam the same way to get a very similar result.

Troubleshooting Frothing & Steaming Milk

So that’s the why things foam part but let’s talk about why things may not foam and properly froth. To understand frothing we need to discuss fat. Now if you’ve made meringues you will know that you should not get any egg yolk into your meringue mix because that will cause trouble.

That’s because the fat there offers a kind of competition to the air bubble. It’s not water either and so the parts of the protein that are looking for, not water, will happily wrap themselves around fat. Fat destabilizes foams in many cases. 

 

There are exceptions to this and it does get complicated, but it is basically true in most culinary cases and certainly it’s an issue with milk. If you steam whole milk alongside skim milk you’ll find it’s much easier to make more volume in the skimmed milk. Air that you put in, stays in.

Whereas with full fat milk, you have to work a little bit harder to increase the volume. That’s because that fat is kind of competing with the air bubble for the protein’s attention. 

 

Now again in the case of dairy milk, fats are important here because of the way that the fats in dairy milk break down. A bunch of those fats are called triglycerides. It’s a glycerol backbone with 3 fatty acids attached to it.

When that breaks down you get your free fatty acids and you get free glycerol. Free glycerol in milk is highly competitive with air for the protein’s attention. An example is milk that has been exposed to a ton of daylight. It won’t foam as well as milk that has been properly stored.

 

Generally milk froth is better the further it is from it’s “used by date” because it’s the sort of breakdown of these fats that reduce its foam ability. When milk foams badly or has this issue you can hear it almost fizz in the pitcher afterwards. If you lift it to your ear you’ll hear a kind of popping sound of all of the bubbles.

 

In some cases, if this is happening and you are doing everything right but you’re seeing big bubbles appear in the milk afterwards; it’s not your fault. It’s the milk. Most likely there’s some free glycerol in there causing you problems, the fat has begun to break down.

There’s nothing you can do to to make that steam any better. There’s nothing you can do in terms of technique or anything else. That milk will probably taste completely fine if you want to use it for something else, but it isn’t going to be great to foam with.

 

Another quick thing about fat that’s also worth noting is that fat affects flavor release in a drink. A full fat cappuccino will have a different flavor profile to a skim milk cappuccino.

In a skim milk cappuccino you’ll have a strong burst of coffee flavor that won’t really linger. However, with a higher fat content in the drink you’ll have a less intense release of flavor that goes on for a lot longer.

That’s kind of an interesting aspect of how fat influences flavor. 

 

Proper Temperature of Froth

So now we need to talk about temperature. We’ve discussed 130 as a kind of good starting point to be turning it off from. At that temperature it’s very drinkable straight away. It’s nice sweetness but no hotter than 150. That’s because after 155 degrees  milk begins to permanently and irreversibly change. (Study Source)

 

Think of it like cooking an egg, once you’ve cooked the yolk there’s nothing you can do to undo that process. It’s a permanent change to the proteins they’ve been permanently denatured. Above 68 degrees, proteins begin to permanently break down. 

 

In some cases milk literally just breaks apart. You’ll get the release of some things that add some kind of cooked unpleasant eggy smell to the milk; that’s unavoidable. If your milk spends time above 155 degrees you will break it. It will not taste as nice and that’s why really great cappuccinos are never really that hot.

Can you Reuse Steamed Milk?

No, that is due to the way that heat affects the proteins. For example, if you steamed up a batch of milk and you didn’t pour it out of the jug, in fact you let it cool down and put it back in the fridge. The milk would be chilled back down again.

If you steamed it the second time the proteins would begin to fall apart sooner because they’ve been affected the first time you steamed them. The first time you heated them. 

That’s why you can’t really effectively reuse milk for steaming and have it taste as good or produce as good a texture. You’ve just damaged the proteins twice, too much, too many times, and they can’t give you the texture or the flavor that you want. 

How Temperature Affects the Sweetness of Frothed Milk

Now the perceived sweetness of the milk is kind of interesting. It’s also temperature related. The sugar in dairy milk is typically lactose and that’s designed to be at its sweetest at body temperature.

The further you get away from body temperature, be it hot or be it cold, the less intense that sweetness will be perceived. Very hot cappuccinos or flat whites will taste less sweet than pleasantly hot ones. If you let it cool a bit more it will get sweeter. 

 

With alternative milks the profiles of sugars are a little bit different. Sucrose has a different curve of temperature to lactose so you might notice some differences there, but with lactose in particular there is quite a distinct curve of sweetness around temperature.

Alternatives to Dairy Milk

Alternative milks are increasingly popular and common in cafes and in homes all around the place. Generally the sort of rules of why they would foam and the textures they create are pretty similar. 

 

If you’re thinking about how to use something like coconut for like a fat content or how to use oat for sweetness or fava beans for a foaming aspect to create a kind of plant-based alternative. Doing that well is difficult. Making something that foams like milk is difficult. However,  there are more options out there in the world today. 

 

If you’re testing them out you’ll find that some out there don’t foam as well or don’t retain or hold the foam as well. You’ll find some variances of texture, of mouth feel and all of those kinds of stuff because you’re getting the sort of fats to work in conjunction with the foaming agents.

This is always kind of tricky, but if you don’t want to drink dairy there really are more options than ever and you should be able to treat it exactly like dairy in the foaming process.

Steam Wand Tips

The last thing to go over is about steam wand tips. How to set up a machine to steam well. There’s a thing that we need to talk about here, which is the idea of pressure versus flow when it comes to steam. (Effects of Steam Pressure Study)

 

Many steam boilers are set to a particular pressure. You’ll see a gauge that might say 1 to 2 bars or something like that. That’s how much team pressure you have. Generally lots of pressure 1 or more bars of pressure is good. If you’re struggling to steam milk lowering the pressure actually doesn’t help you out.

That’s because the pressure is what’s going to be spinning the milk round. Lots of pressure helps create a vortex in the milk, but you might experience a situation where you’re trying to steam just a little bit of milk and it feels like there’s just too much steam to work with and the process is over before you’ve begun. 

 

In those situations that’s where you want to switch out the tip of the steam one for something like a low flow tip. The pressure of the steam coming out remains the same but less steam is able to escape. That will slow the process down.

It’ll give you more time to do what you need to do to add air at the start and to do the texturing, rolling vortex, in the second two thirds. 

 

It’s definitely something that’s easy to do with most machines. They’re relatively universal in terms of threading on them. For most machines there are options available for the size of the holes and the number of holes in the steam tip.

Therefore, if you’re struggling, don’t reduce the pressure, reduce the flow. Change the steam tip. This is good for very small amounts of milk. 

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