Milk Foam: Preparation, Tools and the Right Milk
Here, I reveal all the secrets to making milk foam, whether you’re wanting to use a portafilter, a super-automatic espresso machine or an automatic milk frother.
Here, I reveal all the secrets to making milk foam, whether you’re wanting to use a portafilter, a super-automatic espresso machine or an automatic milk frother.
Milk foam usually tends to play second fiddle – even though I love it! This contradiction can certainly be explained by the fact that, in my mind, for far too long, too much fuss has been made about the foam, while the actual product, the coffee, has been talked about more in passing.
Many readers and users still very frequently ask about milk foam quality when it comes to buying a machine and yet super-automatic machines have less to do with perfect milk foam than you might think.
That’s because achieving the perfect milk foam depends on such a great deal more. You can find out what exactly in this revised how-to article.
I use the best tools, give you tips on how to prepare milk foam without buying a super-automatic machine and pick up again on some of the topics from my Milk Frother Review.
The heart of the matter, of course, is the raw material itself and the big question: which milk makes the best milk foam? The question of whether plant-based milk alternatives produce equally good foam is also becoming increasingly important.
First, the good news: virtually any milk or milk alternative can be frothed. All you have to do is understand what occurs during frothing and adjust your ingredients and tools accordingly.
Table of Contents
The existence of a dissertation entitled “An Investigation of the Characterization of the Macro- and Microstructure of Milk Foams” shows you just how much interest there is in achieving the perfect milk foam (document only available in German).
We have a very narrow view of the most important element of a cappuccino or latte macchiato, but the “extraordinarily complex system of milk” (to quote the dissertation) plays an enormous role in many areas of the food industry.
I do think that especially in the coffee world and with milk froth though, we can see just how much the understanding of quality has changed and, above all, improved.
The sentiment used to be: so long as it’s firm, hot and passes the “cookie test”. Today the motto is: fine-pored, free-flowing, velvety and carefully prepared. That’s because latte art can only be produced with this so-called microfoam.
The fact that milk can encompass both extremes is due to the special structure of the substance. Milk, in this case completely normal whole milk, consists of
We’ll see later how this composition changes with plant-based milk alternatives and low-fat varieties.
In any case, these main components of milk play a decisive chemical role in the preparation of milk foam. Two important reactants, however, are required for this purpose: air and temperature.
In general, such foams consist of air bubbles surrounded by liquid. These air bubbles can be incorporated into the liquid by either a process of condensation or dispersion.
During the condensation process, air is “pumped” into the liquid using changes in pressure. The dispersion process uses the mechanical input of energy. It’s for this reason that milk, regardless of temperature, also becomes foamy in a blender or when shaking it, for example.
Nozzles and membranes, through which the gas enters the structure of the milk, are ideally suited for this process too. That’s why this method is also used in espresso machines and super-automatic machines.
Without getting too scientific, the so-called surface-active agents in milk are decisive. Consisting of both a water-loving and a water-repellent part, these molecules ensure that the air bubbles remain stable within the liquid mixture and thus form a more or less stable foam.
To make sure the foam remains that way for as long as possible, certain proteins and fat molecules take on the role of emulsifiers, binding the whole thing naturally together and delaying the disintegration of the newly created bubble structure.
The role temperature plays in milk foam is twofold: on the one hand, heat helps drive the protein conversion process. On the other hand, none of us want to shock a nice hot espresso with cold milk foam. Cold milk foam is possible though – if you shake it vigorously enough.
Conversely, there is also a clear limit as to the maximum temperature for milk foam:
The proteins denature at temperatures above 70 degrees Celsius (158°F). Denaturation doesn’t just mean that the binding properties change – above this threshold, the milk also increasingly tastes worse and quite literally burned.
If we bring all the scientific findings on milk foam together, then pasteurized fresh milk with a very high fat content is the ideal choice. And that’s for obvious reasons:
If we navigate away from this ideal state, foaming is not impossible however. It just gets a little more difficult, or rather the foam has a slightly different consistency and stability. Not to mention taste.
I’ll now explain what this means in more detail. I must point out though too, that the same type of milk from different suppliers often has different foaming properties.
This hint was provided by a user in the comments section. Thanks for that! You’ll therefore have to spend a bit of time trying things out until you find your favorite.
Full-fat whole milk produces simply superb foam. Even in the form of UHT milk, where it’s been ultra-heat treated and therefore no longer contains all its ingredients in their original form, the fat content is still its most advantageous quality.
That’s because the fat in milk is also a known flavor carrier and ensures an ultra-creamy texture. In addition, it provides your taste receptors with the ideal basis to better discern the nuances of espresso and coffee beans without pushing to the fore any specific flavor of its own.
But: industrial milk production is just as much a crime against nature as every other aspect of mass agriculture. Cow’s milk actually only belongs to cows and calves – people just steal it.
There’s no debating it and that’s why I love the advertising slogan “It’s like milk, but made for humans” from the plant-based milk producer Oatly.
But I shouldn’t swing the moral club around in this regard, because I like to make milk foam with whole milk too. I do make sure to buy organic though and prefer to obtain it directly from the producer.
Interestingly, many shake their heads at the thought of drinking milk straight from the udder. This certainly has something to do with the fact that we prefer not to know the beasts that supply our food.
Germany especially is not a fan of selling raw milk for that reason. See the “Animal Food Hygiene Ordinance” for more information (website only available in German). Only so-called “certified” raw milk is permitted to be sold, i.e. raw milk that’s been filtrated and packaged. But even then, only if the milk hasn’t left the farm in the meantime, the farm holds a permit and many, many other regulations are complied with.
In the US, at federal level, the Food and Drug Administration (FDA) bans the interstate sale or distribution of raw milk: all milk sold across state lines must be pasteurized and meet the standards of the US Pasteurized Milk Ordinance. However, the individual states may adopt their own laws and the sale of raw milk is therefore legal within some states – you can find out which ones here.
I’m personally crazy about milk foam made from certified raw milk because of its incomparable flavor, which has a positive effect on flat whites and many other coffee combinations. However, raw milk doesn’t keep very long and can only be obtained directly from a trusted producer. There’s always some residual risk when it comes to the danger of infection too.
Those of us that watch our weight are often convinced that low-fat or skim milk, at around 0.1 percent fat, is the better alternative. However, there’s now a school of thought that says fat as a macronutrient is really a good thing because it fills you up faster and for longer.
Now consuming coffee and milk foam isn’t about becoming full. But the opposite, restricting ourselves, isn’t the point either: milk foam and coffee are luxury foods that we treat ourselves to, not things we consume in abundance for dinner.
What’s more, because low-fat and skim milks have their fat content thrown away, they inevitably become more carbohydrate rich. Milk carbohydrates aren’t exactly the best either, because they drive blood sugar levels up fast, but cause them to drop off just as quickly too.
Besides, I think that especially when enjoying coffee, we really shouldn’t worry about whether the milk is “making us fat” or not. That’s because the milk is the least of our problems.
Drinking a simple cappuccino daily, rather than a triple caramel latte mocha, really won’t impact your figure much at all.
From a foaming perspective, even a low-fat milk of around 1.5 percent fat content won’t cause you any problems. With skim milk, however, it becomes all the more difficult to achieve foam of proper structure that lasts longer than two seconds. That’s because an important building block of bubble binding is obviously missing. Its overall watery character can’t be overlooked, but it does also still work.
In my opinion, a striking argument in favor of using 1.5% milk is the flavor. It’s definitely different from whole milk and doesn’t feel quite as noticeable in the mouth. Many coffee drinkers are looking for precisely this neutrality or don’t like their coffee being ultra-creamy.
Let’s recall that commercially available whole milk consists of around 5 percent lactose. Some people can’t metabolize this milk sugar.
It’s for this reason that lactose-free milk was developed, where the lactose is broken down into its simple sugars with the help of the lactase enzyme (beta galactosidase). In effect “digestion” already occurs during production, meaning those with lactose intolerance are able to dig in too.
Even if the song and dance about avoidable intolerances has reached completely ridiculous proportions and I too like to celebrate the intolerance to lactose intolerance in a tongue-in-cheek way, lactose-free milk does have one interesting advantage: it’s deliciously sweet. Just damn expensive.
Because only its lactose molecules are messed with, lactose-free milk can be foamed brilliantly. The sweetness is also a great addition to rather dark espresso roasts. I do think it should remain an emergency solution for “real” lactose intolerants, however.
I could write an adventurously long text about the different foaming properties that plant-based milk alternatives have. Some versions even easily match the standards of actual milk.
However, these milks exhibit much greater “foaming disparity”. Soy milk, for example, is an absolute berserk foamer, whereas you can completely forget about pure rice milk.
For just as long as the hype around veganism has been going on, baristas and coffee fans have been desperately looking for a plant-based alternative that almost exactly matches the foaming properties of whole milk.
They haven’t been entirely fruitful as yet and, as we here at Coffeeness discovered back at the Berlin Coffee Festival 2018, the extremely hyped “Oatly Barista Edition” doesn’t fulfill this promise either.
This oat milk version is rather clever, however, because it has a fat content of three percent (compared to the usual 0.5 percent of standard Oatly). More fat is fantastic for flavor and helps positively influence the oat milk’s original protein structure in terms of its foaming properties.
The only thing is that the usual three ingredients (water, oats and salt) become a list of ten individual items in the Barista Edition. Oil and acidity regulators are used, as fat alone doesn’t help produce a milk capable of better foaming.
We can see this with the previously mentioned foaming queen, soy milk, too. It actually contains more than 30 percent protein, which is why soy milk foams like mad and quickly takes on a very strange structure. At the same time, the disequilibrium makes the foam collapse faster. Soy milk has a clearly discernible sweetness too.
At the other extreme, rice milk contains only around 0.2 percent protein and is equally lacking in fat. Its foam is accordingly very lean and even more unstable than its soybean equivalent. The same applies to pure coconut milk too.
Almond milk is one of my personal favorites, less because of the foam and more because of the flavor. Here, however, opinions differ. Its fat content is quite good at around 3 percent, its protein content useful at around 1 percent.
The flavor is quite peculiar, somewhere between nuttiness, sweetness and acidity. Some coffees gain full benefit from this, especially if they possess little inherent acidity of their own. The fruitier the coffee though, the more difficult using almond milk becomes.
The ideal plant-based alternative for frothing is and remains (stock-standard) oat milk. Oatly is absolutely your best bet. I’ve found though that you have to explore a bit until you find your favorite foam and you’ll always have to live with the fact that your coffee very clearly tastes of oats. Light roasts are quickly drowned.
Now that we know what we’re foaming, it’s time to find out how to best foam our milk. The options usually include:
The first of my favorite methods for foaming milk is kind of obvious: I love working with steam lances because they allow you to have a lot of influence and conjure up fine-pored, perfect microfoam. The most useful models only come attached to more expensive portafilter machines, however.
My second favorite method caught my attention during my reviews: I’ve become a real fan of automatic milk frothers! If you choose the right model, you can produce milk foam with absolutely no effort and surprisingly great results. That’s true for the Philips Senseo Milk Twister, for example. Manual milk frothers such as the Bodum Latteo also deliver great results, but are a little more expensive.
With super-automatic machine milk systems, you usually have to compromise on consistency or temperature and many milk systems are a hygiene challenge. They are rarely surpassed though in terms of convenience and comfort.
Among the DIY methods I include, for example, shaking or using a blender. Even taking a whisk to the milk jug, with lots elbow grease, provide results. Since I constantly make use of devices, I’ll again throw the question out to you: which DIY methods work better than expected?
At this point, I want to let you in on some tips, tricks and features of each of the individual milk foaming methods. You can find details in the review reports or in the respective main articles for each device category.
As noted before, nothing’s easier than pressing a button and letting the coffee machine do all the work. With super-automatic machines, milk is drawn up via an internal or external tube, heated and then driven with steam through nozzles that force the air molecules into the liquid.
It functions fully automatically, but in many cases still pretty clumsily. Super-automatic machine foam is often very firm and has a bubble bath-like quality. This is no “manufacturing defect”, but rather is specifically made that way. That’s because many consumers still want this “inferior” foam and the manufacturers duly supply it. Old habits die hard.
Things are slowly changing though, as can be seen with the DeLonghi Dinamica ECAM 350.15.B or the Jura E8.
When making milk foam with a super-automatic machine, these important rules apply:
As a barista, prior to my Milk Frother Review, I was always of the opinion that these specialized devices were only a temporary solution if you didn’t have a super-automatic machine yet still didn’t want to go without milk foam.
I’ve since changed my mind. That’s because the best devices in the review really do achieve excellent results, are much easier to clean than some super-automatic machines and, what’s more, take up very little space.
You have the choice of three basic device types:
All three have their advantages and disadvantages:
|Automatic milk frothers||· Excellent results in some cases|
· Quiet and hygienic
· Everything happens automatically
· Multiple functions
|· Quite expensive and/or bulky, depending on the model |
· Not much ability to influence foam results
|Electric milk frothers||· Very easy to use and super affordable|
· Suitable for many kitchen tasks when used as an "electric whisk"
|· Milk must be heated separately |
· Mostly disappointing results
· Quickly become broken
|Manual milk frothers||· Excellent results in some cases|
· Quiet and hygienic
· Very affordable
· Ability to individually adjust foam results
|· Milk must be heated separately |
· Requires elbow grease
From the table you’ll see that I prefer the manual as well as the automatic milk frothers, whilst the “magic wands” were tested more for the sake of completeness.
The review selection continues to grow, but I do have some clear recommendations for you:
You can find more detailed information on milk, the best tricks and the most important devices in the Milk Frother Review guide.
I’ll never understand why the manufacturers of super-automatic espresso machines regard steam wands as “cheap features”. I can understand, however, that the level of effort and learning involved is out of all proportion to what super-automatic machines fundamentally promise: everything at just the push of a button!
More and more steam wands should be able to function simply by putting a milk pitcher underneath. This is the case with the Siemens EQ 3, for example. But perfect microfoam is only produced when you grapple with the stretching and rolling phases, the temperature change and correct hand movements.
That’s only to be expected because “real” professional portafilter machines, with a permanent water connection and the corresponding technology at an expensive price, play in a completely different league.
That doesn’t mean you can’t produce good milk foam with super-automatic steam wands. You’ll just need a lot more practice and patience and should always keep the water tank filled up, so you don’t have to interrupt foam preparation half-way through.
It’s worthwhile purchasing a particularly small and easy to handle pitcher made of metal, because this allows you to get more out of the radius of action and hit the right angle despite having little space.
When foaming milk with a steam wand, it’s all the more important that the milk comes from the refrigerator. That’s because you need some time to build the microfoam up without the milk becoming burnt.
Also essential are a clean pitcher and a thermometer, so as not miss the ideal time to turn off the machine. Professionals do the “hand test” and will at some point see that the foam is ready. Until then, a thermometer will make your life easier.
Once you have the right equipment, the name of the game is practice. I can’t remove that step for you entirely, but can at least give you a few basic tips:
Above all, you can determine whether you’re doing a good job from the sound:
If its even and quiet, the foam will be even too. Spluttering and noise indicate that you’ve pulled the outlet nozzle too far out or that the milk is already scalding.
A good trick to bring calm to the situation is to keep the steam wand briefly below the surface of the milk at the beginning and to then let the nozzle “tear” very slightly at the surface. It should then go back down to the bottom of the pitcher.
I recommend you watch the various YouTube tutorials available on the subject and familiarize yourself with your particular model of super-automatic machine or espresso maker.
There’s also one hard-and-fast rule when frothing milk with steam wands: hygiene is crucial!
Due to my workload, I often shamefully neglect your awesome comments and questions. I’m so sorry! But that’s also why I’ve started introducing FAQ sections in all categories, where I can gather together and answer the most common and/or interesting questions posed by readers.
I’ll continue to gradually expand these sections and otherwise ask for your patience if it takes some time to get back with an answer. If you need answers urgently, I can recommend our active Coffeeness Community on Facebook too (in both English and German).
To give yourself time for the reaction to take place. The longer it takes for the milk to reach its “transition point”, the steadier and calmer you can go about making the foam. In the case of the automatic systems in coffee machines, it’s mainly to prevent the milk from burning.
For one Coffeeness reader, it was particularly important that I emphasis again:
If your milk becomes too hot, not only will it no longer taste good, but you won’t manage to produce a stable milk foam with it either! At temperatures above 70 degrees Celsius (158°F), the quality of foam goes rapidly downhill.
This question comes from the comments section and illustrates a phenomenon that many who prepare milk foam and coffee completely separately are familiar with.
Ingrid, for example, mentions that she uses an automatic milk frother. That would have been my guess too, because many foams made with automatic whisks “melt” as soon as they meet coffee.
I bet Ingrid uses a spoon to decant the foam. As a result, a small portion of foam hits the metal, cools down and is already colder than the coffee. If this foam then meets hot coffee, the foam structure really does melt because the temperature shock changes the molecular cohesion.
This happens with super-automatic machines or the milk foam made with steam wands too – but at the same time, in these cases, you’re dealing with a lot more foam and the temperature differences are compensated faster, which prevents “melting”.
Furthermore, the foam from a milk frother is not quite as stable as the foam made with methods utilizing steam. This means that the structure collapses faster. I also think that in the case of espresso made in an espresso maker, because it doesn’t have a crema (i.e. its own layer of foam), the surface tensions differ. I could be wrong however.
Definitely protein. While, of course, fat also plays a role in the structure formation of milk foam, it’s the protein molecules that are converted and rearranged. Fat plays a main role as a flavor carrier and has a decisive influence on creamy texture.
Optimal protein content is based on the standard of whole milk and is thus between 3 and 4 percent.
The cold foam setting is practically standard on all automatic milk frothers and can only be found on these devices. Otherwise, with all other foaming methods, heat comes into play – super-automatic espresso machines can’t therefore conjure up cold milk foam.
I don’t know whether you “need” it, but it is an exciting addition to cold brew or in cold soups or desserts.
One user, Kunigunde, tried it out and says it works. That’s because manual milk frothers and French presses are in essence very similar. She was “lucky” however, because a French press that deserves its name usually doesn’t allow you to freely maneuver it up and down like that.
The nets and screens are constructed differently too. But if it works for you, why not?!
Science and personal preference come together here: on the one hand, you have little control over the temperature of the milk during microwaving. On the other hand, microwaving is the fastest way to (further) denature the milk.
I can understand why many of you prefer to take the short cut, but heating the milk slowly in a pot will lay a much better foundation for a stable, tasty foam.
The main differences lie in the stability and quality of the foam, which come down to the different physics involved in the foaming process. Or straight to the point: both super-automatic machines and wands utilize steam, while electric whisks only whip the surface of the milk – without using pressure or anything.
That’s why milk foam made with a magic wand is also very unstable and, because the whisk doesn’t come into contact with the entire milk volume equally, it usually looks like bath foam. An initial remedy is to transfer the hot milk into a smaller pitcher.
Now it’s over to you …
Of course, I still very much look forward to every new comment and promise your questions will find their way into the FAQ section in good time or be answered directly. Let’s hear from you!