Milk Foam: Preparation, Tools and the Right Milk

Funnily enough, in most articles I only ever talk about plain coffee – preferably from a coffee dripper, but gladly also from a super-automatic espresso machine or portafilter.

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.

The 'Complex System of Milk': How Does Milk Foam Form?

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

• About 87 percent water
• About 3 percent fat
• About 3 percent proteins
• About 5 percent lactose

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.

This fact provides us a first clue of how to answer the ‘best milk for milk foam’ question: fat definitely plays a role as a “stabilizer”. If it’s missing, the foam has a harder time asserting itself against gravity and the chemical/physical nature of minimum energy. But its importance is nowhere near as great as we might imagine.

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.

The Best Milk For Milk Foam: Forget the Science!

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:

• Fresh milk is pasteurized only (using a temperature range of 72 to 75 degrees Celsius (162-167 °F)) and retains almost all of its original milk components in the intended chemical
• Full fat means more creaminess, stability and taste

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.

Whole Milk: The Standard Classic, With No Ifs and Buts

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.

Raw or Non-Pasteurized Milk: It Really Doesn't Get Any Fresher

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.

Logically speaking, raw milk would be an unbeatable choice for milk foam because it hasn’t been treated and contains up to five percent fat. The problem is, however, that this milk doesn’t just contain all the good substances but can carry germs and pathogens too.

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.

Low-Fat and Skim Milk: The Naive Fallacy

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.

Lactose-Free Milk: A Possibility…

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.

Plant-Based Milk Alternatives: Options as Numerous as Grains of Sand on a Beach

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.

I’ve heard lots of good things about foaming with spelt milk, but haven’t yet formed any experience of my own. Can any of you help?

Milk Foaming Techniques: What Works and What Doesn't

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 cappuccinatore or automatic milk foaming systems on super-automatic machines
• The steam wands on super-automatic machines or portafilters
• Electric milk frothers
• Manual milk frothers
• DIY methods

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.

Foaming Milk With Super-Automatic Machines: Push a Button and Voilà Foam

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. Heck, the DeLonghi Eletta Explore even has a cold foam function!

When making milk foam with a super-automatic machine, these important rules apply:

• Always use the freshest milk possible, taken directly from the refrigerator
• Clean the milk foaming system daily
• Flush it through once after each run (whether automatically or indirectly)
• Use only well-filtered milk (alternatives), otherwise the nozzles and tubing will become blocked
• Check whether you can regulate the milk temperature and experiment within the ideal range of below 70 degrees Celsius (158°F).

Foaming Milk With Milk Frothers: Simply Brilliant Under Ideal Conditions

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:

1. Automatic milk frothers with induction heating
2. Electric milk frothers with batteries (aka “magic wands”)
3. Manual milk frothers

All three have their advantages and disadvantages:

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:

• The Philips Senseo Milk Twister delivers great foam, but is comparatively expensive
• The Bodum Latteo is my absolute favorite of all the manual models

You can find more detailed information on milk, the best tricks and the most important devices in the Milk Frother Review guide.

Foaming Milk with Steam Wands: Professional Results That Are Worth the Effort

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.

Steam wands fall into two categories: POWERFUL and not quite so POWERFUL. Inexpensive super-automatic machines such as the evergreen DeLonghi ECAM 22.110 have very short, quite movement-restrictive wands that also pump steam into the milk with relatively little force.

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:

• Always fill the pitcher to about one third full, because you’ll need space for the foam and don’t want to waste milk
• The steam wand should initially almost completely disappear into the pitcher, ideally at an angle
• As soon as it’s switched on, slowly pull the pitcher away from the steam wand in a controlled manner. If done correctly, the desired amount of foam will be achieved before the thermometer has even reached 40 degrees Celsius (104°F)
• In that case, the steam wand should again be guided back to the bottom to provide the correct/desired milk temperature

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!

1. Before frothing milk, briefly switch the steam wand on. By doing so you’ll free any milk residue from the nozzles.
2. After foaming, repeat this again and IMMEDIATELY wipe the milk residue off  with a rag set aside for this purpose (!).

Milk Foam FAQ: You Ask, Coffeeness Answers

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).

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!