Is it time to stop steaming milk for coffee?
Ben Mitchell speaks with German barista champion and judge Nicole Battefeld-Montgomery about the art of steaming milk for coffee – and why it could be about to change.
When the first steam wand was invented in the early 1990s, it immediately transformed a simple cup of coffee into a work of art. Designed to inject pressured air into milk at high temperatures, it soon became the key to creating some of the world’s most popular espresso-based drinks, from cappuccinos to flat whites.
Steam wands work on a relatively basic premise: they introduce air into the milk, while unwinding its inherent proteins. This process begins at around 60-65°C. The hydrophobic side of the milk proteins clings to the air bubbles, while the hydrophilic side holds the water close, creating a protective jacket around the air and capturing it within the liquid. This results in a light, airy, and velvety texture.
By submerging the steam wand and positioning it slightly off-centre, a whirlpool motion is created, forcing the air to stir into the milk and whisking larger air bubbles into microfoam – the smoothly textured milk used to pour latte art.
At the same time, lactose breaks down into simpler sugars, making the milk taste sweeter, and balancing the flavour profile of the final beverage with the nutty, chocolatey, or stone fruit flavours of espresso.
Today, steamed milk is a staple in almost every coffee shop around the globe, providing a warm, creamy, frothy texture that enhances the overall coffee-drinking experience. However, while they remain popular, they are not without their flaws. And in recent years, a clever team of innovators have hit on new ways to create milk foam that may make put the steam wand out of business.
The problems with steaming milk for coffee
Steaming milk for coffee is a delicate art, demanding an intricate set of skills that must work in unison. Getting the texture and temperature of milk just right can take months of training, and even then, it’s very easy to make mistakes. Adding too much air or overheating the milk can very quickly lead to disappointing results.
According to Nicole Battefeld-Montgomery, a champion barista and winner of both the German Barista and Brewers Cup championships, steaming milk for coffee is a complex process that requires mastery of a range of skills.
“Beginners often find steaming milk to be the most mysterious part of the coffee-making process, as it requires a set of skills that work together,” she says. “Motion skills, temperature skills to feel the correct temperature, and the ability to listen to the milk as you can hear if milk gets steamed wrong or too hot. Perfectly steaming milk for coffee usually takes a lot of practice.”
Overheating the milk can also lead to denaturation, a process where proteins lose their initial structure, resulting in fewer proteins being available to stabilise the foam. Once the temperature reaches beyond 65°C, sugars in the milk break down further, and negative flavour characteristics begin to take over, such as a burnt oatmeal taste.
What’s more, when temperatures exceed 70°C, the milk can burn your tongue and damage your taste buds, rendering it difficult to taste anything.
Using steam to heat milk also adds moisture, which dilutes the milk and alters the final texture. As a result, a pitcher of milk being steamed can increase in mass by 10-15%, as the steam condenses into water within the milk. It’s vital not to re-steam milk, as this can cause further breakdown of the sugars and proteins, while also introducing more water into the milk.
Finding a better way to froth milk is no easy task. The process has remained fairly untouched for more than a century, with new inventions typically just tweaking the formula rather than transforming it.
However, Milan-based espresso machine manufacturer Heylo Coffee recently hit on a technique that could change steaming milk for coffee forever.
Its “milk module” uses technology that froths milk to the same quality as a steam wand without the use of steam. The aerated liquid is passed through a venturi system, which froths the milk by incorporating air into the liquid.
“We inject air into the milk with a proportional air valve before heating it,” says Heylo’s chief commercial officer, Jaime Gamoneda Larripa. “Depending on the texture we want to get from the milk module, we can work with different air levels to give more or less thickness to the milk.
“From our testing, it gives more density to the milk and so better quality of milk foam, and allows us to deliver cold milk foam’, Jaime says. This is a great function for babycinos and iced drinks.
Frothed milk then passes through two induction coils: one to heat the milk gently, the other to bring it up to the target temperature. The milk is then ready to be dispensed into the pitcher.
When the milk has finished dispensing, water is pushed through the coils to clean out the system with a 0.5-0.7% contamination rate.
This means Heylo’s milk module can run two milks. For example, dairy milk can be served alongside oat – an advantage for cafés with less experienced baristas, as steaming non-dairy milks often proves to be more difficult. Although the process takes a little longer than steam wands, Jaime explains that it helps protect the milk, whether dairy or non-dairy.
“The entire process of delivering 200ml takes 27 seconds, depending on the foam level, milk temperature, and type of milk,” he says. “We prefer to take a little longer compared to our competitors because we prefer to gently heat the milk up.
“This way, we preserve the milk proteins so they don’t break down, and we don’t burn the milk sugars. Thanks to that, we retain as much flavour as possible in the milk. Moreover, we are sure to avoid all sediments from burnt milk that can damage our milk circuit.”
With so many advantages over steam wands, however, the question then becomes whether baristas are ready to accept the change. But as someone who has competed with traditional steamed milk, Nicole says she is ready to back any innovation if it reduces the impact of human error.
“Taking away the moisture from steaming helps create a smoother texture with a more velvety mouthfeel,” she says. “I am a fan of automation and erasing human error from any step of the coffee-making process.”