Barista trainer at Cornico Coffee and SCA AST, Millie Gay, speaks with Tanya Nanetti about how the roast profile you use on a superautomatic coffee machine can make all the difference.

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For centuries, consumers have depended on either their own hands or those of a skilled professional to brew their morning coffee. Gradually, innovation has streamlined and perfected the espresso brewing process, to such an extent that in many cases, it’s now fully automated.

Enter the superautomatic espresso machine. This highly advanced piece of equipment uses dozens of innovative technologies to precisely grind, tamp, and brew high-quality coffee at the touch of a button. 

Although in some cases, the process is truly that simple, some modern “superautomatics” can be programmed down to the last variable. Baristas and prosumers can set the specific water temperatures, the volume of brewing water, the length of pre-infusion, and the total brewing time.

Additionally, most of these superautomatic espresso machines – like the Carimali SilverAce – also have automatic milk frothers that help deliver the perfect latte, cappuccino, or any number of milk-based drinks.

Typically, these machines are ideal for offices, hotel breakfast services, and convenience stores. However, they’re increasingly being adopted in coffee shops and home settings, especially as businesses come to realise that they aren’t here to replace baristas, but to augment their workflow. 

When it needs to, the machine does all the work, but the very best espresso still requires other considerations. Naturally, one concern is the quality of the coffee used. This comes down to several factors, including origin and processing method. However, there is one variable that’s in the hands of the brewer: roast profile.

Businesses generally stick to darker roasts for espresso applications, but it’s a choice that can be altered when needed. And, because superautomatics are so programmable, it’s possible that some roast profiles work better with them than others.

Why does roast profile matter?

Each barista and consumer has their own preferences when it comes to roast profile. The vast majority of the world’s coffee is enjoyed as a dark roast, especially when it comes to Italian-style espresso.

However, by adjusting the roast level, different characteristics of a coffee can be emphasised. Some coffees respond better to lighter roasts, and vice-versa.

Fundamentally, a coffee roast level is determined by how long the coffee has been roasted. Using carefully calibrated “roast curves”, professional roasters are able to manipulate the characteristics of coffee beans as they’re heated.

These curves are defined by a set of parameters related to the roasting process, including charge temperature, roasting temperature, airflow, and roast time. The resulting roast levels exist on a continuum and are typically classified as either light, medium, or dark roast.

Millie Gay is an Authorised Specialty Coffee Association Trainer and a barista trainer at Cornico Coffee. She elaborated on the differences between these three main styles.

“With a darker roasted coffee, the origin and processing methods tend to get lost, creating a flavour that only cuts through milk,” she explains. “In lighter roasts, the more delicate flavour characteristics are much more easily identifiable.”

She adds that sarker roasts tend to lack sweetness and acidity and are higher in bitterness, possessing “that distinctive roast flavour”.

“The coffee bean density also decreases as you continue roasting,” she notes. “You will also find that darker roasts tend to have a heavier body than a lighter roast when it comes to drinking them.”

Density is incredibly important, as it’s one of the variables that dictates a coffee’s solubility. While flavours and aromas are certainly important, solubility and density can also differ profoundly between a light and a dark roast.

“Lighter roasted coffee is less soluble, has a higher density, and a lower extraction yield,” Millie explains. “Darker roasts, on the other hand, are more soluble, with a lower density and a higher extraction yield, as it is easier to get [extract] solubles from each bean.”

Effectively, a darker coffee tends to be more soluble, resulting in a heavier body in the cup. Its flavours lose all their acidity, amplifying sweetness, smoothness, and bitterness, instead.

Most consumers are familiar with this style of espresso. It’s important for businesses to consider this when selecting a roast profile, but it doesn’t necessarily mean it’s perfect for superautomatics.

So, which roast profile is best?

It’s safe to say that for businesses catering to a diverse clientele base, a darker roast is probably preferable. However, to properly extract a dark roast, it’s key is to be gentle with the recipe, as over-extraction is incredibly easy.

More specifically, this means lowering the brew temperature and reducing the brewing time. If done correctly, this will help reduce bitterness and leave the coffee with a little sweetness and smoothness.

This is one of the reasons why superautomatic espresso machines usually work best with darker coffee: the machine’s quick extraction time requires the coffee to be more soluble, and at the same time, the short brewing time ensures there’s still some sweetness left behind. This kind of brew is perfect for both Americano-style black coffees and milk-based drinks like flat whites and lattes.

“There is a strong argument that a darker roast is more suitable for milky drinks,” Millie explains. “If you have an intensely floral light roast, it will be utterly lost in a latte.”

A darker roast that tends to contain more bitter flavours – and fewer delicate flavour notes – will even out and match well with the sweetness of the milk.

“It cuts through the milk, meaning that you still taste coffee rather than it being utterly washed out and lost,” she adds.

However, while it’s almost ideal for superautomatic machines, dark roasted coffee tends to have a greater presence of oils on the surface of the bean, as a result of the longer roasting process. These oils can cling to a machine’s components, potentially ruining them. Furthermore, they can add a rancid taste to the brewed coffee.

To avoid these problems, coffee machines must be subjected to proper maintenance. Modern superautomatics like the Carimali SilverAce are able to self-clean to mitigate this issue, but there’s also another solution: what if, instead, a lighter, less oily roast is used?

If the machine is capable of brewing filter coffee, lighter beans would indeed be useful. Furthermore, if top-end superautomatics are used with the right knowledge, they can brew beautiful light roast espresso, too.

Ultimately, though, when milk-based drinks are high in demand, darker roasts remain the ideal, straightforward choice.