October 9, 2019

How to Adjust Your Brewing Recipe For Coffee Roast Level

Brewing great coffee means balancing many variables. As well as considering the brewing method and ratio of coffee to water, you should keep your roast profile in mind.

Perhaps you have a go-to recipe for making an excellent V60, but if you change from a light roast to medium, you may have to rethink it. Read on for some insights into how to adjust for coffee roast profile.

Lee este artículo en español Cómo Preparar tu Café Según su Grado de Tueste

Coffee beans cooling down after being roasted. Credit:Katja S. Verhoeven

How Coffee Roast Profiles Vary

Roasted coffee is generally divided into light, medium, and dark, and you likely have a go-to roast profile that you prefer for home brewing. But what’s the real difference among roast profiles? 

There’s no industry standard for what is defined as light, medium, or dark, and roasters often use their own names for different profiles. But in general, light roasts retain more of the flavours of the coffee bean and this profile can emphasise floral and citrus notes.  As coffee is roasted darker, these subtle flavours can be overwhelmed by more chocolatey, nutty sensations. If a coffee is roasted very dark, it can become bitter.

Flavour isn’t the only difference among roast profiles. As coffee is exposed to more heat in a longer or hotter roast, it becomes more porous, and therefore more soluble. This is part of why medium or dark roasted coffees are usually used to make espresso – because there’s only a short window of time for extraction, a roast that is more soluble will work better than a light roast.

Learn more in Roasting For Filter Coffee vs. For Espresso

Roasted coffee beans in a bag. 

Why Should You Brew Light & Dark Roasts Differently?

A good cup of coffee is dependant on the right level of extraction. When roasted and ground coffee beans are introduced to water, a number of chemical compounds are extracted. The compounds responsible for fruity notes and acidity are extracted first. Then, sugars are extracted, producing sweet flavours. The compounds responsible for bitterness are extracted later. If a coffee is under-extracted, it can taste sour because the sugars haven’t had chance to enter the brew. If it’s over-extracted, it can be too bitter.

Because light roasts are less porous than darker ones, the compounds will extract more slowly. This is why light roasts are often brewed using a slow method such as a pour over – the beans have more time in contact with the water than in a quick brewing method such as espresso. It also means that if you were to use the exact same recipe with the same coffee roasted to two different profiles, you’d experience different flavours and mouthfeel.

Sam Koh is a barista and the founder of Kaffiend Brews, a coffee shop in Singapore. She tells me that “a light roasted coffee gives you more intricate notes, and these can be best accentuated through a slower brew such as a pour over. A darker roast may not shine through as well through a slower brew due to the rate of extraction, which could cause more acrid or bitter notes to be extracted.”

You may also like Everything You Need to Know to Brew Great Pour Over Coffee

Roasted beans in a cup. 

How to Tweak Your Recipe For a Different Roast Profile

So, you have your pour over recipe figured out but want to try new beans. How can you adjust your method to fit a different roast profile? To compensate for differences in porosity and solubility, you can change a few variables.

Grind Size

When coffee is ground finer, it has more surface exposure. This means that extraction will happen more quickly. So if you’re used to brewing with a medium roast and are trying out a light roast, grind it a little finer. Likewise, if you usually use light-roasted beans, but are going darker, use a coarser grind size.

Marlous Van Putten is a store manager and barista with Dutch coffee shop chain Coffeecompany. She says, “I personally also always grind my beans finer if they’re a lighter roast and dark roasts on the coarser side. This is because dark roast tends to be more bitter in flavour to begin with, so a longer contact time between water and coffee would result in over extraction.”

Find out more in How Grind Size Can Help You Brew Better-Tasting Coffee

Freshly ground coffee beans are poured into a Chemex. 

Water Temperature

There is no one correct temperature for brewing coffee (although there are recommended ranges, such as the SCA’s suggestion of 195–205 °F/90–96°C). But the hotter the water used, the faster the extraction. Some compounds will never be extracted at very low temperatures, which is why cold brew tends to be very mellow and sweet but can lack any bitterness to balance out other notes.

Consider water temperature as one more factor you can adjust to bring out your preferred flavours in your coffee. If you’re using a dark roast, you may want to lower the temperature of the water to avoid over-extraction and reduce the chance of bitter flavours. If you’re using a lighter roast than usual, using hotter water will help speed up extraction a little.

Marlous says, “The normal rule is lower temperatures for darker roasts and higher temperatures for lighter roasts. Side note to this is that darker roast probably won’t taste good if it’s made with water at high temperatures, whereas lighter roast can taste good made with lower temperatures.”

You may also like How to Limit Water Temperature Variation for Better Coffee

Coffee brews in a Chemex. 

Brewing Time

The longer the coffee is exposed to water, the more time there is for extraction to take place. Keep this in mind when choosing a brewing method – as discussed, espresso only has a very short opportunity to extract so a light roast might not be the best choice. 

Within each brewing method, you can also tweak your technique to provide a longer or shorter brewing time. For example, by pouring water more slowly when making filter coffee, or by letting a French press sit for longer before serving.

Sam says, “For coffee that is of a lighter roast, I find that letting it steep longer before first drip gives the coffee more time to exude more complex and intricate flavors.” 

Coffee being brewed on a Chemex. 

Other Factors to Keep in Mind

It can be interesting to use different roast profiles with various grind sizes, water temperature, and brewing time and see how these variables impact your cup. But you should also consider what features can change accidentally.

As coffee beans age, flavour degrades. Oxidation and degassing cause the coffee to lose the important oils and compounds that contribute to body, aroma, and flavour. It’s generally recommended to use roasted coffee beans within two weeks after buying them, to store them in air- and light-tight containers, and to grind them as needed to avoid even faster oxidation.

Learn more in How to Store Roasted Coffee & Prolong Its Freshness

Coffee beans being weighed on a scale before brewing. 

If you know your beans are a little old, you can adjust the recipe to compensate. By grinding light roasts finer, you’ll increase the surface area and the rate of extraction, which should liven up slightly stale beans.

Old dark roasted beans can be very porous and therefore very soluble. Grinding a little coarser or using cooler water will slow down extraction and avoid the brew becoming too bitter.

Marlous recommends keeping in mind a few other factors that may make or break your end result. “What kind of water you use, the freshness of the beans, the quality of the beans, the cleanness of your equipment,” she says. “You have to be aware that every step of the process has an effect on the outcome of the cup.”

Freshly ground coffee. Credit: Noora Alhammadi

Perhaps you have a recipe that you’ve developed through controlled experiments or trial and error. But when you try a new roast profile or beans from a different roaster, it’s time to rethink your method. By understanding how variables including grind size, brewing time, and water temperature can be adjusted, you can get great results with every roast profile.

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