May 29, 2019

Roasting For Sweetness, Decaf & Otherwise: A Practical Guide


Sweetness is one of the universally appreciated characteristics of a good cup of coffee. In fact, it’s the common denominator of just about all roasting and preparation styles. Whether you prefer bright, acid-forward, light roasts or darker, full-bodied coffees, developing and highlighting sweetness is key to achieving a balanced, enjoyable cup.

The same goes for decaffeinated coffees. Now, there are some adjustments that need to be made when roasting decaf coffees. However, there’s nothing stopping your decaf roasts from having just as much delicious sweetness as the rest of your lineup.

Let’s look at some of the factors that influence sweetness in the cup, discuss some practical roasting tips for highlighting sweetness, and examine the changes that need to be made when roasting decaf.

Lee este artículo en español Guía de Tueste: Resaltar el Dulzor en Cafés Con y Sin Cafeína

The last moments of the roast. Credit: CaféLab

What Is Sweetness?

When it comes to sweet flavors in coffee, we are generally speaking about the sugar-browning category: nutty, caramelly, and chocolatey. Yet what causes these flavors?

Let’s get scientific for a moment: proteins and carbohydrates in the green coffee break down during the roast process into caramelized sugars and amino acid complexes. These are responsible for giving coffee its sweetness.

The carbohydrates, in particular, make up over a third of the soluble chemical compounds that contribute to a coffee’s taste. This is why sweetness can be found across a range of roast profiles. While a cupping roast is almost entirely free of bitter notes, and a dark roast absent of acidity, both will have sweetness to some degree.

However, it’s not all about sweetness. There are five basic tastes that the human tongue can detect: sweet, sour, salty, bitter, and umami. None of these exists in isolation; instead, they combine in different ratios in what is called modulation. Focus on one to the detriment of the others and you might have a coffee that has plenty of sweetness but is absent of acidity, dull, and flat: the dreaded “baked” profile.

Additionally, in certain modulating combinations, the presence of one taste sensation can actually increase the perception of another. For example, salts or acids can increase the sweetness of sweet taste sensations.

So, instead of focusing on developing maximum sweetness (converting the most carbohydrates into caramelized sugars possible), it makes more sense to talk about highlighting sweetness in relation to the other tastes and flavors present in the cup.

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Sweet-associated flavors congregate in the upper-left quadrant of the flavor wheel. Credit: CaféLab

Roasting For Sweetness: Practical Tips

What are the important elements to consider when roasting for sweetness? I spoke with several knowledgeable European roasters, who all agreed on three things: green bean selection, pre-first-crack development, and post-crack development.

  • Green Bean Selection

The quality and characteristics of the green coffee are the starting point. Of course, a better-quality bean is going to have more potential for sweetness. As Dimitri Grodwohl, roaster at Bordeaux roastery Oven Heaven, sums up: “a roaster cannot magically create sweetness if the bean quality doesn’t allow it.”

Another important consideration is the bean’s acidity. As mentioned earlier, sweet and sour tastes can mingle and modulate each other in a variety of interesting ways. However, if you’re dealing with an extremely bright or harsh acidity, you’ll need to roast through that in order to find a more ideal balance of sweetness.

There are coffees that are sometimes overlooked in the third wave quest for vibrant, exotic acid profiles. Yet these may be ideal for roasters interested in exploring complex sweet-bitter combinations.

Ignasi Oller, Import Manager at Spanish coffee roaster Cafés Pont, avoids coffees grown above 1,800 when selecting coffees for sweetness. He prefers to work with coffees between 800 and 1,300 m.a.s.l., such as those from Sul de Minas, Brazil.

Coffees highlighting sweetness can go beyond simple nut, caramel, and chocolate notes into the territory of nut butter, raw sugar, dark chocolate, and cacao, as well as aromatic spices like cloves and beyond. These descriptions are evocative in their own right. What’s more, the flavors they correspond to tend to be highly satisfying for a wide range of drinkers.

Green, decaffeinated Colombian Supremo coffee in the roastery. Credit: CaféLab

  • Pre-Crack Development

When it comes to roasting these coffees, the key is finding that balance between sweet, sour, and bitter. Chemical reactions begin at the end of the drying phase, when the coffee begins to yellow, indicating the beginning of caramelization and Maillard reactions. This phase is critical for converting the crude materials in the green bean into the compounds that will come out as sweetness in the cup.

In an SCA article, Rob Hoos writes that the “Maillard reaction affects the weightiness of the coffee and thus the body, as well as the complexity of tones in the medium and low end of the flavor spectrum (think ‘roasted, spices, nutty/cocoa).’”

There are good two points to note here: the development of those sugar-browning flavors associated with sweetness and the development of body, which complements sweetness well. (Just ask yourself which sounds sweeter: milk chocolate or creamy milk chocolate?)

So, adequate development time between the beginning of the yellowing phase and up to first crack is important to caramelize sugars. Additionally, a longer time spent here will contribute to the complexity of sugar-browning flavors, as well as a heavier cup. In turn, this tends to contribute to the perception of sweetness.

At the same time, too much time here can mute the brightness of the cup, leaving the sweetness smothered. Mike Strumpf, Director of Coffee at Swiss Water Decaffeinated Coffee Inc, warns that “to create the right flavor balance to emphasize sweetness, we need to not over caramelize.”

  • Post-Crack Development

After first crack, several chemical events happen quite rapidly. The organic acids still present soon burn out and bitter notes begin to appear. If you are aiming for a sweet-sour combination, your goal is to mellow out the acidity through development while not going too dark.

Dimitri says, “It is indeed necessary to degrade a few compounds that would give vegetal and dry taste to the cup and let the natural sweetness express itself. Too much time after first crack would actually replace these vegetal tones with burnt sugar bitterness.”

Just before second crack, all sour-contributing acids are pretty much roasted out of the cup. Sweetness and bitterness are now the predominant flavors. For Ignasi, the sweetest profiles are “without a doubt” those that arrive to “second crack, and almost half a minute more.”

How long a roast should last will depend on the coffee and its intended market. However, skilfully executed, longer roasts can produce a rich and complex sweetness. The key is to drop the coffee before ashy, burnt, or smoky flavors take over.

Dimitri Grodwohl checks the development of a roast. Credit: Oven Heaven

Decaf: How Should You Change Your Roasting Method?

So, how does all this translate into roasting decaffeinated coffees? Mike explains that the decaffeination process involves hydrating the coffee in order to extract the caffeine, then drying it again. He emphasizes that, at Swiss Water Decaffeinated Coffee Inc, “we try and do everything as gently as we can,” and that, with care, it’s possible to decaffeinate coffee without compromising its flavor potential. But ultimately, the cellular structure of the coffee has been changed and so it will roast differently.

This means that, for the roast process leading up to first crack, a gentler approach is called for. Mike says that “decaf will follow a similar temperature curve when you’re roasting, but the rate is a bit different because the coffee’s been processed… so the way the coffee holds heat is different.”

Freshly roasted decaf coffee. Credit: CaféLab

Dimitri agrees, saying that both batch size and charge time may need to be adjusted for decaf. “We usually roast our decaf with a gentle profile with lower maximum ROR than usual and a smooth defending ROR from maximum ROR to the end of the roast,” he adds.

Fran Bernal, founder and CEO of CaféLab in Spain, tells me that “there are two keys when it comes to maximizing sweetness in the roast of a decaf coffee: lengthening the time and lowering the temperature.” The goal, he says, is achieving a “lighter caramelization up to first crack.”

At first crack, decaf coffees tend to behave quite differently from regular coffees. Mike says, “Once it goes exothermic, the development’s different. The coffee won’t hold energy quite as tight.”

The particular cellular characteristics of decaf coffee can pose a challenge to roasters. On the one hand, it’s easy for the roast to run away and overdevelop. On the other hand, Mike points out that “because it doesn’t hold heat as much, you can’t just drop your heat and let it coast like you would with a non-decaf.”

Mike compares post-first-crack handling of a decaf roast to walking a tightrope. “You have to continue to give it heat but not too much,” he stresses.

So, how can a roaster handle this? Fran opts for a shorter-than-average development time, dropping his roasts around thirty seconds after first crack. He also tells me that a colleague of his further slows her roast down before going into first crack, resulting in a slower, more controlled momentum.  

Cupping decaf and regular coffees. Credit: CaféLab

The roast profile you develop will depend on your specific coffee and your roaster. But there are few attributes as universally loved as sweetness. The good news is that it’s possible to achieve this in most coffees – decaf included.

So, look for quality green beans. Ensure adequate but not excessive caramelization leading up to first crack. And manage the roast skillfully after first crack to arrive at the right balance of sweetness, sourness, and bitterness. This is how you get deliciously sweet coffee, roast after roast.

Enjoyed this? Read What Happens During Coffee Roasting: The Chemical Changes

Feature photo: Roasting coffee at CaféLab, Murcia, Spain. Feature photo credit: CaféLab

Please note: This article has been sponsored by Swiss Water Decaffeinated Coffee Inc.  

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