Underdeveloped coffee: It’s not tasty being green

Imagine a combination safe that opens to reveal a different treasure for each combination. Some combinations unlock marvels; others leave you staring at an empty metal box—and there are a myriad different treasures in between. This is the metaphor I like to use for roasting coffee. The fresh, green bean is the magical lockbox, and the skill of the roaster is the combination.
Too often, roasting is reduced to the exterior color of the bean, which, in the case of our locked safe, is a lot like trying to judge the treasure inside by what color it’s painted. The interior of a coffee bean holds flavor complexities that need to be coaxed out. When coffee is roasted to the color of the outside of the bean rather than allowing the interior to reach a similar roast profile, many undesirable taste characteristics come out. These can include corn, grass, stem, wheat, and any other savory bitterness you can imagine might come from biting directly into the plant itself. This greenness is referred to underdevelopment, and it’s become a trend known euphemistically as “minimal impact roasting” that affects the solubility of the coffee—and, of course, the taste.
Roasting simply to minimize roast impact does one thing very well: it allows the roaster to exemplify the regional character of the coffee. By holding firm to this approach, the roaster avoids many opportunities of full, round, and flavorful coffees. I have left many coffee houses that serve these minimal-roast-impact coffees only to have a decidedly unpleasant, long aftertaste disturb my ride to my next destination.

I strive to avoid these green flavors coming through in the cup in favor of rich, sweet chocolate, caramel, and nut flavors. These work to enhance a fruit-dominant character, while lengthening the finish to a full, round, and pleasantly lingering flavor bomb. These roast-driven characteristics are the boon of a well-developed coffee.

Seeing green
Underdeveloped coffee beans can be tricky to spot. While one might intuit that a quick glance would reveal an under-roasted bean, you simply can’t see how well developed a bean is from the outside. Very basically, it’s only the end temperature of a roast that determines its color. Think of it like searing an ahi steak, but instead of locking the good flavors in, you’re sealing in unpleasantness that will lie in wait until it is ground and brewed. You’re also completely locking in many aromatics and even some of the caffeine because of the insolubility of an underdeveloped roast.
So how do you tell if a bean is underdeveloped? Are you grinding one coffee more finely than another of similar color? Struggling to slow down espresso shots? You’re most likely dealing with an underdeveloped coffee. Can’t easily crack open a bean with your fingers? Likely underdeveloped. Can you see a color difference between the exterior and interior of the bean after you do finally crack it open? Most definitely underdeveloped.

Wood-fire roasted to perfection
Roasting to a darker color doesn’t necessarily make the coffee developed, and a light roast doesn’t automatically preclude it from being so. While roasting darker can certainly help with an underdeveloped roast, it often leads to an overdeveloped exterior. Sure, this means that what’s left is nice and soluble, but everything tasty has been cooked off and lost to the roasting process.
My techniques allow the center of the bean to catch up to the exterior a couple of times during the roast, not late in the process when this window has closed. The precise methodology I use has evolved over the years as I’ve grown as a roaster. As the beans roast, sight, smell, and sound help me get a good idea where the beans are in the roasting process. Color only begins to play a larger role as the center of the beans catch up.
I began to recognize the real impact of temperature as my skills developed. Finding points at which it’s best to apply more heat and learning when to ease off are nuanced techniques to say the least, particularly when trying to predict how these early changes will ultimately manifest in the cup. Through modifying my roasts minimally, I’ve developed techniques for maximizing the development of the whole bean, not just the exterior color.
Roast characters are often a great addition to the flavor of a coffee. Imagine having a very fruit-driven coffee with bright, lively acidity. With small modifications to the roast development it is possible to, with a small impact to these desirable traits, add a hint of chocolate tone and reduce the overall acidity for a creamier mouthfeel. By doing this you totally change the depth and feel of the coffee in your cup. This is how I roast.
I understand the desire to allow what’s essentially the terroir of the coffee bean come through in the cup. In the end, the best cup of coffee is the one that you like to drink (supplanted sometimes by the one in closest proximity on a Monday morning). Minimal impact roasting certainly has its place, but I have found that with some coffees the true wonders come through at just slightly more roast impact.