I began drinking coffee at the uninformed age of 18 with the assumption that all coffee is pretty much the same: hot, bitter, and super useful for staying awake. Since I was a poor college kid, my favorite cup was always the one I got for free. Coffee was a commodity for me, and in one sense, I was right. Barring crude oil, coffee is the biggest commodity in the world, and for many in the industry, the best coffee is the cheapest coffee.
Then one day, a couple of years into college, I got a job in a coffee shop that specialized in single-origin varieties of Fair Trade beans. I had to learn the taste of them so I could describe flavors and aromas to customers. I still remember that first sip of freshly ground, freshly brewed Fair Trade Organic Sumatra. That’s when I stopped viewing coffee as a commodity. All coffee is not the same! Curious, I decided to read up on the variables affecting the flavor of the coffee in my cup. There were a lot!
The two widely cultivated species of coffee tree are Coffea arabica, which makes up 70 percent of worldwide coffee production, and Coffea canephora, which makes up the remaining 30 percent.
Coffea arabica plants can be divided into several varieties that exist thanks to selective breeding or natural selection. Famous C. arabica varieties include Colombian, Ethiopian, Kona, Sumatra, Typica, Mocha, and Bourbon, among others. C. canephora varieties, on the other hand, number just two; of these, Robusta is the only widely cultivated variety. C. arabica varieties have better diversity, aroma, and flavor, while C. canephora (Robusta) is easier to grow and more resistant to disease. Almost all specialty coffees are C. arabica varieties. C. canephora is mainly used in instant blends.
The coffee tree hails from Ethiopia and thus is a tropical plant. Around the world, coffee trees grow in what’s known as the Bean Belt or the Coffee Belt, a strip of land that stretches 25 degrees north and 30 degrees south of the Equator.
Geography, especially altitude, strongly influences a coffee’s aroma and flavor. In the tropics, high elevations of 4,000 to 6,000 feet provide the best growing conditions, because these higher altitudes keep coffee trees in their ideal temperature range of 60° to 70° F. This range prolongs bean maturation time and facilitates complex sugar development for deeper and more interesting flavor. Better drainage at higher elevations also allows coffee trees to concentrate flavor in their beans.
The best C. arabica coffee beans are grown in extremely fertile, often volcanic soil. Proper nutrition allows plants to develop the best-tasting beans, and soil quality helps determine the quality of a cultivated coffee bean. There are two basic ways of growing coffee trees: shade cultivation and sun cultivation.
Shade cultivation is a traditional method that mimics the way coffee grows naturally. Coffee trees are grown as an understory crop beneath local forest trees. This diversity supplies natural nutrients and protects against pests. In addition, farmers use techniques such as pulp composting and crop rotation to enhance the soil. Another advantage of this method, besides the fostering of tastier beans, is the preservation of natural bird habitats.
In the 1970s and 80s, shade cultivation gave way to sun cultivation as part of the general industrialization of agriculture. For sun cultivation, the land is cleared to make way for rows of coffee trees grown in full sun, with heavy fertilizer and pesticide inputs. Sun cultivation increases yields but also degrades waterways, promotes soil erosion, and eradicates natural bird habitats. In fact, wide deforestation led the Smithsonian Institute to name industrial coffee production a major threat to songbirds.
Coffee beans are not really beans. We call them beans because they resemble beans, but they are actually seeds. They’re the pits found inside coffee cherries (also called coffee berries), which are the red or purple fruit of the coffee tree. After the coffee cherries are picked, they must be processed to separate the seeds from the pulpy fruit.
Two methods are used to process coffee berries. In wet processing, the cherry flesh is separated from the seeds and then the seeds are soaked in water for about two days to dissolve any remaining residue. In the other method, dry processing, the coffee cherries are spread out in the sun on concrete or brick for two to three weeks for drying. Dry processing is simpler and cheaper and is used for lower quality beans. Wet processing creates fermented beans that are tastier and more distinctive, but it also generates a lot of waste water.
During roasting, coffee beans lose water and carbon dioxide and develop their characteristic color, aroma, and flavor. The chemical transformation that gives roasted beans their beautiful dark color is common in the cooking world and is known as the Maillard reaction. It occurs at 284° to 329° F and is a reaction between carbohydrates and amino acids found in foods. It’s the dark skin of your salted pretzel, the sear on your steak, and the crisp toasted outsides of your toasted marshmallow.
Roasting induces other changes as well. Aromatic oils and acids weaken, which also alters the flavor. And at 400° F, caffeol becomes more prominent. Caffeol, or coffee oil, is a complicated mix of many different volatile compounds and is responsible for coffee’s amazing aroma.
Thus the degree of roasting dramatically affects the flavor and aroma of coffee beans. Toward the lighter end, the roasted coffee exhibits more of its origin character—the bean’s flavor due to its variety, altitude, soil content, microclimate, and processing. Toward the darker end, the roasted coffee exhibits more of its roasting process, until the roast flavor is so strong that it can be difficult to taste any origin character at all. Lighter roasts are more acidic, or “bright,” and may taste bready, woody, or grainlike. Darker roasts are less acidic and tend to be fuller bodied. They may taste bittersweet or even burnt.
The goal of a good roast is to give the coffee bean its most complete and complex flavor and aroma, and the best roast profile is the one that best matches a coffee bean’s origin characteristics.
Given all these variables, it’s easy to see why there is such a range in the flavor, aroma, and complexity of coffee roasts. All coffee is not the same. So let’s all have another cup!
Jocelyn and Tim Engman are the proprietors of Pickle Creek Herbs in Fairfield.