So far, you know two things from this series: Coffee in moderation isn’t terrible for your health, however certain growing techniques may contribute to some pretty heavy impoverishment and ecological decline. And you’re enlightened on how to make good decisions regarding coffee purchases with these issues in mind. But it all comes down to this: Coffee is widely consumed and traded because it’s just so damn tasty. And stimulating. So why is coffee so desirable? What goes into that perfected, piping cup?
A lot, as it turns out. The process to make the inedible and rather bitter coffee berries into those ground, fragrant beans in your morning brew is rather extensive. Provided here is an overview on the art of preparing and roasting raw coffee to what you know and love:
The harvest.
Depending on the specific region and prevailing weather conditions, coffee trees are ripe to harvest over a 6-8 week blossoming period. To guarantee quality control, this portion of the harvest is largely carried out by hand, and is the most expensive and labor intensive. Each coffee berry (aka cherry) yields two flat sided coffee beans buried within a carmine membrane and pulp. Since these coffee beans only make a third of the total cherry amount, the husk, skin and fruit must be removed by two possible processing techniques…
Processing.
Two different processing methods are used to remove the desired beans from the rest of the cherry: wet and dry processing.
Wet processing (for higher quality coffee): Coffee beans are first filtered through water to soak and clean. This also helps separate the ripe berries from accidental unripe berries that make it into the batch. The selected ripe berries are pressed with a roller to scrape away the outer fruit, and further rinsed with water. Some of this removed fruit is actually mixed with
various minerals and made into fertilizer on the side. Once the majority of the skin and fruit pulp are gone, the beans are fermented in a bath for two days to ensure no residual fruit and outer membrane, or mucilage, remains. The fermentation process imparts some of coffee’s characteristic aroma and flavor. After two days the coffee is washed and its outer husk remains. These beans are then dried on racks in the sun for about a week, periodically rotated to promote even drying. Sometimes automatically rotating drying drums are used for larger scale cultivators. Coffee at this stage is known as pergamino, due to its attractive amber color from the husk. At this point coffee is typically passed on from the cultivator to the wholesale distributor or exporter. At last, coffee is mechanically hulled, sorted and graded based on its properties of size and shape. The resultant beans are actually a gorgeous spectrum of colors- greens, blues, to the familiar tans and browns.
Dry processing (for lower quality coffee): Dry processing forgoes the initial step of washing and soaking the beans, and jumps right into sieving the coffee from debris and drying them out in the sun. Hulling coffee occurs via a similar method as with wet processing, but it doubles to remove the fruit and husk in one step. The rest follows the same as with wet processing.
Roasting.
The best part. Sure, the regional growing conditions, fermentation process, and the plant’s genetics play a large role in the wonderful gustatory experience of coffee. But the roasting portion is what brings about that rich brown color and robust aroma we’re familiar with, as well as the coffee’s “texture” and caffeine levels. Green coffee stays fresher much longer than roasted coffee, so most roasting is done at or near a distribution center, when it’s about to hit the shelves. You can order green beans and roast at home (which is wayyyy better, but takes time), allowing you to control the various properties of coffee and give it a longer shelf life. Batches of coffee beans are subjected to temperatures between 370 and 540 °F, anywhere from 3 to 30 minutes. The total amount of roasting time determines the color, density, and caffeine content of the batch (I’ve omitted the details of the actual roasting machines and what heat sources are used, but more information on that can be found here on Wikipedia). Achieving such temperatures actually changes the chemical and physical composition of the coffee beans. Over the roasting period, the coffee’s complex carbohydrates (sugars) begin to caramelize into simple sugars; water is evaporated and the coffee density decreases; and certain aromatic oils break down, while others form and rise to the outer layer to give the bean a shiny color. Caffenol is one such oil formed at temperatures above 392 °F, and is the primary chemical recognized as coffee’s heady aroma and flavor. After roasting, the coffee can be graded according to color (that is, light roast, medium roast, dark roast, etc.). Darker roasts tend to be smoother, sweeter, less fibrous, and more uniform in flavor and texture. Lighter roasts have higher levels of caffeine and have stronger “origin” flavors that are reflective of the bean type and growing conditions.
A useful chart below (From the Wikipedia page for “Coffee Roasting”):
| Roast level | Notes | Surface | Flavor | |
|---|---|---|---|---|
| Light | Cinnamon roast, half city, New England | After several minutes the beans “pop” or “crack” and visibly expand in size. This stage is called first crack. American mass-market roasters typically stop here. | Dry | Lighter-bodied, higher acidity, no obvious roast flavor |
| Medium | Full city, American, regular, breakfast, brown | After a few short minutes the beans reach this roast, which U.S. specialty sellers tend to prefer. | Dry | Sweeter than light roast; more body exhibiting more balance in acid, aroma, and complexity. |
| Full Roast | High, Viennese, Italian Espresso, Continental | After a few more minutes the beans begin popping again, and oils rise to the surface. This is called second crack. | Slightly shiny | Somewhat spicy; complexity is traded for heavier body/mouth-feel. Aromas and flavors of roast become clearly evident. |
| Double Roast | French | After a few more minutes or so the beans begin to smoke. The bean sugars begin to carbonize. | Very oily | Smokey-sweet; light bodied, but quite intense. None of the inherent flavors of the bean are recognizable. |
This series has been AMAZING! I love hearing from people who really like coffee. Is this series going to include various coffee brewing techniques?
Great series, it would be good to also discuss the antioxidant value of the coffee fruit, the red berry that surrounds the coffee bean (seed of the fruit).
Thank you! Becca is the real mastermind behind the series… She first devised it! It’s a good thing there are so many avid coffee drinkers ’round these parts… We can definitely make a post discussing the various coffee brewing techniques.
And to Shaun: Also an excellent idea. I hadn’t realized the stripped pulp was such a high antioxidant and nutritional food source. Very interesting! Certainly something we will include in future posts.
Thanks for reading!