I just know that all of you lie in bed at night in a cold sweat, screaming a burning question at the darkness: "Why does my Sumatran coffee taste so different from my Guatemalan?" I imagine that the response you finally decide upon takes one of two forms: either you would appeal to the character of the soil, or you would suggest the the varietals unique to each region are the major factor. Try to contain yourselves when I say what I'm about to tell you. The answer involves a little of both of these, but the flavors that make coffee truly unique to an area are not in the bean, but in the processing.Coffee processing includes pretty much everything that happens to a coffee bean from harvesting to export. It involves, in no particular order, numerous steps to separate the ripe fruit from the unripe and rotten, remove the fruit to retrieve the bean, and dry it before being packaged and shipped.
There are four major (and a few minor) ways to process coffee: wet processing, dry processing, wet-hulled (also called Giling Basah), and the pulped natural method. Each has a distinctive effect on the flavor of a coffee. This week, I'll go in depth on wet process, and for the next few weeks, I'll compare this with other processing techniques in terms of the steps involved and the resulting taste.
In wet process coffee production, the coffee cherries are first scanned for rocks, twigs, and other fun stuff, then 'floated' in a vat of water to remove the unripe, overripe, or otherwise defective beans that float to the surface. They are then sent through a pulper. This is a machine specifically designed to remove the outermost part of the coffee to return the seed with some of the fruit still intact. This step is also naturally designed to separate unripe coffee. Unripe coffee cherries are harder than their ripe counterparts, so the machine is finely adjusted to provide the exact amount of pressure to pulp only the ripe cherry. The coffee is briefly fermented for 1-2 days to break down the remaining fruit or 'mucilage' then washed to remove this layer, leaving the bean itself in a layer of parchment. The bean at this point must be dried. High quality coffee is mainly dried in the sun on patios and is raked every half hour or so (for about a week), but mechanical dryers are also common to expedite the final stages of drying. At this stage, the coffee is stored for 30-60 days until it is ready to be dry milled and shipped. Dry milling involves removing the parchment from the coffee, then sorting by density again on a mechanical table. The final stage of coffee processing is to visually inspect all coffee beans to remove anything that looks defective or inconsistent. It is then packed in burlap (or more recently vacuum packed in mylar) and brought to your local roaster to be expertly blended, roasted, and brewed all so you, the consumer, can throw in a mountain of sugar or artificial sweetener and a cow's worth of milk, rush off to whatever stupid meeting you have, failing to even once savor the beverage you possess, and consider yourself a connoisseur, and I detest each and every one of you.
Ahem, vitriolic diatribes aside, wet process coffee tends to have a very clean, bright, and floral character with an accentuated acidity as compared to other methods of processing. The fruit is not in contact with the bean for as long as other methods, limiting the body and complexity that this would otherwise impart. This process is common to all areas typically associated with very clean flavor profiles, namely Central and South America (with the exception of Brazil. We'll get to that later). As a thought to leave you with, if you process a Sumatra, the Dark Lord of coffee, with this method, it can be almost indistinguishable from a bright, cheerful Central American cup. I don't know how far this article will sway you on the whole 'nature vs. nurture' philosophical discussion, but I hope it leaves you as I tend to be, confounded and befuddled by the ambiguity of human existence.
