A great, basic tutorial on green coffee processing. Full article appears on forbes.com.
Coffee is getting complicated. And I don’t mean understanding the difference between an American cappuccino (obnoxiously oversized like a bowl of fettuccine Alfredo from Cheesecake Factory) and the daintier original invented by the Italians (who are generally horrified by both our bastardization and willingness to drink one at any time of day.) But I digress.
Consider the term “green coffee.” Even the hue of standard commodity beans — the second most heavily traded commodity in the world after crude oil –- can be several shades removed. Referring to the color of beans before roasting, green coffee can range from dark raisin to dried chickpea, and the taste profiles, for those attuned to them, can also be wildly different.
This great variation in color derives from the processing and fermentation methods used in different regions, based on their weather conditions and resources. It should not come as a surprise to those with winemaking familiarity that this other carefully cultivated fruit also requires some application of chemistry.
What is processing? For all its negative connotations in the food world, processing freshly picked cherries references the necessary steps taken, which includes some degree of fermentation (yeasts and bacteria break down the sugars found in the mucilage to produce acids and fruit notes), to remove the three layers around the seed in order to prepare it for shipping, and later, roasting. Those layers are first, the outer fruit or pulp, second, the sticky mucilage covering the seed, and third, the parchment, or thin layer covering the seed that is named for its resemblance to parchment paper when dry.
As consumer palates have become more sophisticated, specialty coffee producers have begun using processing methods as a creative tool. Whether accentuating fruit notes, highlighting or softening acidity, and fattening or lifting the body, this creates product differentiation. Think about wine for a minute. Grapes left longer on the vine develop more sugar, thus more alcohol and a bigger body, and riper fruits. Grapes picked earlier have higher acidity, less alcohol, a leaner profile, and tarter fruits. While not an exact comparison, the point is to show that, from a producer standpoint, coffee processing decisions, along with terroir (e.g., a cool, coastal site in Sonoma v. a warm valley site in Napa) and tree variety (e.g., Pinot Noir v. Cabernet Sauvignon), influence the sensory properties of the final drink.
While experimentation continues, the three predominant processing methods you’ll find on the market are dry or natural (labor intensive), washed or wet (water-intensive), and a newer hybrid called honey or semi-dry.