I was recently asked about which step in the processing of the coffee that is most important. "All of them," I replied, and that wasn't an exaggeration! Coffee gets its flavors in many different ways and it's very easy to mess it up somewhere along the chain. The following is taking from a Quora post in response to the very same question.....
Coffee is just very complex, arguably the most complex food humans ingest (roughly 1500 chemical compounds in your cup). What influences the nature and make up of these constituents?
1) Terroir - The land (soil composition, pH), water composition, the amount & timing of precipitation, temperature, elevation, latitude, shade / sun, etc.
2) Cultivation - Fertilizer regimen / nutrition (organic, biodynamic, synthetic, etc.), irrigation, pesticides / herbicides / fungicides, etc.
3) Varietal - Like wine (pinot noir, cabernet, etc.), coffee has varieties: typica, caturra, bourbon, gesha & hundreds more. These varieties have different characteristics (aroma, flavor, body, acidity) that change in response to 1) and 2).
4) Harvesting - Coffee is a fruit. What's sweeter: green, unripe bananas or yellow, ripe bananas? The same applies to coffee. There are different colors of ripe coffee, but ripe coffee will be sweeter, cleaner & smoother if properly grown, harvested, processed, roasted & brewed.
5) Processing - This is perhaps one of the biggest factors determining flavor & aroma. Three main techniques are used: wet / washed, semi-wash / honey, & natural / dried-in-the-fruit.
- The wet method tends to showcase acidity & terroir. The coffee seed (bean) is "washed" by way of removing the fruit skin & pulp (mucilage) surrounding it. This is done in one of several ways: via fermentation, with or without water, or via mechanical removal. The result is an experience true to the variety's response to its circumstances (as mentioned above).
- The semi-washed / honey method is when the coffee flesh is removed but the thin, sweet mucilage layer of pectin / sugar surrounding the bean remains intact while the bean dries. This tends to enhance sweetness, slightly round the acidity & provide heavier body / mouthfeel (usually my favorite style of processing for most coffees).
- Natural processing is when the coffee fruit is harvested & put out to dry, fully intact with its fruit skin surrounding the bean. This results in a very fruit-forward flavor & aroma, often like berries. This method tends to mask or overpower other subtle attributes you might taste in a washed version of the exact same coffee; however, that's certainly not always the case.
6) Drying - Too hot and fast, the coffee tends to have woody, papery flavors. Too slow and incomplete, it will taste moldy / musty.
7) Storage - If properly dried (slowly & evenly), coffee can last 10-14 months in storage with little to no loss of "fresh" quality if the conditions are stable. But taste is subjective. The longer it sits in storage, & depending on the conditions, the more faded the acidity, the heavier the body & the woodier / muskier the flavors. It's all about what you want to experience. The age of coffee can have dramatic results on the cup.
8) Roasting - If you roast too dark, coffee pretty much all tastes very similar -- like carbon -- because what's happened to the organic compounds that give coffee its distinction is that they've been carbonized (which is far beyond caramelization). Once again, this is simply a matter of personal preference. But roasting can ultimately determine whether or not you taste toffee or peaches from the exact same bag of coffee. Everything could have been done to perfection up until this point & then totally ruined with poor, careless roasting. So, roasting is the art & science of presentation: enhancing the desirable intrinsic features while subduing the undesirable (this includes flavor, body, sweetness, acidity, aftertaste, & intensity of all these attributes).
9) Brewing - Pretty self-explanatory... err, well, no. Here are the factors / variables that influence cup quality & attributes:
- The grind: both size and consistency
- The water: temperature, hardness / softness, pH
- Time: length of contact / exposure of coffee to water
- Pressure: espresso, Aeropress, mocha pot, siphon
- Type of exposure: drip, full-immersion (i.e. french press),
- Filtration (or lack of)
This is the struggle, the beauty, the thing about coffee: you can mess it all up at any single step from seed to cup. So delicate & intricate is coffee that it leaves you chasing after its elusive harmony. The “perfect” cup is the experience of an extremely rare consonance of innumerable factors coming together over great distances of space & time. There are tons of variables we still don't observe or understand that explain how coffee from one place tastes different than a coffee 1 mile away.
Original from this blog post http://www.quora.com/Where-do-coffee-beans-get-their-flavor-notes