How Coffee Gets From The Plant To Your Cup
Once coffee is harvested the coffee seeds must be separated from the cherries, a process referred to as milling. As it turns out, removing the fruit from the coffee bean without harming its quality to some degree is exceedingly difficult.
There are three methods to remove the coffee seed from the surrounding berry, The natural method, the pulped natural method and the washed method.
The Natural Method
With the natural method, the fruit is allowed to slowly dry and harden around the coffee bean during a period of 2-3 weeks, and the bean gradually absorbs starches in the fruit. The dried husk is then hulled. The result is that liveliness tends to be muted while body and base notes increase.
This kind of bean is ideal for making an elegant espresso coffee, however the risk of bacterial infection and of fermentation in the bean is very high, which means the farmer cannot guarantee or rely on consistent quality results.
The Pulped Natural Method
With the pulped natural method, the fruit’s skin is removed immediately (the bean is pulped). The remaining fruit, called mucilage, is then dried along with the coffee seed.
Similar the the natural process, the pulped natural process is similar to the natural process: the bean absorbs starches. While this method does not produce as much body in the coffee as the natural process it allows brighter, more floral notes to surface in drip style coffees.
The outer fruit layer is removed immediately; the clinging (wet) inner fruit layer ferments for 20 to 40 hours and is then thoroughly washed off the bean. This method can produce a crisp, clean flavor with great snap.
All three processes are easily botched, leading to off-fruity, rotten and barnyardy characteristics.
Drying Of Coffee Beans
The coffee beans must be dried at a precise rate, not too fast or too slow. Excess can produce extreme off moldy and stale peanut-like flavors.
Once the green beans are free of all outer matter and dried, they are taken to another mill where sorting occurs. The best quality coffees are sorted by:
- Size: to ensure even roasting
- Density: the highest density beans provide the best quality and flavor
- Defects: just one defective bean can add off flavors to an entire pot of coffee.
With the highest quality coffees in the world, a final sorting is done by hand to remove very slight imperfections.
Every coffee that is considered for purchase must be carefully “cupped” as is said in the industry. The cupping process involves detection of any defects or inconsistencies that might appear from cup to cup; one bad bean can destroy even a pot of coffee.
Coffees that are chosen for purchase must be outstanding in clean cup (no taints or dirtiness), sweetness, refined acidity, smooth body, distinct flavor, elegant aftertaste and good balance. All coffees must be measured for correct moisture content before purchase. This is critical since wetter, unstable coffee can deteriorate rapidly.
Green coffee beans are hard and cold to the touch, like small pebbles. The minute green coffee has been dried and made ready for export it starts to age, and then to deteriorate. If the coffee has not been dried to the correct percentage (not easily done in humid climates) or properly dried, it will deteriorate rapidly and within weeks to a couple of months lose everything.
First to go are any fresh floral aromatics, and then sweet, clean fruit flavors fade into baggy (from absorbing the smell and taste of processed jute bags) and sour woody flavors and aromas, as the oils within the bean turn rancid. Indeed green coffee oils quickly absorb odors around them – so what they are transported with is critical!
Many of the greatest coffees are harvested just once a year. Central American and East African coffees are in this category and are harvested during our winter season. The best Kenyans, for instance, are picked in late November. They are auctioned in Nairobi from late February to late May and may not arrive in the US until August or September. By November the deterioration process has set in. Most Central American coffees can start deteriorating between August and November.
Fine green coffees should not be stored in jute bags. Their oils will, over time, absorb odors from the bag itself. Even more important, exposure to the air and changing conditions of humidity and temperature accelerate disintegration.
Even stable fine coffees can decline, when storage conditions are less than ideal. For example, when green coffees come down from the cooler drier highlands where they grow and wait at hot, humid terminals in port, to be then put into containers which can spend weeks at sea.