Where Coffee Grows
The coffee tree is a tropical evergreen shrub (genus Coffea) and grows between the Tropics of Cancer and Capricorn. The two most commercially important species grown are varieties of Coffea arabica (Arabicas) and Coffea canephora (Robustas). The average Arabica plant is a large bush with dark-green oval leaves. The fruits, or cherries, are rounded and mature in 7 to 9 months; they usually contain two flat seeds, the coffee beans. When only one bean develops it is called a peaberry. Robusta is a robust shrub or small tree that grows up to 10 metres high. The fruits are rounded and take up to 11 months to mature; the seeds are oval in shape and smaller than Arabica seeds. Ideal average temperatures range between 15 to 24ºC for Arabica coffee and 24 to 30ºC for Robusta, which can flourish in hotter, harsher conditions. Coffee needs an annual rainfall of 1500 to 3000 mm, with Arabica needing less than other species. Whereas Robusta coffee can be grown between sea-level and about 800 metres, Arabica does best at higher altitudes and is often grown in hilly areas.
As coffee is often grown in mountainous areas, widespread use of mechanical harvesters is not possible and the ripe coffee cherries are usually picked by hand. The main exception is Brazil, where the relatively flat landscape and immense size of the coffee fields allow for machinery use. Coffee trees yield an average of 2 to 4 kilos of cherries and a good picker can harvest 45 to 90 kilos of coffee cherry per day; this will produce nine to 18 kilos of coffee beans. Coffee is harvested in one of two ways:
- Strip Picked – all the cherries are stripped off of the branch at one time, either by machine or by hand.
- Selectively Picked – only the ripe cherries are harvested and they are picked by hand.
Pickers check the trees every 8 to 10 days and individually pick only the fully ripe cherries. This method is labour intensive and more costly. Selective picking is primarily used for the finer Arabica beans.
Aroma and flavor descriptors
Coffee provides a complex blend of different flavors, which together produce a range of sensory experiences. The sensory profile of a cup of coffee varies according to a number of factors: the type and blend of coffee beans; geographical source; roasting method; and method of preparation. The variation in these aspects will impact the overall sensory experience obtained from a cup of coffee during both the preparation and consumption of the coffee.
Specific aroma and flavor profiles are described by sensory experts, to differentiate different types of coffees and roasts. Aroma and taste, are the overriding factors determining coffee preference. Coffee aroma descriptors include Flowery, nutty, smoky, herby, while taste descriptors include acidity, bitterness, sweetness, saltiness and sourness (see Coffee Flavour Wheel).
The level of roasting impacts aroma profiles. Research has suggested that lighter roasts preserve the herb and fruit notes, whilst smoky and burnt aromas are increased, and acidity reduced, in darker roasts.
In vitro research suggests that the release of saliva can affect the aroma experience, with results differing according to brewing method. In addition, it has been suggested that larger sips of coffee appear to generate a stronger release of aroma.
Flavor descriptions are inherently subjective—not surprising, considering how subjective taste can be. Unlike other sensory descriptions that have relatively objective descriptions (loud, soft, furry, scaly), taste (and smell) is often hard to describe. Flavor terms can be divided into roast related descriptors and descriptors related to the bean variety (though this division is not a standard one). The roast related flavors refer to those characteristics imparted to the bean as a result of the roasting process. Varietal and processing terms refer to those aspects that are inherent in bean, or imparted as a result of the green bean’s pre-roast processing. Roasting can substantially affect the intrinsic flavor and aroma of the bean; roasters will act in order to balance this and to enhance the beans’ inherent profile. One further factor is preparation method; this can drastically change the coffee’s character.
Acidity: Related both to the roast and to variety. This term is akin to the description of acidity in wine, not to acid content. Indeed, retailers may avoid using this term in order to avoid confusion, and rely on terms such as “bright” or “lively.” Acidity is more of a sensation than a taste, and is experienced on the tip of the tongue and/or the roof of the mouth. During roasting, acidity varies in an approximately inverse relation to body or bittersweet aspects; as the degree of roast increases, perceived acidity decreases. Coffees without acidity tend to taste flat, lacking a pleasant palate-cleansing aspect. Acidity can often have wine-like aspects, especially in many Kenyan coffees, or can come across as citrusy. When acidity is extreme, it can feel astringent, as if the moisture has been sucked from your mouth.
Aroma: Related to both roast and variety. Most of our taste perception comes from our sense of smell, so the volatile aromatics emitted from brewed coffee play an important role in its taste. Aroma develops during roasting, but as the roast starts becoming dark, the carbonized sugars become dominant.
Baked or Bready: A roast related term. Baked coffee is flat, with little aroma; typically the result of an insufficiently high roasting temperature over too long a period of time. In other words, if the heat applied to the unroasted coffee is too low, the physical and chemical changes do not occur in a desirable fashion.
Balance: Roast and variety related. The pleasing combination of multiple characteristics, none overpowering.
Body: Roast and variety related. Body is a textural quality, a perception of viscosity or fullness on the tongue; one roaster has likened it using your tongue as a weight scale. Body develops with the degree of roast, falling off sharply with over roasted coffee, but it can also vary by origin. Distinguish between body and the “thickness” imparted by some brewing methods, like coffee from a press, where fine particulates remain suspended, or espresso, which contains emulsified coffee oils. Underextracted coffee will also have a defectively light body.
Bitter: Roast and preparation related. This is not always a defect; up to a point, it can be desirable. Robusta is more bitter than arabica, but mild coffees can become bitter if over roasted or over extracted during brewing.
Bittersweet: Roast related term. Often mischaracterized as “strong,” the bittersweet aspect is created by the caramelization of sugars in the bean. The longer the coffee is roasted, the greater the caramelization, until at last the sugars are completely burned, giving the coffee a taste akin to charcoal (see next entry).
Burnt: When very mild, this aspect may be desirable for cutting through drinks containing a lot of milk and/or sugar, though there are those who like it in a straight cup. When overdeveloped, it is the flat taste of charcoal; this taste can be overwhelming.
Clean: Clean-tasting coffees are free of defects or undesirable distractions.
Complexity: Complexity simply means that the cup has many elements–aromas, textures, and tastes–apparent at once, or in succession. Since it is rare to fnd all of the desirable elements in a single origin, roasters often roast different coffees to achieve a varied profile.
Earthy, or Natural: Within limits, this can be a pleasant note, but more commonly a defect in which the brewed coffee has an aftertaste akin to freshly turned soil. Commonly relates to poor processing, one way this defect can occur is when the beans absorb flavor from the dirt on which they were spread to dry. In more muted degrees, this quality can add interesting notes to a coffee.
Flat: Lacking in taste or aroma; low in acidity. Often occurs when the coffee goes stale.
Grassy: Processing related. The aroma and taste of hay, or a newly mown lawn. This can result from prematurely picked cherries.
Musty: Moldy, mildewy ; often the result of some improper storage conditions. Improper aging also can cause mustiness, while proper aging can contribute a desirable flavoring aspect.
Rioy (REE-oh-ee): A harsh, medicinal quality, the term derives from a reference to low quality coffees from Brazil (i.e., Rio De Janiero).
Sour: Unpleasantly acrid or sour, as if contaminated by vinegar. This taste can occur in low-growing, unwashed coffees, but commonly occurs in under roasted coffees, or even properly roasted beans that were then brewed with water that was too cool.