The influence of geography on the flavor of a coffee bean is profound. All coffee grows in the tropics, but the altitude at which it is grown contributes significantly to a coffee’s flavor profile. Mountainous regions of the Coffee Belt, a tropical band extending approximately 30 degrees north and south of the equator, produce the world’s truly great Arabica coffees. Central and South America, southern Asia and some Pacific islands, and mid to southern Africa represent the world’s foremost coffee growing regions.
High altitudes above 900m to 1500m and beyond provide ideal growing conditions for the coffee tree: a frost-free climate averaging 60-70 degrees F year-round, moderate rainfall of roughly 80 inches, and abundant sunshine. Cooler mountain temperatures provide a slower growth cycle for the coffee tree which prolongs bean development. This longer maturation process imbues the coffee bean with more complex sugars, yielding deeper and more compelling flavors. Better drainage at high elevations also reduces the amount of water in the fruit resulting in a further concentration of flavors. The soil in which the finest Arabica coffees are grown is extremely fertile and often volcanic. These rich soils surrender hard, dense coffee beans highly prized for their potential to provide exceptional flavor.
The world's truly stunning coffees are grown between 1200m and 1800m. They are produced from fruit that is picked only when ripe and prepared with care following harvest. Generally, as growing altitude increases, a coffee’s flavor profile becomes more pronounced and distinctive. From the mild and sweet taste qualities of a low-grown Brazilian bean at 1060m to the soaring floral notes of an Ethiopian grown above 1800m, altitude heightens a coffee’s ability to deliver bigger varietal nuance and complexity.
HIGH ALTITUDE PROMOTES DISTINCT VARIETAL CHARACTER
As the "Taste Your Way Up the Mountain" graphic above illustrates, higher altitudes promote increasingly favorable taste qualities in a coffee bean. However, these flavor traits describe a green (unroasted) bean's potential to reveal its inherent flavors, known as "varietal character," that a coffee tree transfers to its fruit which is then absorbed by its seed (coffee bean).
As noted earlier, a coffee bean's flavor is influenced by its microclimate that includes but is not limited to altitude, soil quality, temperature, rainfall and access to sunlight. Varietal character also serves as a primary factor in a coffee's taste profile. Yet, like any other agricultural product, coffee flavor is influenced by other factors--the primary one being the roast level ultimately applied to green coffee. Second only to the quality of the bean itself, roasting ranks as the single most important influence on coffee flavor. An Ethiopian bean, for example, tends to display its full varietal character as lemony with floral aroma when taken to light to medium roasts. Flavor qualities of an Ethiopian bean deepen at darker roast levels and may emerge as dried fruit and caramel in the cup.
GRADING COFFEE QUALITY BASED ON ALTITUDE
Central America grades the quality of its coffee based on the altitude at which it is grown. A strictly hard bean (SHB) designation in Guatemala, for example, signifies coffee grown at or above 1370m. Mexico applies the term Altura, meaning “high” in Spanish, to identify its high-altitude coffees while Papua New Guinea attaches a "Mile High" designation to its mountain-grown beans. These designations reflect the value placed on coffee nurtured in cooler climates that a high-elevation growing region offers.
EXCEPTIONS AT LOWER ALTITUDES
Although the world's finest coffees are found at elevations of at least 1200m, some rare exceptions exist. The celebrated Hawaiian Kona, for example, is so far north of the equator that coffee cannot be grown higher than 600m in that region. The microclimate is simply too cold to sustain a coffee tree that cannot tolerate frost.
Very low-elevation coffee regions impose harsher growing conditions on the coffee tree. Higher temperatures and less rainfall cause coffee to ripen more quickly resulting in beans with taste qualities that range from simple and bland to earthy or murky. The bean structure of these coffees grown downslope are typically softer than the hard-bean coffees grown above 1200m. Consequently, these more delicate coffees do not tolerate darker roasts well, suffer from increased flavor loss when stored, and routinely attract below-market prices on their way to becoming part of an inexpensive coffee blend .
High-altitude specialty coffees, on the other hand, generally command a far better market price due to their exceptional flavor and vibrancy, lower yield per coffee tree, and challenge to coffee farmers in remote mountainous areas who must produce and market their crops. High-altitude coffee farming offers truly superb coffees that represent one of the world's most affordable luxuries. Yet, altitude is but one factor that shapes a coffee’s overall flavor profile.
Note: This blog post, "The Effect of Altitude on Coffee Flavor" was written and posted by Scribblers Coffee on December 31, 2009. The graphic titled, "Taste Your Way Up the Mountain," was also created by Scribblers Coffee in 2009 specifically to illustrate the blog's content. We reposted this blog on our new website in 2017.