As it turns out, the scientific data is equivocal on the subject. Some research
demonstrates a difference in taste as elevation changes while some does not.
Many people in the coffee industry, including this author, have noted that
different altitudes produce different cup profiles; coffees grown higher up tend to
be more acidy and complex while lower elevations tend to be more intensely
coffee flavored.
If there really is a difference in elevation, what’s going on?
Any athlete will tell you that the air is thinner at higher altitudes. This is because
at higher altitudes there’s lower air pressure (the weight of all the air that presses
down on everything), which means less oxygen is present in any given breath of air since it isn’t compressed as much as air at lower altitudes.
Plants, however,
don’t seem to mind this.
While nobody has tested the effects of different air pressures on coffee plants,
researchers doing space research (astronauts need to eat, right?) have shown that
lettuce leaves changed somewhat when grown in different air pressures.
However, none of the research examines the taste. Radishes, on the other hand,
barely responded at all to different air pressures (unless the air pressure was very,
very low). More interesting, the flavor of radishes and some chemical markers
that stand in for flavor didn’t change when the radishes were grown in different
air pressure conditions.
Lettuce (leaves) and radishes (roots) are different types of
plant organs than coffee (seeds), so it is hard to draw a strong comparison from
these examples. However, considering the nature of the changes in lettuce and
the fact that coffee is a seed (organisms tend to be conservative when allowing
things to influence their children), it is unlikely that air pressure is influencing the
cup quality of coffee.
A change in air pressure is only one of the differences noticed at higher altitudes.
The temperature also drops at higher elevations. It has been well documented
that temperature affects many aspects of plant growth and development across a
range of species, including food plants like coffee.
As air pressure doesn’t seem to
be too important in influencing coffee’s taste, it is reasonable to assume, then,
that the change in temperature at higher elevations is what is influencing our
brew.
To support this, we must consider that, across the globe, temperature is
influenced not just by elevation. A major factor is latitude.
As the distance from
the equator increases, temperatures at a given elevation decrease. So, 2,500 feet
(762 m) above sea level in Hawaii is a much cooler climate than 2,500 feet (762 m)
above sea level in Colombia.
Whereas coffee grown in Hawaii at that elevation can be acidy and complex, it is
rarely found to be so in Colombia, even though the elevation is the same. While
many factors influence the flavor of a cup of coffee, the temperature at which it
grows seems to be one of them.
Thus, looking at elevation alone is not very useful, rather, the interaction
of altitude and latitude and their influence on temperature is what matters.
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