Monday, 18 May 2015

Arabica and Altitude

I love coffee. I have just been to Brazil, the largest global producer of coffee, and went to visit a coffee farm.

We heard, while we were there, that arabica coffee is the best varietal, and that arabica grown at high altitude yielded the best coffee... but we didn't quite catch WHY that was.

So I got home and did some digging.

For a start, arabica is pronounced "arab'-ickah" (Howdjsay, 2015). Not arab-eekah'. Okay. 

So why is arabica considered the best variety? Probably because it grows at high altitude. Hang on a minute, isn't that a circular argument?

Well, kinda. Apparently the higher coffee is grown, the more dense the resulting beans are. The best grade of beans - the Strictly Hard Bean - can only be grown at high altitude, usually between 1200 and 1600 metres (3,900 and 5,200 feet). The really dense beans hold together better and, because of this, they roast more evenly. You don't get broken pieces being over-roasted, and tainting the resulting mix with that tell-tale burnt taste (umiat-ga, 2004).

It is the cooler weather of the high mountain tropical coffee-growing altitudes that makes the beans grow more slowly, creating that much more dense, harder bean containing more complex sugars and intense flavours. The higher the altitude, the better the roast and the finer the grind, further changing the taste. Hawaiian Kona coffee has a mild, low altitude flavour at 750m, while Guatemalan coffee is spicy and chocolatey at over 1500m (umiat-ga, 2004; Scribblers Coffee, 2009). 
(Scribblers Coffee, 2009, amended by Young, 2015)
Additionally, average air pressure drops from 1,013 millibars at sea level to around 300mb at the top of Mt Everest, which is 10,000 metres. At 1600 metres, the air pressure is somewhere around 20% less than sea level, or about 500mb (Coffee Geek, 2010). Coffee also can't tolerate frost, so that tropical equatorial band tends to provide the best growing conditions (Scribblers Coffee, 2009).

The arabica bean is harder to grow, and has a lower yield, but prefers land which is cheaper to buy. The big producer, Robusta is a heartier variety with a big yield, growing on lower slopes, where land is more expensive. However, high-end consumers tend to prefer arabica (Johnson, 2013).

So there we have it. Arabica: slower growing at high altitude, more intense, strong, kick-you-in-the-guts-type flavour with a consistent roast. Robusta: faster growing at lower altitude, softer, sweeter flavour, but more likely to be of inconsistent quality.

I am a bit of a Guatemala girl, myself. Pick your personal poison :-)



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