Most coffee is grown between the Tropic of Cancer and the Tropic of Capricorn, in a band centred on the earth’s equator. Here, optimal weather conditions contribute to what’s widely considered the highest quality coffee on the market.
Each growing region displays different characteristics, all of which have an impact on the final flavour in the cup. These characteristics are governed by variables like soil quality, climate, and plant variety.
Arabica (Coffea arabica), for example, makes up roughly 70% of worldwide production. It can tolerate mean annual temperatures up to roughly 73°F (24°C), but it thrives in a temperature range of between 64° and 70°F (18°C to 21°C).
One of the most influential variables, however, is altitude. Not only does it affect the growth of coffee, it also has a significant impact on roasting. To find out more, I spoke with 2019 World Cup Tasters finalist and head of quality control at Bella Vista Coffee, Dulce Barrera.
What is the ideal altitude for growing coffee?
Altitude has a huge impact on a coffee’s flavor profile. Lower altitudes can expose coffee plants to greater heat, less ventilation, and less diurnal temperature contrast, not to mention higher risks of being attacked by insects.
Very high altitude environments, meanwhile, are subject to greater, rainier cloud cover interspersed with very intense periods of sun and high diurnal temperatures.
Generally speaking, higher altitude coffees develop higher acidity and smoother mouthfeel in the cup, whilst lower altitude coffees tend to develop heavier body and lower acidity.
According to a Sweet Maria blog on altitude, beans grown at a higher altitude tend to express greater density, which generally translates to better, specialty quality coffee. High density is pretty much synonymous with Strictly Hard Bean (SHB), the classification used in Costa Rica for the same grade of coffee.
World Coffee Research maintains a list of coffee varieties, and for each variety, the ideal altitude for it to be grown at. Most arabica varieties benefit from higher elevations of between 1,000 masl and 1,800 masl, with some farms in Ethiopia located 2,000 masl and above.
Some arabica can benefit more than others. For example, says WCR, Panamanian Geisha achieves exceptionally high quality at high altitudes.
Unlike Arabica, however, robusta varieties are much more resilient against disease and pests and enjoy hotter temperatures. Robusta can even handle full, direct sunshine. For these reasons, robusta plants benefit from lower altitudes, ideally below 600 masl.
Roasting coffee at altitude
Dulce Barrera is a three-time Guatemalan Cup Tasters Champion. She explains that most roasters take time to get used to their roasting location, roasting machinery, climate, and altitude.
She explains that at higher altitudes, the air contains less oxygen and less moisture. Because it’s colder the higher up you get, you need to increase roasting temperatures. The converse is true for lower altitudes.
“With higher altitudes, more heat is needed to achieve a good curve,” she explains. “Less altitude requires less temperature since it is hotter. If we do not have this experience in roasting at different heights, we can spoil coffee.”
She adds that when moving between altitudes, roasters need to be incredibly astute to avoid burning or under roasting beans.
“If we are used to roasting in high places and we are going to roast in low places, we can burn the coffee, since we are going to use more heat,” she says. “If we go to high places, we can get coffee that’s a little raw because we will use less temperature.”
The question, however, is which altitudes are better for roasting? According to Dulce, the advantage of roasting at higher altitudes is the amount of control a roaster can have on the roast profile.
“We have better control over roasting,” she explains. “The climate is linked to temperature and altitude. Lower areas are normally hotter and humid, which negatively affects the roasting time.”
She notes that it’s still important to avoid the common roasting mistake of scorching beans. This occurs when the initial temperature is too high, leaving coffee tasting flatter, hollower, significantly less sweet, and scorched.
Roasting at altitude: A study
Dulce says that she was involved with a very interesting test conducted by Cropster and several coffee experts. They asked roasters located at different altitudes to roast the same coffee with the same roast profile using an IKAWA.
“We put together a team of roasters (who are also IKAWA users) and had green coffee allocated by the Balzac Brothers,” she says. “The coffee was a washed Bourbon & Caturra from Huehuetenango, Guatemala, grown at between 1,500 and 1,800 masl.”
The roasters were selected according to a semi-even variation in altitude, ranging between sea level and 2,200 masl. Cropster also dispatched AmbientSensors to monitor environmental variables, ensuring that enough data was collected accurately.
The results confirmed Dulce’s insight: at higher altitudes, roasters applied more heat in order to achieve the same exhaust curve, due to the lower air density.
Effectively, the fans inside the IKAWA roasters were always spinning at the same rate, but moving different densities of air depending on the altitude.
In order to produce high-quality coffee, it is essential to grow it at altitude. The combination of warm days and cool nights allow the cherries to mature slowly, helping impart the full, rich, and pronounced characteristics that make the coffee shine in the cup.
However, growing at altitude alone will not produce great coffee. Roasters have a responsibility to unlock the full potential of the beans during a roast, while also preserving the freshness from the roastery all the way to the consumer.
To do this, you need high-barrier coffee packaging – which is where MTPak Coffee comes in. Our team of expert designers can help you create a bag that will keep out external factors such as oxygen and moisture, while ensuring your coffee stands out on the shelf.
We have a range of sustainable packaging materials, including kraft paper, rice paper, low-density polyethylene (LDPE), and polylactic acid (PLA), all of which can be fitted with fully recyclable degassing valves and resealable zippers. We also use low-VOC water-based inks and sustainable printing methods.