A fascinating walk in the clouds

Altitude and coffee quality. What does altitude actually mean? Why should we care as coffee consumers and lovers?

If you take a look at the label of any bag of single-origin roasted coffee, you'll find some information such as the country of origin and region, the flavor notes in the coffee, perhaps the name of the farm or roaster... and, if it's single origin, it will usually tell you the altitude of the farm using the measurement meters above sea level (masl).

Well, if you ask a barista, they will probably tell you that the higher the altitude the coffee is grown at, the higher its quality will be. But in reality, it is a bit more complicated than that. Let’s take a look at the real meaning of what altitude is.

Is altitude a sign of quality coffee?

There is a tendency to associate high altitudes with sweeter and more complex coffee flavours, but this is mostly a correlation rather than a causality. The real reason why coffee is more delicious and of better quality is the temperature.

Coffee trees grow more slowly at lower temperatures. The cherries that contain the seeds we roast and call coffee beans also ripen gradually. This means they have more time to develop more complex flavours.

However, there is a disadvantage: the trees may have lower yields, require more care, and have a harvest later in the year. Coffee should not be grown in a climate that is too hot, but it should not be grown in one that is too cold either.

Reasons why a cooler temperature is good

In addition, at lower temperatures it is difficult for certain pests and diseases to thrive. An example of this is coffee rust , a fungus that attacks the leaves of coffee plants, preventing photosynthesis and the energy required for healthy growth. In 2012, coffee rust devastated coffee-growing communities in Latin America, causing more than a billion dollars in losses in just two years. (USAID). However, Emma Sage, SCA's Scientific Manager, made it clear that rust has its own vulnerabilities and one of them is temperature.

In a 2012 SCAA publication , Sage wrote that the optimal temperature for coffee rust is 21–25 °C/70–77 °F , as the disease cannot survive below 15°C/59°F. The ideal temperature for growing coffee is 17°C – 23°C/63°F – 73°F, and the temperature where it grows least efficiently is 14°C – 30 °C/57°F – 86 °F. This means that at lower temperatures, coffee rust should be weaker.

Similarly, the borer has caused hundreds of millions of dollars in damage, and it grows in warm temperatures of 20–30°C/68–86°F, according to a 2009 study .

Coffee farms that fall outside this range are less likely to be affected by rust, coffee berry borer, or any other pests that have a hard time surviving in colder climates. This translates into fewer defects and, in turn, fewer off-flavors in the final cup.

Not all coffee varieties are susceptible to rust, however, and those that are not can sometimes have a less desirable flavour, as they usually have a Robusta parent, which is a resistant but bitter coffee species. Also, having a lower risk of pests and diseases may encourage some growers to plant higher quality varieties, even if they are less resistant (another specification you can find on the label of a bag of coffee).

Explaining all these complexities takes time and someone willing to listen. For these reasons, when we are asked why altitude is important, we tend to simplify things and sum it all up by saying that higher altitudes produce better quality coffee.

Where we find altitudes below the range

Just as altitude affects temperature, so does latitude. Look at Colombia as an example, a country famous for its high-quality, high-altitude coffees. Farms in regions like Nariño are located nearly 100 miles from the equator, and according to the National Federation of Coffee Growers , are situated at 2,300 meters above sea level. The result? High acidity, sweetness, and a pronounced aroma, resulting in great coffee.

But if we head to Cerrado Mineiro in southern Brazil, more than fifteen times farther from the equator than Nariño, we find that the farms are located at much lower altitudes, between 800 and 1,300 meters above sea level. And according to the Association of Coffee Producing Regions of Brazil, the average temperature of the area is 23 ° C, placing it within the ideal conditions for growing coffee.

So why should we disregard a coffee grown at just 1,100 meters above sea level when the local temperature is relatively cold?

Latitude isn’t the only thing that can affect local temperatures. The Galapagos Islands, for example, straddle the equator with farms at just 200-300 meters above sea level . However, the temperature is similar to that of the Cerrado Mineiro, thanks to the Humboldt current that brings cold air from Chile and Peru. Coffees from this region tend to be sweet and medium-bodied with caramel notes.

We can say that altitude is an unfair benchmark. While it can indicate the quality of coffee, if the context is unknown – a knowledge of latitude, local climate, and more – knowing only altitude may not make much sense. Altitude can be useful when applied to farms in a specific region, but it should not be used, for example, to compare coffee beans from Hawaii and Venezuela or Indonesia and Yemen.

So why do we rely on altitude and not temperature? Because unlike altitude, temperature fluctuates by season, day, and even hour. Also, if the scale is imperfect, we need to know how fast the coffee beans are growing. This will affect the flavors, aromas, and ideal roast profile of the coffee.

How does altitude affect coffee beans?

Roasters have a better way to measure this concept of coffee grown at low temperatures or high altitudes: they talk about density or hardness. Beans that develop slowly are hard or high density; those that develop quickly are soft or low density. Unfortunately, the coffee industry does not have a unit of measurement for density (some countries describe coffees grown above a certain altitude as Hard Bean or Strictly Hard Bean , but this goes back to the original problem: the ideal altitude will vary between countries and regions). Nonetheless, the idea of ​​measuring density breaks the paradigm of the relationship between altitude and quality.

That’s because roasters, even more than coffee buyers, baristas and consumers, need information about bean density. You see, slow development not only results in more complex flavors, it also affects the physical composition of the bean.

As Zach Daggett wrote on Perfect Daily Grind in 2015 , unroasted green beans that are low in density tend to have an open fissure line, as opposed to those that are higher in density, which have a closed fissure.

But if we were to look inside the beans, we would see even bigger differences: low-density beans have more air pockets, meaning that during roasting, heat will be transferred more slowly and erratically. So roasters must use a lower temperature to avoid burning the beans.

Only one part of the coffee quality equation

Are we overreacting to this altitude thing? Is altitude really that important?

Coffee quality is complex. It is affected by many factors: coffee species and varieties, cultivation and processing methods, soil quality, altitude, climate and its variation from one year to the next, storage and export conditions, roasting, preparation…etc.

However, how quickly or slowly the coffee cherry develops can affect the flavor of the coffee in the final cup, not to mention its roast. For this reason, it is valuable to know about altitude. We just need to understand the context of latitude and local climate.

Translated by Alejandra M Hernandez and edited by Ricardo Gallopp Ramirez. Credits: Perfect Daily Grind Español.