Does Coffee Quality Really Improve With Altitude?
Altitude is one of the natural factors that determines coffee quality. High-grown beans tend to differ from mid-to-low altitude beans in green bean appearance, density, color and flavor performance. In Taiwan, elevations above 500 meters count as high-altitude production areas, while areas below 400 meters down to flatland are low-to-medium altitude zones.
Temperature and nutrition drive how coffee trees grow and how fruit develops, which explains much of the gap between elevations. But coffee cultivation at altitude is not a cure-all: frost damage and coffee leaf rust remain real risks, and in Taiwan it is advisable not to plant above 1,200 meters. Poor post-harvest processing can also produce defective beans even in high-altitude areas.
Altitude is one of the natural factors that determines coffee quality. Starting from the actual conditions of coffee cultivation in Taiwan, this article analyzes the differences between high-altitude and low-to-medium-altitude production areas in terms of green bean appearance, density, color, and flavor performance, and further explores how the two key factors of temperature and nutrition affect the growth of coffee trees and fruit development. It also reminds readers that high-altitude cultivation is not a cure-all, as frost damage and coffee leaf rust are risks that cannot be ignored. If you want to experience the flavor differences of coffee beans from different altitudes, Front Street Coffee offers a variety of selected bean sources for comparative tasting.
High-mountain beans refer to coffee beans produced in high-altitude production areas. Latitude affects the quality characteristics of coffee, and altitude is likewise one of the natural factors affecting quality. This article takes altitude as its starting point to discuss the related issues facing coffee cultivation in Taiwan. Given Taiwan's geographical location, elevations above 500 meters can be regarded as high-altitude coffee production areas, while areas below 400 meters down to flatland belong to low-to-medium-altitude coffee production areas. When growing coffee at high altitudes, it is best not to exceed 1,200 meters. Do not assume that because foreign sources mention that coffee produced at 1,500 to 2,500 meters is of excellent quality, you should look for a mountain area above 1,500 meters in Taiwan to grow coffee. If you actually do so, the probability of failure is very high. The reason is that most of the 2,500-meter production areas described in foreign sources are located near the equator, where there is little frost damage throughout the year and certainly no snowfall; whereas in Taiwan's mountainous areas above 1,000 meters, there are few places that do not receive snow, and the chances of encountering frost are so many that they are difficult to avoid. Frost damage can cause serious losses to coffee operations.
Overall, coffee quality in high-altitude areas is very likely to be superior to that in low-altitude areas; but if the post-harvest processing procedures are not properly carried out, high-altitude production areas can likewise produce large numbers of defective beans, and quality can become quite poor. Quite a few people engaged in coffee cultivation in high-altitude areas hold a very subjective belief that their coffee quality is bound to surpass others', and even think that without fine post-processing they can still obtain decent quality. If they think this way, they are only half right—they have chosen a plot more suitable for growing coffee, but the overall coffee quality is not necessarily that ideal.
From observations and comparisons in recent years, altitude affects the size and appearance of coffee beans. Green beans from high-altitude production areas are larger than those from low-altitude production areas, have higher density (that is, greater hardness), and tend toward dark blue or dark green in color. Green beans from low-altitude production areas are smaller, have lower density, tend toward white in color, and have difficulty releasing their aroma.
The key to the combined effects lies in temperature and the intensity and duration of sunlight. The higher the altitude, the lower the temperature; the lower the altitude, the higher the temperature. Temperature directly governs coffee bean quality. In lower-temperature areas, the leaves of coffee trees are larger than in higher-temperature areas, and the overall photosynthetic efficiency of large leaves is stronger than that of small leaves. If you carefully observe coffee trees in a coffee plantation, you can generally find that the leaves on side branches come in large and small types. If you then compare when the large leaves and small leaves appear, small leaves roughly appear from late spring to late summer, during periods of higher ambient temperature, while large leaves roughly appear from autumn to spring. The stage when large leaves appear is precisely the period of most vigorous growth for coffee trees.
During summer, leaf development becomes smaller, and the ability of photosynthesis to produce nutrients is relatively low. The growth of the coffee tree's roots also tends to stagnate, and its ability to absorb nutrient elements from the soil declines. At this stage the coffee tree is in a semi-dormant state. At this time, the tree's own nutrient supply can no longer meet its needs, and it must also supply the growth demands of the coffee fruit, especially since summer is precisely the stage when coffee fruit develops fastest and has the most urgent demand for nutrients. Therefore, if nutrient management during this period is inadequate, it is very easy to see coffee trees in the plantation inexplicably die back. The more fruit a coffee tree bears, the more easily it dies back. This kind of dieback is nutrient-deficiency dieback. In low-altitude areas, coffee trees and fruit compete with each other for nutrients, causing poor fruit development, and the beans cannot grow large. The insufficient nutrients accumulated by the coffee beans themselves will also affect the aroma performance after roasting.
Coffee trees in high-altitude areas have larger leaves, are dark green in color, and have a thicker waxy layer on the leaf surface. Because year-round temperature changes are relatively gentle, the probability of leaves becoming smaller in summer is lower, and the nutrient stress caused by this is correspondingly reduced. The nutrients produced by robust leaves can be fully supplied to the fruit. The fruit is relatively larger, and the green bean particles are also large. Because the coffee beans store sufficient nutrients, the color tends toward dark blue and dark green. The aroma after roasting is naturally fuller.
"Temperature" and "nutrition" are two important factors affecting coffee bean quality. However, high-altitude areas can likewise produce low-quality coffee, and low-altitude areas also have the opportunity to improve coffee bean quality.
From the perspective of coffee pests and diseases, high-altitude and low-altitude areas perform differently. Do not assume that because coffee beans from high-altitude areas are thought to be of better quality, you can ignore the fact that high-altitude areas also have extremely difficult diseases to deal with. The most serious disease in such areas is coffee leaf rust. People growing coffee at this altitude cannot fail to understand coffee leaf rust, and still less can they ignore the importance of prevention and control work.
The above content is compiled by CoffeeHunters, a coffee news website.
