Blog – Temporary Climate Solutions

The Importance of Humidity Control in Coffee Storage Facilities

From picking the berries when they’re the perfect red color to roasting them to the ideal strength to brewing them with the right amount of scalding hot water, a lot goes into a good cup of coffee. Whether you source it locally or from an exotic country, there is one aspect of production that can make or break the quality of the coffee you sell—its storage. Coffee beans spend quite a bit of time in storage facilities before they make it to a tall ceramic mug or iced drink. Ensuring that the storage areas have optimal conditions helps preserve the rich taste, safety, and quality of the beans.

Coffee Storage Challenges

In many parts of the world, growers only harvest coffee once a year. In Costa Rica, for example, growers begin harvesting the berries in November or December, during the summer season. After workers pick the berries and remove the pulp, they dry the beans in the sun or using machinery. The workers then sort the beans by size and place them in burlap bags, which may or may not have a moisture barrier.

After the bagging process, growers ship the unroasted coffee to their customers, who store the green beans until they need them for production. To avoid mold growth and other quality losses that occur with time, coffee should remain in a climate-controlled environment. While coffee storage experts debate what the best conditions are for green beans, they agree that humidity and temperature are among the most important variables.

Humidity Control in Coffee Bean Storage Facilities

In general, growers dry green coffee beans until they have a moisture content of 12 percent, as beans with this moisture content have the best flavor when roasted. If a storage facility is too dry or humid, the beans respectively lose or gain moisture, which impacts their flavor. Therefore, the amount of time a company can store coffee depends on its geographic location. Those with low relative humidity levels can only store coffee for short periods. A company in Colorado or California, for example, may request small shipments every two weeks, rather than a large shipment every quarter.

When storage conditions are too humid, coffee beans acquire a moldy, fermented flavor and a darker color. For this reason, the location of origin makes a big difference in what companies purchase. A roasting company on the U.S. West Coast may favor Latin American coffee over coffee grown in Indonesia because it sits less time in transit. Longer transit times in containers that have no ventilation or climate control tend to experience condensation, weight fluctuations, and higher moisture levels in the beans. Acidity levels in the beans also reduce, making them acquire an old coffee-like flavor.

While experts don’t agree on the ideal storage conditions for coffee beans because of the multitude of variables to consider, they do agree that stable conditions with proper ventilation and insulation are the best because temperature and humidity fluctuations result in condensation and bean fermentation. If the beans get wet, they are likely to experience mold growth if a company doesn’t dry or roast them within a couple of hours. In general, conditions that are comfortable for humans are good for coffee storage.

Just as hot, humid conditions are bad for coffee beans, so are freezing conditions. Roasters advise against ever freezing coffee because it dehydrates the beans and softens its intense flavor. Experts vary on the ideal temperatures for coffee storage. Some recommend temperatures as low as 40°F, while others recommend temperatures between 50°F to 70°F. Humidity recommendations range between 50 to 70 percent relative humidity. In the end, the ideal conditions depend on the climatic conditions of the region in which the coffee is stored. Many have found that humidity control in coffee bean storage facilities allows the beans to retain the appropriate moisture content and flavor profiles throughout the course of a year.

Green coffee storage is an active process that requires continuous monitoring of ambient conditions at all stages of the process to minimize losses and ensure that consumers receive the highest quality product. Polygon facilitates this with its humidity control solutions and monitoring capabilities that alert you to problematic conditions. As you store beans, you may adjust the temperature and relative humidity levels to determine which preserves the quality of the beans the best. Get in touch with Polygon today to learn more about humidity control for your coffee storage facility. 

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