A lot goes into making a good cup of coffee right from picking the ripe coffee cherries to roasting them to the perfect colour to brewing them with the right amount of boiling hot water. As coffee is sensitive to four factors such as air (oxidation), temperature, light, and humidity, the storage of coffee can have a huge impact on the quality of coffee. Making sure that the coffee is stored at optimal conditions would help preserve the rich taste and quality of the beans.
Impact of Humidity on Stored Coffee
Maintaining the freshness of coffee beans and grounds is essential to preserving the overall flavour profile of coffee. One of the major threats to all kinds of coffee is humidity. Humidity is the percentage of water vapour in the air. Too little or too much of it has a serious impact on the flavour profile of coffee. Speaking of green coffee beans, scanty amounts of humidity will cause the beans to dry out too much whereas too much would cause mold growth. This is primarily because green coffee beans are great at absorbing excess moisture in the air.
Humidity also has an impact on roasted as well as ground coffee. Whole coffee beans are easier to care for because of its larger surface area compared to ground coffee, it is less likely to go stale. Just like green beans, roasted beans and ground coffee should be stored in an airtight container and kept in a cool and dark place.
The most difficult tasks would be keeping pre-ground coffee fresh but storing it in an airtight container and a similar condition that whole beans stay fresh in, the ground coffee should last well into a week without any unfavorable flavours forming.
Humidity is measured by an instrument used in meteorological science called Hygrometer
Humidity Control in Coffee Bean Storage Facilities
Normally, grower’s dry green coffee beans until a moisture level of 12% is attained because coffee beans with this level of moisture have the best flavour when roasted.
If the storage facility is too dry or humid, the beans lose or gain moisture which influences their flavour. Hence, the amount of time a company can store coffee depends on its geographic location. Countries with a low level of relative humidity levels can only store coffee for short periods. 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.
Similar to weight fluctuations and higher moisture contents in the beans, acidity levels in the beans also reduce, giving it an old coffee-like flavour.
While experts differ on the optimum storage conditions or coffee beans due to the myriad number of variables to consider they do equally agree that stable conditions with proper ventilation and insulation are the ideal condition because temperature and humidity fluctuations result in condensation and bean fermentation. Some recommend temperatures as low as 40°F, while others recommend temperatures between 50°F to 70°F.
If the beans are moist, they are highly likely to experience mold growth if a company does not dry or roast them within a couple of hours. Like hot and humid conditions freezing temperatures are also bad for coffee. Roasters advise against ever freezing coffee because it dehydrates the beans and softens its intense flavor.
Lastly, the ideal conditions depend on the climatic conditions of the regions in which the coffee is stored. Moreover, the storage of green coffee is an active process that requires continuous monitoring of variable conditions.