To make the perfect cup of coffee, use temperature and humidity monitoring
Thursday, Apr 4th 2013
In comparison to other food items like meat, fish, dairy or produce, the need to use temperature and humidity monitoring equipment for coffee is less immediate. After all, foodborne illnesses spread through perishable food items cause millions to get sick and send thousands to the hospital every year in the United States, but coffee is far less likely to cause such harm. Still, for those that rely on their morning cup of joe to get their day going, baristas should know that the perfect coffee can only be achieved through humidity and temperature monitoring.
"[U]nderstanding coffee packaging can make your coffee a truly religious experience," master barista Giorgio Milos wrote in The Atlantic.
How to best deal with green coffee
Although most of us envision coffee as dark hard beans or as a fine powder, coffee in its raw form is a green bean - this is what is extracted from the coffee tree at harvest time. Coffee roasters, specialty coffee houses or anyone else who might need to deal with these green beans should know proper storage practices.
Writing in the Brazilian Journal of Plant Physiology, Karl Speer and Isabelle Kölling-Speer of Technische Universität Dresden's Institute of Food Chemistry, noted that green Arabica and Robusta beans can contain significant amounts of fatty acids and moisture. Some strains contain as much as 30 grams of free fatty acids for every kilogram of green coffee bean.
To keep the fatty acid content stable and to prevent the green beans from having spiked moisture levels, raw coffee should be stored under specific moisture temperature conditions. Speer and Kölling-Speer found that while free fatty acid and water levels remained mostly consistent when beans were stored at 12 degrees Celsius (53.6 degree Fahrenheit) for as long as 18 months, levels of both compounds spiked when the raw coffee was stored at 40 degrees C (104 F). Levels of cafestol - a compound in coffee which can give the beans a bitter flavor if found in large quantities - also spiked when stored at 40 C versus 12 C.
Properly storing roasted and ground beans
In order to bring out the coffee flavors most people associate with the plant and the drink, the beans must first be roasted. This process changes the internal chemical structure of the bean, and thus monitoring and storage needs have to change as well.
According to Milos, roasting the beans dramatically boosts their carbon dioxide levels - dark roasts of beans can have as much as 10 liters for every 1 liter of coffee. To preserve these levels, roasted coffee needs to be kept away from oxygen at all costs.
"Oxidation is part of staling, and it degrades quality by altering coffee's essential oils and aromatic components, ultimately creating a rancid taste akin to butter left out too long," he wrote
The effects of oxidation can also be brought on by heat and moisture, Milos wrote. The National Coffee Association recommends keeping whole and ground beans stored in airtight containers and kept in cool, dark and dry spots. Humidity monitoring is important at this stage, since excess moisture can damage beans. As a result, coffee ready for consumption should not be stored in a refrigeration or freezer unit. Milos said fresh coffee begins to lose its flavor and aromas when stored at room temperature after around 10 to 15 days.
For instances when whole beans need to be kept around for longer than this duration, freezers can be useful. The NCA said whole roasted coffee beans can be frozen for up to one month so long as the containers are airtight and not used intermittently during that period. However, Real Simple reported that freezing can dramatically affect the quality of the bean and the final cup of coffee.
"The cell structure changes, which causes a loss of the oils that give coffee its aroma and flavor," Scott McMartin, a member of the Starbucks Green Coffee Quality group, told the source.