WHICH FACTORS AFFECT THE QUALITY OF GREEN COFFEE?
Before we look at how long green coffee stays fresh for, let us understand some of the several factors that affect its quality. Green coffee is susceptible to a number of factors during transit and storage. However, as far as agey flavors are concerned, humidity, temperature, and oxygen are the three most important variables.
Temperature
Exposure to temperature extremes affects water activity in green coffee. This causes condensation in the bag and on the surface, which creates a humid, moist environment. This in turn causes the more subtle aromas and flavors in coffee to deteriorate. Temperature extremes also affect the respiration process and change how the water within green coffee behaves. This means that if green coffee is not stored in a cool environment, its flavor degrades over time.
Humidity
Much like temperature, environmental humidity can affect the equilibrium of green coffee beans. If the air is too dry, the moisture can leach out of the coffee. Conversely, if it is too humid, the beans absorb excess moisture, which results in an effect not dissimilar to fermentation, and can even cause mold or mildew to form.
Oxygen
Aside from moisture damage from exposure to temperature and/or humidity extremes, oxygen is also a factor that causes green coffee freshness to diminish. As coffee oxidates over a long enough timeline, its aromatic compounds dissipate, causing undesirable “flat” and “stale” flavors to form.
Light
As with roasted coffee, concentrated light will cause green coffee beans to undergo a process called “photodegradation.” This is where photons slowly destroy organic particles over time, including the non-volatile compounds which contribute to the final cup profile of roasted coffee.
Time
While green coffee is less volatile than roasted coffee, time is still a factor which causes its quality to diminish. However, time itself is not the factor that causes coffee to degrade; instead, it’s a measurement of how much the four previous factors have been able to affect it. Time is not a problem, but over a long enough period, oxygen, humidity, and temperature will cause green coffee to lose its more subtle and delicate aromas.
Extending this time frame is where good storage practice comes in.
SO, HOW LONG DOES GREEN COFFEE ACTUALLY STAY FRESH FOR?
As a rule, most specialty coffee roasters consider green coffee to be fresh for six to 12 months. Moreover, once the year mark has passed and the next harvest lands at the roastery, the coffee is “past crop” – a label associated with undesirable cereal or aged flavor notes. “[Exposure to] heat, light, moisture, insects, and air are the factors that contribute most to the degradation of green coffee.”
Freshness, however, varies depending on the exact coffee in question.
STORING GREEN COFFEE PROPERLY
As part of its Coffee Quality-Improvement Program (CQP), the International Coffee Organization (ICO) recommends that from the time it is processed and ready to be shipped, the moisture level of green coffee should stay between 8% and 12.5%. Similarly, water activity should stay between 0.5% to 0.7% aw in line with food safety protocols.
As a rule, specialty coffee roasters look for moisture levels around 12%. To ensure this, humidity should be around 60% to 65% during storage, and the temperature should stay at or around 20°C (+/- 5°C).
However, ensuring these conditions is easier said than done, and as such, producers and traders are increasingly using hermetic barrier packaging. To achieve this, many are using hermetic bags such as grain pro. As we are now looking at the long end of the 2023 coffee harvest and the 2024 picking season knocking at the door, planning quality storage is important to retain coffee quality and freshness.