How long does green coffee last in storage?
It’s a question every roaster and importer should know, and the answer hinges on a number of important factors.
- Specialty Green Coffee can stay fresh for about 1 year in good storage conditions.
- Keep coffee in moderate-to-low temperature and humidity.
- Use protective packaging to preserve quality and prevent accidents.
- Maintain good warehouse conditions including proper shelving, palletization, and pest control.
The Importance of Quality Preservation
A general guideline might be that under good conditions, green coffee can retain good sensory and physical quality for up to a year after harvest. This lifespan can easily be shortened by poor environmental conditions, but it can also be extended by some savvy techniques.
It’s also worth noting that green coffee may last much, much longer (usually at reduced sensory quality) without posing a threat to a consumer. “Aged” coffees are less popular with specialty coffee roasters than they used to be, but are still common practice in some circumstances. However, most specialty roasters nowadays are concerned with not just the freshness of their roasted product, but also the freshness of the green coffee they use.
As such, proper green coffee storage is one of the most important quality preservation acts a roaster can undertake. Good storage conditions can maintain the integrity of certified coffees, keep green coffee safe for consumption, and preserve flavor. Poor storage practices can leave green coffee susceptible to physical damage and fading flavor profiles. Let’s take a look at some common problem areas and how roasters can follow best practices to get the most out of their green coffee.
Ambient storage temperature for green coffee plays an important role in quality control. High temperatures are particularly bad for green coffee as fragile aromatic compounds and flavors can evaporate. High temperature conditions can also cause moisture loss, which also contributes to loss of flavor complexity over time.
Low temperatures can also be problematic. While cooler temperatures for storage tend to be better in general, cold storage, particularly freezing green coffee can present certain challenges. Frozen coffee without proper packaging can grow ice crystals which will compromise cellular structure. Roasters looking to freeze their coffee should vacuum seal it before freezing, and use the coffee immediately after it is thawed, as frozen coffee can lose quality rapidly once returned to room temperature.
Ideal temperatures for normal warehouse storage in the range of 50-75 F are generally accepted industry wide as best practice.
Humidity and temperature often work hand in hand to help or harm a green coffee. High humidity environments may encourage moisture reabsorption by the coffee beans, while low humidity environments will cause moisture loss. High humidity environments, in the most extreme cases, may promote dangerous conditions where mold and other microbes can affect the green coffee, and should be avoided. Again, moderation is the key to success with this metric, a usual range of 50-70% relative humidity with moderate temperatures is the accepted standard.
The International Coffee Organization cites some scientific studies that help establish these ranges. Cup quality remains stable for 200+ days at 70% relative humidity, while fungal growth is inhibited at 60% and below. Above 80% relative humidity, the risk factors for hygienic storage increase significantly, promoting the growth of fungi.
Humidity’s relationship to temperature is complex, and worth looking at a little more closely. Warm air can hold more moisture, which is why we speak about environmental humidity in relative terms (its percentage) rather than absolutes.
If a coffee is stored in conditions where the temperature fluctuates, then relative humidity is also in a state of flux. At 60F and 60% humidity overnight, the coffee may be in ideal storage conditions, but if the warehouse temperature rises to 80F during the day without the introduction of a new humidity source, the relative humidity will drop significantly and increase the chances of drying out the coffee beans.
Thus, moderate and stable temperature and humidity should be the goal for good green coffee storage.
Coffee traditionally ships in jute bags or similar plant-fiber (like burlap or sisal) weaved packaging. The fibrous material is inexpensive and easy to manufacture but offers very little protection for green coffee during shipping and storage.
Recent innovations in coffee packaging have dramatically improved upon and in some cases replaced plant fiber sacks completely. GrainPro and Ecotact packaging are probably the two most popular among a slew of plastic-type bag liners which are inserted into jute packaging or may be used at larger scale to line an entire 20’ container. The plastic is typically multi-layered with a semi-permeable structure to allow coffee to “breathe” while preventing the loss of organic material due to environmental challenges. Empirical and anecdotal evidence supports the use of this style of liner to preserve physical and sensory quality in green coffee. These types of packaging help prevent loss of organic material during less-than-ideal shipping conditions and may extend a coffee’s optimal shelf life for months. It’s important to securely cinch the semipermeable bag if less than the full amount is used, as a GrainPro bag left open will not have the intended protective effect.
Other common packaging solutions for green coffee include paper liners for jute bags, and jute replacement options like polypropylene (plastic) and vacuum sealed bags. Vacuum sealing green coffee works great for quality preservation and protection from humidity loss, but once the vacuum seal is broke, the coffee should be used within a few days (much the same as with thawed and then frozen green coffee).
Some roasters like to house their green coffee in storage bins. Bulk storage options like silos can be convenient ways to combine larger lots, or store large quantities for long periods of time. Smaller options like plastic Cambros or bins can help keep leftovers from a roast for the next day, and can be fitted with casters for ease of mobility. But storage bins are rarely airtight, and while they may provide better protection that jute, they’re no substitute for hermetic environments, and should be insulated for best results.
If your green coffee is stored in a facility where food or beverages are served (like in a café with a shop roaster), you may be required to keep the green coffee in its original packaging (or use food-grade containers with clear date labels) and store the green coffee in approved food-safe shelving, depending on your local regulations.
Shelving & Pallets
Shelving and palletization of coffee bags is a very common method for storage, and provides a number of advantages for roasters. At scale, large quantities of coffee can be cycled easily through a well-organized warehouse using forklifts to promote a “first in, first out” approach to using green coffee and making it possible to store coffee safely and maximize the use of vertical space. Even at smaller scales, a pallet can make coffee storage convenient, stacking bags to save space and keep the coffee off the ground.
Food service and handling regulations may vary regionally, but the Green Coffee Association has issued a resource that helps to outline some best practices that can be employed at any warehouse size. They recommend the following:
- Keep coffee off the floor, a minimum of 4 inches.
- Keep the pallets clean.
- Keep coffee 24 inches (two feet) from walls and ceilings.
- Store coffee so that at least two sides of each bag are available for inspection and sampling.
- Maintain 20 inches between coffee piles.
Additionally, certified coffees (like organics, specifically) will need isolated and labelled storage areas to maintain their certification. Pallets, shelves, and bins for organic storage cannot be used for conventional coffees.
While coffee isn’t usually the favorite food for rodents or bug, pests still pose a problem for stored coffee and must be monitored and controlled. Don’t provide opportunities for infestation (like holes in your walls and spilled coffee on the floor). Rodents and insects, in addition to being destructive, can be a risk to health and safety and should be taken seriously.
Contacting a pest control professional is a good option for infestations. However, some coffees (like certified organics, for example) shouldn’t be exposed to certain treatments, and chemical solutions in general should be avoided in proximity of all coffees.
For insects, the most common coffee pest, there are a couple of good chemical-free solutions. Infested coffees should be immediately quarantined, and may be subjected to a hermetic environment (GrainPro offers a number of scalable options, for example) where oxygen is either pumped out or at minimum no access to fresh air introduced. Depending on the available oxygen in the environment, the bugs will die over the course of a few days to a few weeks. A more drastic treatment involves freezing the coffee. Royal Coffee was required to subject some coffees to this treatment a few years ago, you can read about the details and implications here.
A few other uncommon problems
Sometimes stuff just happens. While it might not be in the power of the roaster to control all coffee circumstances, you can be aware of the risks and responsibilities at various stages of the supply chain (check your INCOterms) and communicate calmly and clearly with your supply partners (like Royal) who are willing and able to help bring problematic situations to amicable solutions.
Here are a few examples of uncommon problems Royal has experienced in the past.
This container was flooded in transit. Some of the coffee was salvageable (hermetic bag liners really saved us here!), but some was a total loss. Insurance covers catastrophic loss (financially) but we were still in a place where we had to find a quick replacement for contracts which couldn’t be fulfilled due to ruined coffee. Try not to let your coffee get wet!
Transit Damage & Delays
This container was on its way from the Port of Oakland to our warehouse, a pretty short drive. However, the third party trucking company in charge of transporting the container reported a problem. It seems an operator somewhere along the line didn’t double check their equipment, and the chassis separated from the truck, causing some damage to the container and a little bit of coffee loss, as well as a few days delay.
Minor delays like this aren’t usually a huge quality concern, but delays across an entire supply chain can start to add up. This is where important metrics like green coffee moisture, as well as good packaging (e.g., hermetic bag liners) can make or break the difference between a well preserved product and one that shows physical or sensory loss on arrival.
Here’s one more problem I saw once while traveling in Southern Tanzania.
Narrow roads, poorly constructed or subject to harsh environmental factors (like heavy seasonal rains, e.g.) can cause serious transit problems. Not only was coffee damaged, destroyed, and delayed as a result of this head-on collision, but people were injured.
Just another reminder that the supply chain is long, there are a lot of hands involved in getting coffee from the tree to your cup, and that there’s always the chance something unexpected could arise. Being prepared with good storage solutions and in regular contact with your supply partners will help alleviate even the least expected circumstances.