‘Fresh’ is a term in coffee that has been overused by retailers and consumers alike, to the point that it doesn’t mean anything anymore. What is freshness?
Roast dates have become a popular trend amongst quality coffee companies in order to educate the consumer about the importance of having coffee that is roasted recently. The aromatics of coffee only make up for a small percentage of the actual gases in a coffee bean.
^ Close up of roasted coffee
The majority of the gas in roasted coffee is carbon dioxide, which slowly diffuses out of the bean allowing oxidation to occur. CO2 helps to protect aromatic volatiles from oxidization, which is why we notice a drop off in the quality of a coffee 10-14 days after it is roasted when a great deal of the CO2 has diffused out of the bean. The structure of coffee is composed of multiple small chambers that trap CO2 and aromatics, which is why ground coffee degasses much faster than whole bean.
Aromatics are flavor. The notes that we taste in coffee are related to the fantastic smells that we experience when we grind coffee. This is why it is so important to grind coffee right before you brew it. The surface area that allows carbon dioxide to escape is at its smallest when coffee is in its whole bean form. If you grind that whole bean up in to tiny bits then you have ultimately increased the surface area exposing most of the coffee to oxygen greatly decreasing the amount of time we can consider your coffee to be fresh. About 50% of the CO2 in coffee is released within the first 5 minutes of grinding.
Think of an apple. If we allow an apple to sit out in its whole form it lasts for quite a long time. If we cut into that apple exposing its flesh it quickly turns brown.
CO2 can be a bit irritating when we are brewing coffee because it is released rapidly in hot water causing the coffee to bloom and rise to the surface of the brew creating a concentration gradient. This is remedied through pre-wetting the grinds to release CO2 before we add the majority of our brew water or by agitating the grinds to produce a more uniform brew. The closer a coffee is to its roast date the more violent the CO2 reaction will be. Coffee with a few days of rest is much more consistent to brew because the CO2 reaction can interfere with the dissolving of brew solids, and coffee with some rest has far less CO2 than it does directly off of roast.
There are many methods that help to preserve the quality of coffee for longer than the roughly 14-day window after it is roasted. Replacing the oxygen in sealed containers with nitrogen can help to protect the beans exposure to oxygen by balancing the atmospheric pressure because it is a similar weight to oxygen, yet doesn’t oxidize the coffees volatile aromatics. Nitrogen flushing does help to preserve quality of flavor while the bag is closed, but as soon as the bag is opened the degradation of the flavor is far quicker than if you package without the addition of nitrogen.
Freezing is also an option, but a labor intensive one. If coffee that is fresh off roast is not an option freezing may be a last resort technique that might work for you. Typically coffee companies will tell you that freezing coffee is a bad idea, but it is the best option if you want to consume coffee at a date later than two weeks off of roast. The moisture in roasted coffee will not freeze at temperatures that your ordinary household freezer can produce because they are chemically bound to the coffees structure. Coffee will however absorb moisture from the air around it so it is important to properly seal coffee that you will freeze. It is best to package the coffee that you put into the freezer into individual portions so that you don’t defrost and refreeze the coffee. Squeeze as much oxygen out of the package as you can and make sure that the package is sealed to not allow any moisture from the freezer to be absorbed by the coffee. As much as I might like my coffee to taste like the bacon in my freezer, I wouldn’t want the freezer burnt tastes that accompany it.
{ 7 comments… read them below or add one }
I appreciate the QR codes that Ethical Bean has on their packaging, but it is a bit of a double edged sword as I found a lot of 3-6 month old coffee on the shelves, which I refuse to buy. However, I did eventually find one just a week old amongst the pile. It is sometimes hard to find fresh coffee once you leave the major city centres.
If you buy coffee from a cafe there is no reason that you should be sold older coffee. Once coffee is a week old it should be taken down and used to prepare coffee in the cafe. It’s an ideal situation when you can use coffee that is within a 7-10 day zone where the coffee is properly degassed and I find usually at it’s most delicious. If you keep your orders low then age should never be a problem, but you risk running out of some coffees. I don’t think this is a bad thing. If you consistently serve fresh coffee that is a good representation of the quality that a region has to offer then you shouldn’t have a problem building a loyalty towards all your coffees.
Paul,
Freshness in grocery stores in a constant battle. Unless you’re at a more specialty retailer, where staff actually care about food rather than just having a job, you’re going to have problems. They just don’t rotate, they cram the new stuff in the front. They refuse to run out, because they’d lose sales, although I bet they have no metrics on how many they’re losing because they’re product is 6 months old. And last, they want to have every product under the sun, so rather than doing a few things well, they want to cover the entire market.
Do you have any tips on how to spot old coffee (other than not buying from a grocer) when there is no roast date on the bag?
If there is no roast date on the bag you shouldn’t buy it. If the retailer isn’t transparent enough to reveal the age of the coffee they don’t deserve to be given the benefit of the doubt.
Great article, you did the science stuff justice without using the jargon. I feel that when the average consumer is speaking about the ‘freshness’ of their coffee, they’re typically referring to whether that carafe of coffee has been sitting around all day. Thoughts?
Hi Connie.
The word carafe makes me smile. What I usually see is the diner-style heat pads that heat coffee and allow aroma to escape. Thermal carafes are the best choice. If you can find one that maintains heat well and seals the coffee from the outside air your coffee will last a lot longer. When I brew a pot of coffee I have my brewer set up to fill the carafe as much as possible and then I seal it off from oxygen. This substantially prolongs the life of the coffee because it limits the amount of aroma that can escape. After you pour your first coffee space is created in the carafe for aroma to escape and you need to think about how much time your coffee has to remain within delicious territory. Larger airpots are impractical because no cafe will ever be able to go through the amount of drip coffee that they hold within the amount of time that it needs to be sold to still taste good.