Coffee Preparation & Taste
Updated: Dec 17, 2020
Espresso coffee brewing is a process of coffee making that was developed over the last century by the Italian culture.
Espresso is the only coffee brewing method that can extract the best of the over 900 aromatic compounds found in roasted coffee, without including naturally occurring acids.
These 'Chlorogenic Acids' are often referred to as tannins or 'Tannic Acids'.
If espresso coffee is poorly prepared, these acids can give the brew a slightly acidic or bitter (astringent) taste which is quite difficult to avoid in other brewing methods.
As an Amazon Associate I earn from qualifying purchases made through links on this page.
Well prepared Espresso coffee should use "freshly roasted" beans.
Depending who you ask, you will get slightly differing explanations of what "freshly roasted" can mean.
Bagged roast coffee beans often (should) have a roast date stamped on each bag.
Staling of coffee is not a directly time-based process, that is to say that coffee cannot be considered fully stale in x-days or x-weeks, but from the moment coffee is roasted it begins to stale due to oxidation. The more time oxygen has to work on the beans, the more it will stale.
To complicate matters, roasters haven’t agreed upon the definition of what “stale” really means for coffee! James Hoffman in his book The World Atlas of Coffee puts it like this “The specialty coffee industry has failed to make a real impact because there is no strong agreement on how quickly coffee goes stale, and at what point it will have passed its best-before date.”
Each roaster generally has their own use-by guidelines which are generally between two and four weeks.
How quickly beans oxidise after roasting depends a great deal on processes like the packaging.
There are different types of bags like the triple-ply foil which prevent fresh air from getting in but allow the carbon dioxide produced after roasting, to escape via a one-way valve.
There are also other packaging techniques such as nitrogen flushing which helps preserve coffee beans by flushing away the oxygen to eliminate the staling oxidation process, until the bag is opened for use, at which point oxygen then finds its way in and begins to stale the coffee. This does of course mean the beans will have a better un-opened "shelf-life".
With oxygen and moisture being enemies of fresh coffee, the best way to store and keep coffee as fresh as possible is to store it in a cool, dry place. Once water (a.k.a. moisture in the air) comes in contact with beans, it starts the brewing process and extracts the flavour.
Products like the AirScape Coffee Bean Canister are useful to store coffee in, as they also use a one-way valve to push out oxygen and air-tight lid to keep air/moisture out between uses, which helps maintain coffee freshness.
Done properly, freezing pre-ground coffee can also offer benefits. One benefit is that when using it for espresso, if you freeze ground coffee, it’ll dissolve faster in hot water and extract a richer, thicker body with fuller flavour. However, once you take the ground coffee out of the freezer, you mustn't let it thaw before using it, as Coffee is hygroscopic. This means that it absorbs moisture from the surrounding environment very easily, so you need to keep it as dry as possible.
With frozen coffee, any moisture that condenses on the coffee during thawing will start the extraction process and leach out much of the aroma and flavour from the beans or grounds!
Heat is also an issue for storing coffee.
When coffee beans get too warm the oils which provide the major source of flavour, start to sweat onto the surface of the beans. Since these oils are highly volatile, they will quickly evaporate, so once again losing much of the flavour and aroma you could potentially capture during brewing.
You will notice that dark Italian roasts that look almost black on the surface, are quite oily, this is due to the longer or hotter roasting time which reduces the sweetness and leaves an ashy aftertaste.
Optimum coffee storage temperature should be around 20 to 25C
Essentially, you want to store your coffee beans in similar conditions to wine, so always keep it in a cool, dark and dry place and you’ll maintain all of the precious aromas and flavours which make up a superb brew!
What "freshly roasted" means
So after much research and comparison of explanations, it appears that "freshly roasted" (for espresso use) means waiting at least 5 days (typically between 7 and 11) after the roast date before starting to use the beans.
This is because after roasting, coffee emits a number of gasses including carbon dioxide which if not expelled, unfavorably alters the flavour of the coffee.
This happens primarily in the first three to five days and is known as “de-gassing".
The early bulk of the degassing will occur within the first 24~48 hours, so its not unreasonable to grind and brew from then on, but the best flavor will likely not appear till after that.
Completely using those beans should then occur within two to four weeks of the roast date, to mostly produce the best tasting results. After about six weeks many beans will start to taste noticeably "stale" compared to their original rich mixture of flavours.
There’s no defined expiration or "best-by" date for coffee.
As coffee is volatile substance it will change rapidly, so how long coffee beans last also depends on many things including the type of coffee bean.
The one thing you can say for certain is that ground coffee has more surface area for oxygen to leach out the flavour compounds, so to keep coffee fresher longer, leave the beans whole as long as possible and grind them only when you’re ready to brew with them.
The smell of the coffee is probably one of the best indicators of freshness, therefore your nose is probably your best coffee-freshness detector.
The human tongue can only really taste five flavours, sour, sweet, salty, bitter and umami*(see our coffee-language post for an explanation of the "5th taste")
The nose, however, can delineate between thousands and thousands of distinct compounds.
Smell and taste are intimately linked as the brain processes both taste and smell in the same place/way.
So if your nose can’t smell rich coffee aromas, it safe to assume the flavour is also gone.
When all is said, however, as long as your beans are in a relatively airtight and dry environment, they should last quite well and any arbitrary "best-by" date-definition really comes down to when the processed coffee stops "tasting good" ... by your own definition of what "good" coffee should tastes like ... or comparative to what it tasted like immediately after the de-gassing period!
Since flavour is really the most important thing for coffee drinkers, it has to also be said that the freshest beans don’t guarantee the best flavour. Each coffee’s flavour profile is different, but once the volatile aromatics break down, so does the flavour.
During our research we came across comments like these:
"I bought coffee beans en mass for my store 9 years ago, ground them today and they still taste good"
"I had forgotten about a bag of coffee in my pantry, and the label said best before xx/2017. Although its a year old I've been drinking it. It is smooth but has lost a bit of flavour."
... so, you can see that just because the beans are "old" in date-terms doesn't mean they will be un-drinkable
For drip/pour-over, waiting 4~7 days before using the beans seems to be the common recommendation.
Completely use within 2~4 weeks (max 6).
For cold brew, wait 10-14 days before using the beans seems to be the common recommendation.
Completely use within 2~4 weeks (max 6).