Coffee facts · Brewing coffee
How can you tell if coffee is fresh? And what is specialty coffee?
Short answer: Look at the roast date, not the best-before date. Smell it: fresh coffee smells sweet and distinct, stale coffee smells of cardboard and paper. Brew it and watch the bloom: fresh, freshly ground coffee rises in a dome, stale coffee lies flat. Specialty coffee is recognised by traceability and even beans. But the term is not protected, so what counts is the roaster’s information on origin and grading, not the word on the bag.
Roast date, not best before
The first thing to look for on a bag is when the coffee was roasted.
The best-before date tells you how long the coffee is safe to drink and keeps an acceptable quality. On packaged coffee it is often far in the future, because the coffee is packed without oxygen. It does not tell you how long the coffee tastes at its best, and it says nothing about when it was roasted.
A roaster that is proud of its coffee prints the roast date. If it is missing, ask. The answer, or the lack of one, tells you a good deal.
As a rule of thumb for batch brew: many roasteries let coffee rest for a few days after roasting, and after that the next few weeks are the best window. The coffee does not become undrinkable afterwards, but the sweetness and the clearest aromas fade.
Smell it
Open the bag and smell. Fresh coffee has a clear, sweet aroma that differs between coffees: fruit and berries in a Kenyan, chocolate and nuts in a Brazilian, flowers in an Ethiopian.
Stale coffee smells flat and the same whatever its origin. Often of cardboard, paper or wood. Very old coffee can smell rancid, because the oils in the bean have oxidised.
Smell is the fastest test you have, and it is free.
The bloom
Pour hot water on freshly ground coffee and it bubbles, rises and forms a dome. It is called the bloom, and it is carbon dioxide from roasting leaving the coffee. How much the coffee blooms says a lot about how old it is.
| Age of the coffee | What you see |
|---|---|
| Freshly roasted, 1–3 days | A strong, almost violent bloom. Large bubbles, an uneven surface. So much gas that it disturbs brewing, which is why many roasteries let coffee rest |
| 1–3 weeks, freshly ground | A clear dome that rises evenly, fine bubbles, a surface that cracks as the gas escapes. This is the window most roasteries aim for with batch brew |
| 1–2 months, freshly ground | The bloom is still there but lower and shorter |
| 3 months, freshly ground | Hardly any dome. The surface turns dark and wet, a few scattered bubbles, the coffee sinks |
| Pre-ground, opened bag | No bloom. The coffee lies flat in the filter |
A few caveats, so the test does not fool you:
- The bloom shows gas, not flavour. It is a sign of freshness, not a measure of how good the coffee is.
- Dark roasts bloom more at first but lose their gas faster.
- Coffee packed with nitrogen can bloom longer than its age suggests.
- Ground coffee loses its gas fast. The test tells you most when the beans are ground just before.
- A brewer hides the bloom under its lid. Lift it, or do the test with a hand dripper.
As a rule of thumb: a coffee that does not bloom at all has already lost most of what protected its flavour. Why it happens so fast once the coffee is ground is explained in Whole beans or pre-ground.
Look at the beans
Pour a handful of beans onto a white plate, in daylight.
Even colour. Beans from a carefully sorted coffee and an even roast have roughly the same colour. A wide spread can mean the coffee is poorly sorted or unevenly roasted.
Pale beans among the dark ones. A pale, yellowish-brown bean that stands out is often unripe. It does not darken during roasting, and it gives a dry, earthy or peanut-like taste. Specialty coffee should have none.
Broken and chipped beans. A few are normal. Many suggest rough handling or poorer sorting.
A glossy surface. On dark-roasted coffee an oily surface is normal from the start. On a light or medium roast, gloss can mean the coffee is old, because the oils migrate to the surface over time.
Taste it
The final check happens in the cup. Stale coffee first loses what makes it interesting: the sweetness and the bright acidity. What remains is a flat, woody or papery bitterness, and the aftertaste disappears quickly.
Try comparing the same coffee from a newly opened bag and from one that has been open for weeks. The difference is usually clearer than you would expect.
What is specialty coffee?
“Specialty coffee” is not a protected term. Anyone can print it on a bag.
The best-known definition comes from the Specialty Coffee Association. Under the association’s 2004 protocol, specialty coffee must score at least 80 points out of 100 in a standardised tasting, known as cupping. The green coffee must also pass a physical grading: a 350-gram sample may contain no primary defects, such as black or sour beans, and no more than five secondary ones, such as broken beans. In 2025 the protocol was replaced by a new assessment method, the Coffee Value Assessment, but 80 points is still the threshold most of the industry talks about.
You will rarely get to see the green coffee or the score. But there are some clues:
- Traceability. Does it state the country, region, farm or cooperative, process (washed, natural, honey) and variety? The more you know about where the coffee comes from, the more likely it was chosen for its flavour.
- A score or grading. Some roasters state cupping scores. Otherwise, ask.
- Roast degree. Specialty coffee is often roasted lighter, so the origin’s flavour comes through. It is not a rule, but a very dark roast makes it harder both to see and to taste the difference.
- Roast date. Anyone who has paid for good green coffee wants you to drink it fresh.
- The beans. Even colour and no pale, unripe beans.
Price is a weaker clue than you might think. An expensive coffee is not automatically specialty coffee, but a real specialty coffee is rarely cheap.
Roasted on site
If the coffee is roasted where you buy it, or at your own place, you can see it: the machine is right there, and the roast date is yesterday or the day before. Then you also know exactly how long the coffee has rested and can brew it at its best.
What do you do with what you know?
If the tests say the coffee is fresh and good when you buy it, there are two places where it can still be lost: in a bag left open too long, and in ground coffee left standing.
The first you solve with the right bag size and a rolled-up valve bag. The second you solve by buying whole beans and grinding just before brewing. Read why whole beans beat pre-ground.
If you want full control of the chain, you can go one step further and roast yourselves. Then you decide the roast date, and every coffee in the grinder has a known age.
Science Brewing Grinder · Science Brewing Roaster · Green coffee
For the physics behind it: Grinding and extraction in batch brew.
Frequently asked questions
Is stale coffee dangerous to drink?
No, not if it has been stored dry. Stale coffee is a quality problem, not a safety problem. It tastes worse, but it does not become dangerous. Coffee that has become damp or mouldy should be thrown away, though.
How long do coffee beans keep after roasting?
For batch brew, the first few weeks after resting are the best window. Unopened in a valve bag they keep longer than that. Once opened, count on about one to two weeks for the best flavour.
How long does ground coffee keep?
It starts losing flavour right after grinding. Packaged ground coffee keeps a long time unopened because it is packed without oxygen, but the manufacturers themselves say an opened pack should be used within a couple of weeks.
Why doesn’t my coffee bloom?
Most likely because it is old or has been left standing ground. It may also be very dark-roasted and have lost its gas quickly, or the water is too cold.
Is freshly roasted coffee best?
Not in the first few days. Freshly roasted coffee contains so much gas that it disturbs brewing. That is why many roasteries let coffee rest for a few days.
Is an oily bean a sign of quality?
No. On dark-roasted coffee it is normal. On a light or medium roast it is more often a sign that the coffee is old.
Does “specialty coffee” on the bag mean it is specialty coffee?
Not necessarily. The term is not protected. Look for traceability, a roast date and preferably a grading or score from the roaster.
Sources
- Specialty Coffee Association, Grounding Green Grading in Sensory Science (SCA News), on the 2004 protocol and the move to the Coffee Value Assessment.
- Specialty Coffee Association, Coffee Freshness Handbook.
Who we are
Science Brewing exists to end bad coffee. We sell green coffee and build Science Brewing Roaster and Science Brewing Grinder. We roast our own production on the machine, in Halmstad, Sweden.