The Freshness Timeline
| Days After Roast | Stage | What to Expect |
|---|---|---|
| 0–2 days | Too fresh | CO₂ still off-gassing aggressively. Coffee will taste flat, underextracted, and gassy. |
| 3–7 days | Rest period | CO₂ dissipating. Light roasts still benefit from more time. Beginning of drinking window. |
| 7–14 days | Peak window | CO₂ balanced. Full flavor development. This is when most specialty coffee is at its absolute best. |
| 14–21 days | Still excellent | Flavor gradually softens. Most people can't tell the difference from peak. |
| 21–35 days | Acceptable | Noticeable flavor flattening. Less brightness, less complexity. Still worth drinking. |
| 35+ days | Stale | Oxidation has degraded most volatile aromatics. Tastes flat, papery, or cardboard-like. |
What Is CO₂ Degassing?
During roasting, the Maillard reaction and caramelization produce large amounts of carbon dioxide gas trapped inside the bean. After roasting, that CO₂ slowly escapes — a process called degassing (or off-gassing).
CO₂ isn't flavor — it's a byproduct. When you brew coffee too soon after roasting, the escaping gas creates turbulence in the extraction, produces an uneven brew, and blocks water from properly saturating the grounds. The result tastes hollow, sour, and gassy.
The standard rest recommendation is 3–5 days for dark roast and 7–14 days for light roast. Lighter roasts are denser and take longer to degas.
Why the Bloom Step Exists
The bloom in pour over (and other methods) is directly related to degassing. When you pour the first 30–50g of hot water over fresh grounds, CO₂ rapidly escapes — you see the coffee puff up and bubble dramatically.
Waiting 30–45 seconds during the bloom allows the majority of remaining CO₂ to release before you add your main water. If you don't bloom, CO₂ creates gas pockets in the grounds during the brew, leading to uneven extraction — some grounds over-extracted, some under.
The freshness test: If your coffee barely blooms when you pour hot water over it, the beans are probably past their prime — CO₂ has already fully dissipated, taking much of the volatileflavor with it.
Roast Date vs Best By Date
A "best by" date on a coffee bag is legally required in some states but tells you very little about freshness. Many mass-market coffees have "best by" dates 12–18 months after packaging — often beans that were already 3–6 months old when they were roasted and packed.
The only date that matters is the roast date. Specialty roasters like Roast print the roast date on every bag so you know exactly where you are in the freshness window. If a bag doesn't have a roast date, that tells you something.
Signs Your Coffee Is Stale
- No or very little bloom when hot water hits the grounds
- Flat, muted flavor — complexity gone, just generic "coffee taste"
- Papery, cardboard-like aftertaste
- The bag was opened weeks ago and stored loosely
- No roast date on the bag, or roast date older than 30 days
Related Guides
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