37

The rule of thumb is that you first drink coffee approximately 3 days after it is roasted, but what is the exact reason for this?

  • I find approximately 3 to 4 days. It all depends on the bean and the roast level it's important how you store your beans store cool dark area – user2422 Apr 9 '16 at 18:10
  • I just roasted Costa Rican Nectar (private reserve) green coffee beans to a light medium roast. let them cool for a half hour or so, ground them up and made the most delicious cup of coffee I have ever had. So not really sure why one must wait for days for a fresh cuppa. I am just following instructions from someone on u-tube. I drank the coffee black, my normal cup o joe consists of cream and 1 full sugar so this is the best thing ever finally not using cream and sugar in my coffee. It compares to going from white wine to a red wine drinker. I hope my next batch comes out just as good, if so – user3794 Jan 30 '17 at 0:31
30

Fresh off the roast, coffee has high levels of carbon dioxide and nitrogen (based?) gasses. These gasses will greatly contribute to retro-nasal activity as well as initial flavors (think carbonated water). The most apparent flavor one gets from this is metallic. At my work, 4 days is considered minimum for serving and tasting, although there's always exceptions.

  • To extend the question a little. What if the coffee is grinded and left to deoxidize for one day, would it be sufficient to accelerate the process? – JavaCake Jan 27 '15 at 21:16
  • 1
    Coffee degasses and oxidizes faster when ground due to exposed surface area. So yes, grinding coffee greatly increases aging, but not at an ideal rate. – John Snow Jan 27 '15 at 21:20
  • 3
    4 days is quite a bit of time for most varieties of bean. A few varieties benefit greatly from 3+ days of rest, however I believe that is the minority. It's possible your work place made that a standard to avoid serving/dispensing those varieties that need the extra time too early. That being said, I find that almost all of the beans I roast do well with 12 to 24 hours of rest. I notice peak flavor consistently around 24 to 72 hours post roast, and then it drops off after. Waiting 4 days for most of my beans would miss their optimal window. – Suspended User Apr 29 '15 at 23:42
  • I can tell you from experience that when cupping my work's coffee, less than four day old coffee had a significant difference in flavor, leaning towards a tin or aluminum flavor rather than flavor from the salts and acids. I do believe that what you report, is what you experience, but we set those days based on flavor. When I have customers buying our coffee, I tell them how long we wait, because we wait that time for a reason. – John Snow Apr 30 '15 at 0:17
  • @JavaCake in case its not 100% clear, "greatly increases aging" means this is not a good idea. Grinding coffee beans more than about 15 minutes before you use them will significantly degrade the flavor of the coffee. – Rick G May 1 '15 at 17:42
22

The flavor and aroma of the beans continue to develop for the first few days after roasting as the beans release gas (this is the reason some retail coffee bags have valves to let the gases out). The process is similar for bread, with some bakers preferring to let some types of bread rest longer than others.

Right now I am actually drinking a cup of coffee made from beans I roasted this morning, because of poor planning. There's nothing wrong with it but I think it will be better in a couple of days. I find the aromatic qualities peak about 24-48 hours after roasting, but that may be because the off-gassing process is literally emitting the most fumes.

How the flavor changes

Subjectively, I'd say the smell and taste change like this:

During early roasting, there are wood and vegetable smells, like when you put green wood on a fire and it puts out a lot of moisture-filled steam and begins to smoke.

Toward the end of the roast, the smell is more from the browning/caramelization/Maillard reaction and smells kind of like burnt toast. Not really much like coffee.

If you grind and drink it immediately after roasting, it tastes like generic coffee, with those toasty flavors foreground. Very simple and straightforward without a lot of nuance.

After 24 hours the toasted character has diminished and the nuances have developed a lot more. You can really notice the difference between bean origins. There is much more powerful rich "amazing coffee" aroma. I find the sheer quantity of aroma very appealing at 24-48 hours.

Some beans continue to change for several days after roasting. Recently I had a batch of Indonesian beans that were still developing and becoming more characteristically Indonesian after a week. I liked them more, but someone else might have liked them less.

And that, when it comes down to it, is what matters. Some people find some varieties more interesting, more palatable or less harsh as they age. But de gustibus non est disputandum.

It's amazing the human nose and tongue can sense these differences.

See also

  • 1
    +1 for the "see also" section, however the Sweet Maria's link is now 404... – Mark Edington Sep 11 '16 at 2:15
7

Ethiopian coffee ceremony cases from hundred years ago until now, they brew coffee just after the coffee bean cooled, they have no de-gassing time they solve this smoke like off-flavor problem with fine grinding and boiling once again after they pour coffee ground to the Jebena with hot water . Also, they roast coffee to Italian roast degree which has very small smoke remain. Degassing time can be shorten as the roast degree gets darker. My full-city cases it need at least 12 hours and maximun flavor at 3days From Korea, Jinsung Lee Ph.D.

  • 1
    An interesting perspective. – hardmath Feb 23 '16 at 2:20
  • May I ask if your Ph.D. is related to coffee? – CivFan Mar 30 at 0:45
4

Edit 02/26/2016. I am now convinced that resting the beans is necessary. There are just two many roasters I've heard from (on here and in person) that believe it is necessary, and I have seen with my own eyes changes in the appearance of the beans a day after the roast (they seem to darken a bit).

Previously (while still unconvinced). John Snow's and Nathan's answers sound very plausible, but I'm still not convinced that resting fresh-roasted coffee (past the point of cooling) improves its brewed taste. As far as I can tell, no one has ever proven this. DISCLAIMER - I don't want to believe it, because I think brewing after roasting is fun. But I will eventually listen to reason if strong enough arguments present themselves. Below are a couple of points that allow me to remain in disbelief.

There's a guy on YouTube claiming the resting fresh-roasted coffee principle is a myth due to a mistaken case of cause and effect from unskilled coffee shop employees. He goes so far as to tell his own myth of a teenage kid (suffering from acne - nice touch) who sees his employer resting the beans and makes the conclusion that they're better after they sit. But really, the employer is letting the coffee rest because it's impossible to brew large amounts of really fresh roasted (it will explode or something) and the teen is just too lazy to ask. He just wants to smoke weed.

Now if you're not convinced by the explanation above, the only scholarly source I could find is Michael Sivetz's Coffee Processing Technology, Volume 1, where on page 248 he writes,

Beans cannot be ground directly after roasting as they are too soft and would be crushed, flattened, and scarred. When the beans are cool, hard, and brittle, they may be ground.

So I just have to cool them down? Ok, I may be extrapolating a bit since this book is about getting coffee to the masses. And it's very old.

Finally, I'm not a scientist, but I just don't see how carbon dioxide escaping from a bean is going to change the flavor of brewed coffee, especially considering the bean is about to be pulverized and soaked in near boiling water.

  • 2
    I am a coffee roaster, and have experimented for a few years with "resting time" for various coffees. In general, lighter roasted coffees need 1-2 days more time than darker roasts. Most of the coffees I roast need 3-4 days of rest. One crazy outlier was the 2014 Yemen Red Cherry bean. It was not too great after 4 days, and needed at least 7 days of rest. I decided it tasted best at 9 days after the roast. – Rick G May 1 '15 at 17:48
  • Regardless of the actual chemistry involved, my personal experience is that 3-4 days is required for the coffee's flavor complexity to be fully developed. I've tried multiple times to convince myself this is a myth but my mouth knows the truth. Let it rest. – PJNoes Feb 23 '16 at 18:04

protected by Community Feb 27 '17 at 11:47

Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).

Would you like to answer one of these unanswered questions instead?

Not the answer you're looking for? Browse other questions tagged or ask your own question.