This is like a follow up to my blog post of 7 March 2008 called “how can you tell if your beans are fresh“. In summary to that previous post, I gave some pointers on what coffee looks like when it is fresh and extracted. Now, it probably seems like a contradiction when I say”how can you tell if your coffee is too fresh ?” 
 Again, the short answer is that you cannot just tell by looking at it – see above.  You will have to wait until you get home and try and pull an espresso or use another brewing method. In any case, I recently fell victim to this scenario and really the warning bells should have been ringing when I asked the roaster at Alt Wien when the beans were roasted – his answer “a few hours ago” OK! I thought, I should really be happy about this but I recently read that very fresh beans need to “de-gas” before they are ready for drinking. In short, when you roast green beans you are changing the chemical and physical attributes of the coffee bean but the coffee bean needs time to adjust to its changed attribute after being exposed to very high temperatures. What happens is that gases that have attached themselves to the bean need to “come off” so that the bean can return to some sort of natural state – have I lost you ? Perhaps, because I think I have lost myself too. Really, I’m just trying to summarize the chemical stuff that happens to coffee beans after they have been roasted in as simple a way that I can. There’s also some problems with dark roasted coffee beans, where the oil on the bean can be “too oily” leaving oil sediments on your machine.  In short, the coffee beans basically need to “de-gas” or let off some steam literally. I hinted at this to the Alt Wien Roaster and he replied “it’s OK in a domestic machine but for a commercial machine, the beans need to de-gas for at least one week” so I’m thinking, a domestic machine -Yes ! I have one of those, but my machine has some commercial parts (E61 Group head and lots of real brass, etc). I trust him and I pay the price. Sure, the beans smelt really fresh but my first problem was in trying to get the right grind for pulling a shot of espresso in 23-25 seconds. Then I was wondering as the coffee was coming out, why it was bubbly and making lots of hissing noise. So, the first sign is that the espresso shot will have many bubbles – some sort of chemical reaction (see below). 
  I also noticed that once extracted, the coffee was lightish in colour despite the right time for extraction; 
 The final straw was of course the taste test – the coffee was sour around the middle part of your tongue. Now, as you know, really fresh coffee that has been taken care of should not taste bitter or sour, so that got nme thinking – what’s wrong ? I tried stuff like leaving the beans out all night in a big metallic bowl so that they could let off steam, but that didn’t work. I tried another brewing method, French Press, but still the taste was sour. Then I thought, based on stuff that I had read, to leave the beans in their bag for about a week. I was bordering on being mad, because to compensate for my ever increasing coffee appetite, I decided to buy a 500g bag for the first time. In trying to apply my general culinary skills to the situation, I thought, if the bean could talk, perhaps it would say “hey ! I’ve just been exposed to 450 F, let me cool down a bit before you get the best out of me”. It’s almost like trying to toast freshly baked bread – it’s going to burn a lot quicker. In any case, not being a chemist, I thought there’s some sort of proper chemical explanation for this. Anyway, I’m glad to report that after leaving the beans for a week in their original bag, well sealed, with no exposure to air, there was a big difference. Firstly, although the coffee may not have smelt as nice as earlier, it was now easier to find the right grind setting for a 23-25 second pull for an espresso and the colour was back to dark reddish crema – see below;   
 Also, good for latte art and impressing your friends (OK ! I’m joking about the last).   
 So next time your coffee roaster tells you the coffee is really fresh, ask them how fresh. A few days can be good, say 3 days, but I have learnt that the mistake made by the roaster was putting the fresh beans into a sealed vacuum bag immediately after roasting as opposed to letting them de-gas by their own. If it is freshly roasted, it should be left alone and not bagged up.  I can even say now, as I am drinking this coffee (Organic Bolivian)that after about 10 days the coffee is even better, especially for espresso – the sweetish taste is back. Ciao
Passionate about the bean
From Coffee With Love 