Comparing pre-ground and freshly ground coffee over time...
Those of you who know me would likely agree that I tend towards being quite particular. Quite particular about things that evoke my interest and passion. One such topic is coffee and grinders and grinding on demand each and every time one makes coffee. I have, for the longest time, subscribed to the view that in terms of usable freshness, green (unroasted coffee beans) can last for THREE YEARS, roasted (but not yet ground) coffee beans can last for THREE WEEKS, and ground coffee can last for THREE MINUTES.
Time to eat my words (on a couple of different fronts). Firstly, I've been finding that I've been enjoying unground coffee beans for at least double the time recommended above (6-8 weeks). More importantly I decided to look at the difference between pre-ground and grind on demand coffee over time. I ground some Croydon Blend last Wednesday and kept a sample of exactly the same coffee to grind on demand each day and compare.
I was very pleasantly surprised about the quality and flavour characteristics of the pre-ground coffee. I found that it stayed quite fresh up until day two. It is still very pleasant at day eight although bitterness started to noticeably increase at day five and overall intensity and acid quality started to diminish at day three. Today's (day eight) pre-ground coffee was still better than the freshly ground and extracted coffee that I have at most cafés.
I continue to have two fundamental concerns about using pre-ground coffee. The first is that although good, pre-ground coffee does not achieve the intensity nor great balance of acidity afforded by grinding coffee on demand. The difference is noticeable. The second is that as coffee matures (the time since roast date increases) one can grind finer to maintain the quality of the extracted coffee over time. That clearly can't be done with pre-ground coffee. So the quality and consistency of extracted coffee is best maintained by grinding on demand.
The bottom line though, is that I am very pleasantly and positively surprised by my experience with pre-ground coffee. I honestly thought it would be an abomination... how wrong I have been.