I have a De Longhi Espresso machine that takes ground coffee. When I use normal coffee (for example with Illy Classico), the coffee is foamy and generally very good. 

When I do exactly the same thing with decaffeinated coffee (for example Illy Dek), the coffee comes out watery and actually quite bad, with the filter getting almost blocked and steam coming out of the side. With decaf, the coffee seems to block the water, making the flow very slow. I tried to vary the quantity and compactness of coffee in the handle to no avail. I also tried to descale the machine, but the decaf remains watery and undrinkable.

Is there anything I'm missing? Why is decaf behaving so differently?

  • 3
    I like the Supercritical CO2 process myself: en.wikipedia.org/wiki/Decaffeination#Supercritical_CO2_process But if you look at the link, you'll see that decaffeination is basically a chemical horror show. Caffeine dehydrogenase does not work well on caffeine trapped inside ground coffee: en.wikipedia.org/wiki/Caffeine_dehydrogenase No matter how you do the cffeine extraction, you lose a lot of components that are not caffeine. Hence the different behavior. Commented May 20, 2019 at 23:55
  • @WayfaringStranger reads like an answer to me?
    – Stephie
    Commented Jun 2, 2019 at 7:37
  • @Stephie Yeah, I see that, but to do right I need to find 10 or 12 references. -So it's a comment. Commented Jun 2, 2019 at 14:50
  • @WayfaringStranger well, as an experienced mod once told me when I was new on the site: a half-answer can always be edited and expanded, comments are temporary by design. I would hate to lose the information but I will delete the comments at some point.(Partly because we’re trying to enforce the “no answers in comments” policy.)
    – Stephie
    Commented Jun 2, 2019 at 15:36
  • @Stephie OK. I'll see if I can get lucky with refs. I know there was a book published back in the 70's. Maybe Google scanned it. Commented Jun 2, 2019 at 16:02

2 Answers 2


The decaf process alters the grind and other properties in the coffee.

You should first try a more coarse grind.

And don't use a bladed cutting grinder, to much clogging dust, use the grinders with two spaced ceramic disks for better results. Fine tune your grind size.


Decaf coffee has very little or no oils after roast - in order to get a semblance of cream during extraction the grind must be finer than you would have in caffeinated coffee. Also check if the coffee is old, as the age is also a determining factor.

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