Because of the process the structure of the decaf beans are more porous, and easily extracts soluble components and fading quicker.
Of course it depends on initial variety, origin, altitude, roasting profile and date.
Though try to darker roast
- use lower temperature than usually you do for espresso (1-2C lower)
- Take a bit more coffee (0.5-1.5g more)
- Shorter extraction time 21-23sec,
- There is no need to go to the finest grinding, as it will over extract, you can take a bit coarser than you used to, though perhaps use preinfusion
- The best guideline is to check the coffee cake after brewing: water is spread evenly, there are no dry parts of too fine coffee, no left water inside
- decaf can be amazing, If customers are true coffee lovers though have to control caffeine consumption, they have the right not to sacrifice the taste.