+1/2 to this. That is to say, on the setups I've spent much time on, a machine left dirty (or water-backflushed) overnight produces drastically different first and second shots. On some machines I've used, the difference can continue for several more shots. With a detergent backflush and a thorough rinsing at the end of use, the next session's shots generally yield some difference between shot 1 and 2, but the effect is far more subtle if it is even noticeable.tekomino wrote:I find no difference between first and second shot on my clean machines. My cleaning is very thorough and flushing of detergent is complete. Even plain water out of the group head after cleaning tastes neutral...
Also, I meant to include a few links to James Hoffman's on this topic:
- Reducing machine dirt buildup-great thoughts on the taste and cause of off flavors in an espresso shot from a dirty group.
- Seasoning a coffee machine-James suggests that whether you try right after backflushing or the next day, the thermal stability of the machine is at its worst on a machine and this likely accounts for the perception that the post-backflush shot tastes off.