18g in the stock double basket, 36g out, and the shot takes 38 to 42 seconds, which by every guide I have read should be over extracted. It tastes sharply sour with a bitter edge underneath. I have gone three steps finer on the grinder and it just gets slower and more sour. Single boiler machine, medium roast beans roasted 11 days ago.
Second thing to rule out, and it takes 30 seconds: check whether your basket is pressurised. The dual wall ones with a single pinhole underneath produce a slow looking shot with fake crema and taste flat and sour no matter what you do. If you can see many tiny holes across the whole bottom, you are fine.
Many holes, so at least that one is not it.
On a single boiler the brew water is often cooler than you think, especially on the second shot after steaming. Try a cooling flush routine, run water through the group for a few seconds until the boiler cycles, wait 30 seconds, then pull. Low temperature reads as sourness even with a perfect puck.
Grinder quality is the quiet factor here. Cheap conical burrs give you a mix of boulders and dust, and dust over extracts while boulders under extract, so you get bitter and sour simultaneously and no setting fixes it. If everything above checks out and it still tastes like this, that is where the money goes next.
Agreed, though I would exhaust the free fixes first. Plenty of entry grinders make acceptable espresso once distribution is under control.
Just keep grinding finer until it hits 30 seconds, sour always means under extracted.
Finer normally slows a shot down, so chasing a shorter time by grinding finer is going in the wrong direction, and they already said finer made it worse.
@burr_and_bloom · 2mo ago · 3 replies
Sour and bitter in the same cup at 40 seconds is the signature of channelling, not of a grind setting. Water is punching a hole through part of the puck and blasting past the rest, so some coffee is scorched and most of it is barely touched. Going finer makes channelling worse, which is exactly what you are seeing.
Order I would fix things in:
Only once the shot runs evenly should you go back to adjusting grind by taste.
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@soy_pour_sasha · 2mo ago
The puck had a little crater in the middle, so I clearly needed to look at it weeks ago. Paperclip stirring tonight.
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@outthedoor_otto · 2mo ago
Also watch the first few seconds through a bottomless portafilter if you have one. Sprays and jets tell you where the fault is instantly.
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