So the grinder at this new cafe I’m working at has been a pain in the arse.
I can’t seem like to set up the ground so that the colour turns yellow and pale at around 25-30 seconds. It takes like 40 seconds or more! And the taste is very very bitter at 40 seconds. But everything else seems to Ben correct.
Here’s a vid of a shot being poured
Here are the details of the current settings
Double shot powder weight: 20g
Espresso liquid in 29 seconds: 55ml
Machine temp: 125 degrees
Machine pressure: 12.5 bar
Usual approach is to grind finer which I’m sure you’ve tried what was the result? Are you using the setting that they have always used for espresso? If so, and they extracted at 25-30s then maybe they tamped overly hard to compensate for too large of a grind?
Need a bottomless portafilter to see if there are channeling issues.
So, one way of troubleshooting is to stop the shot at 40ml. Check the time and then taste. If bitter still, then 35ml. If not, then 45ml and so forth.
I would find the acceptable taste first, just for cafe service and then work on the problem separately.
Could also be a problem with the machine not generating enough pressure, nevermind what it reports as the pressure.
I wouldn’t get hung up on the color of yellow though, looking more for a transition change of color to a “thinner” color…
Many other people know more than me on this topic, I’m sure they will chime in to help.
To answer your question, I would say that yellow doesn’t necessarily mean perfectly extracted. It is tough to correlate colour and flavour. I would focus more on the recipe.
Maybe try making the grind finer until you get 40ml of coffee in 30s (+/- a few seconds) by making the grind finer and then follow @homecafe’s advice: smaller shot if bitter, larger shot if salty/sour. 55ml is a lot of coffee coming from 20g. Most coffees I work with start getting bitter/dry at around 43g-45g, or smaller (38g-40g) depending on the grinder.
What grinder are you working with?
If adjusting the recipe doesn’t help: can you see any channels/holes in the puck after the shot is done? It looks like it’s coming out pretty thin & fast, and 12.5 bars seems like a lot of pressure. Perhaps the high pressure is forcing the water to channel through the puck?
Also, if Fahrenheit, then 125 degrees is very low, and if Celcius, then 125 degrees would be quite a high boiler temp. Too high a temperature could contribute to faster flow rates than desirable and bitter flavours being extracted quickly. It seems that most people brew in the 195F-204F range (90.6C-95.6C). If your boiler is set to 125C, the water would be coming out at or just under boiling temp.
Hope this helps.