I roasted a light Ethiopian Sidamo a few weeks ago and set it aside in a sealed pint jar to degas (quickly popping the lid from time to time to purge the buildup.) I played with it today using 203F brew temperature and shooting for a 2:1 ratio. No preinfusion just the gicleur slow ramp on the GS3. Once I finally got it to quit channeling with pristine puck prep, I got some pretty nice shots. One was particularly interesting. It was a fast shot at 24s. It had the sourness of being a fast shot but it was intensely sweet. So much so that it tasted like sugar was added. Very intense sweetness. I ground finer which pushed my time up hoping to lose the sourness. The sourness went away but so did the sweetness

My question would be, is there any direction I can go with either temperature, grind, dosing, etc that would keep the sweetness but lose the sourness? I may roast it a hair darker next time.

I'm using the Super Jolly with SSP Red Speed 64mm burrs (which I believe are the "espresso" set from Wholelattelove.) I do not have flow control. I believe it is quite a modification to tinker with flow control on the GS3 AV, but confess that I haven't looked into it much.

I can lower the pressure. It is currently set at just under 9bar using Peppersass's recommended technique.

Jeff wrote:One thing that i might try would be a longer ratio at that "almost great" grind/flow rate. 1:2.5 or even 1:3 might get you there.

A smaller dose might help if you're at 18-20 g. I run 17 g but others like 16, even 15 g as their "standard" for lighter roasts.

If it's not a pain to do, you might try lower pressures as well. I haven't pulled a light roast at over 8 bar in a long time now. Most of my shots are closer to 5-6 bar in the basket (so probably 6-7 bar into a blind basket on a typical machine).

I'm currently at 16g in a 17g LM basket. Curiously, the puck sometimes sticks to the shower screen even though I'm using a dose under the basket's sizing. This happens with both medium/dark and lighter espresso.

I lowered my pressure to ~7.5-8bar but may go even lower. I'll see if the lower pressure has a big difference on my medium/dark roasts. It would be nice to not have to change a lot going between roast levels. The LM GS3 isn't hard to change the pressure but I do have to remove the side and fiddle with the OPV valve on the pump.

another_jim wrote:You might try the finer grind with a reduced dose, so you get the same fast flow as the sweet shot, along with the higher extraction to buffer the acidity. If you're lucky, that won't raise the bitters that reduce perceptible sweetness.

So almost treat it like a turbo shot but to get the fast shot I would grind fine and reduce dose instead of grinding coarser at the same dose (like a normal turbo)?

I'm roasting another round of the lighter coffees and will update how the tips worked when they have degassed.