Hi All,

I have a new bag of coffee from Rounton Coffee Roasters, from Colombia and the description says medium Omni-roast with notes of Strawberry and Lime, they were roasted just before Xmas. I'm using a Gaggia Classic with PID, temp @95°C, 9 bar pressure and a niche zero grinder. I'm using a 1:3 ratio, 18g dose in, in a 18g VST basket and naked portafilter with no visible channeling. I'm also letting my machine warm up for 20 minutes prior to pulling.


I started out at 20 on my niche and have ground finer, with all shots seemingly tasting sour. I am now at 7 on the grinder and I still finding the shot sour. I can't reach the balanced flavours I've had with previous attempts. I can't grind any finer as it either chokes the machine or takes an absolute age to pull a shot.


Could I have gone too fine, is that possible and still get a sour shot?


Has anyone got any advice please?

Some beans are just not suited for espresso. Try V60 maybe?

Does the machine have an adjustable OPV? Try reducing maximum pressure to 7 or 8 bar.

Also, don't try to aim to that standard 25-30 sec shot. There's nothing sacred about this timing. I've had shots that took longer than a minute that tasted great and would definitely not be hesitant to go beyond 40 seconds.

6 weeks post roast may be your problem. Oh, and try shortening your ratio to 1:2. Grinding so fine that the coffee can't pass through and chokes would cause under extraction, resulting in sourness.

Your beans are quite old for espresso. It'll be harder to get a decent extraction with those. For me, I use up my beans within 2 weeks of the roast date. I think your first step is to try to get some fresh beans.

And try maybe let your machine warm up more. It might not yet be sufficiently warmed up at 20 mins.

Otherwise, sour often indicates under-extraction. You can try grinding finer, and ensure no channeling. Also, you can bump up the temp to emphasize more bitter flavors and emphasize sour notes.

I have yet to try this but waiting for my new LMLM but I'm beginning to think water has something to do with it. I've been doing this for 4years and have gone through over a dozen bean varieties. Have upgraded grinder to an Atom 75 have played with a lot of factors and more often than not it all comes out sour. I've tried higher temp, higher ratio, higher dose, tighter grind and just can't shake it. I've done the salami shot which kind of said yes the middle is what I'd like but I follow 2:1 in ~30 sec to no avail. When new machine comes will have to deal with water so maybe that will be the next thing.

1. Try it as a pour over or immersion brew, and see whether you can get a decent brew.
2. What are your shot times looking like? Time is an equally important variable as weights.
3. Assuming it's not a roast quality issue, 1:3 is a big ratio. Try something like 18g IN, 30 to 40g OUT, taking 30 to 40 seconds.

Mm391 wrote: I have a new bag of coffee from Rounton Coffee Roasters, from Colombia and the description says medium Omni-roast
with notes of Strawberry and Lime, they were roasted just before Xmas ...

It's in the flavor notes description "Strawberry and Lime", lime is sour.
Espresso will bring out those notes even more. Try other brew methods people are suggesting.

If you don't like your espresso sour look for flavor notes like Full-Bodied, Dark Chocolate, Chocolate, Nutty, Sweet, Toffee etc.

Same reasoning here. If it says lime that means sour and lighter roasts almost always have sour notes to some degree. A bit sour is something you need to get used when using light roasts but overly sour isn't good. That can be bad temperature control on your machine, bad roasting, just not suitable for espresso or many other things.

And 6 weeks post roast is still good for espresso as lighter roasts need a longer restng period of 1-1,5 weeks and can be used up to 8 weeks although the sweetspot is, most of the time, within 4 weeks. But the age of your beans won't have anything to do with your current result as they won't get more sour as they age.

And light roasts can be less sour when doing long PI (like 20-30s) so you can grind finer, thus extracting more. The problem is that your Gaggia Classic isn't suitable for that and concal burrs do a worse job at that then flat unimodal burrs. So your equipment only makes things worse in this case.

And last but least not everyone likes lighter roasts and there's nothing wrong with that. If it isn't to your tasting just keep enjoying darker roasts. It took me a while to get used to it and getting better equipment als made it more enjoyable so it's also kind of a journey you need to take.