Hello All. I have a Quick Mill Vetrano HX machine and I notice a sour shot taste no matter what. I don't think it is due to too low temp because I adjusted the pressure stat high so that it cycles higher between 1.1 and 1.4, plus I'm not giving long cooling shots. I roast my own beans so they are always fresh. Doing about 18 -20g or so. I'm thinking perhaps the issue is from my grinding. Would the shot taste sour if I grind too fine or too coarse? Would excessive dosing make this taste?

Any ideas, guys?

Thanks for your help!

Have you read through Espresso 101: How to Adjust Dose and Grind Setting by Taste yet?

Thanks. Yeah, I did read this. I'm just really frustrated because after a couple of years I can't get a god shot. if anyone is located in NJ and wants to come over and help, I'll pay you.

Dosing is always consistent, color looks correct, pressure is 9bar. Getting the the typical extraction times for 2 oz, etc... In theory I'm doing everything correct but just getting a bad sourish taste.

Very frustrating. After years I want to just ditch my equipment and start all over - aarg!!!!

If we assume that you have not over-roasted your beans, then the only simple reason for bitterness would be over-extraction (though if your temp is WAY too high, it will result in burnt-taste bitterness). Just adjust to what the basics say not to over-extract. Higher temp (not in this case probably?), higher dose AND coarser grind, shorter extraction time, etc... Maybe also different beans to start with to make sure it's not just the beans?

BTW, bitter and "sourish" should be the opposites. Bitter = over-extracted, sour = under-extracted. Very simple actually. Unless there is something wrong with your roast or your beans, or the machines - are they absolutely clean...? (I'm just asking this to avoid the possibility of contamination, because I've heard of some weird people not cleaning their PFs, baskets and shower screens on a daily basis).

Is it a sour taste or a bitter taste? Sour may come from to low a temperature, and bitter comes from being too hot. Have you tried a professionally roasted coffee?

First, are you sure the problem is sourness and not bitterness? Sometimes people confuse them.

If it is sourness, then there are a number of possible factors:

1. Coffee - under roasted or under developed coffee can be sour. You say you home roast, what is your typical drop temperature? What roast level are you roasting to? As others have suggested you may want to try other beans from a good specialty roaster and go for something FC or FC+.

2. Temperature - if the temp is too low the coffee will be underextracted. Just because you turned up the boiler pressure does not necessarily mean the temp is hot enough at the group. You could have thermosyphon stall. Try to verify the temp at the grouphead. Eric's thermometer is a great tool for this.

3. Grind, dose, and distribution - too coarse a grind will lead to under extraction. The best indicator of this is a gusher. But you also need to look at possible channeling if you have poor distribution. Do you have a naked PF to see the flow? Also, what kind of grinder are you using? These problems can be due to a grinder that's just not up to the task. For example if there are too many fines you'll have to make the grind too coarse to get the right volume in 25-30 seconds and you can get shots that are simultaneously over and under extracted.

More info will help people offer you better advice on what to try.

keno wrote:More info will help people offer you better advice on what to try.

Exactly, the more we know, the more we know how to help...

To start with, is it really bitter or sour? (It sincerely can be hard to describe for some people, so that's why we're asking this. You need to be sure about it, otherwise no one can really help you).

Thanks, guys. Please hold off for now. I think I'm going to drop it off at a local espresso machine service center and see if they can diagnose. I think something is going on with the machine because I bought some pre-ground Illy (yes, a sacrilege at my house and on this forum) and still getting this funny taste. Let you know the outcome.

Thanks again!

I'm not sure preground illy was the best way to diagnose
But hopefully they offer good feedback

Do you have a group thermometer? If not, I highly recommend one.

Also, get a good bag of professionally roasted coffee before you haul it off to the shop. If you want, you could bring your grinder and coffee to my place in Bucks County PA, and try it on my Vetrano.