Had a weird experience. Bought my favourite beans from local roaster (roasted May 27th, Peruvian SO), pulled a shot this morning in about 24 seconds, tasted sour. Tossed it, ground finer, updosed, pulled another in 33 seconds. Same sour taste. Turned it off, let the Pavoni cool, came back and pulled a shot with a Brazilian bean from the same roaster - 26 seconds, gorgeous flecking and tasted incredible and smooth. Pulled a second shot (usually the best on Europiccolas) with the Peruvian, 25 seconds, same sour taste.

What is going on?! I don't think it's the grind, the shot feels and looks normal, but tastes oddly sour, unusual for this bean/roast. Could it be a bad batch? Is it possible that bad beans/roasting could result in a sour taste?

Do they look under roasted? It's a possibility, I've ran across the same thing before with a local roaster that generally roasts really light and they got a little too light. I took it back and they were happy to exchange the bag.

The only way I could tell it was not user error was because the sourness was on a difference place on my tounge than a poorly extracted shot.

Yeah, now that you mention it,when I hold them against the brazil, they are very light - though that could be intentional. Where on your tongue was the sourness? It hits me in the centre back...

I've been going to this roaster for almost 2 years now and this is the first time I've ever questioned his beans, so before I take them back I want to be good and sure it's not my $#ck up. He does tend to roast quite lightly though....

That sounds about right, I tend to taste a bad shot on the upper part of my tounge and along the edges. Of course look at the tasting notes, if it's all lemon peel and grass then well perhaps that's what they were going for? Though you did say you have bought it before...

Try it brewed. If it tastes more tangy than sweet once its cooled, it's going to be hard to get a balanced tasting shot. Peruvian coffees are some of the most acidic in the world, and if the roast on this batch ran 30 seconds too fast, or was pulled a few degrees too early, that could be enough to make it tough going.

Just tasted a cold brew made yesterday - same sour funk. Finally, proof that I'm not crazy and that I'm not THAT bad at making espresso.

Thanks everyone