I recently cleaned and descaled my espresso machine, then I finished the last 3/4 pound of coffee I'd been using (I spit up and freeze five pound bags). The taste of the espresso notably improved and I got a few really good cups out of a bag I didn't particulary care for to that point. Then I went back to my regular coffee, which is the second darkest roast from a local roaster. The coffee was extremely acidic and altogether undrinkable.

My first thought was there's acid in the machine, so I've now run quite a bit of water through it and the coffee still tasted undrinkable. I complained to the roaster, who seemed surprised, but replaced the bag for me from a different batch. This new bag is still very acidic (though not as bad). This is my normal coffee, so I know what it usually tastes like. In the meantime, I picked up a bag of Blanchard's beans from Wegmans and they're a bit bland, but not bad.

I've checked my water, and tried soft and hard water; I've check that the water temperature is right (~200 degrees at the screen), I've tried two tampers, and still, the dark roast coffee has a very sour note. I also tried making this coffee in my mokka pot and it came out equally as bad, but I'll admit that was probably my fault.

I'm at a loss for what to do now. I feel like the coffee is bad since two other brands are coming out alright. Should I take this bag back to the roaster and have them check it? Maybe one of their roasting vats is set wrong? Should I just write off the $50 I spent and find another roaster to buy from?

Or is there something I'm doing wrong? Grinding 18.3 grams using a Sette, making a 37(ish) gram double shot in 30 seconds on a Bambino Plus. The resultant brew is somewhat lighter than I expect from this coffee and has more crema than usual. Thanks for any help.

Incidentally, the first sour bag was just over two weeks after roasting. This one is 9 days.

Can the Bambino Plus temperature be raised? I had that thought too, but couldn't figure out how. When I just let water run through the portafilter, its 160 F in the cup, which I thought was a bit low. I'm not overly happy with this machine. No adjustability and the cleaning sensor is screwed up. Breville says to just reset the chip every time I clean it, otherwise it will constantly ask to be cleaned. If I had to do over, I'd buy the Gaggia.

As far as the ratio, I had a couple cups from both bags come out to about 30 grams when I was dialing it in. Expected bitter coffee, but it was still sour. I'm thinking of just keeping one of these bags around for filter coffee and getting the coffee I had last time.

This may be my problem. I've noticed the espresso in the cup, especially on ristretto shots, has been cooler than when the unit was new. Maybe that's also why the Blanchards beans seem bland.

Unit is three months out of warranty. I tried to file a claim for the cleaning sensor, but Breville said to just reset it to factory settings every 150 shots.

bambino has this limits of temp.

u can follow the temperature thread recommendation.
personaly i find running blind basket twice works better than steaming. just pop the plastic and run. the body of the machine head will be hot enough by then. the pulls will also be more consistent in time. just watch out for ur tray and water.

even then you may hit a limit of either shot time / water deposit time, and for those case your option would be to dose lower.

its a basic machine that can work with easy beans, and does very well at that. i had ims54mm and for dark roasts i can get very close and similar taste to bdb. challenge it with acidic coffee and u'll likely hit the limit very fast.

bdb still lose the insta steam benefit tho. having to wait 8~9+ mins boiling time just for steaming really feels like waste of time and wattage.

This coffee, in the past, has been roasted pretty dark. The last bag I got I thought had been over-roasted, although I didn't particularly mind. Its possible there's some variation in the beans to start with. Its also possible that all this variation I've noticed is down to my machine. I always run one 25 ml shot through before making any espresso. I'll try your trick of running a couple blank shots through. Maybe the whole system just needs to be warmer.

Just tried this. Ran two 50 ml blank shots through, then the coffee. Water came out much hotter and faster, but resultant shot was thin. It didn't taste sour, though. I'll try making another shot later with a finer grind. I don't think the water is actually getting hotter, I think its just staying hotter longer. Its too bad they didn't just make a temperature adjustment. Even a +/- 5 degrees setting would be welcome as there are variations between bags.

I have a bambino plus as well - I always do two single blank shots through a pressurized portafilter on startup. There should be a thread on here where someone did a fairly detailed writeup on the Bambino's temperature profile.

I also dose lower - usually around 15g these days. This allows me to grind finer without choking the machine. I think a lot of the 18g+ dosing recommendations given these days is geared towards people with 58mm machines. We 54mm users need to cut that back a bit so that we don't end up with an excessively thick puck. A dose of 19g on a 58mm portafilter should be equivalent to a 16.5g dose for 54mm.

The temperature experiment: