Espresso Question
 

Espresso folks,

my shots have been sour lately. I’ve tried using better and darker roasted beans and grinding finer, which helps but not enough. I’m doing 21 g coffee into 36 g shot which takes about 35-40 sec. My machine is a heat exchanger type so I can’t change the brew temperature, at least not easily. The only things I can think of are to change my dose or replace my burrs. The grinder is a Mazza Major with about 7,100 shots on the burrs.

Ideas?

Reddit r/espresso will have your answer.

I assume you are using a triple shot basket? This was working well prior? If so check to see if your burs are tight and that everything else in your grinder is fastened properly, dull burs does sound like a possibility but I would not expect that to change quickly. I'm thinking that if the burs are moving around you are loosing consistency in grind size. Did you check if the burr is running concentric?

I would ask James Hoffmann, he seems very nice and might give you a quick answer or possibilities.

I would try to buy some beans from a local roaster who can also pull a shot there in the store. Then try it at home to see if there is a difference. Lots of variables as you all know. For me at 61 I have noticed my taste buds have changed and I no longer enjoy a strong coffee like I used to. I have also moved to more blonde style beans vs dark roast. Our daily routine is a double shot of espresso and add hot water and a splash of half & half. One cup in the morning only.

You may be over extracting it. Bringing out the acids.

Try doing a more loose tamp and a quicker shot and see how that goes.

Agreed about Reddit. Wow. They go DEEP on espresso.

Also, I have a co-worker who pulls the best shots I have ever had. Want me to find out where his beans come from? They are spectacular.

Doubt its the burrs. You can always clean them as a start.
35-40 seconds should be ok, but is on the long side. Long shots do tend to be richer but can quickly veer towards sour.
You're using a triple basket in a bottomless?
I would check your brew temp with a thermometer in the group or cup. Pressurestats can drift over time and require adjustment.
Sour is usually overextracted, so I'd aim towards a lighter grind and tamp and shorter extraction.
Also, I'm assuming that the brewpath and portafilter have been really cleaned at some point with a Caffiza backflush and a soak of the portafilter other than a simple rinse backflush.

I find Long extraction time usually makes taste more bitter, not sour.

Sour pull is underextracted, usually due to water temp being too low. As an espresso, tunneling (too much pressure) or too short an extraction can be a cause. Source, the many James Hoffman videos.

That is also my understanding. Hence I’m doing dark roast, finer grind, longer shot.

I don’t know how to detect tunneling other than looking for a sharp increase in the flow during the shot, the extreme cases of which would be gushing - I don’t have that, I mean not that I’ve never, but not usually.

Should have said I’m using triple basket in bottomless portafilter. Also forgot to mention, I’m also stirring the ground coffee (WDT) and grooming, before tamping.

I will measure temps and try these other ideas, will try a whole range of grind sizes and extraction times.

I do really need to solve this. I used to like my shots, they were better - to my palate, anyway - than almost any shots I get in local cafes (in Portland, 90% of shots are sour to very sour, in my opinion). Now they are mediocre, about the average of cafe shots. Although I did have a very nice shot in a cafe this week, and will have to go back to that place.

Following.

I'm brand new to this but thus far have found lighter roasts to be too sour for me. Haven't yet figured out what temp does for myself. I do a cortado-ish drink but test sip before I add milk to see if I've stumbled on something. The biggest impact, at least that I've found, on milk drinks is the type of milk. More fat gives me a creamier drink.

Current semi-favorite beans are from a hipster guy up the street who roasts in a cast iron dutch oven.

Did you figure out your problem yet? Figure out a way to check your brew water temp.

I was wondering that just now myself.

https://www.aliexpress.us/item/3256806253149211.html

Google grouphead temp sensor or e61 temp sensor and there are a bunch. Most are around 100 bucks and look very much like this cheap one from ali, and all use similar thermometers. There's a 5mm hex on the e61 that unscrews. Its bsp thread irrc. I run a pressure gauge there for my flow control but might ditch it.

Most machines use a Sirai pressurestat Whole latte love has a vid on how to adjust.

Man - there's a lot more to good coffee than pushing the button on my superautomatic apparently. Some day I'll find the time to get into this.

My brew temp is about 200F (holding probe in the stream).

I’m getting best results - like, semi decent - using dark roast and grinding so fine that the shot lasts over 40 seconds. The stream is very thin throughout the shot, doesn’t grow thicker or start gushing, so I think my puck is holding together.

This makes me suspect my brew pressure is low and I will fiddle with that next. I can adjust the pump pressure, but need to take off the case (or I usually burn myself trying to get a stubby screwdriver down there).

Pressure is another one of those critical variables. Over pressure can lead to tunneling and under extraction. I don't remember what the effect of underpressurization is on the pull. There is a Hoffman video where he has a rigged up espresso machine that records temp and pressure variables and the resulting coffee. Dates 2 to 3 years ago.

The CoffeeSensor flow control is probably the best $150 I've spent on my coffee habit. If your grind and tamp are perfect you can just run it at the normal "wide open" setting but you can profile if you want. And if your grind/tamp is a little off, you can usually save the shot with excellent results by increasing or decreasing the flow.