Sour espresso, what to change?

Beginner and pro baristas share tips and tricks for making espresso.

#1: Post by Fili339 »

Filip here, I'm new here, and new in espresso. Also sorry for bad english, hope you will understand me.

Please help me solve my problem, every espresso shot I pull tastes sour. Not fruity sour, but so sour it hurts when I try to drink it.

I use Gaggia Carezza Deluxe machine, but with non pressurized portafilter (I modified it, removed pressurized mechanism), Graef CM702 conical burr grinder and tamper.
Grinder is obviously espresso capable, at setting 4 (of 25) it chokes machine. At setting 5, and 18g coffee dose, i get around 35ml espresso in around 20-25 seconds. As much as I understand, this should be almost ideal.
I tried 3 different coffee beans- medium and dark roast, and literally every shot is very sour.
Before every shot I run hot water through portafilter so it is hot to touch, then wipe it so it is dry - it is never cold before brewing.
Flow looks good to me, and crema looks good.

I think it might have something with shower screen? I will post image how a puck looks after pulling a shot. You can see around centre there is a dent - maybe water hits the puck there and create channels so it is underextracted?

What do you think? What can you recommend to change?
I know it is not great gear, is it even possible to get a good espresso with it? Maybe I can try with smaller coffee dose, or bigger extraction, or shorter extraction...?

Here are pictures of a puck, and crema.

Thank you in advance!

Team HB

#2: Post by ira »

Sour usually means the temperature is too low. How long are you letting it heat up? what happens if you wait 3 times as long for it to warm up?


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Team HB

#3: Post by Jeff »

Welcome to H-B!

Dialing in any new machine or grinder can be daunting. Even more when you don't have a feel for how it went the last time.

First thing I'd check is that you're not "over-dosing" your basket with your coffee. With a firm tamp, there usually should be around 2-3 mm of space above the tamped puck and the shower screen. A coin is a good way to check this. If you lock in the basket and the coin leaves a dent on the surface of the puck, you know roughly the spacing there. If you don't have enough "headspace", it is possible that the puck "cracks" when it expands and hits the shower screen or screw (possible, I can't stick my head in there to tell). If you reduce the dose, you may also have to make the grind finer to keep the same level of "puck resistance" to flow.

With the Carezza Deluxe, it might not have an OPV as it sounds like it was designed for a pressurized portafilter. I found ... iagram.pdf There, #71 might be an OPV, but I'm not sure if it is adjustable at all.

The other challenge with single-boiler units of the Gaggia/Silvia class is that they tend to have a very wide temperature range. If you regularly hit it when the temperature is low, that might be one of the reasons. There are several threads around about "temperature surfing". The basic idea is to pick a time, relative to the ready/heater light either turning on or turning off, that lets you repeat a given temperature a a lot closer than "random" times. The temperature in the boiler is like a saw tooth -- rises quickly when the heater turns on, the thermostat clicks off and it rises a bit more. Then it falls slowly until the thermostat clicks on ant starts the cycle again.


#4: Post by jgood »

I would try to improve puck prep by stirring the grinds before tamping. An example of a homemade distribution tool is attached. In addition, sour means under extracted and/or temp too low. So temp has been discussed in a previous post but are you timing from 1st drops (my preference) or from activating the pump? I am a fan of 20 gram dose/ 35 to 40 sec from first drops to finish / to get a 32 gram output. I use a dark roast. So try for a longer pour. And weigh the dose and the output to get some consistency.

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#5: Post by HB »

According to WLL (emphasis added):
The Gaggia Carezza De LUXE is a semi-automatic machine with a vintage, Italian look, designed to capture the atmosphere of retro cafes. The intuitive push-button interface and pressurized portafilter make for an introductory machine that's easy to master in no time at all.
Entry level espresso machines with tiny boilers often have widely variable brew temperature. You can "temperature surf" by timing the peak of the boiler heating cycle or flicking on the steam switch for a moment. Pressurized portafilters are designed to help make something that looks like espresso, even if you have stale coffee and a mediocre grinder. Pressurized portafilters don't respond normally to grind setting adjustments, i.e., they have a tiny orifice that provides back pressure and a finely ground coffee that's required for a regular basket will choke a pressurized one.
Dan Kehn

Fili339 (original poster)

#6: Post by Fili339 (original poster) »

Thank you all very much for answers.

As I am new in all this, I didn't know I have to wait for machine to warm up! I thought as soon as the light stop blinking, it is ready. That is great advice, I will for sure try to wait 20-30 min before brewing, hope it will make the difference. Turning on steam switch is also great advice, thank you.

Also I didn't know for 2-3 mm space between puck and head, will check that also.

About puck prep - I think it should be good, I take my time doing that - stir it well with a toothpick, tap it lightly with my hand to level it, and then tamp.

@HB - portafiter is not pressurized anymore as I removed that mechanism with a small hole under the basket.

So, tomorrow I will:
- check the space between puck and head, and set the dose so it is 2-3mm between them
- wait 20 min before brewing (I'll try to switch on the steam and then switch it off to speed up warming)

Will let you know how it went.

Supporter ♡

#7: Post by mgwolf »

Don't forget that it could be the coffee! A lot of light-roasted coffee will taste sour no matter what you do with it temp-wise (to my palate). Since you're starting out, you might try to get some fresh coffee that's in the Italian style or some coffee from a local roaster that you're familiar with.

Fili339 (original poster)

#8: Post by Fili339 (original poster) »

Guys I can't thank you enough.

I did what you suggested:
- reduced dose from 18 to 16g because there was less than 1mm space between puck and head.
- waited more than 20 min for machine to warm up (temperature gauge moved couple more milimeters after ~20 min) and then brewed.

Difference is night and day, I can barely taste sourness, and that little sourness I taste may be due to coffee as @mgwolf said.
Because of smaller dose, I ground 1 step finer and got ~35ml espresso in 25 sec, perfect!

Thanks to you, I am now enjoying best latte I ever made at home. :D