I'm relatively new to espresso, just got my Gaggia Classic Pro a few weeks ago and using a Eureka Specialita grinder and been doing double shots with about 18 g of coffee.

I've adjusted the grind size so that I get 36g of output for the 18g of coffee in and been playing around between extraction times between 20-35 seconds but no matter the time, the shot always comes out sour (i.e. underextracted) and I'm kind of at a loss since the grind size seems correct as does the extraction time. The only other thing I can think of is that maybe I should try dosing less, between 16-17 instead?

Thoughts would be appreciated.

Welcome to HB Hyon!

Yeah, try cutting your dose, grind finer and brew longer. If those fail, try increasing the temp a bit more.

Welcome to HB!
Also, make sure you're not using a light roasted coffee, since they will often be sour (or "citrusy"). Probably best to start off with a nice medium to medium/dark comfort roast.

Welcome to HB Hyon!

I agree with TomC; as a starting point, decrease your dose and grind a bit finer to meet the same shot time in order to extract more. Also, if you are using the stock Gaggia double basket, you might want to try the nickel test just to make sure you are leaving enough headspace. When I had my Gaggia, I found that the stock double basket was only good for about 16 grams before I'd start seeing an imprint of the screen on the puck.

If it is still sour, then you may need to work on your temperature surfing technique... Since you can't control the temperature on the Gaggia, you have to "time" when to start your shot. Watch for when the light turns on (this will be just as the heating element turns off) which will be when the boiler is near it's max temp. Then it starts to cool off; when the light just turns off, then the heating element just kicked on and the temperature will be near it's minimum. Time the cycle and then you can start to narrow in on when to start the shot. For example, 10 seconds after the light turns on and then do the same thing every time.

Alternatively, you can do a "steam blip" where you turn on the steam switch for a few seconds to manually engage the heating element... But in order to be consistent, you still have to do this in conjunction with the heating cycle mentioned above...

Hope that makes sense... Do a google search for "Gaggia Temperature Surfing" and you should get lots of information...

Josh

Did anyone say grind finer?

honko802 wrote:I'm relatively new to espresso, just got my Gaggia Classic Pro a few weeks ago and using a Eureka Specialita grinder and been doing double shots with about 18 g of coffee.

I've adjusted the grind size so that I get 36g of output for the 18g of coffee in and been playing around between extraction times between 20-35 seconds but no matter the time, the shot always comes out sour (i.e. underextracted) and I'm kind of at a loss since the grind size seems correct as does the extraction time. The only other thing I can think of is that maybe I should try dosing less, between 16-17 instead?

Thoughts would be appreciated.

Some things to think about to extract more

Higher temp = faster extraction, try and pull the shot when the unit is as high temp as it can be, pre heat everything if temp control is an issue.

Increase dose will contribute to a higher extraction but with espresso you can only play with this ± 1 gram as ideally you should use the dose your portafilter basket is designed for.

Increased yield (the output) will also increase the extraction however there are limits , I noticed you are already doing 35 second shots and this will probably have a higher yeild. Do it ± 1 gram and see if there is a difference but don't go too far with this

Increase brew time which translates to yeild can also be another thing to help increase extraction. The longer the coffee is exposed to water the more extraction your going to get. However the more water you pump through the puck will erode it more and more and chanelling will increase so the extraction gain will have diminishing returns. I think your 35 seconds is already high enough. But still when adjusting ± 1-2 seconds to track the change. I would try and keep it however between 25-30.

Grind and grind prep are larger contributors to extraction. Grind finer = more extraction but don't forget about puck preparation to. Distribute the coffee as even as you can and tamp as even as you can. Do not bump the portafilter or too aggressively put it in the group head as it may break the puck seal or crack it creating channels which leads to extraction problems. Do you have a naked portafilter? If you don't get one so you can see if channeling is happening coffee should come out evenly and if it's at the sides or on one end theres you can quick diagnosis the issue.

My suggestion is grind finer, dose down 1 gram or 2, preheat everything and try and pull the shot when it's at its hottest (as soon as the light turns on). Also respect the puck and give it the attention it needs before pulling the shot.

TomC wrote:Welcome to HB Hyon!

Yeah, try cutting your dose, grind finer and brew longer. If those fail, try increasing the temp a bit more.

mgwolf wrote:Welcome to HB!
Also, make sure you're not using a light roasted coffee, since they will often be sour (or "citrusy"). Probably best to start off with a nice medium to medium/dark comfort roast.

Thanks for the welcome! This is definitely a rabbit hole I didn't intend on going down. To think it innocently started with a moka pot a couple of months ago. I was using a medium-dark roast but looks like it was a dosing problem.

jrham12 wrote:Welcome to HB Hyon!

I agree with TomC; as a starting point, decrease your dose and grind a bit finer to meet the same shot time in order to extract more. Also, if you are using the stock Gaggia double basket, you might want to try the nickel test just to make sure you are leaving enough headspace. When I had my Gaggia, I found that the stock double basket was only good for about 16 grams before I'd start seeing an imprint of the screen on the puck.

If it is still sour, then you may need to work on your temperature surfing technique... Since you can't control the temperature on the Gaggia, you have to "time" when to start your shot. Watch for when the light turns on (this will be just as the heating element turns off) which will be when the boiler is near it's max temp. Then it starts to cool off; when the light just turns off, then the heating element just kicked on and the temperature will be near it's minimum. Time the cycle and then you can start to narrow in on when to start the shot. For example, 10 seconds after the light turns on and then do the same thing every time.

Alternatively, you can do a "steam blip" where you turn on the steam switch for a few seconds to manually engage the heating element... But in order to be consistent, you still have to do this in conjunction with the heating cycle mentioned above...

Hope that makes sense... Do a google search for "Gaggia Temperature Surfing" and you should get lots of information...

Josh

Thanks for recommending the nickel test Josh! I looked it up to see what it was and when I tried it out the nickel was embedded into the puck. Your recollection of the stock double basket was pretty spot on as I had to get the dose down to 16.4 grams to remove any sign of the nickel (almost 1.5 grams smaller than the dose I was using!).

This in conjunction with paying more attention to the heating cycle helped get a much better shot. I also ordered a spring kit to reduce the brew pressure to 9 bar so we'll see if that has any effect.

DamianWarS wrote:Some things to think about to extract more

Higher temp = faster extraction, try and pull the shot when the unit is as high temp as it can be, pre heat everything if temp control is an issue.

Increase dose will contribute to a higher extraction but with espresso you can only play with this ± 1 gram as ideally you should use the dose your portafilter basket is designed for.

Increased yield (the output) will also increase the extraction however there are limits , I noticed you are already doing 35 second shots and this will probably have a higher yeild. Do it ± 1 gram and see if there is a difference but don't go too far with this

Increase brew time which translates to yeild can also be another thing to help increase extraction. The longer the coffee is exposed to water the more extraction your going to get. However the more water you pump through the puck will erode it more and more and chanelling will increase so the extraction gain will have diminishing returns. I think your 35 seconds is already high enough. But still when adjusting ± 1-2 seconds to track the change. I would try and keep it however between 25-30.

Grind and grind prep are larger contributors to extraction. Grind finer = more extraction but don't forget about puck preparation to. Distribute the coffee as even as you can and tamp as even as you can. Do not bump the portafilter or too aggressively put it in the group head as it may break the puck seal or crack it creating channels which leads to extraction problems. Do you have a naked portafilter? If you don't get one so you can see if channeling is happening coffee should come out evenly and if it's at the sides or on one end theres you can quick diagnosis the issue.

My suggestion is grind finer, dose down 1 gram or 2, preheat everything and try and pull the shot when it's at its hottest (as soon as the light turns on). Also respect the puck and give it the attention it needs before pulling the shot.

Thank you for the in depth explanations of different variables I can change and how that might affect the end product. I did end up dosing down 1.5 grams as I was apparently using way too much for the basket I have.

As far as puck preparation, a naked portafilter is definitely next on my list of things to get because even using the double-spout, I sometimes get shots where the espresso comes out of one side 2-3 seconds before the other. Would be nice to see exactly where my deficiencies are.

I'd also suggest increasing output. You'd be surprised at how delicious a 3:1 extraction in 25-30 seconds can be.