Hi all,

I'm relatively new to the coffee world. I just opened a new coffee shop in Colombia (Cartagena, to be more specific) and I'm very happy that I can contribute to my country, in terms of a good cup of coffee. So the thing is, I'm having a really hard time when it comes to brewing a nice espresso. I have nice equipment to be honest, Nuova Simonelli Appia II espresso machine and a Victoria Arduino Mythos One grinder. Thing is I'm constantly getting sour espressos, even tho our customers at my shop doesn't seem to care/notice because they all leave with a smile on their face. Anyways, I'm dialing the grinder in such a way that I get a very sweet flavorful espresso, but an hour later I start tasting this sour-tingling note that wasn't there. So I have to battle for a long time trying to obtain a good espresso.

I know underextracted espressos are sour and that a grind too fine can achieve sour results, too. So I have a couple of questions:

1) The pressure gauge of my machine is fluctuating between 0.75 bars and 1.1 bars hence I'm asking myself if this is affecting my brew temperature. My machine doesn't have PID. I measured the temperature on the portafilter with the group running and its showing me 92 celsius.

2) I'm altering extraction time before any other variable since it will not alter the other ones. If the sourness is not gone then I change my dose and finally, if that doesn't do the trick, I change my grind setting to finer so I cant extract more flavor from my fresh grinded beans.

Anyways, I'm having constantly fluctuating results and I'm not being able to pull decent espressos in a fair interval of time. The coffee shop is located in a place with A/C so changes in room temperature are not an issue. I'm receiving my coffee from a company with HIGH reputation in 3kg canisters with nitrogen atmosphere so the degassing process is considerably stalled. Climatic conditions in my city are quite humid and hot as hell (34 celsius), but then again we have 24/7 A/C and we store our beans after each service in a refrigerator in kilner jars with almost no space for them to lose all of the CO2 from one day to the other. Roasting date was 8 days ago, using the last cannister of beans.

Any suggestions?

Try another bean... see if it was really the equipment at hand that is causing this problem...

Flush routine for Nuova Simonelli Appia

Checkout this thread.

Focus on water temperature? Perhaps as you pull more shots, maybe your boiler isn't recovering fast enough? As a general rule, lower temperature = sour, higher temperature = bitter.

Just putting a variable out there that you previously didn't mention.

Are you making sure you are pulling to the same recipe an hour later? Are you using the volumetrics? If so you may just need to redial those in throughout the day (which you should be doing anyway). I doubt it would be temperature. I am assuming it's a 2 group and not the compact? If so it should be temp. stable and no water dances should be needed. You want to look into replacing the restrictor though (with the one from the Aurelia) and that will give you a better preinfusion and better temp. stability.

I see no reference to your dose or the weight of espresso being made and in what time ...
What is your brew ratio as this is this adjustment is first port of call to adjust to achieve balance , i am presuming that there is nothing wrong with your machine , as commercial beast should not need minster flushing and should be temp stable unless faulty

Hi everyone. Thank you all for taking some time to answer my questions. I will answer everyone in the same order replies were made:

1) TheJavaCup77 - The beans are ok, I'm using one of the top rated beans in Colombia so I don't think that's the issue.
2) Bill33525 - Thanks for the info, will read it asap!
3) Sideshow - I raised the temperature a little bit further and my espressos definitely got better. Most of the acidic part is gone and I'm being able to pull shots that are far more balanced that the ones I was doing before. Thank you very much!

4) Ellejaycafe - I'm using the same recipe. I'm currently using 22 grams of coffee in VST baskets and pulling shots of 42 grams - 44 grams. I bought the semiautomatic version since I don't like volumetric one, every other worker just want to press the damn buttom and magically get excellent espressos. Will check the restrictor part tho I don't know how this would influence my machine in order to get better espressos.

5) Mrboots2u - Currently using 22 grams of medium roasted coffee. Pulling shots from 42 grams to 44 grams. I always modify extracting time first since this variable won't change any of the other ones. If it's not time I will change dose and if the issue is not gone I will change grind. This is my variable priority.

Thanks everybody!!! Additional information is always welcome!!!

Glad things are improving. Perhaps if I'm ever in that part of Colombia, I'll stop by for a shot!

seolinogue wrote:Hi everyone. Thank you all for taking some time to answer my questions. I will answer everyone in the same order replies were made:

1) TheJavaCup77 - The beans are ok, I'm using one of the top rated beans in Colombia so I don't think that's the issue.
2) Bill33525 - Thanks for the info, will read it asap!
3) Sideshow - I raised the temperature a little bit further and my espressos definitely got better. Most of the acidic part is gone and I'm being able to pull shots that are far more balanced that the ones I was doing before. Thank you very much!

4) Ellejaycafe - I'm using the same recipe. I'm currently using 22 grams of coffee in VST baskets and pulling shots of 42 grams - 44 grams. I bought the semiautomatic version since I don't like volumetric one, every other worker just want to press the damn buttom and magically get excellent espressos. Will check the restrictor part tho I don't know how this would influence my machine in order to get better espressos.

5) Mrboots2u - Currently using 22 grams of medium roasted coffee. Pulling shots from 42 grams to 44 grams. I always modify extracting time first since this variable won't change any of the other ones. If it's not time I will change dose and if the issue is not gone I will change grind. This is my variable priority.

Thanks everybody!!! Additional information is always welcome!!!

have you cupped or brewed the beans ? Are they more balanced in the cup then , if so id be adjusting your recipe , perhaps 44-46g . Although these are now big espresso's are they for large milk drinks? You could save some cash going to 19-20g adjusting the grind , adjusting the recipe to 40-44 g , perhaps even getting a sweeter brew into the bargain

seolinogue wrote:
I know underextracted espressos are sour and that a grind too fine can achieve sour results, too.

It's the other way around, grinding coarser will increase the flow, reduce shot time, underextract, and accentuate sour flavors. On the other hand, grinding finer will slow the flow, increase shot time, increase extraction, and accentuate more bitter flavors. Are you perhaps adjusting your grind incorrectly?