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Discussion Starter · #1 ·
I have a 2019 Gaggia Classic which I did not use over the summer. Since I restarted using it in September (it was properly cleaned and descaled before), I experience the following: my shots taste perfectly in the morning (for me, at least), with notes of dark chocolate, no matter how many I make (usually just one cup), but the after-lunch shots seem to taste and smell always bitter and burnt. The next morning the espresso tastes amazing again followed by the burnt shots of the afternoon.

I use the same coffee beans, same weight and grind setting, I flush the machine before brewing and clean the group head properly after my morning use, I even change the water in the tank.

Could the problem be temperature related?
I always turn the machine on for approximately half an hour in the morning, and I tried to experiment doing the same in the afternoon, as well as starting brewing the moment the temperature light first switches on (after 2-3 minutes of turning the machine on) but it seems not to influence the bad taste.

I don't particularly remember having this problem before the summer (perhaps my taste buds became more delicate) the only thing I changed in my set-up was my grinder, I used to have a Delonghi KG79 before which was changed to a Lelit Fred stepless grinder.
 

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Intriguing. Could it be they your tastebuds, or whatever you have for lunch may influence in defining your afternoon coffee taste?

If you follow the same routine, there should be no reason why it should be any different.

Are you purging the grinder to get rid of stale grinds?

If it's related to the equipment, the explanations I can think is:

- your machine is running hotter in the afternoon, or your grinder is grinding finer (due to humidify, temperature) and over extracting it. Do you notice a significant difference in the shot timing?

One thing you can try is to one day skip the coffee in the afternoon or morning and see if your observations still stand.
 

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Discussion Starter · #3 ·
Intriguing. Could it be they your tastebuds, or whatever you have for lunch may influence in defining your afternoon coffee taste?

If you follow the same routine, there should be no reason why it should be any different.

Are you purging the grinder to get rid of stale grinds?

If it's related to the equipment, the explanations I can think is:

- your machine is running hotter in the afternoon, or your grinder is grinding finer (due to humidify, temperature) and over extracting it. Do you notice a significant difference in the shot timing?

One thing you can try is to one day skip the coffee in the afternoon or morning and see if your observations still stand.
Many thanks for the quick reply!
Actually, I have also been wondering if it is only down to my tastebuds working differently before breakfast and after lunch. Nevertheless, the difference in taste (and smell) is way too radical for me for it being the sole cause.

I always try and empty the grinder but even if there is some stale coffee left, it should affect the morning shot more significantly than the afternoon one as the time difference between shot times is way higher there.

Anyway, first I try and see if there is any difference in the shot timing, paying extra attention to keeping the brewing process consistent and then I will skip first a morning and then an afternoon shot. I will let you know the results of my experiments.
 

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Only changes could relate to ambient temp and/or boiler temp

Are you in a cold climate and in the afternoon are you turning your machine back on or has it been left on since the morning?
 

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Discussion Starter · #5 ·
Only changes could relate to ambient temp and/or boiler temp

Are you in a cold climate and in the afternoon are you turning your machine back on or has it been left on since the morning?
I live in the West-Midlands, this month it usually starts around 3-4 degrees Celsius in the morning and goes up to 7-10 degrees in the afternoon. Not too radical, I guess, although there is also humidity present in the room indicated by the condensation on the windows. I am not sure, however, if the change in humidity during the day should significantly influence the shot itself.

I always turn the machine off after my morning shot and then turn it on again for half an hour before the afternoon one. The new Classic turns off automatically after approximately 20-30 minutes, this is what I usually use as an indicator that the machine has sufficiently heated up. Once I also tried to start brewing without letting it warm up properly but it did not seem to take away the burnt taste.
 

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Daft idea but have you tried a thorough clean back flush style and behind the shower screen? I'm wondering about the different times standing idle between the shots and contamination. Early morning wets it and it dries out overnight. The water tank is an unlikely source but pipes can be. A tank filter could be as well.

I have had a bit of similar especially behind the shower screen thanks to Sage's cleaning instructions. Wasn't bad but noticeable. Tank - I make sure it turns over regularly. It wont on many machines when people are just pulling shots. Mine empties every couple of days or shorter. As I am an ex caravan user I'm happy with that from experiences. Longer needs tablets adding.

John

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Seems like you've rejected the idea that it's taste bud related but it could of course be part of the explanation coupled with some other factor that I can't even hazard a guess at.

I know I always prefer a chocolatey Brazilian coffee in the morning as something like a washed Ethiopian - which I would love in the afternoon- is just too much for my sleepy taste buds and doesn't taste good at all to me!
 

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Discussion Starter · #8 ·
Many thanks to everyone for all the responses and I apologise for the late reply. After some experimenting, here are my thoughts on different aspects which may cause this phenomenon:

Cleaning: I daily backflush the machine with water and I did it also with some pullycaff several times along with some descaling during the past few weeks to make sure the everything is clean, hence I eliminated this factor.

Water: I use Brita cartridges for softening the water and I refill the tank before each use. I also tried mineral water (Highland Spring) and I also tasted the hot water itself coming out of the group and it tasted just fine so it is not the water IMO.

Taste buds: this is perhaps the most likely explanation, however, as I recall, whenever I am in Italy and I go to my favourite bars after lunch for a shot I always find the taste just the same delicious as in the morning. To justify my memory, today I went after lunch to a local Italian deli where I got my latest beans from and the same espresso from the same beans tasted just fine without this weird bitter taste or burnt smell. I went back home straight and my shot did taste badly although the extraction looked fine.

Extraction: I am a big fan of Italian espresso and Italian brew ratio - 14-15 g in, approx. 50 ml out in 25-30s splitted into two cups. As volume is a bit misleading due to the crema, I try to gain approx. 40 ml. The time for extracting this weight stays approximately the same for both the morning and the afternoon shot.

Beans: I know this goes against to what most of the members here like but I fell in love with espresso in Italy and the reason why I bought the Gaggia is that I want to get that taste back, my taste buds really cannot stand the light roasts I get in a third-wave coffee shop. I am not saying that is bad espresso, it simply comes down to preferences. I have a contact in a smaller roastery in Faenza, called Mokador, and I usually try and get their freshest roasts. As I mentioned before, I also got a bag from a local deli where I like the coffee and I am using that now until I get my next Mokador package. But the problem stands for both: in the morning I do get the chocolatey Italian taste that I desire with loads of crema (thanks to the 10-20 percent of Robusta) and in the afternoon I get this unpleasant, maybe bitter, rubbery taste.

Grinder: I use a Lelit Fred grinder, which is stepless, has stainless steel conical mills and does a pretty good job with keeping the grind consistent IMO. I don't think it overheats the beans as I use it once in the morning for 10-15s, so even if the burrs are a bit heated up there is no way they would not cool down in 3 hours. I always try to get rid of any remaining grinds but again - if those were the problem they would influence the morning shot even more.

Pressure: I did a mod on my new Classic and installed the pre-2015 adjustable OPV so I could set the pressure to 9bar (the 2019 OPV is not adjustable). I tried to do some low-pressure preinfusion and pressure profiling by overheating the boiler with the steam button before brewing and then opening-closing the steam valve during the extraction but that did not seem to take away the bad taste - and obviously induced a significant heat loss but I gave it a try anyway.

Temperature: this is something I could not fully investigate as I have not yet installed a PID - it may be that the boiler temperature fluctuates differently after the first use in the morning. I always turn it off in the morning and turn it on again after lunch. I tried 30min preheating and no flush and also long flush until brew light goes off, wait until it comes back then start extraction - I got different colours in the cup but the bad taste remained for both. I am going to install the PID though to make sure I create exactly the same environment in the morning as in the afternoon.

As you can see I tried to look at the problem from many perspectives. I skipped the morning shot several times- the afternoon one was still bad. Perhaps it really is my taste buds... anyway I cannot accept that simply I shouldn't enjoy my afternoon espresso so if anyone can recommend a further testing scheme or a suggestion where the problem lies I would be delighted to hear it!
 

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The gagia isn't well known for temperature stability. Some time ago I saw some plots from some one who had fitted pid and expected a constant temperature

I have use a Piccino. A dual boiler that uses small boilers and simple temperature control. The boiler size means that it can't provide a constant temperature throughout a shot. The general consensus on machines with this sort of control is that temperature surfing techniques must be used. One way of doing that is to connect a small neon indicator to the boilers heating element. A shot would mean, flushing to heat some internal parts, fit the portafilter, wait for the neon to go out and then pull the shot. This after a 1/2hr heat up time to get the grouphead and portafilter up to temperature. The boilers take about 3min. The flush is needed to heat the shower screen stuff. This is the simplest way of getting a constant temperature profile. It also has the advantage that it gets over the heat off, heat on temperature differences involved with this style of control. What it doesn't get over is additional heating available from the actual heater as it will be hotter than the water surrounding it. That might help actually when cold goes in. I don't know how the light on a Gaggia functions so it may do this already. It might not.

Ideal PID finishes up with the heating element at the same temperature as the water around it. In practice some overshoot might be an advantage to get the best average temperature flow with minimum deviation.

What I do know from the Piccino is that another machine using same weight and ratio gave a different taste using the same bean. The interesting aspect is that the Piccino gave a very nice taste. The other machine did as well. They were just different. Both within the realms of what the bean should give. The Piccino was more mellow. A change of tuning may have changed that.

On this machine I found, heat up, flush, prepare grinds, fit and pull the shot kept things constant.

Not sure if this will help but maybe you can find out what the brew light on the machine actually indicates. If it's only on when the heating is on fine but it's probably done some other way. You may need to find some other way to use the machine and despite all of this a temp surfing neon might not help.

:) Can't think of anything else. Maybe a nice chunk of Chedar 10min before your shot might help taste buds. A curry etc wont.

John

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Discussion Starter · #10 ·
Thanks Jon! Generally in a Gaggia Classic the brew switch lights up when you reach the correct temperature. I used several recommended techniques but I don't think I can achieve a consistent temperature until I get a PID to check on the boiler ... However, I'll give a try to the cheddar in my fridge next time... cheese and wine make a superb pairing well, perhaps cheese and coffee is the next hit? ??
 

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I would have tried any one of these connected to the heater. Doesn't matter which way round they are connected and can be 220v or 240v

https://www.ebay.co.uk/sch/i.html?_from=R40&_nkw=neon+indicator&_sacat=0&LH_PrefLoc=1&_sop=15

They need to be neons. Similar using bulbs are available but usually don't last as long. A decent neon can last for donkey's years. ;) Hope China haven't fixed that.

Flush a bit and it will come on. Pull the shot as soon as it goes out.

Then later I may have added something a lot more expensive.

John

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Assuming you havent sorted it by now, try freezing your morning dose, preferably vaccuum pack it. Use this for your afternoon espresso. If it tastes the same as in the morning then it's due to changes in room temp &/or humidity. I'm ruling out grinder temp as I doubt you're hammering your grinder between morning and afternoon coffee's
 

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Im wondering, I'm using glass bottles to store my coffee and keeping them in the freezer instead in vacuum bags.. Is there any difference? Bottled beans taste very nice and there is no condensation on top of the beans or any water held in the bottle.
 
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