E61 HX w/thermometer, consistently more sour last two weeks

Beginner and pro baristas share tips and tricks for making espresso.
PaulSA
Posts: 28
Joined: 2 years ago

#1: Post by PaulSA »

Hello coffee gurus.

I was wondering if anyone else has experienced this seemingly "inexplicable" sudden and consistent "on the sour side" taste and might be able to help me pinpoint if the issue is my e61 thermometer or something else inside my San Remo Treviso HX (from the '80's), E61 machine.

I've noticed a consistent sourness in the cup for the last two weeks (throughout two different batches of beans, so it's not the beans/roast. Beans are medium/dark roasted). I always use a scale and nothing has changed (over the last couple of years) of grams in the portafilter or liquid in the cup. I aim for about +/- 18g in and 23-26g out, and that's still the case (even though it's on the underextracted side now). Thus, the only variable I can think of is the temperature. I use a temperature chart (for the flush-and-go method) and it's been great till now. I've tried overcompensating (always using the 96 / high end range and even raising a couple / up to a few degrees higher), and it still seems to be on the slightly sour/underextracted side. Or, sometimes, perhaps less so, but still, it seems something has changed and I'd like to pinpoint what that is.

I use a Geisinger e61 thermometer (had it a bit over a year now) and it's been great. Haven't noticed any discrepancies which would indicate different temperatures than I'd expect. The only thought I've had is perhaps I need to recalibrate it (although the creator of it says it usually doesn't need that, nor from my observation would I expect it's gotten out of calibration).

Before I do that, I just wanted to see if anyone else had an idea of what else it could be. Meaning, could there be something in my Treviso that might need to be looked at or that could cause a drop in temperature in the cup which I wouldn't notice with my thermometer? I can't think that would be the case ... but, any ideas?

Thank you!

User avatar
Jeff
Team HB
Posts: 6906
Joined: 19 years ago

#2: Post by Jeff »

Other possibilities are that the roaster changed batches, blend, roast profile, or all of those.

I didn't read that you had adjusted grind or ratio to see if you could get an enjoyable cup.

PaulSA (original poster)
Posts: 28
Joined: 2 years ago

#3: Post by PaulSA (original poster) »

I have adjusted grind, grams in the PF, etc ... but I generally hold to my recipe as above. (about 18g in and 25 out in the same amount of time (about 28 seconds) ... but since it's a general, under-extracted taste, not some other taste that I'd associate with a variance amongst different beans, (I've tried various beans (but I always roast my own as well)), it seems to me a temperature-related issue.

Over the years I've not experienced what I described (a taste of being under-extracted). Again, it seems I can minimize it (by raising the temperature much higher (less of a cooling flush) than I've been doing till now, but to me, that's a sign that somethings wrong in the hardware somewhere... and the taste still lingers a bit... Thermometer, or machine?

PaulSA (original poster)
Posts: 28
Joined: 2 years ago

#4: Post by PaulSA (original poster) »

I've noticed as well my thermometer reading kind of jumps around a bit with a difference of about one degree up and down constantly.

e.g. 100, 99.6, 99.8, 99.4, 99.6, 99.0, etc... switching between the varying temperature readings every second of two... seems to me it should be pretty much constant, and not going down at all.... at least not like that.

Pressino
Supporter ♡
Posts: 1390
Joined: 3 years ago

#5: Post by Pressino »

How about the possibility something in your grinder has changed? There are things (like burr wear, burr chamber retention of stale coffee, and some alignment issues) that could alter the grind characteristics (uniformity and grind size profile) in ways that would change extraction but not necessarily dosing and extraction flow rates.

What grinder(s) are you using? Have you opened them up to check them out?

PaulSA (original poster)
Posts: 28
Joined: 2 years ago

#6: Post by PaulSA (original poster) »

I haven't checked the grinder. I have a DF64 about a year and a half old. (Also got the upgraded burr when I got it and I doubt it's worn by now, just two people @ two coffees a day each for a year / year and a half.) It's a zero retention system with the billows to blow out grinds each time it's used.

However, a friend said it's probably the vibration pump that needs to be replaced. Loss of pressure = under extraction. (Sounds plausible to me.) So I'm taking it to him next week and he'll replace the pump and a few maintenance goodies.

Anyone else had this kind of issue with a vibration pump in their machine?

Pressino
Supporter ♡
Posts: 1390
Joined: 3 years ago

#7: Post by Pressino »

I suppose there could be an issue with pump pressure, but I'd imagine if that were the cause then your extration time would also have changed for the same dose and volume out. Let us know if exhanging the pump fixes the problem.