Hey all,

I'm using a Gaggia Evolution and a Nemox LUX grinder.

Overall, I was pretty satisfied with my results, but as my palate got more and more sensitive to the flavours and I've stopped adding sugar to my espresso I noticed a burnt-bitter flavour hiding. Now, that I "discovered" it I can't notice anything else and it doesn't let me enjoy the cup anymore. I've tried anything I could think of, temp surfing to the lowest temp possible (that only added a sour note, the burnt flavour stayed), different grind levels, different tamp pressure, etc.. and nothing helped.

About 30 minutes ago, I got the idea that maybe the PF is too hot when I grind the coffee into it and it burns the coffee even before brewing. I've tried making an espresso from a totally cold PF and not even letting the machine heat enough (only a minute or so till the boiler is ready), and guess what? the burnt flavour wasn't there. The espresso wasn't good (too sour - but I guess that's because the machine and the group head were too cold), but for the first time - no burnt or bitter flavour. Is it possible that hot PF was the problem? Do people let the machine heat up without the PF in the group? it just seems odd to me...

I can't really test it again since it was the fifth double I had today and I think that's enough caffeine for the day, but I just wanted to get your input on the subject... so what do u say?

Since my Expobar runs quite hot, one of the things I've been playing with is; after flushing and removing the portafilter, dipping it (the PF) in a container of warm water for just a second to cool it slightly. Then drying and filling. I've had some good results.

kramerica wrote:Is it possible that hot PF was the problem? Do people let the machine heat up without the PF in the group?

I'd suggest (with no scientific evidence behind it, just my feelings on the matter) that if it were hot enough to damage the beans, it'd be hot enough to send you running for salve, if not the emergency room.
Of course, I could be wrong.
In any case, I keep my baskets in the drawer, and the PF holder in the machine. I fill the PF and then distribute, level and then put it into the PF handle to tamp, lock back in and pull.

I've thought about this as well, and wondered how it may preheat the coffee. I avoid this with my routine, in which ground coffee goes into a room-temp basket, which I keep separate from the portafilter, which I keep locked into the machine until I'm ready for it.

When the coffee is loaded into the basket and tamped, and the machine has been flushed, I slide the basket into the portafilter and I pull my shot. I use ridgeless baskets so installing and removing them from the portafilter is a snap.

I think it's much more likely that the new routine is simply causing it to brew at a lower temperature. Higher brew temperatures than the blend wants often cause the sort of bitter, burnt taste you're describing. Your machine has a snap-action thermostat. Try running water out of the steam wand until the heating element turns on, then pulling the shot.

Best,
David

RAS wrote:I use ridgeless baskets so installing and removing them from the portafilter is a snap.

Or not, actually! ; >
You can use quite a few different kinds of wires to hold the PF in, just far more gently. There are some heavy gauge guitar strings that'll do the trick nicely, so you can use your old ridged baskets adn still get 'em in and out easily.

Interesting. I see that a lot of you have routines that bypass that potential problem. keeping the basket away from the PF until grinding seems to be a nice solution. I'll try that tomorrow.

Psyd: Well, it doesn't heat that much but I certainly can't touch the metal more than a second. It is hotter than the espresso itself for example.

DavidMLewis: I've tried your tip before and like I wrote it just added an unpleasant sour note to the espresso, the burnt flavour was still there. That what made me think that the problem is not the water temp and that the burnt flavour is not from the brewing process at all.

I'd suggest either a dirty machine, or a transient high temperature.

If it's a dirty machine, it will be present in almost every shot. However, dirty machines taste a little different than hot machines. If you purposely burn the shot, does it taste burnt in the same way, with more "burntness?" Or are there two flavors - this flavor you're describing, and the purposely burnt shot flavor that you've added. This procedure will confirm you are indeed burning the coffee.

Then i'd guess it might be a transient high temperature. I don't know much about your machine, but if it can't hold the temp over the entire shot, you might get a burnt flavor initially, then good espresso as the water cools. (or vice versa). If you lower the temp a little, you'd get a sour and burnt shot. If you lower the temp a bunch, you'll get a sour shot. I'm guessing this because you mentioned getting a sour and burnt shot. I don't know how to check for this condition short of a scace. Plus, I don't know how you'd get a transient unless you have some sort of heater blanket on your machine or a really small grouphead that can't dampen the shot temps.

I've also burned my beans when roasting them too fast. Do you roast your own beans? If you don't, have you tried switching blends?

First of all, I'd like to thank you all...

I decided that my body will handle the 6th cup and tried the "separating the basket" trick, heating up only the PF itself. Well, I'm so happy to say that it did the trick, no burnt flavours at all... only a hint of bitterness in a good way. That was the best cup I've ever had and I couldn't resist having the 7th double right after.

popeye: Although I solved the problem, since you asked, I do roast my own beans and its a great blend of PNG, Yigarcheff, Brazil and Guatemala, all roasted to FC-FC+

Unless there is something SERIOUSLY wrong with your machine, your portafilter should not be hot enough to burn your coffee.

Look at the portafilter/basket combo. There is actually a VERY limited amount of contact between the two - and good airspace around the basket.

I'd look at something more likely as the culprit (flush routine, dirty equipment, uneven extraction due to either distribution or grind quality, coffee quality).