The Brewtus has a large brew boiler, so try flushing a litre or so through the group to get fresh water into the brew boiler, if you're only making a few coffee's a day you may have tainted water in the brew boiler, I have seen this happen on a friends minore IV.

Flushing 500mls through the group every couple of days is a good idea.

Sorry for the late reply, I just got back from holiday so hadn't been able to experiment further

boar_d_laze wrote:You may well end up going to 100C -- but do the warming flush first. The ideal espresso brewing temperature for something over 90% of coffees lies between 90C and 96C. A beginning brewing temp of 93C won't be too far off. It's a good enough starting point that, with practice, you can come within 1C of ideal in one, and certainly no more than two shots.

So... what are those signs? Bad flow rate -- too fast or too slow -- is the most common. Your flow time for a 66% to 40% brew ratio should be in the low twenties to low thirty seconds; call it 26sec plus or minus 6sec. If your times are below 20sec or higher than 32sec for an appropriate brew ratio, go ahead and adjust for dose and grind.

A very wet puck (as in so wet that it's liquid) is an indication of under dosing.

The nickel/dime test is a good way of establishing whether the basket is over or under filled.

However, the best test is staying within the nominal range for a given basket. I don't remember what that is offhand for the basket Expobar ships, but I think it's 16g - 18g. If you can manage to dose 17g and get the right flow rate for an appropriate brew ratio, you should be close enough.

Thanks for the long reaction, appreciate the effort and time!
So today I picked up a bag of fresh beans to start again. I set the temp to 93C and let the machine warm up for 90min. Using a 17g dose I adjusted the grinder to get an appropriate flow rate, aiming for 28g-30g espresso (so a brew ratio of about 55%-60%). This was done after 2 shots and then I tried a couple more. I flushed a lot before the shots and a bit less in between, used WDT, pucks looked good (not overly wet) and the dose passed the dime test. The numbers all seem to be okay but the thing that matters most, the taste, still isn't..

Also tried a shot without WDT using the same dose and grind. Just grinding into the basket, level, tamp and go. This resulted in a quicker pour (22sec instead of 25sec) and tasted less bitter but more acidic/sour.

I filmed a WDT shot and the non-WDT shot but there seems to be something wrong with the non-WDT video so I'll redo this another time.

This is the shot without WDT
It's hard to judge this myself but I'm guessing this doesn't look too good?

How is your water?
What is the hardness? pH? and TDS?

Buy Volvic mineral water at the supermarket and try again!
http://shop.delhaize.be/Drank/Water/Pla ... 0194900000

Minor flaws in distribution, but not enough to worry about. Let's mess with brew temp a little more. The overall strategy is "bracketing." That is to get your pulls to go sour by using the usual techniques, than back off til you hit "balanced."

Grind and dose don't seem to be much in issue, although you may end up having to adjust them if all else fails. In your case, the "all else" is temperature. Try 90C on your PID and see if you can't get it the pull to go sour.

Remember that your PID reading is only an abstraction, and not necessarily reflective of actual brew temp. The PID has an offset, and can be adjusted so that the readout is quite accurate. But for the meantime, use the numbers solely as reference points on the hotter/cooler continuum.

Over-Extracted <-> Hotter <-> Bitter. Under-Extracted <-> Cooler <-> Sour.
Have that tattooed backwards on your forehead, so you can read it in the mirror every morning.

If you can't get the brew to go sour no matter how cool you brew, the next most likely candidates for the problem are your perception of bitter/sour or some residual contamination in the machine.

You can check your palate for bitter/sour with a lemon. The pith is bitter, the juice is sour. Also, make sure you stir your coffee thoroughly before tasting. Taste by the spoonful instead of by the cup, because it allows you to taste a dozens of pulls in a session instead of getting over-caffeinated after a couple of cups.

Rich

The PID offset is really something to consider. On my Alexia, its abour 23 degrees, so I set the PID to 214f to get around 191f at the group. If your machine has an offset, this could be the issue. The PID measures boiler temp, not group temp.

Jim

It's not difficult to measure temperature in the coffee cake while pulling a shot. You might try searching "poor man's Scace" on this site. My adaptation of that is to sacrifice a filter basket, drilling a hole in the bottom with the basket inserted in a naked portafilter to insert a thermocouple that's attached to a thermometer. Some people fasten the probe tip with JB Weld. If you have a thin wire thermocouple you can even fit it at the top of the coffee cake before locking in and avoid sacrificing a filter basket. A thermometer with thermocouple is maybe $12 on eBay. That measurement will tell you any offset between your PID reading and actual brew temperature.

NelisB wrote:How is your water?
What is the hardness? pH? and TDS?

Buy Volvic mineral water at the supermarket and try again!
http://shop.delhaize.be/Drank/Water/Pla ... 0194900000

I'm using bottled water (Colruyt).
pH = 7,5
TDS = 477 mg/l

boar_d_laze wrote:Minor flaws in distribution, but not enough to worry about. Let's mess with brew temp a little more. The overall strategy is "bracketing." That is to get your pulls to go sour by using the usual techniques, than back off til you hit "balanced."

Grind and dose don't seem to be much in issue, although you may end up having to adjust them if all else fails. In your case, the "all else" is temperature. Try 90C on your PID and see if you can't get it the pull to go sour.

Remember that your PID reading is only an abstraction, and not necessarily reflective of actual brew temp. The PID has an offset, and can be adjusted so that the readout is quite accurate. But for the meantime, use the numbers solely as reference points on the hotter/cooler continuum.

Over-Extracted <-> Hotter <-> Bitter. Under-Extracted <-> Cooler <-> Sour.
Have that tattooed backwards on your forehead, so you can read it in the mirror every morning.

If you can't get the brew to go sour no matter how cool you brew, the next most likely candidates for the problem are your perception of bitter/sour or some residual contamination in the machine.

Started at 90 today and went up after each shot and I think I went from sour-ish with bitter at 90C to only bitter at 95C. But there never seemed to be a point of balance of "sweet spot" where I actually liked what I tasted, it's always very harsh..

boar_d_laze wrote:You can check your palate for bitter/sour with a lemon. The pith is bitter, the juice is sour. Also, make sure you stir your coffee thoroughly before tasting. Taste by the spoonful instead of by the cup, because it allows you to taste a dozens of pulls in a session instead of getting over-caffeinated after a couple of cups.

Tried this today, and using a lemon I can definitely tell bitter from sour, but with espresso I'm still not sure..

aerojrp wrote:The PID offset is really something to consider. On my Alexia, its abour 23 degrees, so I set the PID to 214f to get around 191f at the group. If your machine has an offset, this could be the issue. The PID measures boiler temp, not group temp.

Jim

But shouldn't I be getting all sour shots then? If mine is set at 92 and there's an offset of 20 for example, the group would only be 72..

hnnsnrt wrote:Started at 90 today and went up after each shot and I think I went from sour-ish with bitter at 90C to only bitter at 95C. But there never seemed to be a point of balance of "sweet spot" where I actually liked what I tasted, it's always very harsh.

It sounds like 90C might actually be pretty close, but still too hot. Go to 86C, and if that's definitely sour (not sour-ish with bitter), go to 88C; and if that's still too sour, go to 89C, or if it's becoming unpleasantly bitter go to 87C.

In other words keep bracketing the brew temperature, until bitter and sour is as balanced as temping will get it. Temperature is one cause of over or under extraction, and seemed the most likely based on your description -- but it's not the only cause. If the shot's still unpleasantly bitter, the problem is other.

"Harsh" is something of a jargon term, usually associated with over dosing. That might be something you want to investigate. Dosing tends to be more basket/machine specific than anything else. Nearly all dosing problems can be solved with the nickle test.

Another common cause of harshness is under rested beans; although we seemed to have isolated that particular variable out. But still, you might want to try different beans.

Yet another possibility is contamination in the grinder, the water path, or the pf. Clean the hell out of everything.

hnnsnrt wrote:Shouldn't I be getting all sour shots then? If [my PID] is set at 92 and there's an offset of 20 for example, the group would only be 72.

No. For one thing the offset could be in the other direction. For another, you're postulating a 20C offset based on a different machine.

The offset on yours could be considerably less. And since you're getting something which is recognizably espresso -- even if its too bitter -- while brewing in the 90C - 95C range, the inference is that you need to adjust your offset no more than 5C.

If water reading 90C on the PID is still bitter with overtones of sour, then the real brew temp is probably pretty close to 95C. I don't know the actual numbers but a preponderance of coffees will temp pretty well at 91C-92C actual; especially "medium roast" SHBs.

If it's any comfort, you wouldn't get much extraction at all at 72C at an espresso flow rate. The resulting shot would be too weak to analyze for other taste defects.

Don't get hung up on the PID's temperature readout. It's only a repeatable marker, not a message from God.

Rich

boar_d_laze wrote:Don't get hung up on the PID's temperature readout. It's only a repeatable marker, not a message from God.

This could be a featured quote. Very nice. If stepping down through temperatures doesn't get you there, I encourage a temperature probe at the top of the coffee cake to finally resolve the temperature question. Here's my sloppy way of doing it, but it worked. I plugged it into a digital thermometer I bought online for less than $10.

I feel like we are chasing the wrong lead here with temperature. I may have missed this, but have you pulled a shot of water without coffee and tasted it. Perhaps there is something in the machine that is imparting the bitter taste. I know that a poorly cleaned machine will certainly produce bitter nasty coffee. Not that I'm impugning your cleaning habits.