Hi everyone,

Based on descriptions promising a liquid candy bar from Toscano, I recently signed up for a subscription. My first bag arrived a couple of weeks ago, and the shots I pulled on the first few days were, in fact, pretty darn good. However, that stopped; now, I'm either getting shots that are unpleasantly bitter, or shots that are simply very dull.

I thought this might be due to aging beans, but I'm getting the same result from fresh ones I just received.

My setup includes a Silvia (v2) with an Auber PID, and a Rocky doserless. I've measured the offset on the PID and, based on that, have experimented with brew temperatures from 197-203. I weigh the ground coffee to within 0.1-grams, and use WDT.

I've tried varying the dose and grind, of course, but it hasn't helped much. (Actually, I've found that I don't have much room to vary the grind. One or two grinder clicks is the difference from a shot that flows way too fast to one that is nearly choking the machine.)

The best I can get is a shot that isn't overpoweringly bitter, but which also just tastes really "blah." No rich coffee aroma, no sweetness, certainly no chocolate or caramel. The taste of the espresso kind of reminds me of how laser printer toner smells, if that makes sense. The shots do look good, though, with excellent color and good crema and body.

My machine is very clean; I backflush and descale regularly. I've read through a number of threads relating to Toscano and Silvia, but no luck so far.

Any ideas would be greatly appreciated!

When was the last time you've taken the dispersion screen out for cleaning? Backflush and descaling don't take care of the oil build up in the group head. The smell you are describing probably comes from that build up (that is if everything else hasn't changed, such as your water or mold in the tank, etc).

You can try running an empty shot (just water no coffee) into a clean cup and smell it. If you notice hints of car oil-like smell, then work your way back. I'd suggest to take out the screen, jet breaker and the disk which they mount on. If you haven't done this before you'd be amazed of how much of a build up you have to get rid of.
I can elaborate on how you can clean it well, but maybe you're already familiar with the procedure. Let me know if you are not.

If it's not all of that then perhaps I would check the reliability of the PID . Have you actually measured the temp and compared it to the PID readings?

I can assure you it's not the beans. I use Toscano as our "everyday" blend for espresso at our new coffee bar in Centerville, Ohio - Nonnie Waller's Parlor, and receive great feedback on its taste, body and fullness. I use a La Marzocco GB5 semi-automatic so equipment probably has a lot to do with consistent extractions. Also something sounds odd if one or two clicks goes from super fast to choking your machine.

What's your brew recipe? You mentioned grams in? What about grams out? What's your shot time?

I'd be surprised if it's your machine all of a sudden but do make sure like gedit said to clean your dispersion screen.

It's also weird that such small grinder adjustments are having such an impact. Fwiw I can easily adjust Toscano to go from a 20g - 40g shot in 30s. Granted I'm using a Super Jolly Grinder but my friend with his Breville can too.

Thanks for all the suggestions, everyone. Here are follow-ups/responses:

gedit: I removed the shower screen and soaked the parts in hot water + Cafiza. So far, I haven't noticed any change. (There wasn't a whole lot of buildup because I had cleaned the shower screen not too long ago.)

One thing I did notice is that the heavy brass disc above the shower screen, on my machine, doesn't look like the ones I've seen online. Once I cleaned mine, the top of the disc was the color of a copper penny -- not yellow-green like brass should be. The bottom of the disc is brass-colored. Have I somehow stripped off an important coating? And could that be affecting flavor?

As for the PID, I used Jim's suggested method of finding the flash-boil point and subtracting 212F. I don't know anyone with a Scace I could borrow, so that's the best I've got for now.

One thing about the PID that seems a little weird is that it seems to affect the pump pressure whenever it switches on the boiler. When brewing a shot, you can hear a pulsing sound in the pump, and if it's a tight grind, you can even see the stream flow decrease a bit each time the boiler light comes on. I know it's not a bad pump, because I just put in a new EX5 one week ago. Is this normal?

Joco: The least bitter recipe is 16.5 grams in, 30 grams out, 25-26 seconds, at approximately 199F.

HB: Good point. My burrs are very old. I just ordered new ones; hopefully this'll help!

caffevespa wrote:
Joco: The least bitter recipe is 16.5 grams in, 30 grams out, 25-26 seconds, at approximately 199F.

Can you increase your dose at all? Ive had good luck with about the same brewing ratios but I follow 18g in and 36-38g out over about 29-31 seconds. Maybe you'll get a slightly higher extraction.

I see.
Discoloration of the heavy brass is normal, no special coating other than the coffee oils (which appear as a thick black coat). so no worries there..
By the way when you took out the this assembly, how does the jet breaker look like, have you noticed any cracks on its base (the joint of the little cylinder and the disk)? Do you have the old version or the newer? that can greatly affect the flow.
As to your observation of the pump pressure. Absolutely. When the boiler kicks in, it draws most of the power at that moment and there will be a drop in pump pressure (because of drop in power that goes into the pump). You should not pull shots when the boiler kicks in, if PID is accurate, at that point water is cold for espresso.

Is your grind coarser than before?
Have you ever set the OPV? What is the pressure?

I don't think you can pack more than 16g into the Silvia unless you have a triple. The double with more than 16g, pushes back on the screen/Jet breaker.

Joco wrote: It's also weird that such small grinder adjustments are having such an impact. Fwiw I can easily adjust Toscano to go from a 20g - 40g shot in 30s. Granted I'm using a Super Jolly Grinder but my friend with his Breville can too.

The Rocky has significantly large steps between clicks. This is normal that even 1 click can change things by a full second either way. An SJ or Vario would be an improvement in control. (I owned the same Rocky many years ago.
Maybe the new burrs will be the ticket.) Couldn't hurt.

Of course, NOW he'll have to break the new burrs in a bit. I'd suggest hew use something OTHER than Topscano for that chore!

The jet breaker looks normal to me; I don't see any cracks or anything like that.

I'm intrigued about the PID/boiler/pump thing. I have an Auber PID. My unit turns on the boiler pretty much immediately whenever there's a slight drop in temperature, including brewing. So, say, if I choose a set point of 217F, the PID will get there and hold it indefinitely. Once I engage the pump to brew, though, the temp reading starts to fall (as you'd expect), which causes the boiler to come on immediately in an attempt to maintain a constant 217F. As far as I know, there isn't a way to force the PID to go "hands off" during the brew cycle. Or am I missing something perhaps?

I think my grind is a little coarser than it used to be. If I go finer, the pump cycling thing is worse (the stream actually breaks up into dribbles intermittently), and there's very thin crema.

I haven't adjusted the OPV. I don't have a gauge, so not sure about brew pressure. I did do the blind filter basket-flow rate test, and I'm getting 196 cc / min, which is supposed to mean about ~10.5 atm of pump pressure.