# Bitter aftertaste.



## Ridley

Hi,

I'm having a slight issue with my shots leaving a bitter aftertaste at the back of my throat, I'm at a loss as to why.

I use a Fracino Cherub & a Rocky grinder, VST 20 gram basket which I dose with 21 grams of coffee, I tamp at about 15-20Ib, I have tried slightly more but no change in taste with a slightly coarser grind.

I flush for about 4-5secs through filter then dry & grind directly into it, tamp then run a little more water through group before fitting portafilter.

shot time is about 28 secs from hitting switch for a shot weight of 32-34 grams, there is about 5 secs delay before liquid comes out, first it's quite dark & thick & after about 4 secs forms a nice stream of lighter liquid which looks the same as most vids I've seen. I get nice tiger strip effect & good crema.

I've tried drinking it as espresso & cappuccino, both leave a bitter aftertaste, I do often get some dark bubbles appear on a cappuccino after a few minuets standing, I don't know if that's a clue. I can't say I've noticed that at the coffee shop I go to.

Beans are fresh, I've tried different types, some from a roaster near me, where I drink coffee & tastes great & also from Hasbean.

I've tried using an 18gram VST & also the double basket that came with the Cherub, I'm at a bit of a loss as all the figures seem to add up.

Machine has been back flushed & I've drank the water on its own & it tastes fine (Brita filtered)

Any ideas please?

Cheers Simon.


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## ronsil

Try the brew water at a slightly lower temperature. Bitterness can arise from using too hot water. Sourness as opposed to bitterness comes when the water is too cool


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## garydyke1

Is it possible you are getting channeling, have you got a naked portafilter to view the extraction?

Have you tried different flushing regimes?

Have you tried getting your target yield in 25-26 seconds, slightly coarser grind


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## shrink

I have similar issues with my setup. I'd blamed it squarely on the grinder, but curious that you're also using a cherub!

Going to try a new grinder shortly and will report back.

Is possible you're just not getting the right grind with the stepped rocky, the cherub should be capable of excellent results.


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## Ridley

garydyke1 said:


> Is it possible you are getting channeling, have you got a naked portafilter to view the extraction?
> 
> Have you tried different flushing regimes?
> 
> Have you tried getting your target yield in 25-26 seconds, slightly coarser grind


Hi,

I'm using a naked potafilter & have no signs of channeling, pucks are slightly wet but fully intacked with no holes.

How long do you think I need to flush?

I have had some unplanned faster shots which I think tasted the same but will try again.

Cheers

Simon.


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## Ridley

shrink said:


> I have similar issues with my setup. I'd blamed it squarely on the grinder, but curious that you're also using a cherub!
> 
> Going to try a new grinder shortly and will report back.
> 
> Is possible you're just not getting the right grind with the stepped rocky, the cherub should be capable of excellent results.


Hi,

I did see your thred saying you we're having similar issues, I've made my Rocky step less but am getting a better grinder anyway so will see if that helps.

Cheers

Simon.


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## lookseehear

It might be that you're flushing too much. Fatboyslim has a Cherub and has told me the design of the Cherub thermosiphon through the group means that you don't really need to flush more than about 20-30ml.


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## fatboyslim

Theoretically you don't need to flush at all as long as the machine hasn't been idle for too long. Thermosiphon is very efficient!

I still do flush but mainly for temperature consistency. What pressure does your p-stat click off at?

Should be around 1.05-1.1 bar.

Might be worth checking your burrs out? They could be blunt and giving an inconsistent grind.

As lookseehear suggests, try flushing much less than you are now but I'm convinced its a grinder issue.


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## Ridley

fatboyslim said:


> Theoretically you don't need to flush at all as long as the machine hasn't been idle for too long. Thermosiphon is very efficient!
> 
> I still do flush but mainly for temperature consistency. What pressure does your p-stat click off at?
> 
> Should be around 1.05-1.1 bar.
> 
> Might be worth checking your burrs out? They could be blunt and giving an inconsistent grind.
> 
> As lookseehear suggests, try flushing much less than you are now but I'm convinced its a grinder issue.


Hi,

Grinder is only about 3 weeks old.

P-stat sits at pretty much exactly the figure you quote so I guess all is well there.

I will try just a very quick flush, in the morning machine has about 45 mins to warm up, at the weekend it has much longer, but results seem the same.

Cheers

Simon.


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## fatboyslim

Well one explanation could be that the grinder is too new and the burrs haven't been properly seasoned.

Straight off the shelf burrs often have imperfections that need to be 'blunted out' by running 1-2Kg of coffee through them.

Sounds silly but it took about 4kg to season my mazzer burrs completely.


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## Ridley

Ok, I think it's probably had about 1.5-2kg through it.

The upgrade bug has already bitten & I've ordered a Mazzer Mini, so will have to run that in & see, no sleep for me!

Will try less flushing & see if that makes a difference, I did try the double basket that came with Cherub in place of the VST & it was slightly more bitter, that was the second shot, timing & weight was the same.

Cheers.


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## MWJB

The weights & times are only relevant within the context of a good tasting shot. A shot could be spot on at given weights/times, or horribly over/under extracted.

Where in your mouth do you feel this bitterness?

Keep everything the same and run the first 20s into a shot glass, switch glasses for the next 5s, again for the next 5s, again for the next 5s (keep them in order). Taste #1, then add it to #2...better, or worse? Add #3 & so on. Or just taste the tail end shots & see which ones are absurdly bitter & work back from there.

If you are making coffee in a cafe, you want to have a regime that works by the numbers after dialling in (because you can't taste every shot) & reasonably consistent shot sizes. But if you are making coffee at home you don't need to adhere religiously to a given output...you want a nice tasting shot, whether it be 24g or 54g.


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## Ridley

MWJB said:


> The weights & times are only relevant within the context of a good tasting shot. A shot could be spot on at given weights/times, or horribly over/under extracted.
> 
> Where in your mouth do you feel this bitterness?
> 
> Keep everything the same and run the first 20s into a shot glass, switch glasses for the next 5s, again for the next 5s, again for the next 5s (keep them in order). Taste #1, then add it to #2...better, or worse? Add #3 & so on. Or just taste the tail end shots & see which ones are absurdly bitter & work back from there.
> 
> If you are making coffee in a cafe, you want to have a regime that works by the numbers after dialling in (because you can't taste every shot) & reasonably consistent shot sizes. But if you are making coffee at home you don't need to adhere religiously to a given output...you want a nice tasting shot, whether it be 24g or 54g.


Hi,

I taste the bitterness at the back of my tongue in the middle, also it seems to coat the top of my mouth at the back.

I will try that & report back.

Cheers.


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## shrink

i will be watching this thread with interest.. as i've not had a decent tasting coffee out of my setup in ages. Drinkable yes, but by the standards I assume the cherub is capable of, its just not there. No complexity in flavours, no smoothness, just bitter roasted coffee flavours.

When i'd had coffee training, we tried upping the P-stat as we felt some shots were coming out too sour, but i backed this right back off to try and combat bitterness. So it shouldnt be temperature, as i'm running pretty much bang on cherub factory settings.

I still think my pour times are a bit weird though... if i want anywhere near the 1-2oz range in 25 ish seconds then first pour wont hit until at least 10 seconds. If i go coarser to speed up the initial pour, then the shot blondes in about 16 seconds. Made me worry that perhaps my pump pressure was too high?

but overall, i think i'm pointing the finger at the grinder!


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## garydyke1

Hmm. Why is this a 'problem' ? ''if i want anywhere near the 1-2oz range in 25 ish seconds then first pour wont hit until at least 10 seconds''

Id say most of my shots see the first drips hitting the cup 10-12 seconds after flipping the switch. The vibe pump/e61 combo has a slow ramp up which adds a few seconds of pre-infusion


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## shrink

fair enough, i'll worry less about that. It just seemed that 10-12 seconds was on the slow side!

they still taste pish tho


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## garydyke1

shrink said:


> fair enough, i'll worry less about that. It just seemed that 10-12 seconds was on the slow side!
> 
> they still taste pish tho


An easy test to see if your machine is running too hot (and you dont have PID control) - dont keep your portafilter in the group, use it from cold. If the shots start to taste better ..........

As for OPV setting can you reduce pressure by 1 BAR and retest?


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## shrink

i'll need to research how the fracino adjusts OPV.

i should be getting a loan of a vario to try over the next while, so i can eliminate grinder for sure.


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## gman147

I reckon it is your grinder Shrink. When I switched to the SJ my shots were instantly much much smoother.


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## fatboyslim

shrink said:


> fair enough, i'll worry less about that. It just seemed that 10-12 seconds was on the slow side!
> 
> they still taste pish tho


I would also advise that a delayed start to the shot is ok if not highly desired! What this essentially means is that the brew water is filling headspace between puck and screen then fully saturating the puck before starting the shot.

I believe this is the intended design of the Cherub. Try to let a few shots run to 40-50 seconds from the first sign of golden delight to see if that improve things. Obviously grind fine and keep tamp constant (not too much pressure) till you achieve this.

Do this at least until you can upgrade the grinder. I do get upgraditis about my SJ but its mainly for a doserless grinder rather than the grind quality! Surprisingly fluffy!


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## gman147

I can't think of anything I'd rather have than the SJ for the domestic setup. Maybe a K30, Royal, Robur but anything else I wouldn't see as an upgrade in my eyes. T o be honest, the SJ is probably too good for home use. haha. Prob could've easily done with a mini or vario.


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## gman147

Another thing I would suggest is - when was the last time you took it apart and really cleaned out the burrs and vanes? This can change tastes significantly with all that stale gunk and crud all mixing up with your lovely fresh grinds.


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## Ridley

Well my new grinder arrived today & after an hour or so messing around dialling in & adjusting dosing I got a very nice double shot.

I got about 1.5 oz in 26 secs, very smooth & tasty. Non of the burnt bitterness I've suffering 

Grind is much more fluffy with no clumping at all, it feels like starting all over but results worth it.

Cheers.


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## gman147

Mazzer power!


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## shrink

Well thanks to Michael from funinacup, i now have a vario on loan.

either my MC2 is broken, or its just not a good grinder, because these shots are in a different league. Smooth, tasty and now i can pick up the fruit flavours in rave signature.

-much more even pours. Starting earlier and running through perfectly to blonding in about 27 seconds

-less clumping... meaning my PF is less full and doesnt spill all over the place!

-Less mess

-its epic quiet compared to the MC2

-almost no grind retention

my MC2 is going off to be looked at by iberital. If its broken, it'll get fixed, if its not it'll get sold!


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## coffeechap

Finally! I really hope it is broken, or its time for the wallet to get spanked.....


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## shrink

well playing around more, shows that the shots are not night and day different.. its just that the vario tastes smoother, and has more layers of flavour than the MC2.

based on other reports i'm not convinced the MC2 is broken, i just dont think its a very good grinder!

i'm now trying to decide whether i want to send it off for warranty work, and risk having to pay postage if they find nothing wrong... or just sell it on ebay and be rid of it.


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## The Systemic Kid

shrink said:


> well playing around more, shows that the shots are not night and day different.. its just that the vario tastes smoother, and has more layers of flavour than the MC2.


Interesting what you say about the Vario opening up the bean flavour profile - couldn't agree more. Paired with my LI, the Vario doesn't fall short.


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## shrink

indeed.... i didnt want to like the vario.. i've always been set against its plastic build and rather dubious longevity concerns.

But... as a domestic grinder, its clearly been purpose designed to be as little hassle as possible


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## autopilot

The Systemic Kid said:


> Interesting what you say about the Vario opening up the bean flavour profile - couldn't agree more. Paired with my LI, the Vario doesn't fall short.


Excuse my ignorance, but can someone explain the science behind this? Assuming the grinds are of the correct size, and consistent, what is it that makes such a difference in taste?


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## The Systemic Kid

autopilot said:


> Excuse my ignorance, but can someone explain the science behind this? Assuming the grinds are of the correct size, and consistent, what is it that makes such a difference in taste?


Good point but if you have a look at grinds multiplied several zillion times, you will see that the fines are not all the same size. The Vario does a very good job, IMO, and I get a very open profile when properly dialled in. But, with the same beans, my HG One produces what I can only describe as a different class of grind. It's much more fluffy - what you get from using a bigger burr set in your grinder. I think there is a post on the Londinium blog - I'll post a link to it if I can find it or perhaps someone else can?


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## coffeechap

The way coffee is ground by different grinders is well different. For example the quality of the burrs, the spin rate, the size of the motor, the adjustability(stepped vs stepless adjustments) all play factors in the quality and consistency of the final grinds. Usually, but not always, the more you spend on the grinder the better the quality at the end.


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## autopilot

coffeechap said:


> The way coffee is ground by different grinders is well different. For example the quality of the burrs, the spin rate, the size of the motor, the adjustability(stepped vs stepless adjustments) all play factors in the quality and consistency of the final grinds. Usually, but not always, the more you spend on the grinder the better the quality at the end.


Ok, thats the difference in grinders, but is there something other than consistency and grade (which I realise varies a lot between grinders); is there another significant aspect? Shape of the grinds?


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## The Systemic Kid

autopilot said:


> Ok, thats the difference in grinders, but is there something other than consistency and grade (which I realise varies a lot between grinders); is there another significant aspect? Shape of the grinds?


Here's a link to Londinium blog expanding on why burr size matters.

http://londiniumespresso.com/blogs/londinium-espresso-blog?page=24


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## coffeechap

Shape of grind is about consistency, a key factor in the quality in the cup is the regularity of size of each grind, thus if a grinder is capable of grinding each and every ground exactly the same size then it will mean a perfectly consistent pour provided they are evenly distributed in the basket and even and level pressure is applied during the tamp. Thus the big conical burr grinders produce the most consistent grind quality, then the bigger flat burr grinders, as the coffee is graded better through a bigger burr. Also the spin rate of a grinder directly affects the temperature of the coffee and thus a slower spin rate means cooler ground coffee, less heat in the process means better tasting coffee; the unfortunate aspect here is that to get a slow spin speed with the bigger burrs ( best combination) you need a huge motor or a geared motor to spin the burrs correctly, or alternatively a geared hand conical like the hg1


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## garydyke1

autopilot said:


> Ok, thats the difference in grinders, but is there something other than consistency and grade (which I realise varies a lot between grinders); is there another significant aspect? Shape of the grinds?


You cannot make espresso without fines - grinder design A (Compak K10 WBC)

Good brewed/filter coffee relies on as few fines as possible - grinder design B (Uber grinder)

Design A will have a much smaller range of usable grind settings...design B can do turkish all the way up to small rocks


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## gman147

Been trying to tell you all this since I got my SJ!!


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## shrink

Now you're on the Inker cups too Poona... i think you've been sneaking into my kitchen and stealing ideas again







hehe

I've ordered some hasbean cachoeira. A bean im very familiar with, to act as a kind of control measure. Theres still something i'm not 100% happy about, but it may just be the Rave Signature I'm using, or the fact they are approaching 2 weeks old at this point.


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## fatboyslim

Or could be your evil LM 17g basket. I couldn't get on with mine so I sold it.

Love the extractions from EP HQ Double!


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## shrink

an interesting observation for sure. My extractions look much better now... and taste a lot better. You can see the difference in the extraction caused by the better grinder.

With the MC2, the pour would alternate from dark to light mid-pour, clearly some bad channeling.

With the vario, its a lovely steady stream, much more consistent and controllable all the way through the extraction. Not sure if the basket could be screwing with flavours, I'm not familiar enough with how rave signature "should" taste, to know if what im getting is just how it is.


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## gman147

The LM basket is great. You using a good filter Shrink?


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## gman147

Good shout going back to Cachoeira. It's a very forgiving bean too. You should get good results with it.


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## shrink

its really just to make sure its not the machine in some way. I've ruled out the grinder, and although results are significantly better, its not quite the coffee taste i'm looking for.

but i have absolutely no way to know if thats not the Rave. So back to a bean I know well

then perhaps back to allpress redchurch, which I Know can taste epic


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## gman147

You need to try Finca Loma mate. By a country mile the nicest bean to come out this year.


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## Walter Sobchak

poona said:


> You need to try Finca Loma mate. By a country mile the nicest bean to come out this year.


How is it with milk?


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## fatboyslim

shrink said:


> its really just to make sure its not the machine in some way. I've ruled out the grinder, and although results are significantly better, its not quite the coffee taste i'm looking for.
> 
> but i have absolutely no way to know if thats not the Rave. So back to a bean I know well
> 
> then perhaps back to allpress redchurch, which I Know can taste epic


If you're ruling out technique then temperature is an obvious one. Pump pressure also but I have no idea if Cherub OPV can be adjusted as simply as the Gaggia one.

I am interested to borrow someone's pressure gauge and try it on my Cherub.

Shrink if you have plenty of rave left why not try knocking out shots back-to-back and slurping each one and spitting out again. A shocking waste of coffee but if you consume them all you'll go to the warpy zone for sure.

Its always fun to do this if only just to see if you can pick up subtle changes to temperature and the affect that has on taste/flavours.


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## garydyke1

Walter Sobchak said:


> How is it with milk?


Superb. Delicious sweet chocolate cuts through in the finish, esp as a ristretto base


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## garydyke1

fatboyslim said:


> If you're ruling out technique then temperature is an obvious one. Pump pressure also but I have no idea if Cherub OPV can be adjusted as simply as the Gaggia one.
> 
> I am interested to borrow someone's pressure gauge and try it on my Cherub.
> 
> Shrink if you have plenty of rave left why not try knocking out shots back-to-back and slurping each one and spitting out again. A shocking waste of coffee but if you consume them all you'll go to the warpy zone for sure.
> 
> Its always fun to do this if only just to see if you can pick up subtle changes to temperature and the affect that has on taste/flavours.


Try some 1:1 ristrettos


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## garydyke1

Shrink , its time to video your process so we can see whats going on in your bitter world ; )


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## shrink

todays flat white was yummy yum yum!!

very pleased with the results. and that was with rave sig.

ive got some familiar coffee on the way to me, to act as a yard stick









i think my pstat could back off by maybe 0.1bar... but no more,. not sure what difference that will make temp wise


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## garydyke1

Still want a video : )


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## shrink

haha then come hold a camera


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## garydyke1

For my videos I prop my phone up against something


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## shrink

I'm usually propping me against something









When i get my two bags of redchurch, i'll see if i can make a video of the process!


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## Walter Sobchak

garydyke1 said:


> Superb. Delicious sweet chocolate cuts through in the finish, esp as a ristretto base


Thanks, will give it a try when I order my next batch of beans.


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## gman147

Walter Sobchak said:


> How is it with milk?


Delicious! I had two espressos and the rest were cappus and flat whites. As Gary said, it's very nice with a longer pull


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## gman147

It's so good that once I arrive at my house in about 5 minutes from work I shall have 750g waiting on me


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