# Adjustments for 6 bar



## Phobic (Aug 17, 2016)

I've just changed my machine to 6 bar, only on my 2nd shot and can see a marked improvement, there's more clarity, softer, rounder tastes.

I've used exactly the same brew ratio and grind settings as I did for 9 Bar.

just want to check if I should change anything else to compensate for 6 bar e.g. temp.

My initial thought was I'd need to grind coarser as the longer pull times would mean more contact time with the grinds and therefore higher extraction rates - however on the 2nd spro at 6 bar (this months LSOL) the increased clarity makes me want to increase the grind as I can now taste a bit more acid.

it's almost like a veil has been lifted, bit of a revelation if this is all down to moving to 6 bar!

inclined to just trust my taste buds but it's a bit counter intuitive in my mind.


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## Dylan (Dec 5, 2011)

Thats all well and good, but important questions first... are you still getting donuts?


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## Phobic (Aug 17, 2016)

Dylan said:


> Thats all well and good, but important questions first... are you still getting donuts?


yes


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## Phobic (Aug 17, 2016)

also got the new jet fitted, no difference


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## Mrboots2u (May 10, 2013)

How does it taste ...

Your making coffee for yourself not the Internet ...


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## 4085 (Nov 23, 2012)

you need to grind finer, not coarser. That was the advice from Garyd so don't ask me why


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## Phobic (Aug 17, 2016)

Mrboots2u said:


> How does it taste ...
> 
> Your making coffee for yourself not the Internet ...


it tastes great, but as has been proven in other threads, you can learn a lot from others and avoid some pain/time in the process


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## Phobic (Aug 17, 2016)

dfk41 said:


> you need to grind finer, not coarser. That was the advice from Garyd so don't ask me why


good to hear as that's what I'm finding.

@garydyke1 and others, out of interest any rationale/thinking/science on what's going on to mean that you can/need to grind finer at lower pressure?

I'm trying to think through what's happening, lower water debit means that you need to grind finer to hit the right extraction rates.

By going to 6 bar are we able to control the extraction better i.e. with finer granularity, and/or are we fundamentally shifting the proportions of flavour compounds that are being extracted?

is this why moving to PP gives better control > you're able to balance the flavour compounds more precisely?

just trying to understand what's going on as it's interesting, and helps me see the value in PP.

Thanks

Pho


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## urbanbumpkin (Jan 30, 2013)

I think the lower pressure allows the water longer contact with the puck without causing bitterness /non tasty shot.

Not sure of the science, im sure one of the guys can explain better than me.


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## Phobic (Aug 17, 2016)

I can understand the longer contact with the puck point, however I thought different flavour compounds have different solubilities with bitter compounds being the least soluble, therefore bitter requires the most water contact to extract.

what I can't seem to get my head around is the relationship with pressure, is it more like

flavour compound extraction = "flavour compound solubility" * "water contact time" * pressure

so pressure plays an active part?

or is pressure just a funtion of water contact time i.e. water debit (flow rate), for any given flavour compound.

(hope that rambling makes sense?!)


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## Phobic (Aug 17, 2016)

it's been 20 years since I did A-level chemistry!

I had to go and google things.



> Liquids and solids exhibit practically no change of solubility with changes in pressure


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## Xpenno (Nov 12, 2012)

Phobic said:


> I can understand the longer contact with the puck point, however I thought different flavour compounds have different solubilities with bitter compounds being the least soluble, therefore bitter requires the most water contact to extract.
> 
> what I can't seem to get my head around is the relationship with pressure, is it more like
> 
> ...


Lower pressure means you can grind finer which Increases extraction yield, this can be preferential when using grinders like the EK43.

Lower pressure also causes less stress on the puck which means less channels and therefore increases evenness. Evenness is good.

It's not really to do with contact time as for 2 shots at the same recipe (say 20g into 40g in 30s) but using different pressures should result in the same contact time.


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## MWJB (Feb 28, 2012)

Phobic said:


> I can understand the longer contact with the puck point, however I thought different flavour compounds have different solubilities with bitter compounds being the least soluble, therefore bitter requires the most water contact to extract.


You're equating bitter to over-extraction. Over-extraction can be & is usually bitter & drying, but over-extraction is an objective measure - Are you over-extracting? If not, using bitterness as a synonym for over-extraction is pointless. Bitterness may be there for other reasons, like low/uneven extraction.

Some coffees can have bitterness at nominal extraction & that may be normal for that coffee, low side of normal extractions can also be much less sweet than mid-box extractions, or those at the higher end of tasty where they start sweet & bitterness may creep in at the very last sip(s).

Some components are pretty universal to coffee generally, other specific compounds are there from source. Extraction is about achieving balance in flavour, representative of that coffee, not a taste-o-meter ("Hold the fruit, turn up the choc, here lies oranges, make my Indonesian taste like Ethiopian" etc.).


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## Phobic (Aug 17, 2016)

Thanks both, very useful explanations which helps my mental image of what's happening a lot!


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## DavecUK (Aug 6, 2013)

Phobic said:


> Thanks both, very useful explanations which helps my mental image of what's happening a lot!


If it helps, my observations and experience of pressure and it's affects.

*Pressure is that thing that when changed can allow you to change grind level and achieve the same flow in any particular time, for machines that give a constant pressure. Or lower/raise the pressure to change the flow (within limits) for any given grind.*

*
*

Changing grind level changed flavour/extraction whatever you want to call it.

Different coffees prefer being ground finer/coarser (or I prefer them that way)

Roast level can affect flavour indirectly, because it can affect grind

Changing the Gicleur will allow you to change the overall maximum flow rate (and by definition the ramp rate slightly) but will not affect the max pressure. Of course this overall maximum flow rate really only matters when it is less than that of the puck itself.....which it almost never is. Hence a Gicleur change (if it's going to have an effect) mainly affects the beginning of the shot and ramp rate. I tried running a Vesuvius without a gicleur and the results were a disaster, as the pressure can be low, but through a fire hose!





*
A machine that can vary pressure during a shot, the effect is different, because now the above statement won't necessarily hold true.*

*
*

How the pressure is initially applied to the puck is very important

Ramp rate is important

Overall max pressure is important

These other factors can change the flow rate significantly. A machine set at a constant pressure of 8 bar may choke on a grind that might extract perfectly well on a pressure profiling machine using long low pressure preinfusion and the pressure ramped up slowly to 8 bar. Of course that doesn't mean the shot will be better, just that there is a much wider set of parameters to play with for any particular coffee.

To widen the parameters further would be the ability to vary flow as well as pressure e.g. for the same varying pressure profile a very small gicleur and a large one would give a whole new set of pressure flow characteristics. Here the concept of a hi flow and low flow pressure profiling machine would deliver this. The problem is, this change in flow cannot be delivered by the pump, that won't work, because pressure and flow are linked. Using a manual valve, means you won't have consistency and you can't program it. On a pressure profiler using a valve and flow rate to control pressure (dynamic pressure) you can't do it, again because pressure and flow are linked in a different way to pump controlled pressure. There is a way to do it and for it to be programmable, but for now, that's my little secret.

Ultimately though, I personally believe for both above scenarios, the ultimate effect on taste is grind level and of course the amount of water through the coffee per unit time. This is all any machine is doing. Just the range across which it can do it varys.

and lets not even talk about temperature..........


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## Phobic (Aug 17, 2016)

Thanks Dave, very interesting read.

what do you think about the DE implementation of flow profiling then?


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## DavecUK (Aug 6, 2013)

Phobic said:


> Thanks Dave, very interesting read.
> 
> what do you think about the DE implementation of flow profiling then?


Not sure till I see it...the El Roccio implementation was a disaster and that used Vibe pumps. The other big problem is a lot of stuff can be hidden in software should the manufacturer choose to. It's made doubly difficult because measurements at the puck are not easy. The DE thread is so long and so full of crap that I can't be bothered to pull the wheat from the chaff. It would be better if there was a detailed technical implementation from DE that explained how these things work.....well for a reviewer at least, who would get them in commercial confidence.

However for various reasons, I don't think I would review the DE machine if Bella Barista purchased one and sent it to me for review at this time. However, I would review the DE machine, for DE, if it came directly from DE at their expense *and they follow my rules, which are either don't publish, or publish with NO edits.*

However I think it's academic, like many new products today many start up manufacturers prefer to sell without detailed long term proper reviews....and the customers seem happy to buy them. Of course one that happens you tend to get the positive reviews of owners. If the machine is bad, last thing they want to do is say it, as then it's difficult to resell. Or you get the type of Amazon review of discount purchasers, or those that got the machine free....which are valueless.


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## Phobic (Aug 17, 2016)

I've read the whole thread and don't remember them stating how they do it, and a quick search through doesn't show any explanation that I can see.

will be interesting to see what peoples views are once a few more get out into the wild.

it's a bit of a shame on the price point of the DE1+, if it were a bit more reasonable I'd take a punt on it but as it stands it will need to prove it's significantly better at tastiness production first.


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