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What I learned on Twitter yesterday about refractometers & bright coffee
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jonr
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Joined: 25 Jun 2013
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Posted Fri Apr 18, 2014, 8:38am
Subject: Re: What I learned on Twitter yesterday about refractometers & bright coffee
 

gera Said:

does taste actually correlates to extraction levels across all coffees, all situations all roasts? NO!
... yes you can correlate taste to extraction, ...

Posted April 17, 2014 link

That's confusing.  I suggest that it always correlates, the questions revolve around how, what values, is it portable, is it useful, can it replace some tasting, etc.
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jpender
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Posted Fri Apr 18, 2014, 9:30am
Subject: Re: What I learned on Twitter yesterday about refractometers & bright coffee
 

Even with my very limited experience I know for a fact that it does not correlate in all situations.
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MWJB
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Posted Fri Apr 18, 2014, 9:31am
Subject: Re: What I learned on Twitter yesterday about refractometers & bright coffee
 

jonr Said:

That's confusing.  I suggest that it always correlates, the questions revolve around how, what values, is it portable, is it useful, can it replace some tasting, etc.

Posted April 18, 2014 link

Your edited quote would seem to make the statements more confusing by removing context. I don't know why you have decided to suggest something without any apparent basis for that suggestion. I don't recall anybody asking whether, or suggesting that, a refractometer can replace tasting...if it can, then who would brew coffee purely for sampling in refractometer?

As to portability, the refractometer in it's (optional) Otter case with room for wipes, pipettes, spare batteries (syringes & filters, if required, need to be carried seperately) is ~9"x5"x3.25" & weighs 756g. The software is as heavy as the laptop/phone/tablet that carries it.
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gera
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Posted Fri Apr 18, 2014, 11:31pm
Subject: Re: What I learned on Twitter yesterday about refractometers & bright coffee
 

jpender Said:

Gera, that was the best explanation I've read.

But what about in terms of a person at home, pulling shots or brewing coffee from different sources, either roasted at home or purchased from different roasters? How portable is the extraction to taste correlation from one coffee to the next, or even as a given coffee ages? It would seem difficult to explore the extraction space so fully if it might require hundreds of shots each time when a 12oz bag of coffee contains far less than this. Do you think the VST would be less useful in that environment as opposed to the one you work in?

Posted April 18, 2014 link

Well it is harder to develop an accurate correlation between extraction ratio and taste without a large enough data base. As a home user you might start with just measuring some (or all) your shots and brews and just log them in to a data sheet. Pull shots, or brew as you normally would but make sure to measure everything, from brew ratios, doses and extraction times to grind setting, taste, bean age or even ambient moisture and temperature (that's what I do). Over time (hopefully) there will be some patterns emerging, you might notice that there is a particular extraction or TDS range you enjoy for most of your coffees Maybe a particular extraction time provides you with the best results with your equipment regardless of coffee type or roast It might be good enough to just identify a recipe for only one coffee to start with It might not work for all coffees in all situation but it could give you a starting point to work from. In any situation a refractometer, when used correctly, could only be a helpful tool, if you can afford it that is :)
There are always adjustments that have to be made, even using the same coffee every time. If the roast is very fresh you might need some extra water to mellow the acidity. If the coffee was roasted a bit too dark maybe a tighter shot could help avoid nasty roasting flavors. You don't HAVE to have one to make good coffee, but it those help in taking some of the guesswork and trial and error out of the process.
Gera
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gera
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Posted Fri Apr 18, 2014, 11:44pm
Subject: Re: What I learned on Twitter yesterday about refractometers & bright coffee
 

jonr Said:

That's confusing.  I suggest that it always correlates, the questions revolve around how, what values, is it portable, is it useful, can it replace some tasting, etc.

Posted April 18, 2014 link

Yes you got it right Extraction values do correlate to taste, what I was trying to say (in a weird and complex way) is that the same value (for example 16% extraction) would not taste the same with different coffees, using different equipment or whatever.

Even with the same coffee 16% extraction could not possibly taste exactly the same every time, but over a number of shots there will be some consistency in the flavor profile at that range. There is always a need to taste the coffee though. In no situation can a refractometer replace taste, small changes in coffee age, roast profile, blend composition, green bean quality est... create small changes in the taste profile and require small adjustments to the recipe. It is much easier to make those changes when you know where you are, where you are trying to go and how to get there and a refractometer does help in doing those things faster and with more accuracy. IMHO.
Gera
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jonr
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Posted Sat Apr 19, 2014, 6:27am
Subject: Re: What I learned on Twitter yesterday about refractometers & bright coffee
 

"predictable dependence" is probably the concept some are referring to.

Say I'm adjusting various parameters trying to find the optimal tasting espresso.   At some point, I pull a shot that measures 1% extraction.  Should I:

1) taste it, because it might be the god shot I've been looking for or,
2) dump it in the sink because I'm sure that it won't be any good

Hint: my answer is 2, which is why knowing % extraction can replace "some tasting'.
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MWJB
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Posted Sat Apr 19, 2014, 7:00am
Subject: Re: What I learned on Twitter yesterday about refractometers & bright coffee
 

jonr Said:

"predictable dependence" is probably the better phrase.

Say I'm adjusting various parameters trying to find the optimal tasting espresso.   At some point, I pull a shot that measures 1% TDS.  Should I:

1) taste it, because it might be the god shot I've been looking for or,
2) dump it in the sink because I'm sure that it won't be any good

Posted April 19, 2014 link

If your shot is over 300g in weight & you like brewed coffee at the weaker end of the scale, then you might love it...in reality this is a little unlikely, but until we taste it the jury's out.

%TDS is common to solutions, never noticed "ppm" on your bottled water? Your local water authority can supply figures for the various elements in your tap water & these are in much, much smaller proportions than the dissolved coffee solids in your espresso.

1%TDS = 10,000ppm, many people prefer/recognise espresso to be a drink anywhere from five to twenty times more concentrated than this. Brewed coffee can be preferred at a wide range of concentrations from a little over 1% (typically) to 4 or 5 times this.

I think you are reading too much emphasis into "%TDS", it's not the answer in itself, it's the mechanism used to calculate yield - the ratio of the dry dose that turns into brown liquid in your cup (after all, what can impact the cup as much as how much of the coffee you use actually ends up in in it?). If you forget to dose your portafilter you get 0% yield (hot water), if you are somehow able (it's not common, as Gera describes) to extract everything the beans can give up, you might hit around 30% yield.

An ideal yield is extracting as much as you need from the beans to give a pleasant flavour balance, or even hone in on certain aspects of the profile. Concentration (regarding coffee as a whole, not specifically espresso) is enjoyed at a huge range of concentrations, but a much, much smaller range of yields. But a specific yield preference can "float" for a number of reasons.
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jonr
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Posted Sat Apr 19, 2014, 7:06am
Subject: Re: What I learned on Twitter yesterday about refractometers & bright coffee
 

Your post came in while I was correcting %TDS to % extraction.  So would you bother tasting the latter at 1%?
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MWJB
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Posted Sat Apr 19, 2014, 7:29am
Subject: Re: What I learned on Twitter yesterday about refractometers & bright coffee
 

jonr Said:

Your post came in before I corrected %TDS to % extraction.  So would you bother tasting the latter at 1%?

Posted April 19, 2014 link

A 1% extraction is probably quite hard to achieve (for espresso it would be more viscous that many would even dare try to taste), I haven't tasted extractions that low, I have tasted brewed extractions at 4% upwards (notes say "green, pithy, bitter, carbon, choc" for a range from 4-8%). I don't feel they are in any way representative of what we recognise as coffee, I personally find it hard to imagine that anybody who has tasted coffee before would have a preference for such low yields. Once you start getting above 12% things begin to improve, even if the coffee is 'generic', 15% to 17% Gera has discussed.

Pull a shot as you normally would, then pull another dividing it up in several shot glasses, or one of those ice-cube trays, taste the different portions of the shot in isolation, see how the parts taste individually compared the the whole shot.

It may be enjoyed below & above the "ideal range", but whether it typically is, or whether people should be advised to aim outside it (without careful & specific consideration) is another matter?

There are undoubtedly folk who never get into the ideal range & still enjoy their coffee...but without exploring the possibilities (if that is a practical option) how can they be sure they are getting the best out of it?

The grower grows the coffee, roaster selects & roasts it, but it's not actually a beverage until someone brews it...if we brew it and immediately want to spit it out who do we blame? Are we confident we are presenting that coffee in a manner that does the grower & roaster justice? Are we tasting what it has to offer, or are we tasting foibles in our brewing?

Coffees are different from one to another & will always display different characteristics & flavour compounds, this is an objective measurement that can help establish typical preferences, for a given method, for a majority of coffees & tastes.
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boar_d_laze
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Posted Sat Apr 19, 2014, 10:08am
Subject: Re: What I learned on Twitter yesterday about refractometers & bright coffee
 

Mike,

I get how you organize the (coffee) world.  Actually, you've always made sense to me -- and I'm certainly in no position to cast stones at you for being long winded or recursive as a way of meeting predicted criticism -- but we are.  So sue us.  

While the methodology (any accurate methodology) is too clunky for anyone brewing at a less than industrial volume, and has practical utility limited to consistency, you raise some interesting thoughts about whether "the box" matters, and if so, where it really sits.  

It's nice to have quantifiable data about good vs bad coffee.  On the other hand if my coffee tastes bad because it's both bitter and "in your face," I'll dose lower, grind finer, brew cooler, and/or work to a lower brew ratio; and can by God guarantee that tweaking by taste (a) will not only make the espresso taste good, but put it "in the box," too; or (b) if it doesn't put it in the box, that there's something wrong with the box.  

I tried to get Mark to say something along those lines but he got shy and started distinguishing between competence and excellence while denying his obvious excellence.  The thing of it is though, this sort of control is competence and nothing more.
__________________________________

Gera,

My apologies for being so blunt.  Please don't take this as personal criticism; you've obviously invested a lot of time and considerable intelligence into the inquiry.

But for now, your approach seems to be to gather as much data as possible without any particular plan and either (1) hope a pattern emerges; or (2) claim a pattern will emerge but that the pattern is specific to every individual coffee.  I'm not sure which, it seems to depend on the post.  In any case, it's non-scientific, non-explanatory and insufficiently predictive to be useful as a guide to better coffee at any level of volume.  

Furthermore, you've made it clear that if there's a pattern you can't describe it; and you can't use any particular refractometer reading to guide you to making better coffee.  

Again, pardon me for being so blunt.  
____________________________________
____________________________________

Bottom Line

Taking espresso as an example:  By far the most common problems are diagnosed on the basis of whether the shot is over or under extracted (bitter or sour, respectively); and/or attenuated or "in your face" (too dilute or too concentrated).  Possible causes are limited to roast, technique and/or machine.  

These problems are either easily recognized as problems, or they aren't problems.  If the coffee tastes bad -- problem.  If the coffee tastes good -- no problem.  If you're not sure, you need to work on your palate.  No device can replace your palate.  

Fixing almost every espresso problem is either a matter of adjusting temperature, grind, and/or dose; or replacing the beans.  The more you know about the general principles of brewing espresso and the better you know your specific (equipment) setup, the easier and more consistent that becomes.  After awhile, it's not so much problem solving as the dialing-in process of Get it? Got it? Good.

If you're still in the process of developing your palate (or, probably more likely, learning to trust yourself) and learning your equipment -- it can seem daunting.  But, trust me, all it takes is practice and self-confidence.  

In my experience, there's a limit to how far you can tweak coffee.  For instance, adjusting ~18g doses by the nearest 0.1g isn't going to make a detectable difference in the cup.  Differences which are detectable only as a function of some non-sensory measurement (e.g., %TDS. 1sec difference in pull time, etc.) are only important if they lead to differences which are taste detectable.  

And so far, that doesn't seem to be the case.  Or -- if it is -- no one's giving the specifics.

The whole "non-linear" thing is an interesting observation, but not predictive, and consequently non-helpful.  Measurements are interesting information only insofar as information conveyed, not in and of themselves.

If I can pull a great shot dosing at 17g, I don't particularly care if I can pull a similar shot at 19.5g but not through the range of 17.5g - 19g.  Why would I?  I'm after the great shot, not a complete phenomenology of a Las Lajones Natural Caturra roasted C+/FC according to a particular profile and pulled as espresso.  Like nearly everyone else in the universe, if 17g makes a great shot, I'll just keep dosing at 17g, thank you very much.

I'd love to buy a refractometer because I like toys.  But an accurate refractometer is too expensive to buy on a whim and, sadly, so far no one's supplied a cognizable excuse.  

Rich
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