Options for measuring dissolved solids

Coffee preparation techniques besides espresso like pourover.
day

#1: Post by day »

First, there was a recently locked thread. This is specifically NOT supposed to be like that. That was going crazy so just wait for it to reopen to continue that.

There was a recent post on a video by Tim windolbe that sold me on the importance of knowing what is getting in my cup scientifically. I am dirt...well i had to use my credit card to buy Dirt for my garden this week so maybe poorer than Dirt poor (just an elementary school teacher after all :) ) so of course i have to save up and go Dirt cheap.

As i look at options i see things like this

http://www.amazon.com/gp/aw/d/B007Z4IN58/

And this for way less

http://www.amazon.com/gp/aw/d/B003H7ILCW/

On coffeegeek there is a forum that gives a simple equation to say .85xbrix to begin calculating percent, why wont these cheap options work, or will they?

The real problem is trying to evaluate roast and brew methods at the same time
Yes, i you per this on an iPhone

chris_n

#2: Post by chris_n »

be careful or the VST mafia's long arms will silence this thread too

samuellaw178
Team HB

#3: Post by samuellaw178 »

You can always go back to oven drying and do a Brix calibration standard curve (dried TDS vs Brix). That's the old(and gold) standard of establishing TDS, in anything. Not just coffee. And I am confident that is the method to establish TDS way back when they do the golden cup experiment. I figure they don't have a time machine to teleport back a 'patented VST refractometer' for Lockhart to create the strength vs extraction chart(that derives the 18-22% extraction preference). I may be wrong about that though. :oops:

If that is infringing the "VST patent", I dunno what else doesn't. Or probably I should quit the coffee hobby, until I pay the VST royalty. :mrgreen:

Make a big pot of espresso. Dilute them to different concentration, measure each dilution with a Brix meter. Once you get the oven dried weight data, plot them with corresponded Brix reading on Excel.

You need an accurate scale and syringe to filter the undissolved solids though.

The caveat is that the accuracy/precision of unknown Brix meter may not be that good or reliable (thus I see the advantage of VST, and why cheaper meter doesn't work that well). Your TDS reading may be slightly different from the VST meter, so you can't compare with those who are using one. But doesn't really matter because the point here is to check our consistency, who cares about being on the same page with the VST.

Time consuming? Yes. But that's what you pay for others to do the job (VST). If I want to measure TDS on my coffee, that'll be the way I do it. Honestly, I see the overzealous protection does more harm than benefit to the product itself.

chris_n

#4: Post by chris_n »

^^ well said. i've been just doing the drying/weighing method, but it gets tiresome waiting...

day

#5: Post by day »

Keep it on track guys if you can, i am totally new to understanding how to properly measure tds and all the innuendo and references make it very confusing

And for the record, the question is not "did they have a time machine" but rather "is there anything special about that moment in human development that would cause our future generations to travel back to that point with the data once time machines are invented" ;)
Yes, i you per this on an iPhone

chris_n

#6: Post by chris_n » replying to day »


to properly answer your initial question, yes, they will work. the quality of data you get from the instruments you mention will be dependent on your prep techniques. (filtration, cooling etc). repeatability may possibly be an issue for the digital instrument, but the analog one should do just fine!

don't expect your results to correlate directly with what VST users will be getting. in order to find a baseline to compare your results, I would perform multiple side by side measurements using a dehydration method.

day

#7: Post by day »

chris_n wrote:to properly answer your initial question, yes, they will work. the quality of data you get from the instruments you mention will be dependent on your prep techniques. (filtration, cooling etc). repeatability may possibly be an issue for the digital instrument, but the analog one should do just fine!

don't expect your results to correlate directly with what VST users will be getting. in order to find a baseline to compare your results, I would perform multiple side by side measurements using a dehydration method.
So if i understand correctly, if i learn how to do the drying method (will
Have to read more about that as well...think i laughed at that concept not long ago) and then correlate that data with what i read on the analog brix, do that several times per change of brew parameters and then over several extraction parameters to plot a basic line to identify the relationship and change in brix reading vs actual tds, then the brix reading should be easily converted to percent?
Yes, i you per this on an iPhone

chris_n

#8: Post by chris_n » replying to day »


absolutely. this is essentially how all methods get evaluated and validated.
compare x number of repeated readings via new method and old method

x is up to you, but tbh, if you maintain good practice over the controllable variables, you should have no problem with 10 datapoints. the standard deviation should be well within bounds

baldheadracing
Supporter ♡

#9: Post by baldheadracing »

Funny, the conclusion that I drew from Tim Wendelboe's recent videos (and the recent threads) was that I have no need for a refractometer - because I can taste what I make, and taste trumps instrumentation.

Now, if I can't taste what I make, for example, if I was working in or owned a café or roastery; or if I/staff had to produce consistent repeatable results for weeks/months/years at a time; or if I was constantly working with new equipment and/or new (green) beans; then I could see the benefits of using refractometers and an associated software ecosystem like VST's.

Otherwise, I can think of better ways to improve my espresso - for example, taking courses and workshops.

YMMV.
What I'm interested in is my worst espresso being fantastic - James Hoffmann

day

#10: Post by day » replying to baldheadracing »

What i took from the video in this regard was a result of several factors.

1. I roast on a moderately ghetto rig though am looking in the next year for an sr700 with hf dimmer or a behmor plus. Either way, being able to use this to help me compare different roasts of beans, extraction % and thereby reduce variables and truly evaluate my roasting would be huge imo.

2. Just to really master and perfect shot pulling and dialing in, the impact of various grinds and pressure etc in a quantifiable way i think it would be invaluable.

3. To play with various brew methods and keep track of hard data to correlate my findings and really fully understand each coffee prep and technique
Yes, i you per this on an iPhone