Options for measuring dissolved solids - Page 2

Coffee preparation techniques besides espresso like pourover.
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another_jim
Team HB

#11: Post by another_jim » May 26, 2015, 10:34 pm

The problem is not converting brix to TDS. The basic 0.85 equation has been around since the mid 1990s, and is not part of the VST patent. The problem is getting replicable and reliable results. This requires good temperature compensation and filtering the brew. Moreover, while all brix meters are accurate enough to get a rough estimate of TDS, you need an expensive one to get it accurate enough to work back to a useful extraction percentage. The VST gear is a packaged "selling water by the river" solution for doing that. If you want to do it yourself, get an accurate meter, and be prepared to take some time and trouble.

My personal advice is to ignore TDS and extraction levels and brew by taste ...

The TDS and extraction levels that are tastiest vary by coffee, roast and prep method. All you truly need to know is that grinding finer gets you higher extractions; and that higher extractions taste mellower, while lower extractions taste rawer (the mild flavor and body compounds extract last, the strong flavor compounds extract first). You can measure until you are blue in the face and you will learn nothing more than this. Taste the brew, then adjust the grind to taste; and that is all there's to it. The rest is commercial BS and "selling water by the river"
Jim Schulman

chris_n

#12: Post by chris_n » replying to another_jim » May 26, 2015, 10:42 pm


this absolutely. since this is HOME-barista, everyone should absolutely be brewing by taste.

the reason for many advocating using this in a production setting is for QC purposes from batch to batch, product consistency and eliminating human error. all this happens in the lab and doesn't really happen on the bar side of things.

Ben Z.

#13: Post by Ben Z. » May 26, 2015, 11:52 pm

I haven't tried measuring my espresso with my Homebrewing refractometer. What is the purpose of filtering? I know if I measure cloudy wort, the line is blurry, is that it? As to temperature, doesn't the ATC function on my refractometer take care of this?

I guess another cheap alternative would be to directly measure density using a hydrometer, Unfortunately you'd need a couple of shots! Nice thing there is that they are insensitive to suspended solids (there is a nice poodles in a pool analogy that I remember).

chris_n

#14: Post by chris_n » replying to Ben Z. » May 27, 2015, 12:07 am

analog homebrewing refracs are exactly as you suspect. when you measure cloudy wort, the line is blurry.

that is it!

it's a bit more troublesome for digital methods hence the filtration.

as far as atc goes, it depends on the ranges it can compensate for. in short, just always take your readings at the same temperature.

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Andy

#15: Post by Andy » May 27, 2015, 3:04 am

chris_n wrote: if I measure cloudy wort, the line is blurry
Correct, but that doesn't necessarily mean it is inaccurate, only that it is imprecise. I don't know whether such a low-res reading is useful for determining extraction rate. Anyway, I agree with another_jim's approach.

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AssafL

#16: Post by AssafL » May 27, 2015, 3:10 am

At least for me, the first couple of uses of the refractometer were interesting. Then it got placed in a drawer (too fussy, and also why would I waste time confirming a sink shot measures poorly or even worse, why would I waste a precious drops of the extracted elixir of a great shot to a 'fakate' prism?).

I really don't need a daily refractometer routine to tell me that my coffee is underdeveloped (Blech!) or how to adjust grind (albeit the first couple of days did confirm assumptions).

The only reason I could find to use a refractometer at home (until now) was to get an unbiased confirmation that any hack/adjustment/calibration "whatchamacallit" that I do to my grinder does indeed reflect in EY.

The problem the refractometer solved for me is confirmation/myside bias (Like the Beranek Effect in Audio) whereas if one realigns the burrs - is it a real improvement? or is it an imagined improvement (or even worse - leads to a deterioration in extraction).

That being said - I do use refractometers extensively for other uses at home. My main use is making ice cream which I can't imagine doing without my refractometer hanging on a lanyard from my neck. It isn't a very accurate method, but I developed my own "recipes" with the correlation I made for different fruit purees and what I am looking for in terms of "Brix" for the fruit puree. I say "Brix" - because that is the vernier. What is actually measured is a fruit puree which has many things other than sugar. The refractometer does help in trying to balance the formula for AFP (freezing point depression) and SP (sweetening power). One of the advantages of an Atago is that it also does Brix and can cover both uses. It may be possible to ask Misco to add a Brix table to the VST - but I am not sure.
Scraping away (slowly) at the tyranny of biases and dogma.

Mrboots2u

#17: Post by Mrboots2u » May 27, 2015, 8:15 am

chris_n wrote:this absolutely. since this is HOME-barista, everyone should absolutely be brewing by taste.

the reason for many advocating using this in a production setting is for QC purposes from batch to batch, product consistency and eliminating human error. all this happens in the lab and doesn't really happen on the bar side of things.

I find the inference that people, who have or use a refractometer, dont " brew by taste " funny..Of course we do...
If this is HOME barista - perhaps we should all dump the commercial equipment we have too..

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canuckcoffeeguy

#18: Post by canuckcoffeeguy » May 27, 2015, 8:23 am

I completely understand the urge to take espresso analysis to an extreme. We wouldn't be in this game(specialty coffee) without being fussy, particular, picky, exacting, precise, obsessive, discerning, passionate, etc. about pursuing coffee excellence. We're coffee nerds, home baristas, coffee geeks(hope that's ok to say) and we wouldn't have it any other way. We spend more on coffee equipment than some people do on a car. Our co-workers marvel at our dedication to high standards of workplace brewing. And our spouses/significant others put up with us.

However, for me, coffee is a sensory experience. A magical one, when the myriad variables that need to be mostly right, are mostly right. It's experiential. And reducing this experience to an algorithm is not for me.

I can see how in some situations measuring TDS could be useful, say for roasters or grinder manufacturers. But for the average home barista, just do your thing and taste it. We are drinking this after all, right? I doubt I'd enjoy a Michelin starred meal if, instead of chowing down, I had to feed it to the Hadron Collider first.

Having said this, the various TDS related threads have been entertaining. If only for the intrigue and dramatic interactions. Not that i understand much of the science being discussed. Maybe that's why I'm not buying in.

Nike says, Just Do It. I say, Just Taste It.

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HB
Admin

#19: Post by HB » May 27, 2015, 8:34 am

Mrboots2u wrote:I find the inference that people, who have or use a refractometer, dont " brew by taste " funny.
Jim said "My personal advice is to ignore TDS and extraction levels and brew by taste." Chris agreed. Neither suggested those who pay attention to TDS and extraction levels ignore taste.
canuckcoffeeguy wrote:I can see how in some situations measuring TDS could be useful, say for roasters or grinder manufacturers. But for the average home barista, just do your thing and taste it. We are drinking this after all, right?
I agree. Similarly, the Scace Thermofilter provides a standardized way of measuring brew temperature readings, but I could not justify the cost if I didn't review espresso equipment. Others may decided differently and that's perfectly fine.
Dan Kehn

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canuckcoffeeguy

#20: Post by canuckcoffeeguy » May 27, 2015, 8:46 am

HB wrote:I agree. Similarly, the Scace Thermofilter provides a standardized way of measuring brew temperature readings, but I could not justify the cost if I didn't review espresso equipment. Others may decided differently and that's perfectly fine.
For sure. In my case, I can see the value of a scace to calibrate your machine and/or identify temp problems. I have an Erics thermometer on my E61 HX. These tools definitely can help people understand how their particular machine works and its inherent temp profile. But once you start getting down to business and pulling shots, that's when I opt for diagnosing by taste. Kind of like making sure your barbecue is working correctly. But once you grill that steak, judgment comes when you dig in and eat it.