Measuring Brew Strength - Optical Refractometer - try it travel thread!

[John F]

Man, I could even smell the oregano in the sauce that would be coming my way..

Well....

Does anybody past coffee year #1 have a desire to "put out a consistent product" in the kitchen for their personal consumption?

[ecc]

Man, I could even smell the oregano in the sauce that would be coming my way..

Well....

Does anybody past coffee year #1 have a desire to "put out a consistent product" in the kitchen for their personal consumption?

Maybe I missed the point here, but I would think a lot of people would be guilty of this. Anybody with a PID on their espresso machine, or that weighs coffee and/or water before brewing, that does a water dance, or uses a timer to control brewing variables is interested in consistency.

[John F]

Maybe I missed the point here, but I would think a lot of people would be guilty of this. Anybody with a PID on their espresso machine, or that weighs coffee and/or water before brewing, that does a water dance, or uses a timer to control brewing variables is interested in consistency.

I see your point..

I'm not advocating using no units of measure and swinging wildly every time you step up to the beans.

I'm saying that the point of dialing down to the level of total dissolved solids and brix (the way I see it) is ultimately only going to be useful to lock down an exact measure for standardization.. Producing the same cup predictably with repeatability.

I like the PID to lock down the variable of temp so I am within spec but that is a far cry from locking down the TDS, brix, and producing the SAME shot over and over. See what I'm saying? While I want to remain in a predictable temp zone the last thing I want is to produce the same shot over and over... 

[ecc]

You may be overestimating the effectiveness of this device, I highly doubt it will make your (or any other GCBC member) coffee brewing too controllable and predictable.

Join the travel loop and try it. Resistance is futile.

[John F]

I'll decide after the Bl java first look review.
 

[BoldJava]

I'll decide after the Bl java first look review.
 

I don't expect it to do anything except quench or further stretch my curiosity -- have a terrible dose of those on most things I don't understand. 

B|Java

[gt]

yakster,

Although it was hard to use, could you get meaningful readings with your floating hydrometer?  For example, could you see a difference in say a TDS of 1.2 versus 1.3?

[John F]

Hydrometer...

 

[ecc]

Thanks yakster, the hydrometer walk-through and pictures are great!

[gt]

Yes thanks yakster, it would be nice if there was a hydrometer that was spread out just over the brewed coffee range.

[John F]

What does measuring the gravity of the coffee tell you......the gravity of course but how does that correlate to something you are trying to find out?



 

[ecc]

Specific gravity is just a fancy way of saying density compared to water.  Just another way of sneaking up on how much brown stuff actually made it into the cup.

[John F]

Specific gravity is just a fancy way of saying density compared to water.  Just another way of sneaking up on how much brown stuff actually made it into the cup.

Yeah..... isn't it odd to move from such fine measures like TDS and brix to very crude measures like gravity?

[BoldJava]

...

TDS is 85% of Brix,  use this extraction chart as a guideline as to what the tds "should" be for your coffee:water ratio.  Note how the 19:1 ratio has the biggest window of "acceptable" tds values.  Please don't let this dogma blind you ...

<Hand raised>

So, brewed a vacpot of Dominican Corazon de Oro.  68 grams to 42 oz water.  TDS came back 122 at room temp with the refractometer at 1.20.  When I am looking at Bunn's (SCAA) chart, I am not sure what I am reading.

Is the chart measuring refraction or TDS?

...and yes, it was a very good cup (primary measurement).

B|Java

[ecc]

...

TDS is 85% of Brix,  use this extraction chart as a guideline as to what the tds "should" be for your coffee:water ratio.  Note how the 19:1 ratio has the biggest window of "acceptable" tds values.  Please don't let this dogma blind you ...

<Hand raised>

So, brewed a vacpot of Dominican Corazon de Oro.  68 grams to 42 oz water.  TDS came back 122 at room temp with the refractometer at 1.20.  When I am looking at Bunn's (SCAA) chart, I am not sure what I am reading.

Is the chart measuring refraction or TDS?

...and yes, it was a very good cup (primary measurement).

B|Java

The chart is showing TDS, you get your water:coffee ratio and plot it against TDS solving for extraction rate.

So (42oz * 30g/oz)/68g gives you a nice 18.5 ratio, which is pretty much the middle band. The middle band gives the most area in the "ideal" box.  I tend to dose at a lower ratio, (more coffee) I use the higher bands and have a narrower "ideal" window.

TDS measuring 1220 would put you right in middle of the box.  The refractometer reads in Brix, which correlates to TDS/850.  If I multiply 1.20 * 850 I get 1020, which puts you lower left of ideal.  

The Bunn chart recommends you will get an even better cup if you grind a little finer, or brew a little longer.  Although it is interesting to see what their recommended cup tastes like, the meter can also indicate how consistent your brew method is in terms of strength, and your general preferences vs their "research".  

Also interesting to test local coffee shops, compare against same technique/coffee/dose on a friends grinder, etc.

One thing I forgot to mention:
The refractometer can be calibrated by using distilled water.  The line should go to zero, the scale is adjustable with the set screw on top.  The unit will read strangely if the prism and the fluid measured are at different temperatures, and will always read weak if the coffee is warm at all.