<p><strong>Refractometers</strong> are widely used to measure the opaqueness of the coffee during brewing to timely determine the extraction time.</p>

<p><strong>Spectrophotometers</strong> are used to measure color instead of opaqueness. They are mostly useful to determine the roast degree.</p>

<p>So, why not?</p>

<p>However, in my opinion, <strong>perfect</strong> is something defined by personal preference when considered with coffee.</p>

<p>If you want to find the perfect roast degree, you may choose your specific beans first, specific brewing method, etc. Then choose the specific roast degree. After that, a spectrophotometer may help you to find that exact point each time you <em>repeat</em> the roasting process. Similar to that, during brewing, a refractometer may help you to find that previously decided specific point each time you <em>repeat</em> that brewing process.</p>

<p>In summary, there is no guidance you can hear as <em>the perfect point</em> that you can scientifically lean on. But you may hear some advice based on the coffee community's common experience. Generally, if you are not into industrial production, you don't generally need nerdy equipment to follow such advise.</p>

CC BY-SA 3.0
2016-09-27T06:32:25.573Z
But nerdy = fun.... ;-)
Stephie
CC BY-SA 3.0
2016-09-26T12:34:50.137Z
2016-09-26T12:34:50.137Z
MTSan
<p>I know it's down a different line (I like the idea of using light though) but the most common way to test proper extraction is to perform a TDS (Total Dissolved Solids) test. This is the industry standard.</p>

<p><a href="https://tylercipriani.com/coffee-extract/" rel="nofollow">https://tylercipriani.com/coffee-extract/</a></p>

<p><a href="http://www.tdsmeter.com/what-is?id=0010" rel="nofollow">http://www.tdsmeter.com/what-is?id=0010</a></p>

<p>I don't believe handheld meters to be too expensive but not sure.</p>

CC BY-SA 3.0
2016-09-29T23:53:02.140Z
2016-09-29T23:53:02.140Z
roasterbob 
<p>I was wondering if I could get perfect extraction timing by measuring the light transmittance (of course with the same coarseness of grind) like a Beer's law sort of thing. Anyone have any readings? Or like a method you use to determine optimal extraction?</p>

<chemistry><extraction>
Could light transmittance be used to timely determine extraction?
Joshua Ye
# Could light transmittance be used to timely determine extraction?

(Asked by: username_0 on 2016-09-26)

I was wondering if I could get perfect extraction timing by measuring the light transmittance (of course with the same coarseness of grind) like a Beer's law sort of thing. Anyone have any readings? Or like a method you use to determine optimal extraction?

**Tags:** chemistry, extraction


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## 2 answers

### Answer by username_1 on 2016-09-26. Score: 2

**Refractometers** are widely used to measure the opaqueness of the coffee during brewing to timely determine the extraction time.

**Spectrophotometers** are used to measure color instead of opaqueness. They are mostly useful to determine the roast degree.

So, why not?

However, in my opinion, **perfect** is something defined by personal preference when considered with coffee.

If you want to find the perfect roast degree, you may choose your specific beans first, specific brewing method, etc. Then choose the specific roast degree. After that, a spectrophotometer may help you to find that exact point each time you *repeat* the roasting process. Similar to that, during brewing, a refractometer may help you to find that previously decided specific point each time you *repeat* that brewing process.

In summary, there is no guidance you can hear as *the perfect point* that you can scientifically lean on. But you may hear some advice based on the coffee community's common experience. Generally, if you are not into industrial production, you don't generally need nerdy equipment to follow such advise.

> **Comments:**
> **username_2**: But nerdy = fun.... ;-)  

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### Answer by username_3 on 2016-09-29. Score: 1

I know it's down a different line (I like the idea of using light though) but the most common way to test proper extraction is to perform a TDS (Total Dissolved Solids) test. This is the industry standard.

<https://tylercipriani.com/coffee-extract/>

<http://www.tdsmeter.com/what-is?id=0010>

I don't believe handheld meters to be too expensive but not sure.


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