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Author Topic: Will a Brix/SG refractometer measure invert sugar?  (Read 1274 times)

Offline raf

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Will a Brix/SG refractometer measure invert sugar?
« on: March 24, 2019, 09:33:57 am »
Hi all. Apologies if this has been answered elsewhere, but if it was, I couldn't find it.

During hydrolysis of sucrose, the angle of polarized light shone through a sample rotates (or "inverts") from what it had been when the sample was still sucrose. Not sure what implications this has for an instrument that measures refractive index.

I see that Milwaukee, Hanna, and other manufacturers make designated meters specifically for measuring invert sugar content, which leads me to believe there's something different here from measuring refraction through a disaccharide.

Reason I'm asking this is that I brewed a strong bitter yesterday and used a pound of #3 invert syrup. I used a refractometer to take my OG measurement and found that it was about five points lower than anticipated given my boil gravity and boil-off volume. However, when I backed the invert syrup out of my predicted OG calculation, the refractometer reading was spot on.

I know, I should have taken a hydrometer reading. Next time.

For the folks here who have used invert syrup, have you noticed any discrepancy in your refractometer and hydrometer readings?

Offline Robert

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Re: Will a Brix/SG refractometer measure invert sugar?
« Reply #1 on: March 24, 2019, 11:14:05 am »
I use a Hanna digital refractometer,  and often have brewed with invert syrup without noticing any discrepancy.   In fact readings taken before and after adding the Invert to the wort show exactly the increase in density expected.   
Rob Stein
Akron, Ohio

I'd rather have questions I can't answer than answers I can't question.

Offline dmtaylor

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Re: Will a Brix/SG refractometer measure invert sugar?
« Reply #2 on: March 24, 2019, 09:00:48 pm »
Should read the same as regular sugar.
Dave

The world will become a much more pleasant place to live when each and every one of us realizes that we are all idiots.

Offline raf

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Re: Will a Brix/SG refractometer measure invert sugar?
« Reply #3 on: March 25, 2019, 06:58:31 am »
Thanks guys.