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Apparently no direct relationship between Brix and water content???

Could anyone explain to me why there is not a direct relation between the Brix scale and the water contents scale on my honey refractometer? At the low end of the Brix scale (60-70), the match is perfect, but not at higher Brix. I suspect this has something to do with the fact that there is a non-linear relationship between sugar concentration and density. It would, however, be very nice to know the proper theoretical background... :-)

Any help will be greatly appreciated, as I have been unable to find any information at all on the web. Thanks! 

Best regards,
tome


lemonie4 years ago
This any good?
www.2spi.com/catalog/ltmic/brix.html
The Brix scale is a w/v, non-linear I can't see on that basis - what result(s) suggest that to you? It might be down to your device?

L
tome (author)  lemonie4 years ago
Thank you for your replies!

The information I have is all based on w/w, not w/v, but nevertheless...

I plotted SG information taken from the Merck Index against sugar contents, and estimated the Brix value based on a formula taken from Wikipedia. The results (see the two included images) corresponds well with the scale on my refractometer. The differences that are there, may well be due to a w/w vs w/v mismatch.

So.--- As far as I can tell there really is a small non-linearity in the correlation. Sugar chemistry is more complex than I can handle (being only a biologist....)..

Any suggestions?

Best regards,
tome
Brix estimation 1.pngBrix estimation 2.png
lemonie tome4 years ago
Yes w/w against w/v are two different things.
Sugar chemistry is a field of science in it's self, but this is just physics really. You see the non-linearality at one end of the scale, but now you've got this nice data - have you answered your question?

In w/v you've got a shift from sugars mostly bonding to water, towards sugars bonding with sugars and some water in between, the volume per unit weight changes. Or 1 litre of water doesn't weigh the same as than a sugar-crystal 10x10x10cm.

L
tome (author)  lemonie4 years ago
I am well aware that w/w and w/v are two different things. I see no reason, however, why one should not be linear if the other is.

These data (along with the scales on the reticle of my new refractometer) were the reason I began to wonder in the first place, so I'm afraid I have not answered my own question....

I know from making histological fixatives that there is not a good coorelation between molarity and osmolarity for sugars (making determination of tonicity more empirical than theoretical). I assume this is related to the non-linear SG correlation, and that both have to do with hydration patterns in some way or another.

I really can't explain _why_ there is no linearity. I'm still a "fresh" beekeeper, but a fellow beekeeper tells me that everybody assumes that water contents is equal to 100-Brix. If there is no linearity, that assumption can not be correct.  I have a strong dislike to things I don't understand, so even though the error is likely to be small, I would very much like to know what exactly is going on.....

Best regards,
tome
lemonie tome4 years ago
The w/w w/v was something I thought you knew, just a re-iteration. I've done my best at an explanation - we know as well as each other here I think.

L
tome (author)  lemonie4 years ago
Thank you for ideas and discussion!

I think it may be time to call one of my old professors....

Have a fine day!

Best regards,
tome

lemonie tome4 years ago
Fine evening (I am thanks) - I'm most likely in a different time-zone...

You too.

L
lemonie4 years ago
Oh hang on, water content. As you add sugar, the proportion of sugar increases, so 100% sugar - no water. Hmm, I can't explain this, but I can imagine / see a non-linearity in it.

L
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