North American Fruit Explorers mailing list at ibiblio

[Claude Jolicoeur <cjoli@gmc.ulaval.ca>]

Earlier today, I wrote:
>I also remember I had made a relation
>between % sugar and specific density, but I don't find the message here at
>the office. I will look for it at home this evening.

Here is the relation - I hope it may be helpful to some who were not member
of the list at the time. I wrote this on November 13, 1999:
>1- Relation between Brix and S.G.
>If I make a simple linear relation between these 2 scales on my hydrometer,
>I get the following relation:
>Brix (in %) = 0.557 + 236 x (D-1)
>which is accurate within + or - 0.1% between D = 1.030 and D = 1.080, D is
>the specific gravity (S.G.)
>
>2- Relation with refractive index measurement, and acidity
>I found in Smock and Neubert "Apples and apple products" this interesting
>table:
>Apple variety :        Jonathan      Winesap      Delicious
>S.G.                    1.057         1.060         1.064
>% S.S.                  13.8          14.5          15.5
>Total sugar (%)         11.7          12.1          13.4
>Acidity (as malic, %)   0.45          0.48          0.21
>pH                      3.56          3.59          4.02
>Calculated Brix (%)     14.0          14.7          15.7
>
>The line % S.S. is soluble solids obtained from the refractive index.
>The line "Calculated Brix" is from the abovementioned relation. We can see
>that Brix scale is very close to the % S.S. The real total sugar is a
>little more than 2% less than either Brix or S.S. number.
>
>As of acidity, from the table, there is no direct relationship between pH
>and titration result. We see that Delicious has higher pH and lower acid
>content - this is normal. However, between Jonathan and Winesap, we see
>more acids in winesap with a higher pH (a higher pH indicates less
>acidity), which apparently is a contradiction.

Claude

 

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