Rule of 87 or 86

[MillbrookMaple]

We just were thinking about the rule of 86 or 87 depending on if you are in VT or not. To figure how much sap makes a gallon of syrup you divide 87 by your sugar content. Simple, 2%sap 86/2 it takes 43 gallons of sap to make a gallon of syrup. Well we have 100 gallons of 12% sap and wanted to know how much syrup we will have when we are done. Rule of 86 is 86/12 =7.25 100 gallons 100/7.25 = 13.79 gallons of syrup. Here is where I get confused. If I have syrup at 66% sugar then the rule of 86 would say it takes 1.3 gallons of syrup to make a gallon of syrup. This makes no sense. Can some one clear this up? Thanks

[spencer11]

its syrup at 66%. i think the rule of 86 is just an "estimate" so your not dividing your sugar content by 86.1 or 86.2, cause it would obviously be harder that way. i could be way wrong here though.

spencer

[happy thoughts]

Well we have 100 gallons of 12% sap and wanted to know how much syrup we will have when we are done. Rule of 86 is 86/12 =7.25 100 gallons 100/7.25 = 13.79 gallons of syrup. Here is where I get confused. If I have syrup at 66% sugar then the rule of 86 would say it takes 1.3 gallons of syrup to make a gallon of syrup. This makes no sense. Can some one clear this up? Thanks

This came up a couple of weeks ago. The rule only works for sap with sugar concentrations you might normally expect from the tree. That's what the formula is based on, not sap that has been concentrated. In sap taken directly from the tree, brix and sugar weight /volume are roughly equivalent so the math works.

[bowtie]

if you do the math backwards for 12% sap by "diluting" down to 2% sap instead of 100 gallons you would 600 gallons and by applying the the rule of 86 you will still get the same amount of syrup 13.95 gallons approx. the "breakdown" only occurs for finished syrup, i think this is due to the fact that it does not take into account the volume of the syrup minus the sugar, which is approx. 34%, which breaks down to roughly 1/3 of gallon and this is where you come up with 1.3 gallons to make 1 gallon syrup. it would take 1.33 gallons of 66% sugar/syrup concentrate to make 1 gallon of 100% maple/sugar concentrate.

[happy thoughts]

if you do the math backwards for 12% sap by "diluting" down to 2% sap instead of 100 gallons you would 600 gallons and by applying the the rule of 86 you will still get the same amount of syrup 13.95 gallons approx. the "breakdown" only occurs for finished syrup, i think this is due to the fact that it does not take into account the volume of the syrup minus the sugar, which is approx. 34%, which breaks down to roughly 1/3 of gallon and this is where you come up with 1.3 gallons to make 1 gallon syrup. it would take 1.33 gallons of 66% sugar/syrup concentrate to make 1 gallon of 100% maple/sugar concentrate.

The formula only works with sap at normal sugar concentrations as measured directly from the tree for the reason I mentioned. It is based on sap as collected and will not work at higher concentrations of sugar since brix value and volume/weight will not be equivalent at higher concentrations.

Jones rule of 86 as explained in an old 1970's copy of the "Maple sirup producers manual "
http://www.archive.org/details/maplesirupproduc00willrich

"Since the solids concentration of sap is comparatively low, its Brix value and percentage of solids (weight-volume) are essentially the same. Therefore, the percentage of solids (weight-volume) of the sirup divided by the Brix value of the sap equals the number of gallons of sap required to produce 1 gallon of sirup."

[bowtie]

you can not deny the math though. it should not matter what the concentrate is if it started at roughly 2% from the tree, you need only back figure the amount started with if you use an r/o. the figure 66% is not a brix value but % of sugar in maple syrup. maybe wrong but if do the math it should work out.

[CBOYER]

Jones rule of 86 was made in 1933, and Vermont Syrup standard at this time was 65.5 brix. thats why it have to be adjust now.

[happy thoughts]

you can not deny the math though. it should not matter what the concentrate is if it started at roughly 2% from the tree, you need only back figure the amount started with if you use an r/o. the figure 66% is not a brix value but % of sugar in maple syrup. maybe wrong but if do the math it should work out.

You almost lost me on the math but that's not surprising given my fear of math lol. But that said, where did you get 34%? The rule of 86 takes weight by volume into consideration, not just weight or volume alone. And 66 brix *does* mean 66% sugar so not sure why you say it does not. What I think you're not considering is what that 66% sugar accounts for in the weight of a gallon of syrup. It is not 66% but 86%.

Anyway, as I understand it, in 2% sap the sugar content accounts for about 2% of it's weight by volume thus brix and weight by volume are equivalent. In a gallon of syrup at 66 brix, the sugar accounts for about 86% of it's weight. This is where the 86 comes from in Jone's rule. Thus the weight of water accounts for only 14% of a gallon of syrup's weight by volume (not 34%) and the formula will not hold because 66 brix is not equivalent to 86% sugar by volume weight.

CBoyer is right, since the brix of finished syrup has been increased a little over the years, the rule of 86 is more of an estimate these days but it stills works as a good guestimate. But even back when the rule was first postulated it was never meant for calculating anything but the sap to syrup ration of sap straight from the tree. At higher sugar concentrations it just doesn't work.

[lew]

When we read a hydrometer and it reads 2, it means 2 degrees Brix, not 2%. the Brix scale and percent scale are very close when we are reading at relatively low sugar contents as found in sap. the higher up the scale you go the farther the 2 scales diverge. That is why when we get to syrup density you see that 66 does not equal 86.

[mtnmeadowmplfarm]

A hydrometer measures soluble solids in sap or syrup, of which sugar comprises roughly 98%. As sugar is concentrated so are the other soluble solids. That accounts for the variation between Brix and %sugar. Also, at 66.9 Brix (VT min density) we need to replace 86 with 88 for the constant in Jones rule.

[oneoldsap]

Post # 7 had the correct answer . When the syrup brix was changed from 65.5 to 66.9 , the rule of 86 became the rule of 89.2 ! If anyone will make the syrup and do the math , you will be making the amount of syrup you should , using the rule of 89.2 . All of your "shrinkage" will disappear , with the right formula !

[adk1]

I made mostly 70-72 brix xsyrup this year. I like it heavy so do my customers.

[CBOYER]

I made mostly 70-72 brix xsyrup this year. I like it heavy so do my customers.
It is illegal to sell syrup over 68°brix, and call it syrup...at least in Québec

[ToadHill]

When you exceed 68 brix you are creating a supersaturated sugar solution, i.e. some of the sugar will crystallize as it returns to a balanced concentration. That is why you get sugar crystals in the bottom of a container when you make your syrup to dense.

[802maple]

The best rule of thumb is to boil it down to 66.9 and measure how much you have, it is never wrong. LOL

[Maplehobbyist]

Taken from the OMAFRA Fact Sheet for measuring syrup density:


The density of maple syrup is a measurement of the percentage of dissolved solids, which includes sugars and minerals. However, sugar accounts for about 98% of the dissolved solids in the syrup. Therefore, by measuring the density as a reading of dissolved solids, a reasonably accurate estimate of the percentage of sugars in the syrup can be made.

Taken from the Wiki for Brix:


Degrees Brix (symbol °Bx) is the sugar content of an aqueous solution.

One degree Brix is 1 gram of sucrose in 100 grams of solution and represents the strength of the solution as percentage by weight (% w/w) (strictly speaking, by mass). If the solution contains dissolved solids other than pure sucrose, then the °Bx is only approximate the dissolved solid content.

And later in the same source:


When a sugar solution is measured by refractometer or densitometer, the °Bx or °P value obtained by entry into the appropriate table only represents the amount of dry solids dissolved in the sample if the dry solids are exclusively sucrose. This is seldom the case...In such cases the °Bx value clearly cannot be equated with the sucrose content but it may represent a good approximation to the total sugar content.

Syrup that is measured at 66 Brix is 66% sugar, which is a weight-to-weight comparison. A 100oz solution would contain 66oz of sugar. A gallon is 128oz so there are 84.5oz of sugars (.66 x 128 oz) in a gallon of maple syrup.

Density compares weight/volume. Sugars account for only 98% of the dissolved solids in syrup and density measures all the dissolved solids, so 84.5/.98= 86.2oz of dissolved solids in a gallon of maple syrup. That, I believe, is where the rule of 86 came from.

If you adjust for 66.9% Brix, it becomes the rule of 87 (.669 x 128/.98 = 87.4).

The link below contains a table that lists the amounts of sucrose at different degrees Brix.

1 Brix has 1.002grams of sucrose
2 Brix has 2.012grams of sucrose
3 Brix has 3.030grams of sucrose
12 Brix has 12.558grams of sucrose
66 Brix has 87.280grams of sucrose

So its easy to see that happy thoughts was correct about the math not holding for higher concentrations of sugar.

http://www.boulder.nist.gov/div838/SelectedPubs/Circular%20440%20Table%20114.pdf

[SPILEDRIVER]

this stuff makes my brain hurt so im just gonna keep makeing syrup the way ive allways done it and leave all this scientific stuff to the smart people!!!!

[mtnmeadowmplfarm]

Maple sugar is not exclusively sucrose though, glucose is also present in much smaller quantities. Might that affect the accuracy of the Brix scale as well?