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

[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

[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.

[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/S...able%20114.pdf

[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/maple...oduc00willrich

"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."