Syrup Yeild From Sap

[lharris1]

May be someone can straighten me out on this. I'm kind of new at this thing but I have heard about the rule of 86 where you divide your sap hydrometer reading into 86 and subtract 1 to get the gallons to boil off to get one gallon of syrup. Since the sap hydrometer is a brix number and the target for making syrup is a brix number of 67, why would you not divide 67 by the sap brix number.

Our average sap this year probably was not more than 1.7. Dividing that into 86 give about 50. We fairly accurately totaled the sap volume we gathered and when I divide that by the syrup gallons made I get 39, which is also the number you get dividing 67 by 1.7. What am I missing? :?:

[DougM]

This is the explanation from the North American Maple Syrup Producers Manual. I think the last paragraph probably explains part of your difference.

S = 86/X
where "S" is the number of gallons of sap required to produce one gallon of syrup, "X" is the Brix value of the sap, and 86 is a mathematical constant representing the percentage of solids on a weight-volume basis that is in a gallon of syrup (see following discussion).

It follows, then, that the number of gallons of water that must be evaporated from sap to obtain one gallon of syrup can be calculated by subtracting "1" from the above equation:

W = (86/X) - 1
As an example, using sap with a density of 2° Brix requires 43 gallons of sap to produce 1 gallon of syrup:

S = 86/X = 86/2 = 43 gallons sap
and 42 gallons of water must be evaporated to produce one gallon of syrup:

W = (86/X) - 1 = (86/2) - 1 = 43 - 1 = 42 gallons water

The "Rule of 86" calculates a good "working" estimate of the number of gallons of sap required or water that must be evaporated to produce a gallon of syrup. It is not exact because the mathematical formula was developed when "standard density syrup" had a density of 65.5° Brix. Syrup of this density contains 86.3 percent solids, hence, the "Rule of 86." Current "standard density syrup" has a density of 66° Brix and contains 87.2 percent solids. Further, geographic regions and individual producers differ slightly in the desired finish density of syrup. Nonetheless, the "Rule of 86" is a tradition in the maple industry and is quite satisfactory for practical purposes.

[lharris1]

Thanks, but I'm still a little confused because of our actrual evaproating experience this year. It seems to fit better with the dividing the brix number into the syrup brix number.

[Maple Hill Sugarhouse]

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[WESTVIRGINIAMAPLER]

Larry,

I am always about 50 to 1 sap to syrup ratio. Can't imagine you would be 39 to 1 as you are only about 2 to 3 miles away as the bird flies. :? :?

[Maple Hill Sugarhouse]

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[forester1]

Actually Brandon it would be possible for sugarbushes nearby to have different sugar percent in thier trees. It would depend more on genetic selection, diameter and crown size. Also slope aspect and nearness to water table or bedrock. Larger trees with larger crowns generally being sweeter. Location in relation to other maples would have little to do with it.

[DougM]

And, it doesnt' take much difference in the sap Brix to make a big difference in the final result:
using 87.2 instead of 86, sap at 1.70 Brix = 50.29:1
at 2.18 Brix = 39.0:1
at 1.97 Brix = 43.26 (our average this year)

[WESTVIRGINIAMAPLER]

Jerry,

I know that and agree with you totally. The problem here is that most of my trees are very large with very large crowns and have great spacing and I still get that kind of sugar content. It has always been that way for me and seems the same in the area from my experience with other producers and past producers. :D

[lharris1]

Kevin: I have a sap hydrometer and have tested all of our sources. Some of our major volume came for 1.0% sap. When we found that out we went looking for sweeter sap. Two other areas were around 2.2. Some of our new sources ranged from 2.0 to 3.5. We even found one that checked out at 5.2. It really tasted sweet but it did not flow good. All of our sources weakened during runs and especially on our final run.

The guys I work with logged each day how much we collected and they feel like they did a good job of recording it. Looks like it would have taken a gross error to go from our calculated 39 to the expected 50 range. I don't know how but may be we did fail to record some of our collections.

[Maple Hill Sugarhouse]

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[lharris1]

That is interesting. May be some low sugar trees begat all the others making the whole area low.

Does liming or fertilizing make much difference?

Very near this sugar bush is a stand that is more in the open that has much higher sugar content. I think they are not as crowded and have a better crown.