There is a point when sap becomes syrup.
That point is at approximately 219F. Maple syrup boils at a temperature seven degrees higher than that of water. Water usually boils at 212F but not always. At higher elevations where there is less atmospheric pressure, it boils at a lower temperature. Or if a weather system comes through and changes the pressure, water can boil either above or below 212F. This, of course, means that syrup can boil either above or below 219F.
Because of the uncertain nature of boiling points, sugar makers tend to use temperature only as a guide. The density of syrup is used as law. In Vermont and Hew Hampshire, maple syrup has to have a density of 66.9 Brix. Elsewhere in the U.S. and in Canada it can be 66 Brix. (So if you ever thought syrup from Vermont or New Hampshire tasted better —- it does!)
Sugar content in aqueous solutions is measured in degrees Brix. One degree on the Brix scale equals one gram of sucrose in 100 grams of solution. So maple syrup has 66.9 grams sucrose for every 100 grams. The other 33.1 grams is water.
A hydrometer is used to measure the density/degrees Brix of syrup. A syrup hydrometer is made of glass shaped into a cylindrical stem and has lead shot at the bottom to make it float upright. The hydrometer is placed into a hydrometer cup and syrup is added until overflowing and the hydrometer is floating freely. You can then read the degrees Brix off the side of the hydrometer.
We’re measuring the density of hot syrup at 211F which is has a density of 59 Brix. Perfect syrup. When it cools to 60F it will be 66.9 Brix.
In my own investigation of other foods carrying heavy sugar loads, this is what I found.
Food Degrees Brix
Maple Syrup 66.9
Sauvignon Blanc 20
Pinot Noir 26
The human quest for sugar is epic. Michael Pollan chronicles it well in his 2001 book Botany of Desire where he follows the domestication of the apple as a means of harnessing sugar.
But not all sugars are made equally. So choose wisely. We crave. Plants deliver.