Well Keith just added that they add sugar. This would allow you to convert an alcohol content far higher than what is in unconcentrated sap to become what most would consider a wine. And being exposed to oxidation once primary fermentation is completed would move on to souring to vinegar. The “wine” would be very raw or “young” without the secondary fermentation or “aging” that characterizes modern “wines”. Not saying an alcoholic drink from birch isn’t possible was just uncertain how it could be done with straight sap or be considered wine. For us a birch sap flow has always been shortly after our maple has finished and only been for a few days. Not near the same volume per tree as sugar maple don’t expect a lot. I do want to explore this more as we make finished wine from our maple sap without adding sugar(partially concentrating sap to higher brick) and so this would be fun to try with maple sap as well while waiting for that aging to happen. I don’t think one can expect much on palatability though or I don’t see why it has faded with time and more modern fermentation. Meads were made under many peoples beds.

We tap trees every spring. We make ice cubes for later and drink the sap straight, tastes like lightly sweetened water. Has slight laxative properties. Gets kind of off tasting if it sets too long. I was not aware the Xylitol could ferment. It takes 120 gallons of sap to make a gallon of syrup.