Similar to maple syrup in many ways, but with a subtly different flavour and an entirely different chemical structure, birch syrup is nevertheless obtained in a very similar way. The predominant, natural sugar in birch syrup is fructose; maple consists primarily of sucrose. Fructose is believed to be more digestible, and birch syrup itself is high in vitamins and minerals, including vitamin C, potassium, manganese, thiamin and calcium. Birch syrup lends itself to marinades, barbecue sauces, coffee, baked squash, breads, shakes and, of course, ice-cream.
Originally, collecting birch syrup was a work-intensive and time-consuming procedure. When the spring came and the sap began to rise in the trees a camp would be set up amongst the birch trees, home to the collectors for a week or more. Medium-sized trees seemed to produce the best sap, and each tree would only be tapped once every two years - essentially being given a year off to recover. An upwards, slanting cut with a hatchet would produce a curl of bark on the selected trees. When propped open with a small twig, the sap would drip from this jutting curl into tin pails, propped against or tied to the tree. Collecting the pails was usually the responsibility of the children; some trees gave several gallons of sap, some only produced a cup or so. However much was produced, it was brought back to the camp where it boiled in a large kettle over an open fire.
Boiling the sap was a delicate process: it must be kept boiling; there's an awful lot of extra liquid to evaporate before you end up with sweet birch syrup. Too little cooking and the syrup would be watery and may even ferment later. Too much and it would crystallise and turn into sugar. Eventually, however, the syrup was ready to pour off and cool, maybe producing three or four gallons of precious syrup.
Nowadays, in early April the sap of the Alaska paper birch begins to rise. Ten to fifteen percent of each tree's sap is removed through a tapped, 7/16" hole which is plugged at the end of the season to preserve the tree. Time is saved by running the sap through a reverse osmosis machine which quickly removes seventy percent of the water, concentrating the sugar to approximately five percent. Concentration to sixty-seven percent is completed in a wood-fired evaporator. The total production of birch syrup from Alaska in 2000 was less than a thousand gallons. At present there is little or no commercial production of birch syrup anywhere else in the world, although as birch syrup becomes increasingly popular amongst gourmet chefs, production is likely to rise to meet demand.
Sources: www.lights.com/waterways/native/birch.htm, http://www.alaskabirchsyrup.com/ | 
