Transcript:

Mystery of Maple SyrupThis season of the year in New England, the sap is flowing in sugar maple trees. It's time to begin harvesting this year's crop of maple syrup. I'm Jim Metzner, and this is the Pulse of the Planet.ambience: Syrup boilingWe're at Butternut Mountain Farm in Johnson, Vermont, where David Marvin, the farm's owner explains that sap is collected from maple trees and boiled down to make syrup.Marvin: Well, maple syrup is made from the sap of sugar maple trees. Sap is a very dilute sugar solution, perhaps two percent sugar. Sap flows from holes that are drilled in the tree, three inches deep, and it's cooked down in an evaporator over a wood or oil fire, typically, to a concentration of mostly sugars with the flavors of maple.Maple syrup really has only two ingredients. The first is the sap, and the other is patience, because 40 gallons of sap need to be boiled down to make one gallon of syrup. It also takes a little bit of faith, because even after hundreds of years of making syrup, the farmers still don't really know precisely why sap flows.Marvin: It would be wonderful if we knew what makes sap flow, but exactly how the tree works is still a mystery. Clearly, though, the maple season is primarily affected by the weather during the production time, that is - in March and April. We need very very cold spells followed by rapid warming to have good sap flows. A typical year we'll have two or three good runs of sap, and then several days, maybe even a dozen, where we have small flows of sap. The average tree in an average year will produce about ten gallons of sap and that produces about one quart of syrup per tap hole.I'm Jim Metzner and this is the Pulse of the Planet.