Maple syrup is made by boiling the sap of sugar maple trees until it thickens.

The longer version

Sugar maple sap is mostly water with a small percentage of dissolved sugar, so concentrating it requires removing a great deal of liquid. Collected sap is heated in open evaporators, and as water boils away the sugar concentration climbs until the liquid reaches a density where it resists spoiling.

The sap is nearly colorless at first, so the familiar amber color and caramelized flavor develop during that long boil, when sugars begin to brown and new aroma compounds form. The grade assigned to a batch depends largely on how late in the season and how hot the boil ran. Flow depends on freezing nights followed by thawing days.

Where this entry sits

Everyday ingredients turn out to be full of quiet chemistry and long history. This collection gathers short, plain explanations of how bread rises, why onions sting, where common spices originate, and how coffee, tea, and chocolate reached the modern kitchen. The full list sits on the Food and Drink page, where every entry is listed in order.