Things You'll Need
Colander or wire mesh strainer
Sterile Mason jars or other containers
In much of New England and Eastern Canada, springtime is mapling time. That's when woodlot owners throughout the region tap their maple trees for the sweet sap that becomes maple syrup. It takes 30 to 40 quarts of sap to make 1 quart of table-ready syrup. Traditionally the sap was boiled in large cauldrons over a wood fire to concentrate the sugar content, giving the syrup a pleasant hint of smoke. For backyard hobbyists, boiling away the sap on a stovetop requires a great deal of time and energy. A Crock-Pot is slower but more energy efficient.
Preheat the largest available Crock-Pot or other slow cooker on its "High" setting.
Line a colander or wire mesh strainer with a large coffee filter. Place the colander over the Crock-Pot and filter sap into the pot until it's almost full.
Bring the sap to a simmer on the cooker's "High" setting, then turn it to "Low" until the sap has reduced by half, usually eight hours or more.
Filter additional syrup into the Crock-Pot until it is nearly full again.
Continue refilling the Crock-Pot until all the sap is used, and the resulting syrup has the desired flavor and consistency.
Pour the hot syrup into one or more sterilized Mason jars or other containers. The syrup will keep at room temperature until it's opened. It should be refrigerated after opening, to prevent mold.
This process is best suited for small amounts of maple syrup, but producing even 1 quart of syrup means boiling off 30 or more quarts of water. Do this in a well-ventilated area, or outdoors on a protected patio, to avoid humidity problems in your home.
Use a wire-mesh spatter screen over the Crock-Pot so steam can get out, but insects can't get in.
The larger your Crock-Pot is, the better it will work. The sap will evaporate more efficiently from a large surface area.
Maple sap ferments readily, so keep your raw sap refrigerated until you pour it into the Crock-Pot.
The process is much quicker if you boil the sap for even an hour or two in a conventional pot to begin concentrating it.
Crock-Pot brand slow cookers stabilize at 209 F. Other brands may be higher or lower, which will affect the overall cooking time.