Earth Eats: Real Food, Green Living

Boiling Sap Down To Syrup

It takes hours to boil maple sap down to syrup, but with the help of his decidedly low-tech maple syrup evaporator, Michael Bell is up to the challenge.

Mike Bell Boiling Maple Syrup

Photo: Annie Corrigan/WFIU

Michael Bell uses a hydrometer to test the sugar content of the sap as he boils it down to syrup.

Outdoor Adventures

“The other day I was here for about 10 hours and we boiled about 75 gallons of sap down to 15 gallons,” says Michael Bell, chair of the grounds committee at the Hinkle Garton Farmstead.

He spends much of his time these days huddled in a makeshift sugar shack in the backyard of the farmstead. He doesn’t seem to mind the long hours, though. Once you get close enough to the bubbling pans of maple liquid, you can understand why — the smell is intoxicating!

DIY

His maple syrup evaporator is decidedly low-tech. He fashioned it out of an old legal-sized filing cabinet. He cut the drawers and back out and fit it with a barrel stove conversion kit. The fire door is at one end with an 8-foot smoke stack at the other.

He’s on his own boiling maple syrup today, so he’s constantly in motion. If he’s not splitting wood, he’s feeding the fire with wrist-sized pieces of lumber.

“It’s not like a wood stove where you stick a big log in a you have this nice gentle fire that burns for hours,” he says. “This is almost like a blast furnace. You want an awful lot of heat.”

Slaving Over A Hot Stove

40 gallons of sap will boil down to one gallon of syrup, “so you have an awful lot of boiling to do,” says Bell. “That was never driven home to me so much as the first year when we were boiling inside.”

The rule of thumb is one square foot of surface area will boil off one gallon of water per hour. So in his 14-inch pot (approximately one square foot of surface area), it took him 40 hours of boiling on the stove to fill one bottle of syrup.

A Long Way To 66%

In addition to looking at color and consistency, he’s constantly measuring the maple liquid to judge its progress. He knows he’s reached syrup when it measures 66 percent sugar content.

One vat off to the side contains sap that’s been only lightly boiled, giving it a golden hue. He grabs his hydrometer and dips it into the vat, pulling out a sample of the liquid. The weighted bulb bounces up and down and settles at 5 percent, which is almost twice as sugary as when it was collected from the tree.

“I’ve got a long way to go!”

More: Listen to the first part of the maple syrup making process when Michael Bell taps the many old maple trees at the farmstead.

Annie Corrigan

Annie Corrigan is a producer and announcer for WFIU. In addition to serving as the local voice for NPR's Morning Edition, she produces WFIU's weekly sustainable food program Earth Eats. She earned degrees in oboe performance from Indiana University and Bowling Green State University.

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