How sap becomes syrup

A crowd gathered at the Harriet Alexander Nature Center in Roseville last year to learn how maple syrup is made. (submitted photo)

If you have ever wondered how the watery sap from maple trees becomes the sweet, thick syrup you pour over your pancakes and waffles, this weekend’s your chance to find out. 

The Harriet Alexander Nature Center in Roseville is hosting its annual “It’s Tapping Time!” event on Saturday and Sunday from 10 a.m. to 4 p.m.

Volunteers at the nature center will go through the whole process -- from tapping maple trees and collecting the sap, to cooking it to make maple syrup.

Harriet Alexander teacher Pam Schweitzer says it’s a fun event and a chance to learn about local history. Volunteers at the center make maple syrup the old-fashioned way much like the local Indian tribes and pioneers once did.

After the sap is slowly collected one drip at a time, it is cooked over a fire in a pan for up to 12 hours. The sap has high water content and as the water evaporates, its sweetness and maple flavor become more concentrated. During this process the sap thickens and eventually turns into maple syrup. 

The sap needs to be stirred frequently and Schweitzer says the night before the event, a group of people will often spend the night and stir the sap and make sure the fire never goes out.

Along with learning about traditional syruping methods, those who attend the event will have the chance to taste maple treats, make a fun craft and hear Native American stories. 

Kinderberry Hill Child Development Center has donated silver maple tree seedlings, which will be distributed free at the event while supplies last (one per family).

The Harriet Alexander Nature Center is located just south of County Road C at 2520 N. Dale Street in Roseville.

Tapping season varies

Jerry Jacobson, president of the Minnesota Maple Syrup Producers Association, says tree sap can be collected only when temperatures are above freezing during the day and below freezing at night. The change between freezing and thawing temperatures — ideally daytime temperatures in the 40’s during the day that drop into the 20’s at night — creates pressure that makes the sap flow.

Jacobson notes the window of opportunity varies in Minnesota from year-to-year. The tapping season can start as early as February in the southern part of the state and continue through April in northern areas.

“Once it’s too warm or buds appear, it’s over,” he says. “Sap can take on a buddy flavor, which you don’t want.”

Jacobson owns Jake’s Syrups and Natural Products in Vergas, Minn. where he has roughly 2,000 taps to collect sap from maple trees. He started the small business, which now sits on 120 acres, in the central-lakes region after retiring in 1994. Jacobson says he sells between 300 and 400 gallons of maple syrup a year on average, but that can vary depending on the year.

“We try to stay local and sell our products within a 50-mile radius,” he says.

Many maple syrup producers prize the sugar maple sap for its high sugar content, which averages around 2.5 percent, Jacobson says, adding that any tree in the maple family can produce quality syrup. The four varieties commonly found in Minnesota are red, sugar and silver maples and box elder.

If you have ever wondered why pure maple syrup is so expensive, consider this: it takes about 40 gallons of sap to produce one gallon of syrup.  

While larger maple trees are generally preferred for tapping, Jacobson says sap can be collected from less mature trees as well. When tapping a smaller tree, a smaller diameter spout should be used so the tree heals faster, he added.

“Maples are generally slow-growing tress,” Jacobson says. “If you are an older person, or don’t want to wait for the tree to grow, you can tap a tree that is 8 inches in diameter or larger. They can still produce a lot of sap.”

Joshua Nielsen can be reached at or 651-748-7824.

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