Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

Photo of girls and maple sap bucket © DNR Photo

The dripping sap is collected in buckets that are covered to keep out animals, water, bugs and potential contaminants

February 2010

A sweet treat in the season of melting snow

Maple syrup time offers a chance to cook up a mix of science, culture and good eats in a hands-on day outdoors.

Story and Photos by David L. Sperling

Some of the trees are banded with bright yellow marking tape and a few have yellow wooden boxes with handles you can crank. There's a light warm breeze and the air smells clean this early spring day as we shuffle our feet through piles of last fall's leaves drying out under foot. Gordon Dunn, volunteer tour guide, greets Janice Uhrig's fourth graders from Waunakee who are piling off the yellow school bus on the hilltop parking lot of the Mackenzie Environmental Education Center in Poynette.

"We bring our class to MacKenzie every year to study maple syrup making," Uhrig says. "It's sugar time!"

The students will spend about three hours outdoors in the fresh air visiting various stops on a tour, gazing at trees, tapping into maples and soaking up a blend of science, culture and history. It's a hands-on story that appeals to all the senses and ends with a sweet treat. In this short stay the students will see for themselves how trees are tapped, how the sap is collected and then cooked and finished in front of their eyes.

Dunn starts with a few questions asking why we grow and use trees. The eager students raise their hands and talk about providing shade and having wood for products like pencils, paper, toothpicks, furniture, fuel and food. Dunn guides the friendly conversation into an appreciation that trees give off oxygen, absorb carbon dioxide, and harness the sun's energy through photosynthesis. The group talks a bit about other values like providing a home for wildlife, growing landscaping around houses, anchoring the soil and controlling erosion.

We learn why maples were tapped to make syrup and why at this time of year. Many hardwood trees yield a slightly sugary sap in spring. Walnut, birch, hickory, sycamore, ash, basswood and butternut all have sap that contains about one percent sugar. And many types of maples can be tapped too, like box elders, silver and black maple, but the sugar maple's sap is particularly prized because it contains 3-5 percent sugar. Dunn says most people can recognize maples just fine once they leaf out, but how do you recognize them in winter for tapping? Good question. Just as we can recognize people by features like height, shape, facial features, skin and hair color, tree types have different features too. He shows the students the distinctive branching, bud and bark characteristics of the sugar maples, then he points out that the sugar maples in this area of the property have all been wrapped with a bit of yellow marking tape.

Trees are tapped in a short season from late winter when nighttime temperatures still dip below freezing but the daytime temps rise into the low 40s. This season of melting snows had many names in Native American culture. Sisibaskwatokan is an Ojibwe word for the maple sugarbush where concentrations of maples in the forest (Manakiki in Ojibwe) were ripe for the tapping.

"It's been said that to make maple syrup, you need mud," Dunn says smiling. The freezing temperatures at night alternating with daytime thawing create pressure in the xylem and phloem layers the sapwood sandwiched under the bark and the thin growing cambium layer before you reach the dense heartwood in the middle of a tree. The sap provides nutrients to carry food up, down and around the tree to stimulate early growth. As the weather warms up and trees get ready to leaf out, the sap turns bitter. Trial and error proved that once the tree buds swell to about the size of a squirrel's ear, it's time to stop tapping and the sugaring season is over.

Time to tap

As the students move downhill toward another area with maples, Dunn explains how maple sugaring was done in outdoor camps near large groves of sugar maples. You look for healthy trees that are free of dead branches, rotten areas and cracks. You seek big trees that will produce a lot of sap and older trees that are at least 10 inches in diameter (about 40 years old). A 10-inch diameter tree can accommodate one tap; a 15-inch tree, two taps. Bigger trees can accommodate more taps. Dunn says an easy way to tell if a tree is big enough is to give it a hug. If your hands reach your elbows when you wrap it around the tree, it's still too young to tap.

Tree taps, called spiles, were whittled from branches of basswood trees or elderberry shrubs whose soft, pithy centers could be poked out to form natural pipes that were pounded into holes drilled into maples. Dunn demonstrates how holes used to be drilled by hand with a brace and bit about four feet up the tree. Tap too low and animals can get into the buckets; too high and the full buckets are too hard to remove and empty without spilling. Similarly the holes are drilled about three to four inches deep angled toward the tree crown so gravity will help the sap flow through the spile. Each child is given a chance to make his or her own spile and take a turn twisting the bit and drilling into the maple before a spile is tapped in with a small hammer. Today, the sap starts flowing right away and everybody lines up to catch a drop or two of sap to see what it tastes like fresh from the tree – pretty watery with a very slight sticky sweetness. A lid is replaced over the pail, the tools are cleaned up. The dripping sap is collected in buckets that are covered to keep out animals, water, bugs and potential contaminants. He also explains that holes in the sapwood from tapping won't open the tree to infection or bugs.

"The holes heal very well," Dunn says. "We don't use Band-Aids."

Collecting and boiling down sap

As we head to the next station, Dunn explains how commercial syrup makers use both plastic tubing and plastic bags to collect sap these days. He contrasts that with the birch bark containers and clay pots that Native Americans crafted to collect and transport sap in days past. He also talks about the division of labor in the sugaring camps for each task like tapping trees, hauling sap and boiling it down. Native Americans used birch bark containers and colonists, wooden buckets that they carried on shoulder yokes to a central cooking area. Dunn explained that sap naturally contains bacteria and as daytime temperatures rose above freezing, it had to be processed fairly quickly to avoid spoilage. The students learn that Native Americans often kept reducing and concentrating the maple syrup until it formed a solid maple sugar that could be stored as granulated crystals, a hard candy, or gum-like form that would last without spilling or spoiling. Maple sugar was used in foods as seasonings, in medicines and was traded for other goods.

On the east side of the road, we approach a sugar house and finishing house where students will see how the sap is processed into the liquid goodie we so enjoy on pancakes and waffles. Outside, two demonstration areas show historical methods of processing syrup. There is a series of three metal kettles heated over a bed of wood coals that show how sap was boiled, stirred with wooden paddles and reduced to a thicker solution. As the syrup thickened up, it was transferred to smaller kettles over lower heat so the hot liquid could be carefully tended so it would form syrup and would be removed from the heat before it scorched, burned or boiled over. The smaller kettles ensure that the heat is more evenly distributed to the syrup from the bottom of the kettle to the rim. Similarly, there is a demonstration of a backyard syrup evaporator you can make where a wood fire is contained in a brick barbecue pit of sorts that is topped with a cooking grate. Old cake pans are used to boil off the thin sap into a syrupy mix that can be finished on an indoor stove when the syrup is almost done.

We learn that maple sap with 3-5 percent sugar has to be boiled down and concentrated to forma sweet, stable maple syrup. When a batch reaches 219° F and 66 percent sugar content, it is done, but concentrating that syrup requires a lot of boiling, constant stirring, careful attention and periodic testing. Also, we see that one has to be really careful as the fires are hot, the bubbling sap gives off clouds of swirling steam and the product is boiling hot. It takes huge quantities of sap to make syrup.

At MacKenzie in the Wallen sugar shack, a wood fire burns in the belly of an arch stove that has a big, flat top to hold a large metal evaporating pan with about four inch sides. The "sugar makers" tending the bubbling liquid keep adding more sap and measuring the percent of dissolved sugar in the watery solution. A handheld device called a spectrometer is a combination of a hydrometer and a refractometer that measures the density of the sugars remaining in the syrup. Under ideal conditions the crew aims to keep the syrup at a rolling boil and a depth of 1.5 to two inches in the evaporator pan. That seems to evaporate about 10 gallons of water an hour from the sap as the sugars concentrate. The highest quality syrup is produced when the sap is processed as soon as possible after collection and it takes several hours of evaporating each day. As the syrup gets thicker and the possibility of scorching the final product becomes a concern, the hot syrup is drained out of the pan when it reaches about 62 percent sugar and strained through filter paper and clean felt to remove any wood ash, other impurities and small sugar "sand" crystals. Then the amber liquid is taken into the finishing house where the syrup is heated in big pots under controlled conditions on a gas-fired range to more slowly drive off the last bit of water until it reaches exactly 66 percent sugar content. The finished syrup is canned and sealed in glass jars.

The color and taste of the syrup vary a bit each day depending on the presence of natural bacteria and how early in the sugaring season the trees were tapped. Early tappings tend to produce lighter colored syrups with higher sugar content (Grade A) so less boiling is needed. Longer boiling later in the season produces darker syrup (Grades B and lower). Some people prefer the richer, more caramel-like taste in the darker grades of syrup. The length of the syrup-making season depends on the weather and how fast it warms up in spring. It may run for 20 days or more. In 2007, the season only lasted 12 days as warmer spring weather came on very quickly.

At the last tour stop, the students visit a replica of a Ho-Chunk longhouse called a Che-PO-ta-kay, an arch-shaped hut formed from bent slippery elm saplings that are lashed and covered with fleshed skins and birch bark. These temporary structures provided shelter for Native Americans when they remained in the sugarbush during the syrup-making season. During our visit, volunteer Jon Langsdorf of Dekorra Township talked with students about the Native American ways of life, respect for Earth and elders, and a bit about the nature of Native American culture.

"I give them no more than it appears they can handle," Langsdorf says. And after a few questions and a taste of the finished syrup, the students head back to their buses with a sweet reminder of an interesting morning afield.

David L. Sperling edits Wisconsin Natural Resources magazine.

Book a sweet trip

More than 1,200 fourth-grade students book a trip to the MacKenzie Center's maple program each March and it takes time from 60-70 volunteers to make the program happen. A Maple Syrup Festival is held the first Saturday in April each year (April 3 in 2010) where the general public can enjoy an all-you-care-to-eat pancake breakfast, live music, demonstrations, tours of the grounds and guided tours of the sugarbush. To book school tours or find out more about the festival, contact (608) 635-8105. Reservations for school group tours are booked on a first-come, first-served basis starting on a call-in date set in mid-February.