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Maple trees release sap using stored starch produced through photosynthesis. Photo by Kathryn Coleman.

Sweet Success: Researchers Tap into Oklahoma Maple Syrup Production

Tuesday, May 28, 2024

Media Contact: Sophia Fahleson | Digital Communications Specialist | 405-744-7063 |

In a land known for its prairies and plains, a new chapter is unfolding — one that promises to add a touch of sweetness to Oklahoma’s agricultural heritage.

A team of scientists are rewriting the narrative of maple syrup production — not in Vermont or Quebec — but in Oklahoma. The potential of its native maples is about to be revealed.

Native Americans in Oklahoma collected maple sap for years, said Lu Zhang, Oklahoma State University horticulture and landscape architecture assistant professor.

“Traditionally, they use maple sap in ceremonies,” Zhang said. “It’s not for commercial use.”

While the Indigenous people capitalized on Oklahoma’s trees for decades, the rest of the population has no idea what has been under these trees’ bark, Zhang added.

Mike Schnelle, OSU Extension ornamental floriculture specialist, discovered Oklahoma’s Native American families had explored this production for many years.

“I had a chance to go over to the OSU Center for Sovereign Nations and learn from some of the undergraduates,” Schnelle said. “All of a sudden, I started hearing, ‘Oh, yes, our family has done maple syrup for X number of years, also maple candy.’ All of these spin-off possibilities got me thinking.”

Along with learning about the Native Americans’ production, Zhang and Schnelle’s colleague, Youping Sun at Utah State University, encouraged them to try this research, he added.

“The first question we asked was if we could attempt to gather the maple sap in Oklahoma,” Zhang said. “The next questions were ‘what is the volume, how much production, and what is the tapping window?’”

An opportunity arose to submit a grant proposal for the research through the U.S. Department of Agriculture, Schnelle said.

“As a forester, we never thought we’d ever be doing maple syrup in Oklahoma,” said Bob Heinemann, senior superintendent of Kiamichi Forestry Research Station. “I initially solicited letters of support with the Choctaw Nation, the U.S. Forest Service, Oklahoma Forestry Services and Little River Conservation Commission for the grant.

“With a solid application including the support letters, OSU scored a $500,000 grant,” he said. “The next thing I knew, they called and said, ‘Hey, Bob, can you help us tap trees?’”

Heinemann and his team set out across eastern and southeastern Oklahoma to identify large groups of maple trees to sample, he said.

“From winter 2022 to spring 2023, we worked on the site selection,” said Lu Zhai, natural resource ecology and management assistant professor.

Landowners must have control over their land to be eligible for the study, Schnelle said.

“They must have one of the four native maples that we’re hunting for,” Schnelle added. “Not only are the traditional sugar maples going to get us maple syrup, but so are box elders, red maples and silver maples.”

These four species of maple trees are being researched at three Oklahoma locations.

“We’re working near Idabel, Talihina and Miami,” Zhang said. “That covers the southeast, east central and northeast parts of Oklahoma.”

Part of the USDA grant looks at what smaller trees versus larger trees produce, Heinemann said.

“The volume of sap produced varies by the size of the tree,” Heinemann said. “We have a sample range from small trees to big trees. We have 10 trees per species per site per tap type.”

Climate and temperature play a large part in maple syrup production, said Niels Maness, horticulture and landscape architecture professor.

“The sap flow season is driven by not cold, not hot, but by freezing nights and non-freezing days,” Maness said. “That’s what pushes the sap flow up through the tree.”

The window of opportunity for sap collection in Oklahoma will be late December to early February with the best production in January, Heinemann said.

“In New York, the season normally would start at the end of February and run through mid-March,” Heinemann said. “You’re looking at a temperature differential as you are moving into spring. If you think about that here in Oklahoma, you’ve got to move the timeline forward.

Once a tree begins growing its leaves, you can no longer collect sap, Maness said.

In January 2024, the trees tapped by the Kiamichi Forestry Research Center staff were averaging a gallon and a half of sap per tree while using a vacuum collecting system, Heinemann said. Other trees produced a gallon of sap with the gravity flow system or around half a gallon with the bucket system, he added.

“The active vacuum system has a pump on it, and it keeps the trees at a -25 psi,” Heinemann said. “They’re constantly under a vacuum pull, and they’re definitely producing the most.”

The gravity flow system relies on gravity to provide the vacuum in the tubes, Heinemann said. Unlike the active vacuum, this passive system does not need an active power source.

“The gravity flow systems self-start every day as the temperature rises and the trees begin to drip,” Heinemann said. “If there are no leaks in the system, the sap will be pulled to the collection container downhill.”

Heinemann described the bucket system as the traditional method. A spile is tapped into the tree, and a bucket is hung underneath it to collect the dripping sap.

“The advantage of the maple project is maple syrup has been made for a long time, just not here,” Maness said. “We have a lot of technologies we can bring over to Oklahoma and compare what we produce here to what is produced in the more common states, like Vermont, and up into Canada.”

In the field, researchers look at the sap in terms of brix, Maness said. Brix is the refraction of light that roughly tells them what the soluble solid contents are, Maness added.

“Most of those soluble solids are sugars,” Maness said. “We bring the sap back into the lab, and we look at the actual sugars that are present.”

Sap is conventionally turned into syrup by manually boiling the water away and evaporating it to have a higher sugar content, Heinemann said.

Sap begins with a 2% sugar content. To be considered a syrup, a product must contain 66% to 68% sugar.

“At that point, the product becomes shelf stable,” Maness said. “There’s so much sugar that microorganisms don’t like to grow. If you go over 68%, that sugar begins to granulate and fall out of the solution.”

With the large amount of water to be removed from the sap, researchers are considering reverse osmosis to take the 2% up to approximately 6% sugar, Maness said.

“That doesn’t sound like much,” Maness said. “But, that’s about 75% less water to deal with, so it becomes a lot more efficient.

“Reverse osmosis just uses membranes,” he said. “Water will flow through the membranes. Sugars are more or less filtered out by the membrane, and you concentrate it.”

The project to test sap quality is funded at the state level by the Oklahoma Department of Agriculture, Food and Forestry.

“I put in an ODAFF proposal to look at sap quality, trying to differentiate the different maple species,” Maness said. “Then, we make lab batches of syrups and look at the quality of it.”

The Oklahoma product will be compared in the lab to sap and syrup from the Northeast, Maness said.

“The general idea was we can determine how much sap we can produce in Oklahoma,” Maness said. “But, what difference does it make until we know the quality of the product?”

To find the quality of the syrups’ taste, Maness is looking at the organic acid content, he said. Imagine a bland tasting strawberry versus one you take a bite out of and the flavor hits you, Maness said.

“The difference is the sugar to organic acid ratio,” Maness said. “Higher organic acids give you more of a punch from the product.”

One of the things that sets maple syrup apart is the aroma, Maness said, so researchers also explore the aromatic quality of the syrup in the lab.

“If the syrup has a high quality, we could develop an industry here,” Zhang said. “Our product could be a fresh and unique syrup.”

Oklahoma maple syrup could have a different flavor from the Northeast because of more sunshine, Zhang said. The ongoing testing will investigate this theory, she added.

“I’m pretty excited about maple syrup production as a supplemental income,” Schnelle said. “It is a no-brainer for landowners. They have maples on their land. The trees are there for the tapping.”

Collecting maple syrup is easy for landowners to begin, Heinemann said. All the supplies can be found online.

“It’s just a matter of identifying your trees, figuring out how much you want to tap, and deciding how you want to tap it,” Heinemann said.

Part of the USDA grant is outreach, Heinemann said. A series of free workshops were offered last fall, and another series is set to begin in November 2024.

The workshops in November will provide an overview of maple syrup production, time commitment and potential income, Schnelle said.

“We will take participants to the woods, and we’ll show them how to tap,” Heinemann said. “Everybody who comes will get a tap set. We’ll give them a bucket. We’ll give them a spile and show them how to do it.”

Many people are willing to plant and wait many years for chestnuts or other long-term crops, Schnelle said.

“Why not think about deliberately planting maple trees that are indigenous to the land?” he added.

“I certainly am starting to put that in people’s minds,” Schnelle said, “particularly for younger people who have time on their side or for generations that want to be able to pass this down to their children or whoever inherits their land.”

Story by: Laramie Coffey | Cowboy Journal

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