(THE WASHINGTON POST) - Sugaring season in northern New England still conjures up romantic images of bearded woodsmen in plaid flannel, hauling metal buckets of fresh sap on horse-drawn sleighs to a creaky old sugarhouse that is billowing with steam, where a wood-fired oven boils the sap into maple syrup.

That is the notion I always clung to as I drizzled maple syrup on my pancakes - at least until a few week ago.

On a warm, sunny spring day in the sugar bush at Butternut Mountain Farm, as the deep snow began to thaw, there were no buckets or sleighs in sight and I was the only romantic rube wearing plaid flannel.

Here, surrounded by kilometres of plastic tubes, weaving upwards through more than 360ha of forestland, owner and founder David Marvin showed me how maple syrup is produced in 2018.

The spider web of tubing connects Butternut Mountain Farm's more than 20,000 taps in its maple trees. Those taps, with the help of a vacuum system, extract the trees' sap, sending it winding through the tubing network down to the sugarhouse.

"We probably have over 170km of tubing," says Mr Marvin, who has been producing maple syrup since 1972 and whose company now packages and sells more than half of Vermont's maple syrup. "We can take you on a snowmobile all the way up, if you want to see."

As it turns out, I do not have to take a snowmobile ride. We can view the network of tubing from a desktop monitor inside the warmth of Butternut Mountain's sugarhouse. The maple workers can even get alerts on their iPhones from sensors inside the tubing designed to detect leaks.

As sap gushes into the sugarhouse, its first stop is to undergo reverse osmosis to extract water, which significantly cuts down the sap's boiling time, reducing fuel and increasing efficiency. "This machine is taking about 7,600 litres of sap an hour and reducing it by two-thirds," Mr Marvin says.

Yet, even surrounded by technological advances, he reminds me that maple syrup is a natural, unprocessed, unadulterated product - simply boiled tree sap, the same as it was 100 years ago.

"Maple is a bright spot in agriculture," he says. "It's healthy and sustainable. You'll tap the same trees for decades."

"Wow, this is really running today," he says, excitedly, as he fills up a cup of fresh sap and hands it to me. "On a good day, this is almost as sweet as Kool-Aid. It's magical."

We taste some finished syrup before it is poured into a metal barrel. Sugar-makers never really know how light or dark the finished sap will be until it is finally boiled.

"Hmm. This is on the darker edge of Amber Rich," says Mr Marvin, referring to the grading system that classifies syrup as Golden Delicate, Amber Rich, Dark Robust or Very Dark Strong. "It's got a good maple base, with a little bit of caramel. It's got such a bouquet. Sometimes, it's almost as complex as Scotch whisky.

"Part of the magic of maple is that we don't know everything. I hope we never do."

What we do know about maple syrup these days is its huge growth, driven by consumers who are looking for natural sweeteners and moving away from refined sugar and corn syrup.

Maple's advocates also tout it as a source of minerals such as manganese and riboflavin. In Vermont, the nation's leading maple-producing state, production has tripled in the past decade, from an average of 2.3 million litres a year in the late 2000s to about 6.8 million litres a year now.

Since 2013, Vermont producers have installed 1.2 million new taps.

"Maple is pretty big business in Vermont," said Ms Amanda Voyer, communications director of the Vermont Maple Sugar Makers' Association, one of the oldest agricultural associations in the nation, founded in 1893. "It used to be more of a cottage industry, a side business. Now people are using it as a real income generator."

Traditionally, maple was a part of a dairy farmer's annual work cycle, a source of supplemental income in the early spring. But by the 1970s and 1980s, Vermonters were making less than 1.1 million litres a year. In fact, all the current maple growth is only restoring things to former prominence.

In the 1860s, when maple sugar was cheaper than cane sugar, production was much larger than it is today.

In the early 20th century, Vermont produced more than 34 million litres of maple syrup a year.

"The imagery of maple hasn't really moved out of the 1860s, but the technology has," said Mr Mark Isselhardt, a maple specialist at the University of Vermont's Proctor Maple Research Centre.

Until recently, maple production was limited by how much human labour could be put to work in the snowy woods. But technology is rapidly changing that. "We know you can get more sap out of a tree than is currently typical," said Mr Isselhardt.

Alongside growing demand and advanced maple technology has been relatively stable prices. That is mainly thanks to producers in Quebec, who own 70 per cent of the international maple market and whose trade federation tightly controls supply and pricing. Those factors have made Vermont's maple forests attractive to big-money investment from outside corporations.

One of the largest has been the Maple Guild, in Vermont's Northeast Kingdom, owned by Sweet Tree Holdings and funded by a private equity firm from Montreal called Fiera Comox that invests heavily in agriculture.

The Maple Guild, which began in 2013, owns more maple trees than any single producer in the world, with 400,000 taps over 6,500ha of forest, and with 2,900km of tap lines. "A million taps would be our goal," said Mr John Campbell, the Maple Guild's vice-president of sales and marketing.

He refers to the company's "tree to table" approach and talks about "disrupting the maple syrup category."

Disruption might be a few years away, but the Maple Guild's model, and the number of taps, is unique in Vermont, where the largest companies generally buy syrup from smaller producers. Even a company such as Marvin's Butternut Mountain Farm, which packages maple syrup for Whole Foods, Walmart and Williams Sonoma, produces only a small portion and acquires most of its supply from a vast network of sugar-makers it has worked with for years.

At the Maple Guild, I was given a tour by facility manager Jesse Hutchinson. "No one's tried to create a multi-million-dollar business off maple," Mr Hutchinson said. "It's romanticised, but it's pretty simple. You put a hole in a tree and let it drain the sap, and then cook it."

However, once the syrup is finished at the Maple Guild, that is only the beginning. "We take the syrup and use it to make other things," he said. "We're not treating it only as maple syrup for pancakes. We're treating it as a sugar that you can do all these beautiful things with."

Those other "beautiful things" include organic black and green teas sweetened with maple, as well as experiments such as bourbon-barrel-aged maple syrup, and syrups infused with vanilla bean, cinnamon and salted caramel.

"In autumn, we'll make a pumpkin spice," Mr Campbell said.

Then there is the Tapt brand maple water ("winner of the Hydration Award" by Runner's World), which is water that has been removed from the sap via reverse osmosis, then infused with a touch of syrup and flavours such as grapefruit, blueberry and cranberry-pomegranate. Promoted as hydration that is low in sugar and high in electrolytes and antioxidants, maple water has been trending as the "next coconut water" and Tapt has competitors such as Vermont's Drinkmaple (which markets its maple water as being pure sap tapped directly from the tree).

The global marketing research firm Technavio predicts that the demand for maple water will grow 30 per cent by 2020, and that tree sap (which includes maple and birch water, as well as cactus and watermelon water) will become a US$2 billion (S$2.6 billion) industry by 2025.

When the Maple Guild does use the sap to make syrup, it even goes about it non-traditionally, using a steam-based technique that converts the sap at a lower temperature (called "steam-crafting," a trademarked term). The Maple Guild says that creates a purer, less-cooked syrup.

The Maple Guild makes only the lightest syrup, graded as Golden Delicate.

Some of us, however, enjoy our maple on the darker, more robust end of the grading scale. I happen to love the deep, dark syrups that used to be called Grade B.

In fact, that whole maple syrup grading system changed in 2015: Fancy became Golden Delicate; Medium or Dark Amber became Amber Rich; Grade B became Dark Robust; Grade C became Very Dark Strong; all four are now Grade A.

Seeking out those darker syrups, I visit Couture's Maple Shop and Bed & Breakfast in Westfield, Vermont. Up the road from the white clapboard farmhouse and red dairy barn is Jacques Couture's sugarhouse. When I arrive, he is loading wood into the blast furnace that he uses to boil his sap.

Mr Couture, 67, a past president of the Vermont Maple Sugar Makers' Association, has 7,500 taps and makes about 9,500 litres a year. He has been making maple syrup since he bought his farm in 1970 and, although he is not a small producer, maple has always been a side business to his 150 head of dairy cattle.

The idea of a producer like the Maple Guild, with its Quebecois investors and 400,000 taps, unsettled a traditionalist like him. "These kinds of operations never used to exist," he said. "For a family operation like ours, it's a little scary. I worry about demand not keeping up with supply."

He has embraced some modern technology: He replaced buckets with tubing in 1979 and has used reverse osmosis since the early 2000s. But he remembers riding into the woods on a sled as a child to go sugaring. And he remains committed to boiling his sap over a wood-fuelled furnace.

On that day, as we wait for the sap to reach its boiling point, he tells me that the darkest syrup would come with later-season sap, as the weather warms up. Now, in the cold early season, it would be mostly lighter syrup.

"We're hoping for some dark syrup because our customers really like it," he said. "But you can't just say, I'm going to make 50 litres of Amber Rich today. You really don't know what you're going to get until after it boils."

I want to know, did cooking with wood make any difference?

"All things being equal, the wood shouldn't make a difference in flavour," said Mr Couture. "But maple tends to pick up the smells surrounding it. We hear our customers say they can taste the wood smoke, but I don't know if it's psychological or scientifically proven."

He smiles and shrugs.

On an earlier visit, Couture and I taste through all his syrups. Maybe I am also moved by romanticism, but I have tasted a lot of liquid things in my life and I believe that I tasted smoky notes in the Dark Robust and Very Dark Strong, creating some of the most memorable maple syrup I have ever tasted.

Almost too complex for pancakes. Almost.