How Maple Syrup is Made in Vermont

Maker Tour

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Who: Charlie and Helen Robb of Robb Farm Sugar House
What: Makers of pure Vermont maple syrup
Where: Brattleboro, Vermont

Early April is mud season in Vermont, as I discovered when I drove up there last week. Powering through the wet, muddy roads (yay for all-wheel drive!) and seriously questioning Apple's GPS navigation, I'd almost given up when I saw the plume of smoke rising from a wooded house in the distance. Wood burning fire? That was the heat source, I'd soon learn, but the smoke was actually steam from a large tank of boiling maple sap. I had arrived at the Robb Farm Sugar House, and was about to see maple syrup in the making.

The back side of the sugar house.
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A Brief History of the Robb Family Farm

Although there have been sugar maple trees on this slice of Vermont land for decades, Charlie and Helen Robb ran a dairy farm here up until two and a half years ago. When the economics of that became too difficult, the Robbs switched to sugaring, and their maple syrup business took off! They now own roughly 400 acres and 3,500 sugar maple trees. In a good year, they'll make 500 or more gallons of maple syrup. Here's how they do it:

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How the Robbs Make Maple Syrup

Sugaring season in Vermont typically starts in late February with tree tapping. Larger-scale sugar makers like the Robbs use a pipeline tap system, wherein all 3,500 taps on their property (usually one tap per tree, although sometimes more!) are connected to miles of blue pipeline that run into a central black tube which moves the sap to a holding tank near the sugar house. Tree tapping on the Robb farm takes about a week to two weeks to set up.

But don't think just because you've tapped a tree that the maple syrup will start flowing.

If there's one thing you should know about making maple syrup, it's that the process is almost entirely dependent on the weather. It it's too cold and the ground is frozen, the maple sap can't move up through the roots. But once it gets too warm and buds have sprouted on trees, the sap gets a funky "bud-y" flavor, and stops running altogether.

Because of the extended cold weather this year on the East Coast, the maple sap on the Robb farm didn't start running for a full three weeks after tapping. This delay meant that they missed the window for the very lightest maple syrup grade, what Vermonters call the fancy. Maple syrup gets progressively more robust as the season progresses, so by the time the sap was running this year, it had already progressed to the Amber, or medium, grade.

Ideal conditions for a good maple sap run are 24-25 degrees Fahrenheit at night, and 45-50 degrees Fahrenheit in the daytime.

Once the maple sap is flowing and funneling its way through the tubes to a central holding tank, it's ready to move (again, via a large tube) into the sugar house to start the transformation from maple sap to maple syrup.

The Robbs make maple syrup "the old-fashioned way," as Helen tells me, which means they boil the sap in a large open vat (as opposed to making maple syrup via the more modern method of reverse osmosis). The Robb operation is also totally wood-fired, which Helen believes gives their maple syrup a richer, more caramelized flavor.

The vat of boiling maple sap!
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The family starts boiling maple sap around 10:30am, and does its first draw-off test about an hour later. To get a draw-off taste, they turn on a spigot connected to the tank, which pours maple syrup into a bucket for sampling and measuring. They'll continue to draw off samples for the next 20 minutes or so to test for flavor and color. The day I was there the boiling sap had a 2% sugar content, while the day before it came in at 3%.

Roughly speaking, a 2% sugar content translates to an Amber or medium flavor grade, while a 3% sugar content gets a Golden or fancy grade. Typically higher sugar content makes for a lighter syrup, although this changes as the season progresses. For example, you could get a 3% sugar content and a very dark syrup late in the season. "Mother nature controls this game," as Charlie Sr. says.

Contrary to popular opinion, you don't change the grade of the maple syrup the longer you boil it. You could boil the sap all day, and you'd still have the same grade. It's the sap sugar content that determines the grade, not the length of the boiling time.

When the syrup achieves the desired color and taste, the Robbs grade it (Golden, Amber, Dark, or Very Dark — no more Grade A or Grade B!) then run it through a 16-filter press to remove impurities and sugar sands. The end result is crystal clear maple syrup ready for bottling!

A bucket of maple syrup, ready for tasting.
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After boiling and filtering, the syrup gets transferred to barrels, brought to the kitchen, reheated to 180 degrees, and then bottled. (Maple syrup must be hot when it gets bottled, otherwise it won't hold a seal.) The Robbs sell their maple syrup in their farm shop, as well as online.

And that's how this Vermont maple syrup goes from sap to bottle! Although the process itself is straightforward — tap, boil, filter, bottle — it's pretty labor-intensive, since it takes 40 gallons of maple sap to make 1 gallon of maple syrup.

Later this week I'll share how to read and understand the new labels for maple syrup and five maple syrup facts that will probably surprise you, including what you should do if your maple syrup ever grows a little mold. Stay tuned!

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Thanks, Charlie and Helen!

More posts in this series

Maker Tour: Vermont Maple Syrup

(Image credits: Cambria Bold)