Historic Aldie Mill back in service; will grind corn, wheat for local distiller’s bourbon

The historic Aldie Mill — at a time Loudoun County, Virginia’s largest grist mill — will be back in service Saturday afternoon, helping turn grains into bourbon whiskey for a local distillery.

“Aldie Mill was built between 1807 and 1809, and it operated until 1971,” said Tracy Gillespie with the Northern Virginia Regional Park Authority, which operates Aldie Mill Historic Park, located on Route 50.

The mill uses twin waterwheels, powered by the Little River, on 2,000 pound grindstones.

It was built and owned by Charles Mercer, an early entrepreneur and lawmaker. He hired a miller, who would purchase the grain from the farmer, grind it and bring it to market.

The historic Aldie Mill in Loudoun County will be back in service soon. (Courtesy Peter Ahlf)

In the 1800s, “Aldie Mill provided a service for farmers in Loudoun County,” said Gillespie. “Any farmer could come here, with his grain, get it weighed, and then go home with money.”

From noon until 5 p.m. on Saturday, Mount Defiance Cider and Distillery will be using the old-school technology to produce bourbon.

“Like those farmers of old, we’ll be trucking our grain to the mill this weekend,” said Peter Ahlf, head distiller. “We’ll be bringing in 2,500 pounds of corn and 1,000 pounds of red wheat.”

Aldie Mill will grind grain this weekend for Mt. Defiance Distillery's bourbon

“We just picked up the corn and wheat from a farmer down in Charles City, Virginia,” said Ahlf. “When we buy it from him, it’s dry corn kernels that have been cleaned, and put into 50 pound sacks.”

In these modern times, Ahlf typically buys pre-ground bags of grain. However, for this weekend, “I had to specify please don’t grind my grain, because I have a more fun way to do it.”

The grain will be ground at Aldie Mill during Saturday’s event, which includes demonstrations of milling, bourbon tasting, and it’s open to the public.

Turning grain into bourbon whiskey

Ahlf said the sacks of corn will be poured into the hopper one sack at a time to be ground into cornmeal, resembling the type you’d buy at the grocery store.

“We want it to be as fine as possible, because that exposes the starches that get converted to sugars, that get converted to alcohol,” he said.

The ground grain will be brought back to the distillery, which is located in Middleburg. In addition to the corn and wheat, Mount Defiance’s bourbon includes a small amount of barley.

“The first step is called a mash, which is basically cooking the grains like you’d make a porridge on your stovetop,” said Ahlf. “The purpose of the cooking is to have enzymes convert the starches in that porridge, into sugar.”

Ahlf said the porridge process takes a day, followed by five days of fermentation. “And then it has to be distilled twice, because we’re using old-fashioned equipment.”

Grains ground at Aldie Mill will eventually become bourbon, and stored in barrels at Mount Defiance Cider and Distillery (Courtesy Peter Ahlf)

Eventually, the bourbon is put into new charred American white oak barrels.

“The barrel aging gives it a wonderful caramel sort of flavor. The wheat makes it very smooth — hints of toffee, nice kind of smoky flavors,” said Ahlf.

Then, the recipe calls for patience.

“We age ours for at least two years, most of our bourbon is three years or older,” said Ahlf. “So, what we’ll be doing this weekend, unfortunately, people won’t be tasting for two to three years.”

Aging bourbon requires corn, wheat, barley -- and patience

Neal Augenstein

Neal Augenstein has been a reporter at WTOP since 1997. Through the years, Neal has covered many of the crimes and trials that have gripped the region. Neal's been pleased to receive awards over the years for hard news, feature reporting, use of sound and sports.

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