AT ONE TIME, there were something like 300 operating mills in Bucks County. Nowadays, by Mark and Fran Fischer's count, there's just one. It's theirs - Castle Valley, a family-run operation shocked back to life by figurative grit and actual grits.

After painstakingly restoring an 18th-century mill that's been in Mark's family since the '40s, the second-career Fischers are cranking wheels in an interesting headspace. Harnessing the burgeoning consumer and culinary interest in whole foods and back-to-basics processes, they're leveraging an antiquated past to build a sustainable future.

Old-country echoes

The Fischers, who met at Lafayette College, did not grow up in milling families - nor did they consider themselves one, until 2011. Mark, an electrical engineer, was a safety consultant for corporate aviation clients, while Fran worked in securities and commodities. But the milling heritage of Mark's Bavarian immigrant grandfather, Henry Fischer, has always cast a literal shadow on their day-to-day.

Ever since he was a kid, Mark was curious about the dilapidated mill that sat next to his family home, on about 20 acres along Neshaminy Creek in Doylestown. Though Henry made a living stateside in the moving business, he stayed connected to his original vocation back in Germany by collecting old mill equipment.

"You could not walk through the place," Mark recalled of his childhood explorations of the building jammed to the gills with his grandpa's dusty tools and general junk. "It was just floor to ceiling stuff. It was kind of like finding a pirate ship stuck in a cave."

A dream realized

After he and his wife purchased the old family plot and moved there to raise their three children, Mark's curiosity only grew. He had his now-or-never moment after agreeing to a buyout from the aviation industry, a deal that came with a noncompete clause. It turned out to be as good a time as any to pick up where Henry had left off - a challenge that's demanded contributions from the entire family. "We're using everything we've learned," said Fran.

Training through the Society for the Preservation of Old Mills helped Mark and his now college-age son realize exactly what they had on their hands. The family mill was built in 1730, well before Philadelphia inventor Oliver Evans' development of the automated flour mill (U.S. Patent No. 3), an innovation that helped kick-start the American machine age. But the building was equipped with Evans' efficient technology, like bucket elevators, meaning former operators had upgraded their digs at some point.

SPOOM also helped the Fischers learn how to repair and restore the original mill equipment on hand, most of which dated back to the 1800s - stuff like sifters, cleaners and aspirators, in addition to the stone-wheel mills.

For the Fischers' purposes, it had to operate, not just look cool. "I'm not preserving it in a museum," said Mark. "I wanted to make it work."

Word gets out

They started out running local corn through a portable mill built in 1878 and selling it to a handful of customers with the hopes of subsidizing repairs to the mill. But it didn't take long for word of Castle Valley's unique products - locally grown and sourced wheat, rye, spelt, farro and corn, ground in small batches by antique stone wheels and otherwise unadulterated - to spread through the chef and food-geek communities.

"A wheat seed is one of the most nutritionally packed foods in the universe," said Mark of what separates Castle Valley's products from the rest. "When you take all of the components of the seed out, you just end up with this dead starch." His old-school processes, meanwhile, keep the wheat, bran and germ together, boosting both flavor and nutritional value. "It's like scrambling an egg," he said. "Everything's in there."

Before long, the Fischers were ramping up their output, which demanded even more specialized repairs. Though the mill runs on an electric turbine, they hope to harness the intense power of the nearby creek sometime soon. There's also a plan to get two enormous French buhr stones made of freshwater quartz - "the Cadillac of mill stones," according to Mark - up and running. "We're always between restoration and production," he said.

From the ground up

Castle Valley's attention to detail, as well as its willingness to customize products for chefs and bakers, is a major reason why they've proven so popular with restaurant clients.

Chef Sean Magee of the brand-new Heritage in Northern Liberties orders Castle Valley products through the Lancaster Farm Fresh Co-op. He uses their winter wheat for bread service, and he's sprouted their farro to garnish a kale dish; he's also working on a smoked grit cake he plans to serve with pork belly and mussels. "It sounds weird, but it tastes like the earth," he said.

"They are a really important link between farmers and consumers - the bakers are kind of the last step," said Alex Bois, who uses multiple Castle Valley products in his acclaimed breads at Fork and High Street on Market. Bois' co-worker Sam Kincaid, a pastry chef, also looks to Castle Valley for inspiration, and their products often end up on the savory side of things, as well.

Castle Valley's relationships with the independent farmers who harvest their raw products, many located right in Bucks, is yet another strong link in the local food chain. Guaranteeing these small-scale operations consistent business where high-value crops are concerned helps preserve the agricultural viability of the county. "This is the most fertile land in the world, and we're planting houses on it," said Mark.

If you ask the Fischers, simply prioritizing taste is that vital first step toward sustainability. The farms supplying them are "breeding for flavor, not yield," said Mark. "It sounds like a totally new concept, but it's what they did 200 years ago."

Castle Valley Mill, 1730 Lower State Road, Doylestown, 215-340-3609, castlevalleymill.com. The mill is not open to the public. Check the website for retail locations where its products are sold.