Ignorance is one way to keep a product pure. “I don’t know what potassium sorbate is,” says Wendy Achatz, owner, with her husband Dave, of the Achatz Handmade Pie Company. “Is it a powder? A liquid? Where would I buy it?” asks Achatz (pronounced ACK-its). Her point is that potassium sorbate, a preservative, is found in many commercial pies–but not in hers. All of her sixty flavors of pie, Achatz says, are made of pure, natural ingredients with no preservatives. Usually about forty flavors are available at any one time.

The company’s signature and best-selling pie is the Michigan Four Berry pie, but Achatz has a personal favorite: “Oh man, right now that would be the cannoli pie. We use our homemade pastry cream, which is made from milk with no hormones or steroids.” Though it can’t be said of the cannoli pie, almost all of the Achatz fruit pies are vegan; the exceptions are a few that use a bit of butter in the filling. (The crusts are made from palm-flower oil which Achatz says has less saturated fat than palm kernel oil.) And assistant manager Julie Lawler-Hoyle promises that you can flip an Achatz pie over and the bottom crust is just as flaky as the top.

In early November, Achatz was still a few days out from opening her eighth pie store on Ann Arbor’s north side, testing and tinkering with the ovens and running a staff training session. This is her first freestanding outlet in Washtenaw County, and it’s also the first that will be baking pies on-site.

Achatz began making pies eighteen years ago, while raising five kids in the tiny town of Armada in Macomb County. She’s not the old-fashioned girl in ponytail and crinolines featured on the company’s logo. Nearly six feet tall, athletic, with thick, long, russet hair, she was wearing a flowing knee-length cardigan and–like chefs everywhere–Dansko clogs.

Achatz pies have been sold for years in Ann Arbor’s finer grocery stores: the Jonna family, owner of the Plum Markets and before that, the Merchant of Vino, was one of her earliest wholesale customers. “I brought a pie in to Ed Jonna at Merchant of Vino, with a little Avery label on the box that I’d printed on my dot matrix printer. I was so nervous. Eddie was so awesome.”

Despite the fact that Achatz has no idea what potassium sorbate is, and has never been to cooking school, her family is big in the food industry. Her mother-in-law, Irene Achatz, started Irene’s Catering (in Adair) in 1963, a business now run by son Steve. Irene’s salad dressing and Steve’s soups will be sold at the pie store. The most famous member of the family is cousin Grant Achatz, whose Chicago restaurant, Alinea, was named number one in the country by Gourmet magazine in 2008.

Achatz Pies isn’t that famous, but it is in a growth spurt: Achatz says business has grown by 49 percent in the last year. She recently navigated the expensive and labor-intensive process of obtaining Department of Agriculture certification, allowing her to expand into meat pies. She recouped some of that expense by taking on a contract to produce 350,000 potpies for another company at the end of last year, though she says they had to scramble to do it. The last quarter of the year “is like Super Bowl for us anyway. We can barely keep up with our own orders.”

Baking pies in-store is another first. “We want to see if we can do it here. It will be the flagship store to offer partnerships or franchises to other people.” The small shop, next to the Traver Village Kroger, is decorated with warm, homey touches, like chandeliers and a salvaged church pew. “We’re trying to bring in a little taste of the country, and what it’s like in our original Armada store.” The Armada store sits on the edge of the Achatzes’ forty-acre apple orchard.

Once it’s up and running, Achatz expects to spend little time at the Ann Arbor store. Manager Tim Turner and assistant manager Julie Lawler-Hoyle will be much more familiar faces. But like all Achatz stores, this one will close at sunset on Friday and remain closed all day Saturday. “I’m a Seventh Day Adventist, so we keep the seventh-day Sabbath,” Achatz explains.

Achatz Handmade Pie Company, 2643 Plymouth Rd. (Traver Village). 369-2460. Sun. 8 a.m.-5 p.m., Mon.-Thurs. 8 a.m.-8 p.m., Fri. 8 a.m.-sunset. achatzpies.com