by Cathy Huyghe

The first misconception to clear up about Apfel Eis, or apple ice wine, is that it’s made year-round rather than just in the fall when apples are harvested.

“We make it every week of the year,” Wade Holtzman of Still River Winery says with the certainty of a man personally responsible for processing the 100 gallons of pressed apples that Still River receives weekly from Carlson Orchards, Holtzman’s neighbor in Harvard, Massachusetts.

What makes it possible for Holtzman to make their wine year-round is Carlson’s cold storage technology, which keeps their apples fresh the whole year.

Holtzman receives shipments of five different kinds of pressed apples. To a winery, 100 gallons is not very much. But Holtzman breaks that amount down even further and ferments the juice in small batches. He then mixes the batches together to achieve a consistent taste and style.

Sounds simple. Right?

“It doesn’t look complicated,” Holtzman says as he looks around his winery stocked with freezers, jugs, carboys, drips and a few beakers and pipes. “But it’s hard to figure out how to turn juice into concentrate.”

The first step is to freeze the juice solid in 5-gallon jugs. Since water freezes at a higher temperature than a solution of sugar, apple solutes and water, the concentrated apple/sugar solution slowly separates from the water/ice. Holtzman then sets the jugs on racks to defrost with collection containers underneath to catch the concentrated solution when it runs out. It takes about a day for a 5-gallon container of the concentrated apple/sugar solution to defrost, separate and run out, leaving the ice behind.

Holtzman then repeats the process, freezing the juice and letting it thaw then drip for a minimum of three times. He ends up with about a gallon of must.

The idea is for the must to achieve a given level of concentration, measured by the solution’s specific gravity, which Holtzman monitors throughout the freeze-drip routine. When the specific gravity reaches the desired level, Holtzman knows the must has the correct amount of sugar and apple flavors to start fermentation.

To ferment the concentrate, Holtzman pours it into 5-gallon glass carboys, which he stores at 50 degrees in a walk-in cooler. The fermentation takes about three months, since it’s a very slow process—especially in comparison to making wine from grapes, which can ferment as quickly as two weeks at much higher temperatures. The slow fermentation at a lower temperature maintains the apples’ sweet flavors and aromas of freshly picked fruit. Holtzman experimented with many different types of yeast and different kinds of apples, and he also experimented with fermenting at a higher temperature, but he has settled on his current recipe.

Once the must is in the carboys, Holtzman babysits them and keeps track of each one’s pH level and specific gravity; this is because at a low temperature the yeast is on the edge of its ability to remain active and complete the fermentation process of turning sugar into alcohol. When the must in each carboy reaches 12 percent alcohol, Holtzman stops the fermentation. Technically, the must is now wine. Normally the must is at a 12 to 12.5 percent residual sugar. Next he selects various 5-gallon batches and blends 10 of them together into 50-gallon stainless steel containers. That’s how he is able to maintain the product’s consistency.

Just like winemakers who often let Chardonnay sit on its grape lees (the yeasts and solids that have settled to the bottom) during fermentation, Holtzman lets his wine sit on its apple lees for a few weeks. Then he’ll rack (siphon) it off the lees and pass it through a gross plate filter into a bottling tank. At bottling, the wine passes through an ultra sterile filter to remove any remaining yeast because if any yeast were left, the wine would continue to ferment in the bottle.

Filtering the wine also removes the type of bacteria that can turn the wine to vinegar. Filtering off another type of bacteria also prevents malolactic fermentation from occurring. The acid in apples is almost entirely malic acid, which has a tendency to convert to lactic acid; the challenge when it comes to apple ice wine is to keep it crisp (malic) rather than smooth (lactic). That’s why Holtzman filters the bacteria that would convert the malic to lactic.

Finally the wine goes into bottles, which are sealed with treated and sterilized corks, and labeled. The wax coating over the neck of the bottle seals it completely, lessening the chance of extraneous oxidation.

The finished product looks simple but tastes rich and textured, just as the winery process looks uncomplicated but is in reality technically sophisticated and complex. It is, in other words, quite a long way from the beer Wade and his son Leif Holtzman have been brewing at home for several years.

The shift to ice wine started as a hobby (“on a whim,” Leif said) two years ago after a trip to Quebec, where the traditional method of producing apple ice wine is practiced. The Holtzmans came home and began experimenting, they asked friends to try their wines, they continued to experiment and tweak the process. Eventually they realized they could make a business out of it.

“It was really Leif who got the winery going,” said Margot Holtzman, Wade’s wife and Leif ’s mother, “since Wade and I are so laid back about things.” Margot, a learning specialist by trade who had worked in the Cambridge Public Schools for 30 years and is now with the Cambridge Friends School, scaled back her work schedule to accommodate the demands of handling sales for the winery. Wade, who makes the wine, also continues to work as a restorer of antique furnishings, a craft that he studied in England after graduating from Boston University.

For his part, Leif graduated from Harvard College in 2005 with a double concentration in psychology and economics. Today he is responsible for marketing the Still River product and growing the business. “The important thing about a wine is to make it something special,” he said. “The apple ice wine is something different and attractive for retailers to have on their shelf.”

Still River debuted their wine in 2008 at the Newport Wine Festival to an overwhelming response. A meeting with a distributor in Rhode Island helped them build momentum initially, and now the wine is in over 120 locations, including Whole Foods markets and the Mandarin Oriental hotel. With the recent addition of a second cold room to their winery, Still River’s annual production is now 800 cases, up from 400 cases four months ago.

Notice that it’s an annual production, not just a seasonal one.

That’s where Carlson Orchards comes in. The sophisticated year-round cold storage system at Carlson’s, which is also located in Harvard, Massachusetts, is the backdrop and the infrastructure to the success of Still River’s wine.

Carlson’s cold storage facility is perfectly clean, with no odors of yeast or mold or vinegar. It’s “controlled atmosphere” storage, meaning the storage rooms are sealed air tight once they have been packed floor to ceiling with efficiently stacked crates of apples. The door to the storage room is sealed with petroleum jelly, then liquid nitrogen is dispersed into the room. Carlson’s regulates oxygen and carbon dioxide levels throughout the winter.

That process, and their judicious use of an ethylene-blocker product called Smart Fresh, effectively enables Carlson’s to preserve their harvest of apples throughout the year. Frank Carlson explains that Smart Fresh is used as a preservative on produce like avocados and apples, and “it makes for a better, crunchier apple off-season.”

Take Rome apples. “There’s no market for fresh Rome apples,” Carlson said, “so we Smart Fresh those, and use them for ‘peelers’ in the summer.” Carlson’s also manufactures (that is, cores, peels, and/or chunks) different varieties of their apples and sells them to venues like bakeries and the kitchens at Whole Foods market.

The system—especially the year-round preservation system—favors clients like the Holtzmans at Still River, because as apples get older, they get sweeter. That means that the pressed apples from Carlson’s that Wade Holtzman brings into his winery in, say, March will still be crunchy, fully intact and even sweeter than those he brought in shortly after harvest in the fall. Carlson’s also supplies Harpoon Brewery with the base product of Macintosh juice for their hard cider.

At a time when eating local matters more and more, it is comforting for the enthusiastic drinkers among us to know that the options for drinking local are expanding alongside it.

To find Still River Winery’s Apfel Eis go to stillriverwinery.com.

Cathy Huyghe directs the food and drinks community at WGBH and WGBH.org. She also runs a daily email service, Red White Boston, that highlights wine-related events throughout the Boston area. Cathy can be reached at cathy@well.com.