For the St. Pepin grapes at St. Croix Vineyards, it had been a long, languid, blissful summer. Their prime predators, the birds and the bees, had been kept at bay. Their mortal enemy, hail, had not reared its golf-ball-sized head.

By the end of Sept. 21 -- a bright, sunshiney day -- they would be crushed. And pressed. And hosed into a storing tank, en route to fermentation and bottling and consumption, maybe with an apple fritter from the adjacent Aamodt's farm.

Such is the lot in life of Minnesota-grown grapes, which begin their transformation to wine on sun-kissed autumn days such as this one. (Picking in rain is bad for the grapes, which absorb water. "We did that two years ago, and we had to store them before crushing," said operations manager Martin Polognioli. "That didn't work out too well.")

The amber grapes' journey from vine to tank took place on one of the most hectic days of the year at the Stillwater vineyard. The fields, the machine-laden winery and the tasting room were as busy as the bees trying to get one last nibble of the surprisingly sweet grapes.

Yellow jackets swarmed around the rejected Maréchal Foch grapes that volunteer picker Katie Smith had discarded. These were more likely to have cracks, which are a magnet for the bee's stingers. Most of the grapes, however, were healthy and destined for crushing.

"Being in Minnesota and being outside in a vineyard, I love the novelty of that," said Smith, 23, an Atlanta-area native. "It's just such perfect weather, I couldn't resist." Her rewards for picking grapes all day: a sandwich lunch from Jimmy John's, a couple of bottles of wine and almost certainly a gleaming suntan.

She was one of about a dozen volunteer pickers, none of whom appeared to be over 30. All of them, though, were older than Noah Hemstad, son of Peter Hemstad, a co-owner of the winery. Noah was working up a serious sweat a few hundred feet away, where a truckload of 8,600 pounds of La Crescent grapes from a Janesville, Minn., farm had arrived.

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Noah, a flame-haired 19-year-old, was wielding a hoe and using his free hand to help get those grapes into and through the crushing machine, a churning metal block that separated the stems (or most of them) from the crushed greenish sludge. The crushed grapes worked their way through a 4-inch-wide tube called the Anaconda, which, true to its name, snaked its way inside.

"That looks excellent," said Paul Quast, the winery's other owner, as Marier guided the neither-solid-nor-liquid substance into a huge metal tank. Next up: a full-court pressing.

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Manning the long, cylindrical pressing machine was Polognioli, the Argentinian operations manager who Hemstad calls "the shepherd of everything" at the winery.

Inside the machine, a horizontal "bladder" -- basically a tube hooked to an air compres- sor -- expanded to push the grapes against the machine's inner walls.

As Polognioli worked switches that inflated the bladder and rotated the machine one way, then the other, green juice -- called "must" -- began dripping into long pans beneath. The must was free of most of the sediment, but still far from clear.

Pressing one load takes an hour or so and produces about 125 gallons. "But cleaning the press takes multiple hours at the end of the day," Hemstad added. "This was not designed for easy cleaning."

The cleaning would come later -- workers were amid a 14-hour workday -- but in the meantime, the must had to travel to what is called simply the cold room. A very long tube transported the opaque juice around two corners into tanks, where the last of the gunk would settle down. "Every little bee antenna is going to be at the bottom of the tank," Hemstad noted.

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Two days later, the cleaner juice on top would be funneled into an adjacent room, where yeast would be added to begin the fermentation process. That's also where the sugar and pH levels would be checked and decisions on blending and tweaking the wines took place.

The fermentation room stays at about 65 degrees, 10 degrees warmer than the cold room in summer and exponentially so for a few weeks every winter, when it seriously lives up to its name. That's when the wines generally are "cold-stabilized," a process that eliminates tartrate "crystals" in the wine, which most Americans find off-putting, even though they are harmless.

"That's the one advantage we have over Napa," Hemstad quipped. "We can just open the doors, turn on the fan and get that room to 20 degrees pretty fast."

Bill Ward • 612-673-7643