Up until just two years ago, Summerfest offered something very unique at a few of the beer stands on the grounds.

If you looked hard enough, you could find special red and white wine coolers, with the closely-guarded secret ingredients, that were made just for the Big Gig … and the mix came together by accident.

However, Summerfest has since changed its vendor for the iconic wine coolers, and they taste nothing like the 1976-vintage anymore. Now they’re bright pink and sweet, like something you could find a liquor store. Back in the day, they were still dark red and white, and not sweet at all – and I asked the people in charge of the beverages at the festival what made them so special.

In 2008, then director of concessions, Tracy Spoerl, told me the wine cooler origin story. "It was handmade at the bar, and it was a last-minute thought. We said, 'Let's try it.'"

Linda Pankau, Summerfest's now Marketplace Manager, also remembers the early days – though she was just a kid helping out back then – when the wine coolers were invented at the old comedy stage (which is now the Potawatomi stage).

"Early on, it was messy," said Pankau in ‘08. "It was a lot of fun, but making them was time-consuming."

Spoerl said the first wine cooler ingredient list contained just soda and wine, but they sold surprisingly well. Soon, they added Welch's grape juice to sweeten up the recipe.

"We received such a high demand for them, that the next year, they couldn't keep up, so they made them in five gallon containers," she said.

For those first couple of attempts, the wine coolers were a little inconsistent: sweeter or stronger, depending on the batch that day. "In the early years, quality control wasn't there."

Spoerl said the operation was "very rudimentary" in the beginning but got sophisticated quickly. Her team worked with Pepsi to develop a machine that pumped full containers of Teem – a Pepsi brand white soda– into vats, where they could add the wine mix, then pump the product back into containers for serving.

Eventually, Summerfest found a way to replicate the taste of the original wine coolers – but with consistency and at a much higher volume.

"We tried to find a wine product that had a high sugar content, and that turned out to be port," said Spoerl, who started working part-time at a Summerfest wine tent in 1977 and became full-time the next year. "We experimented until we found the right one."

Spoerl didn’t reveal the exact ingredients, but she said the red wine coolers still used port at the time of their discontinuation. That wine provided a good shelf life, as well as a unique taste: "Not too sweet, but popular."

"Only four or five of us know the secret," said Pankau. "Not even my children or husband. I had it written down, and it had to be thrown away."

Summerfest doesn't disclose total beverage sales, but their wine coolers make up a small percentage of alcohol purchases – and perhaps that’s why they finally ditched the recipe last year. Summerfest did tell me, however, that they evaluate their beverage choices annually, so maybe these "homemade" drinks aren’t gone forever.

At the time, Spoerl told me that while she believed the Big Gig is the only festival in the country that produced its own wine coolers, "but there's no way to know that certain." And sales were split evenly between red and white wine varieties. "They pretty much go neck and neck," said Spoerl. "When temperatures go up, the sales go up. It's a more refreshing drink to some, than beer."

For years, it was the only alcoholic alternative to beer. In 2000, the festival added champagne, and more recently, began serving actual wine.

Summerfest had contemplated selling its wine coolers in liquor stores, but it was an idea that hasn't been pursued.

"It's special because it's only available at Summerfest, and (selling in stores) could take away its allure," she said.

Pankau, who said she drank one or two white wine coolers during the festival – for tradition's sake – agreed.

"We (made) it with tender-loving care, and it's a drink for 11 days ... then it's gone."

Sadly, for "connoisseurs" of the special drink, it’s now gone again – but hopefully not for good.