Granite City brews with 'Fermentus Interruptus' process

Melody Baetens
The Detroit News
R.J. Nab, Granite City's director of field brewery operations, talks about the patented "Fermentus Interruptus" brewing process Friday, February 5, 2016. The brewery opens in the Renaissance Center Wednesday.

When Granite City Food & Brewery opens its first Detroit location in the Renaissance Center Wednesday, diners will be able to see large fermentation tanks from the dining area and signature and seasonal Granite City beer will be available on draft and in take-home growlers.

While “brewery” is in the name, much of Granite City’s beer-making process is actually done out of state at a brewing house in Iowa. We spoke to the director of field brewery operations RJ Nab about this patented “Fermentus Interruptus” process and why it’s used.

“We’re an all-malt brewery; we have the same process as most every other brewery,” says Nab.

Where Granite City’s process differs, he says, is between the whirlpool phase, when the product is clarified and cooled, and the fermentation process. Before it’s fermented and turned into alcohol, the beer, or wort, is cooled to a safe storage temperature of about 38 degrees and is then driven in 18-wheeler trucks to the 35 Granite City locations “on an as-needed basis.”

“The reason we did this is, as we started growing the company in 1999, after three locations they realized the start-up costs (and that) we could save a lot on transferring our wort, our beer,” says Nab. “They really didn’t know how to do that and keep it consistent. You gotta keg it, you have to preserve it, go through distributors, the middle man, markups, all of the above, not to mention taxes and such.”

Because the wort hasn’t fermented yet and is not yet alcohol, the legalities of distributing alcohol across state lines do not apply. Nab also says that because all the Granite City beer uses the same source for the starting ingredients – yeast and water – it allows for uniformity in taste.

“We have our own yeast propagation system, we’re creating our own yeast strains, we have our own lager strain, our own ale strain, we have our own Belgian strain, we have our own German hefewizen strain … for the quality and consistency for the style of beer we’re trying to brew,” he says.

“It gives us consistency across the board with no preservatives needed, no middle man, we’re shipping the flavored water, wort, across state lines to ourselves, not shipping it through distributors. It’s not alcohol. So we get consistency across the board with our all malt beers and the cost savings up front. To build a brewhouse in every location is not cheap.”

Nab says the savings in not building a brewing house in every location allows them to spend more money on premium ingredients.

Nab, who started at Granite City as a bartender at a Kansas City location, has been at the Detroit site for about six months, since construction started. He says one of his favorite things about his job is training the staff about beer and the patented brew process, and he can see that Michigan workers are already familiar with craft beer.

“It’s really night and day different from a lot of the states where we’ve opened because the knowledge the staff already has about craft beer is awesome,” he says.

“They’re teaching me stuff about craft beer. It’s so much fun to train here in Michigan because they take their craft beer seriously and that’s what we want to be a part of because we do the same.”