× Expand Robin Shepard O'so Brewing Company of Plover is in the midst of expanding its barrel-aging program.

Change is in the air at O'so Brewing. The Plover-based brewery has started producing a new line of sour beers, and is giving more attention to its barrel-aging program. Plus, O'so just recently hired a new head brewer. So there's a lot of inspiration for Winds of Change, one in the brewery's new series of sour beers.

What is it? Winds of Change from O'so Brewing of Plover, Wisconsin.

Style: The base beer in Winds of Change is a standard American pale ale (APA). The style is medium-bodied and known for its firm, medium- to high hop bitterness in flavor and aroma. APAs feature American hop varieties with assertive citrus or resiny character. They range from 4.5% to 5.5% ABV. Winds of Change is a departure from the typical pale ale because it is made, in part, with wild yeast for a sour edge.

Background: Winds of Change is part of a new project that O'so Brewing started last summer. "I wanted to put something out there to let people know we are exploring different directions. This beer signifies the change we're going through," says brewery owner Marc Buttera.

Winds of Change is more complex than most American pale ales because it is intentionally soured with Brettanomyces, a wild yeast strain that lends an earthy, sour and tart character to beer. Brettanomyces is more commonly associated with beer styles like Belgian Lambics and Flanders red ales. Part of the beer was made like an APA, with West Coast hops and ale yeast, to which the Brettanomyces was added. It was then aged in oak barrels. A second batch was fermented just with the wild yeast and aged in stainless-steel fermenters. After six months, the two batches were mixed together and then dry-hopped with German Tettnanger hops. "We used a lot in the dry hopping, about one pound per barrel. It's really in your face," says Buttera.

The sour and tart qualities of the wild yeast really stand out in Winds of Change. Buttera describes it as "more funky than sour," a reference to the off-flavors imparted by the wild yeast and bacteria, which are accentuated during the aging process.

Winds of Change finishes at 6.1% ABV, with about 45 IBUs. It's sold in single 750 mL bottles for around $12-$13/each. O'so released only 4,000 bottles; look for it in the larger or more specialized beer stores.

O'so Brewing has recently been expanding its barrel-aging program, and is also making Lambic-style sour beers in collaboration with Funk Factory Geuzeria, a project started by Levi Funk of Madison. Funk is a home brewer who became captivated by Lambics and beers made with open (to the air) fermentation, so he designed a portable coolship that is being used by O'so to make sour beers.

A coolship is a shallow stainless-steel tank that is filled with wort and left outside, often overnight, to expose the liquid to wild yeasts in the surrounding air. Currently, O'so is storing the coolship at Central Waters Brewing in Amherst and moving it to Plover when needed. So far, Buttera and Funk have collaborated on one beer in the coolship, conducted over the last weekend in January, but they hope to make others in the months ahead.

Along with Winds of Change, O'so other new sour and Lambic-style offerings include: Scarlett Letter, a sour blonde ale made with cranberries; Sikaru, a brew based on ancient recipes of Sumerians that is made with dates; and Dweller on the Threshold, a sour beer aged in French oak barrels for 18 months. All were offered in very limited quantities (only about 400 bottles each) for sale in the O'so taproom. Sour beers are growing in popularity, and multiple Wisconsin breweries are expanding their production of the style.

"This is a good [market niche] for us," explains Buttera. "There are people who are passionate about the sours, the funky beers and hops. I want to be known as offering some of the best of those."

In another surprise change, Steve Buszka joined O'so as its brewmaster in early February. Buszka has been brewmaster at Potosi Brewing since 2009. Prior to that he served as head brewer for Bell's Brewery in Kalamazoo, Michigan.

"I'm really excited about all the barrel-aging and sour beer," says Buszka. "I've always wanted to break out in the wilder styles, so it will be a learning experience for me." It's a little early to know which beer Buszka will put his signature on first, but expect something surprising for the brewery's next one-off.

Meanwhile, Buttera says his next 750 mL bottle release is a beer named Convenient Distraction. It's a version of Night Train (porter), made with coffee and vanilla beans, and finishes at nearly 10.5% ABV. Look for it in April. Later in the year, Buttera is also planning to release a coconut porter aged in rum barrels, and he'll be bring back Goldilocks' Revenge, an imperial stout aged in brandy barrels. O'so's 2014 summer seasonal will be Picnic Ants Farmhouse Ale, a Belgian saison that rotates with other summer brews and only appears every few years.

Tasting notes:

Aroma: Assertive floral earthy-sourness that lets you know that you're about to drink a beer fermented with Brettanomyces.

Appearance: Bright hazy orange-copper color. A bubbly tan head.

Texture: Bubbly, sharp and dry. Medium-bodied.

Taste: The fruity lemon-sourness, most likely from a combination of the Brettanomyces and the heavy dry hopping, comes in early and sticks around. The bitterness of hops is more in the background and finish.

Finish/Aftertaste: A pronounced dryness; however, it doesn't linger long.

Glassware: This will be appreciated in a medium-sized chalice-style glass, one with a slight inward taper to the lip to focus the aromas while showing off the brilliant orange-copper color. Find one with a long enough stem to keep your hands away from the bowl of the glass to maintain a cool temperature, which accentuates the crisp sour-tartness.

Pairs well with: As a pre-meal beer, the sour-tart flavors in Winds of Change will sharpen the palate and stimulate the appetite. It's a little tricky to pair with entrees because anything with hearty flavor will make you lose some of the dry hoppiness in the finish, which is what I enjoyed most about this beer. However, an aged brie is a good choice for a cheese companion.

Rating: Two Bottle Openers (out of four)

The Consensus: 81 (good) at BeerAdvocate and not enough ratings to be evaluated at RateBeer.

The Verdict: Winds of Change is indeed a funky beer -- perhaps a little too funky. The earthy tones and lemon tartness are memorable. The light dry finish leaves an impression much like a crisp summer saison, only with a lot more sour character. There is a faint oakiness in the finish that complements the dry, hoppy ending. This is a fun beer to try, especially for those looking for something new. But at $13/bottle, the fun (and funk) for me goes only so far. I admit I'm a little hard on the Brett-hop combo because I don't find it pleasant, especially when the sour competes to win. Yes, it's interesting, and I enjoyed trying it. But it's not a beer I'll return to very soon. However, sour-funky beer fans will likely find redeeming value in it.

I wished the flavors focused more on the beer's pale ale roots and used the sour as more of an accent. Winds of Change is an intriguing beer from O'so. Now that Buttera has Steve Buszka on board to complement his other brewers, it will be fun to see where those winds take O'so.