NEW YORK (MainStreet) – The folks at Boston Beer really want you to try a sour beer, but they're far from the only large U.S. brewer making the attempt.

At the 2014 Beer Bloggers Conference in San Diego back in August, Boston Beer's Samuel Adams brand debuted its Samuel Adams Kosmic Mother Funk Grand Cru. It's a unique Belgian ale that was aged in Hungarian oak vessels for more than a year and fermented with wild yeast from the barrel room at the company's test brewery in Boston built little more than two years ago.

It's on a dozen-city tour through November, has a tartness commonly described as “sour” and is anchoring a line of similarly brewed and aged Belgian style beers that Boston Beer has dubbed the Barrel Room Collection. Why would the largest U.S.-based brewer — a brewer that generated $790 million in revenue and 3.4 million barrels of beer last year — dedicate so much effort to a nice product? Because other big, U.S.-based competition is already doing so.

New Belgium Brewing in Fort Collins, Colo., produced 792,000 barrels of beer in 2013, making it the fourth-largest U.S.-based brewer behind only Boston Beer, D.G. Yuengling & Sons and Sierra Nevada. The brewery itself was launched in 1991 after co-founder and Chief Executive Kim Jordan and her ex-husband took a bike trip across Belgium and became enamored of the wood-aged, bacteria-infused Belgian style of brewing. Its year-round offerings include Belgian-style Dubbel and Trippel long-fermentation ales, while its limited-release lineup has an entire section dedicated to wood-aged “sours” including its La Folie sour brown ale (a take on a Belgian Flanders Red), its Transatlantique Kriek cherry lambic and its Le Terrior dry-hopped sour ale.

By the end of next year, it will open a second brewery in Asheville, N.C., that should not only more than double the company's overall brewing capacity, but open up markets New Belgium hasn't reached in the Northeast, including Boston Beer's stronghold in Massachusetts. It's in a position not only to push Boston Beer, but also to test it with styles Boston Beer doesn't produce.

During the first six months of 2014, SymphonyIRI notes that sales of Boston Beer company beer and cider in stores were roughly $167.6 million. New Belgium's sales were only $61 million then, but rose 41.2% during the first half of 2014 from the same period a year ago. That outpaced Boston Beer's 31.5% growth over the same stretch and did so at less than a quarter of Boston Beer's production capacity.

There is also mounting pressure from Belgium itself. According to the Washington, D.C.-based Beer Institute industry group, imports of Belgian beers to the U.S. were up 33.6% through July to 1.8 million barrels. That put them ahead of Canadian beer imports for the first time and made Belgium the No. 3 source of U.S. imports behind only The Netherlands (roughly 5 million barrels) and Mexico (more than 14 million).

The Belgians are making their presence felt on U.S. soil as well. Belgian family brewery Duvel Moortgat has owned Cooperstown, N.Y.-based Brewery Ommegang since 2003 and has helped it produce not only its Witte witbier and Rare Vos Belgian amber, but also its Zuur and Rouge sour Flemish reds. In the first six months of 2014, its Belgian style red ale Fire & Blood from its HBO Game Of Thrones series was the sixth best-selling new craft beer brand in the country.

Last year, Duvel bought Kansas City, Mo.-based Boulevard Brewing for upward of $100 million to become the 14th-largest beer company in the U.S., making its U.S. presence roughly the same size as Galesburg, Mich.-based Bell's Brewery and larger than either New York's Brooklyn Brewery, San Diego's Stone Brewing or Boston's Harpoon Brewing. Boulevard has regularly produced Belgian-style ales such as its Love Child wild yeast beers and its Tank 7 farmhouse ale, but now has motivation to make more.

The biggest and most threatening Belgian push, however, is coming from big brewers such as Anheuser-Busch InBev and SABMiller/MolsonCoors joint venture MillerCoors. MillerCoors' Blue Moon series of Belgian-style wheat beers celebrates its 20th anniversary next year and sold more than 2 million barrels of beer in 2013. According to Moody's, that's enough to give Blue Moon a nearly 9% share of the overall craft beer market. In the first six months of 2014, SymphonyIRI notes that Blue Moon Belgian White was the 15th best-selling beer brand in the U.S., with sales up 2.7% from the same time last year.

Meanwhile, Anheuser-Busch InBev not only imports Belgian lager Stella Artois — the 14th best-selling brand with a 9.4% jump in sales in the first half of 2014 -- but its Chicago-based Goose Island brand has a full slate of barrel-aged Belgian-style varieties. Its Matlida Trappist-style Belgian Pale Ale, Lolita raspberry Framboise, Juliet sour wild yeast ale and Madam Rose Flanders brown are still limited releases, but have given A-B InBev a degree of loyalty among appreciators of the style. As a result, Goose Island production nearly doubled from its acquisition by A-B InBev in 2011 to last year.

In fact, SymphonyIRI notes that styles specifically identified as Belgian (Belgian Dark Strong, Belgian Witbier, Belgian Ale "other," Saison, Belgian Golden Strong Ale) accounted for 13.1% of all craft beer sold in the first six months of 2014. That's a bigger share than either pale lager (12.6%) or pale ale (11.2%) and trails only India Pale Ale (18.6% for the craft lead). With Belgian styles accounting for at least some portion of the 8.2% of craft beer identified as “seasonal/other,” Belgian-style beers may have an even greater share of the market than the identified Belgian styles indicate.

Boston Beer and Samuel Adams aren't trying to force Belgian styles and sour beers onto an unsuspecting beer-drinking public: They're just giving a large segment of those drinkers something they increasingly want. If anything, Samuel Adams is catching up with U.S. craft brewers in their race to the Belgian-style barrel room.

— Written by Jason Notte for MainStreet.

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