401: Superior Stouts and Standout Sours With Louisville’s Atrium

Feb 22, 2025

Mark Rubenstein, cofounder of Atrium Brewing, and head brewer Spencer Guy dive into the art of brewing. They explore the success of their award-winning barrel-aged stout, discussing innovative techniques like reiterated mashing for sweeter stouts. The duo elaborates on blending bourbon and brandy barrels for complexity and crafting flavor-forward fruited sours, incorporating unique ingredients such as yogurt powder. Their passion for experimentation shines through as they share insights on brewing lagers and pilsners alongside their specialty beers.

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ANECDOTE

From Wales Trip To Brewery Founder

Mark fell into brewing after an archaeology trip to Wales and a homebrew kit that set his stove on fire.
He later worked at University of Louisville, retired, and co-founded Atrium with Princeton Hearst.

ANECDOTE

Early Homebrew To Head Brewer

Spencer started as a homebrewer, ran beer events, then became a head brewer in his early twenties.
He joined Atrium months before opening to develop recipes and get equipment online.

ADVICE

Brew To Let Adjuncts Shine

Build stout recipes to showcase the intended adjunct, not to compete with it.
Brew lower roast and lower IBUs when you want coffee or cacao to be the star.

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In our latest issue, Louisville’s Atrium Brewing scored a category-leading 98 for their barrel-aged stout Denny-Lou, Blend 1, and that was as good a reason as any to check in with cofounder Mark Rubenstein and head brewer Spencer Guy for some background on brewing stouts. Their proximity to some of the best distillers in the Western hemisphere informs their approach to both aging and blending, and they take the same iterative approach to building flavor in more ingredient-laden beers.

In this episode, they touch on:

brewing flavored imperial stout as well as barrel-aged stout
using a reiterated mash in lieu of longer boils for higher starting gravity
building lower color stout with very low bitterness to let coffee shine
balancing sweetness with tannins in barrel-aged stout
blending with multiple stout threads
the impacts of brandy and bourbon barrels
kettle souring with a hazy IPA grain bill
using probiotic beverages for kettle souring
adjusting acids in the brite tank for proper fruit expression
choosing fruit formats for clarity and quality
spinning tanks then bench testing between each ingredient addition to confirm quantities with sensory
constructing fruit blends and highlighting with yogurt

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