Scattered elsewhere around his house are half a dozen carboys, filled with various experiments, including a tart stout with blackberries and Cape Cod beach plums, two dark, funky saisons, and a Galaxy dry-hopped sour cider. Also kicking around are a few hundred bottles of previous beers from batches brewed as far back as 2006. “I’m a nut,” says Tonsmeire.

In a temperature-controlled basement room in his residence outside Washington, D.C., are two full-size wooden barrels, one that previously held red wine, the other apple brandy. Each is capable of holding 50 to 60 gallons of whatever brew Tonsmeire is aging at the moment.


He’s also really knowledgeable. An economist by day, the Wayland native spent four years letting his passion for sour beers bleed onto the page of his blog, The Mad Fermentationist (www.themadfermentationist.com). He recently published a book, “American Sour Beers,” detailing the complicated biology behind a segment of brews transitioning from geeky to mainstream.

Created by the use of specific yeast strains, sour beers encompass a variety of old beer styles that are traditionally acidic, as well as newer variations.

Not exactly a quick read, “American Sour Beers,” which came out last year, is a deep dive into the history of sour brews (sours were made across the centuries in several countries) and a detailed primer on how to brew your own. Over nearly 400 pages, Tonsmeire acts as both enthusiast and mentor, providing a reference guide for anyone who’s ever liked a barrel-aged beer and wondered if they could brew one themselves. “When I started brewing sour beers, there were very few resources like this book,” writes Vinnie Cilurzo, founder of Russian River Brewing Co., in the forward.

Tonsmeire says he applied to dozens of brewing jobs when he graduated from college, earning only one low-level offer. “Looking at the pay, benefits, and what the work would consist of, I decided I’d rather have a desk job and a cool hobby,” says Tonsmeire. “That was the best thing that could have happened to me.”


Through furious bouts of home-brewing, Tonsmeire increased his knowledge to the point where he felt that writing a book could help others. “American Sour Beers” is geared for people who can already brew clean, consistent batches of beer. Tonsmeire outlines his own methods, as well as those of noted sour beer breweries like The Lost Abbey and Jolly Pumpkin.

To understand sour beer, you need to understand yeast. In that realm, Tonsmeire shows off, describing the flavors various yeast and bacteria impart to different brews. Despite the living, and sometimes unpredictable, nature of these microflora, Tonsmeire outlines methods to keep brewers fully in control.

He also encourages trying new things. “I advocate that home-brewers take a recipe that they are already comfortable with, something not too hoppy, dark, or high alcohol, and pitch extra microbes to convert it into a sour beer,” says Tonsmeire.

Both Tonsmeire and Cilurzo acknowledge that American brewers of sour beer have a long way to go to catch up to their European counterparts. A book that celebrates the brews certainly helps.

Gary Dzen can be reached at gary.dzen@globe.com.