The wine world owns the concept of terroir, which refers to the influence that particular climates or soil types have on the grape crop, making the same varietal taste very different depending on where it is grown. But beer is a more complicated beverage, with roughly twice the number of ingredients, and that makes local idiosyncrasies easier to iron out, especially in a modern, technologically advanced brewhouse. Still, something very like the notion of terroir had an enormous influence on the development of beer styles around the world, and this is a good month to tell that story.

If you order a pint on St. Patrick’s Day, there’s a decent chance that the beer in your glass will have been dyed green. But there are two very good reasons to fight this trend. For one thing, who wants to drink a beer that looks like it has been inoculated with algae? But more importantly, if you want to raise a pint in honor of Ireland, the more logical beer color is black. It’s surely not news to you that Ireland is known for its stouts—Guinness or Murphy’s, depending on whether you are near Dublin or Cork, respectively—but what is less widely appreciated is why that is. The answer, it turns out, is terroir.

Like us, beer is mostly water. But I’m not talking about pure H2O here. The water that serves as the base for every batch of beer is typically more chemically complicated than that, harboring minerals and other compounds that help to promote yeast health and enzymatic activity. These days, breweries can strip their tap water of its naturally occurring minerals and start with a blank slate, but it wasn’t always so. Hundreds of years ago, breweries had to work with their local water supply as it was au naturel, and adapt the rest of their recipe to make things work out.

Historically, the water in Dublin was chock-full of minerals, and for various complicated chemical reasons, the presence of those minerals will ruin a beer if they aren’t bal-anced out in some way. Also, again for various complicated chemical reasons, it turns out that heavily roasted barley is exactly the sort of thing that will balance out the effect of those minerals. And, of course, it’s the use of heavily roasted barley that makes a stout black. So, to make a boring story short: they started brewing stouts in Dublin because, well, they had to.

At the other historical extreme was the city of Plzen, in what is today the Czech Republic. This city is the namesake for the style of beer called “pilsner”—which, as you probably know, is one of the most delicate and lightly-colored styles. Again, this isn’t an accident. The water in Plzen is more or less the opposite, minerally speaking, of the water in Dublin. And the lack of minerals threatens to ruin a dark beer. So the Bohemians brewed lightly-colored beer because, well, they had to.

So, this March 17, if you are looking for something to pair with your shepherd’s pie and soda bread, respect the terroir of Irish beer and opt for black instead of green. My favorite local Irish stout is Menace Brewing’s brilliantly-named Muinness Draught. At under 4 percent alcohol content, and served out of a creamy nitro tap, you’ll want more than one. Sláinte!

Check out Neal’s January article on Dark Beer by clicking here!

"But beer is a more complicated beverage, with roughly twice the number of ingredients..."