The sometimes-overlooked truth about beer styles is this: They’re always in motion. Fashions change, technology evolves, wars strike, and those styles that survive always end up transforming in the process. There may be no better example than the Irish stout, a 4 percent ABV session beer now engineered to be drunk in threes and fours down at the pub.
This stout is marked by a silkiness that comes from the special nitrogenated dispense system invented for it and has a classically roasty character. But start traveling backward in time, and this ubiquitous beer—the only style besides pale lager found everywhere (usually in Irish pubs)—becomes by increments more and more unrecognizable.
A Porter by any Other Name
The original Irish stouts came from London about 300 years ago, and they were called porter. Their hallmark character came from a particular ingredient known as brown malt—the lowest, roughest grade. It was kilned in such a way that sudden heat caused it to explode like popcorn, and that gave it a burned, acrid flavor—a “smoaky tang” as William Ellis described it in 1736. Brewers hadn’t yet invented sparging and instead drew off successive worts (or “gyles”) from the mash. In other styles, brewers would blend these to produce beers of different strengths; for those early porters, all the gyles were blended back into one “entire” beer.