|If roasted barley gives Guinness its dark color and nitrogen bubbles give it a frothy head and light texture, what could possibly prevent anyone from making it the pint of choice this St. Patrick's Day?
The swim bladders from fish, which is why vegans and vegetarians probably shouldn't be among those knocking back one of the more than 3 million pints that Guinness parent Diageo (DEO) estimates Americans will consume during the holiday. It's an unpleasant surprise for The Huffington Post and beer lovers who try to avoid brews made with animal products like gelatin, but it's been a part of Guinness' brewing process since the 1800s.
The swim bladders -- commonly known as isinglass -- help a fish swim and remain buoyant in water, but they also help brewers clear floaters and other particles out of their beer. The isinglass is quickly removed by brewers once it's done its job, but its use and the off chance that trace amounts of it can end up in beer make Guinness off limits for vegans and vegetarians.
While isinglass doesn't appear on Guinness' list of ingredients -- it's more of a filter than a component -- Guinness hasn't exactly been shy about discussing its use when asked. The company told vegan booze site Barnivore flat out in 2011 that a different Guinness product, Guinness Black Lager, "is not suitable for vegans." In another email to the site in 2012, it explained that isinglass is still part of the filtering process -- known as fining in brewing circles -- and that it has struggled to find "any alternative that is as effective or environmentally friendly as isinglass."
The problem is that many of the products used for this purpose are similarly animal-based. The gelatin used by other beer and wine producers in their fining process is also an animal byproduct often derived from bones. Oyster stouts, meanwhile, both clarify the beer by filtering it through oysters at the bottom of the conditioning tank and sweeten it by using the oysters themselves as ingredients.
There are chemical alternatives, but brewers are somewhat hesitant to use them because they're just a bit detrimental to the environment once they've been removed. When they're not filtered out properly, however, they're extremely risky for humans.
That said, both Barnivore and PETA list a whole lot of brewers that use non-animal alternatives or more time-consuming filtering processes to make vegetarian- and vegan-friendly beers. Guinness, it turns out, has had far worse animal accusations thrown its way.
A common urban legend about Guinness claims that, sometime in the early 20th century before Diageo bought the Dublin-based brewer, brewmasters had drained the tanks for cleaning and found the bones of dead rats at the bottom. Putting aside the fact that beer tanks of that size are usually steel behemoths sealed tighter than the Federal Reserve, the story alleged that it was the rats that gave Guinness its distinct flavor.
Boston Celtic punk band The Dropkick Murphys did little to dispel that myth when it teamed with Shane MacGowan, lead singer of The Pogues, in 2001 for an ode to the storied brewhouse vermin called "Good Rats."
While Guinness has never addressed the tale directly, a brewer's toughest job is to keep its process as free of contaminants as possible. Rats don't help in that regard, but fish bladders do -- even if they filter out a portion on the beer-buying base as a result.