Guinness has brewed its iconic stout for 256 years. But this week, the Irish beermaker announced a big change to its signature brew: by the end of 2016, the beer will no longer be made with isinglass, a gelatin-like substance made from dried fish bladders.
In other words, Guinness will be vegan.
"Isinglass has been used widely within the brewing industry as a means of filtration for decades," the brewery said in a statement. "However, because of its use we could not label Guinness as suitable for vegetarians and have been looking for an alternative solution for some time."
When you hold a commercial beer up against light, you typically won't see bits of yeast floating around in the glass. That's because of filtration; stray yeast wouldn't change the beer's flavor, it could add an ugly haziness to the brew. As K. Annabelle Smith reported for Smithsonian in 2013, most breweries uses systems to that filter beer quickly, so they can ship it out to store shelves and bars.
Wondering why Guinness doesn't have a fishy flavor? That's because the isinglass is strained out, along with the yeast, before the beer is bottled and seatled. The end product might technically be vegetarian, but trace amounts of isinglass may linger, making it off-limits for vegans and strict vegetarians, Liam Stack reports for The New York Times. "We are always happy to see another product become suitable for vegans, especially because this one is very iconic here in Ireland," Edmund Long, a spokesman for advocacy group Vegan Ireland, tells Stack. "It's one of the products you associate with Ireland."
As Smith reported, isinglass has been around since at least the end of the 18th century. First used by Russian glue makers, early experiments revealed that it could also make stale beer taste better. When isinglass was added to fresh beer, brewers discovered that yeast and other particulates would clump together at the bottom of the barrel, where it could be easily removed. Guinness has used isinglass to clarify its beer since at least the 19th century.
Though the Irish brewery has promised to replace isinglass with "a state-of-the-art filtration system," it's unclear what it will use instead, Alexandra Ossola reports for Popular Science. There are a few different tried-and-true ways of clarifying beer without using isinglass, such as tannic acids or a combination of chemical and physical filters like silica and diatomaceous earth. But so far, nobody has found a perfect replacement for isinglass. "Brewers use diatomaceous earth because it's a very good filtration system to take out very sticky stuff like yeast," biochemist and Cornell University food scientist Karl Siebert tells Ossola. "But it's pretty hard to come up with something that works as well as a gelatin or isinglass."
For now, thirsty Irish vegans will have to wait. According to Stack, Guinness doesn't expect to sell animal-free pints until the end of 2016.