Stories about beer cans exploding have been doing the rounds over the past few months, particularly in the US, where some products now come with warnings that “refermentation may occur”.
It’s all part of a risky new trend in craft beer. As the obsession with fruity beers continues, some breweries have started adding puree after the brewing process has been completed to maximise fruit flavour. Like milk – which starts to bulge in the carton if kept out of the fridge for long – these particular kinds of fruit beers need to be kept cold or the sugar in the puree will restart fermentation, overcarbonating the beer and rupturing the can.
“Must remain cold at all times” is written on a can of beer made by New Jersey’s Magnify Brewery. The beer, which also comes with a “requires responsibility” warning, is a fruit gose called Trade Proof with a label of a ticking time bomb.
There's other, more unintended reasons, however, why a can of beer can explode. Philip Woodnutt, who runs a quality-control laboratory for Irish microbreweries as part of the Wicklow Hops Company in Newcastle, says the use of wild yeasts can expose breweries to infections. These unpredictable yeasts – like the one used for making Saison beer – can spread to other beers using the same canning or bottling line in a brewery, "waking up" after packaging and starting to referment beer, particularly if they're kept on a shelf instead of cold storage.
“Most of these beers don’t usually reach the consumer,” says Woodnutt, who adds that many Irish breweries are becoming more wise to the risks of wild yeasts. “Breweries have really improved their yeast-handling skills.”
Who knows if the new dangerously fruity beer styles will come to these shores from the US but it’s always a good idea to keep beers chilled and to check the best-before date – fresher is always better.
@ITbeerista beerista@irishtimes.com
