26 MAY / JUNE 2022 popularmechanics.co.za
W
E ALL KNOW THE SOUND: TSCHHHK
followed by a fizzy hiss. It’s the
sound of cracking open a crisp, cold
beer. But there’s another, much less
inviting sound you might have been
unlucky enough to hear: the loud
and definitive pop of an exploding
beer can. This explosive phenomenon gained notoriety in
2018 when cans of craft beer, often made with fruit, were
spontaneously erupting. In February 2021, one US craft
operation voluntarily recalled one of its sour ales for the
same reason. The good news is breweries go to great
lengths to ensure that these bad batches are the exception,
not the norm.
Whether it’s beer, seltzer, or soda, as carbonated
beverages warm up – from cold refrigeration to room
temperature and beyond – the carbon dioxide becomes
less soluble, leaving the liquid and moving to the air space
at the top of the can. Aluminium cans are built to withstand
this normally slight increase in pressure, but at excessive
carbonation levels, they’re likely to burst at the seams.
This becomes a problem with beers that are prone to
refermentation, a process in which yeast and microbes
continue to process sugars, expelling additional carbon
dioxide. It’s most common with increasingly popular
fruited or flavoured beers because they have both active
yeast and fermentable sugars.
‘It’s a constant balance between safety and flavour,’ says
Matthew Farber, creator and director of the Brewing
Science Certificate Program at Philadelphia’s University
of the Sciences. When brewers add fruit purees or extracts
just before canning, they’re feeding active yeast a ticking
time bomb.
Lucky for fans of fruit beers, breweries have several tools
at their disposal to prevent disaster. Cascade Brewing in
Portland, Oregon, is known for its barrel-aged sour ales.
‘Our sour beer programme is probably about 80 per cent
fruited,’ says Kevin Martin, Cascade’s director of brewery
operations. Fruits are added about three-fourths of the
way into the ageing process, giving sugars three to six
months to ferment. ‘You want to give the yeast enough
time to do that in the fermenter tank so that all those
fermentable sugars are gone by the time you put the beer
into a can or a keg,’ Farber adds.
Brewers, including home DIYers, have other options to
avoid a boom. Right before canning, they can filter out as
much yeast as possible using sterile filters or a prolonged
cold-conditioning stage, called cold crashing, in which the
beer is rapidly chilled and then held cold for a few days or
weeks so the yeast settles at the bottom of the tank. Then
they can siphon off the beer, or with the proper equipment,Some of
the trendiest
craft beers are
exploding. Huh?!
HOW YOUR WORLD WORKS
DRINKS
/ B Y C L A I R E P O R T E R /