Fermented is a nice way of saying rotten.
And many of our favourite foods are basically delicious decay. Every year, the average South Koreans eats 40 pounds of spicy, rotten cabbage, better known as kimchi. Booze is rotten fruits or grains. And your mother's delicious banana bread? Full of sludgy, decomposing bananas.
But the uncontested dark lord of fermented foods is surströmming, which unlike the aforementioned foods, does little to conceal its rancid, rotting state. It's a creation so foul that it has led to evictions, violation of EU food regulations, and is not allowed on most airlines.
And yet, for all of its notoriety, surströmming is beloved in Sweden, where it was once used to pay workers. But even in Sweden, the putrid smell of canned Baltic Sea herring can lead to security concerns.
For instance, earlier this week, rescue services in Stockholm were called to the scene of what many tenants thought was a potentially explosive gas leak.
"We received the alarm at 19:53 on Wednesday with residents reporting a weird smell in their apartment building, suspecting it might be some sort of a gas leak," Johanna Björnfot, a spokeswoman at the Fire and Rescue Services in Stockholm, told Swedish news site The Local.
"We responded to the call and alerted Stockholm Gas [about the possible leak], but when we got to the scene and started to investigate the smell, one of the residents informed us that they were eating fermented herring, which turned out to be the cause," she said.
Obviously, anything this smelly has serious potential for pranksters. And fears of the explosive qualities of surströmming are not totally unfounded.
Around this time last year, someone strapped a small bomb to a can of herring at Sweden's Uport music festival in Ulricehamn. No one was hurt, but the IED ended up blasting shrapnel and rotten fish all over festival grounds. "Outside there was a huge cloud of smoke and it reeked of gunpowder and fermented herring," festival general Sebastian Andersson told a local paper.
Like many fermented products, surströmming releases stinky gas as it rots, which may have been the root of the confusion here. In fact, this incident isn't even the first time that police have been called because of a surströmming-related gas scare. The Local also reported that in 2012, two fire trucks and two police cars ended up being called to another apartment in southern Stockholm "after anxious neighbours had reported a suspicious stench in the house."
So next time you decide to throw a surströmming and kimchi party in your apartment, do the right thing and tell your neighbours about it. You could also invite them over, but they probably won't come.