Fermented herring is a Scandinavian delicacy. It could be indelicately described as rotten fish, but you should not say that in Sweden, where it is prized. Surströmming is kept in cans and served at parties specifically arranged for eating it. Such an event is called a surströmmingsskiva.
Fermented herring is most popular in Sweden, but it is eaten occasionally in Norway. Cans of it may, if left too long, swell as the fish ferment. This caused a problem in a rural home in northern Norway, where a can dating back to 1990 was wedged in the rafters. The can has swelled so much that it’s lifting up the roof.
The owners would like to remove the can, but are afraid that if they mishandle it, the can will explode, sending bits of the notoriously noxious food everywhere. So they called in Ruben Madsen, an expert on the disarming of surströmming. Madsen assured the homeowners that the danger was slight. The Local reports:
Despite initial fears expressed by Haugen and others, surströmming expert Madsen said the aging can of herring poses no danger to the public.
"There really isn't any risk for an explosion. Of course, some fermented herring might come spurting out when we open it. And yes, it will smell," he said. […]
Madsen explained that he gets "two or three calls a year" from people who have found old cans of fermented herring and don't know what to do with them.
However, the discovery of the can in Norway has the fermented herring aficionado's mouth watering at the prospect of tasting surströmming that's been aged to perfection over the past 25 years.
"I have my own collection of vintage surströmming with several cans that are more than 15 years old," he said.
"The taste certainly gets richer with age. The longer you wait to open a can, the more complex the flora of tastes you get."
-via David Thompson