Rotten fish? It's a delicacy

It has been banned by airlines as an offensive weapon, its smells like a gas leak and it is Swedish schoolchildren's favourite way to cause classroom chaos. Yet thousands of Swedes regard it as a culinary delicacy. Emy Gelb reaches for a clothespin and takes a look at the famous Swedish "rotten herring" - surströmming.

• Sweden sells toxic Baltic salmon to EU: report (8 May 13)
• Abba - The Museum opens in Stockholm (7 May 13)
• VIDEO: Mamma Mia like you've never seen before (6 May 13)

Surstömming is a Swedish oddity. Its aroma - or more accurately, odour - is so pungent that it is banned from many Swedish apartment blocks, yet it is considered such an important cultural phenomenon that a society has been established dedicated to protecting its future.

Surstömming is a very special dish from northern Sweden and roughly translates into "sour herring." It's often described in English as rotten herring, although it is actually fermented. The fish was first used by Swedish troops in the 17th and 18th century, when they needed non-perishable food that would last for long marches.

The Baltic fish is caught in the May and June, fermented for one to two months, then tinned. Inside the tin, the fermentation process continues. After 6 months to a year, the fish releases a variety of gases that make the can bulge in weird and bizarre ways.

For many, surströmming is known as one of the most offensive delicacies in the world, rivaling other objectionable treats like southeast Asia's durian fruit or Norway's lutefisk. The foul odour comes from a cocktail of different bacteria that produce carbon dioxide and numerous other compounds. These conspire to create a smell similar to rotten eggs mixed with rancid butter and vinegar. A website dedicated to odd foodstuffs describes the delicacy as "the foulest-smelling food you can ever imagine."

Late August is the traditional period for Swedes to eat surströmming. Ruben Madsen, the President of the Surströmming Academy, explains that the classic way to serve the fish is on thin, crisp bread, with 6 slices of potatoes, each topped with a small piece of surstömming, red onions, sour cream, dill, and tomatoes. Older generations say that milk, snaps, and Wisby Weiss beer is the best way to wash the taste down while the younger ones claim that a dry rose or a dark rum is what truly complements the fish.

While it is generally recommended to eat the fish outside, Madsen claims you can eat it inside too. However, he suggests, “if you live in a big apartment building, put up a sign saying that you are having a surströmming party, just so the neighbors know that it’s not a gas leak or anything.” He adds that cooler temperatures also help to curb the smell, so in order to limit intensity of the odor it is best to open the fish in cold water or in the freezer.

In 2006, several major airlines including Air France, KLM, and British Airways, banned Surstömming from their planes, claiming that the swollen cans are potentially explosive. Swedish producers rebutted by calling the airlines “culturally illiterate,” arguing that it is solely a myth that tins are dangerous. Madsen said the claims were outrageous.

"It is a family meal, how could that possibly be a terrorist weapon? Can you believe something so crazy? I find it humorous they think that a meal could explode"

Unfortunately, he still doesn’t think that Arlanda will start selling the fish again anytime soon.

While not a terrorist weapon, surströmming is still a force to be reckoned with. According to urban legend, school children have been opening tins of the pungent fish to get out of class for decades. Madsen confirms the myth, saying that stink bombs disrupt around 25 schools a year.