People across different cultures have been using food preservation methods for centuries. But few preserved food can be quite as "stinky" as the fermented sour herring, also known as Surstromming in Swedish. Marked with a pungent flavor and the swollen appearance of its containers, Surstromming is considered a traditional delicacy in north Sweden.
To prepare Surstromming, salted herrings are placed in barrels and then airtight cans for fermentation. Due to the lack of oxygen and presence of high salt content, anaerobic halophile microbes play an important role in the fermentation process. Halophiles (meaning "salt-loving" in greek) are microorganisms that thrive in a highly salty environment. These bacteria turn the glycogen in fishbone into organic acids such as propionic acid, butyric acid, and acetic acid, causing the fish smell and taste sour. Just how bad can the smell be? Take one of the decomposition product, butyric acid, for example, it makes up the smell of human vomit. Therefore, it really takes some serious (acquired) taste to appreciate this scandinavian dish.
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