what is fermented herring

Fermented herring, also known as surströmming, is a traditional Swedish delicacy that has been enjoyed since at least the 16th century. It is made from Baltic Sea herring that is lightly salted and left to ferment for at least six months, giving it a strong smell and somewhat acidic taste. The fermentation process continues even after the fish is canned, resulting in a bulging tin of fermented herring. The aroma of surströmming is pungent, and the taste is rounded yet piquant with a distinct acidity. The fermentation originates from a lactic acid enzyme in the fishs spine. Surströmming is usually eaten outdoors due to its strong smell when opened. The official fermented herring premiere is on the third Thursday of August, but it is also enjoyed in late August until early September. Surströmming can be found in traditional restaurants in northern Sweden, particularly in the Ulvön islands in the High Coast, where it has been produced for over a hundred years.