Surströmming

Surströmming in a traditional preparation: served on flatbread with boiled potatoes and salad

Surströmming has been part of northern Swedish cuisine since at least the 16th century.

Fermented fish is an old staple in European cuisines. The oldest archeological findings of fish fermentation are 9,200 years old and from the south of today's Sweden.[5] More recent examples include garum, a fermented fish sauce made by the ancient Greeks and Romans, and Worcestershire sauce, which also has a fermented fish ingredient.

Preservation of fish through fermentation in a weak brine may have developed when brining was still expensive due to the cost of salt.[6] In modern times, the fish are initially marinated in a strong brine solution that draws out the blood, and then fermented in a weaker brine in barrels prior to canning.

The canning procedure, introduced in the 19th century, enabled the product to be marketed in shops and stored at home, whereas at one time the final stage would have been storage in large wooden barrels and smaller, one-litre kegs. Canning also enabled the product to be marketed farther south in Sweden.

The fermentation happens through autolysis and starts from a lactic acid enzyme in the spine of the fish. Together with bacteria, pungent smelling acids are formed, such as propionic acid, butyric acid and acetic acid. Hydrogen sulfide is also produced. The salt raises the osmotic pressure of the brine above the zone where bacteria responsible for rotting can thrive and prevents decomposition of proteins into oligopeptides and amino acids. Instead, the osmotic conditions enable Halanaerobium bacteria to thrive and decompose the fish glycogen into organic acids, making it sour (acidic).[7]

The herring are caught in April and May, when they are in prime condition and just about to spawn, and have not yet fattened. They are put into a strong brine for about 20 hours which draws out the blood, after which the heads are removed and the fish is gutted and put into a weaker brine solution. The barrels are placed in a temperature controlled room kept at 15–20 °C (59–68 °F). Canning takes place at the beginning of July and for five weeks thereafter. Ten days prior to the premiere the final product is distributed to wholesalers. The fermentation of the fish depends on a lactic acid enzyme in the spine that is activated if the conditions are right (temperature and brine concentration). The low temperature in Northern Sweden is one of the parameters that affects the character of the final product.

Prior to modern canning methods, surströmming was sold in wooden barrels for immediate consumption, as even the smaller one-litre kegs could leak.[8]

Fermentation continues in the can, causing it to bulge noticeably, which would usually be a sign of botulism or other food poisoning concern in non-fermented canned foods. Species of Halanaerobium bacteria are responsible for the in-can ripening. These bacteria produce carbon dioxide and a number of compounds that account for the unique odour: pungent (propionic acid), rotten-egg (hydrogen sulfide), rancid-butter (butyric acid), and vinegary (acetic acid).[7] Due to these gases, a thousand cans of surströmming exploded over a period of six hours during a fire at a Swedish warehouse in 2014.[9][10]

Surströmming is commonly sold in grocery stores all over Sweden.

Surströmming with potatoes and onion on buttered tunnbröd, served with cold milk

Swedes usually consume surströmming after the third Thursday of August, labeled as "Surströmming day", through early September.[11] Because of the strong smell, it is often eaten outdoors. The pressurized can is usually opened some distance away from the dining table and is often initially punctured while immersed in a bucket of water, or after tapping and angling it upwards at 45 degrees, to prevent the escaping gas from spraying any brine.

Surströmming comes both ungutted with just the heads removed and as fillets. Regarding the first version, the fish is gutted prior to eating, and the backbone and sometimes the skin are removed. Roe from strömming is commonly eaten along with the fish.

Surströmming is often eaten with tunnbröd, a thin, either soft or crispy bread (not to be confused with crispbread).[12] The use of tunnbröd originated in the High Coast area, where the tradition is to make a sandwich (known as a surströmmingsklämma) using two pieces of buttered hard tunnbröd. In addition to the fish, the two most common toppings are potatoes (either sliced or mashed, often almond potatoes) and finely diced red onion. Surströmming is also commonly eaten without bread together with the accompanying ingredients. To balance the strong flavour of the fish, Västerbotten cheese is sometimes added.[13]

In the southern part of Sweden, it is customary to use a variety of condiments such as diced red onion, gräddfil (fat fermented sour cream similar to smetana) or crème fraîche, chives, and sometimes even tomato and chopped dill.[14]

Surströmming is commonly served with snaps, light beers like pilsner or lager, svagdricka (a type of small beer), water, or cold milk. What to drink with surströmming is disputed among connoisseurs. Surströmming is usually served as the focus of a traditional festivity called a surströmmingsskiva.

Some people do not care for surströmming.[15] It is a food which is subject to strong passions, as is lutefisk.

German food critic and author Wolfgang Fassbender wrote that "the biggest challenge when eating surströmming is to vomit only after the first bite, as opposed to before".[16]

On 4 June 2005, the first surströmming museum in the world was opened in Skeppsmalen, 20 km (12 mi) south-east of Örnsköldsvik, a town at the northern end of the High Coast.[23] The name of the museum is "Fiskevistet" (translated to The Fish Encampment).

• List of delicacies
• Pickled herring – A traditional way of preserving herring

Other fermented fish dishes

• Cantonese salted fish
• Colatura di alici – typical sauce of Amalfi connected with garum
• Fesikh – Egyptian fermented fish
• Garum – fermented fish sauce popular in classical Rome
• Hákarl – Icelandic fermented shark
• Hongeo-hoe – Korean dish consisting of fermented skate
• Kusaya – Japanese fermented then dried fish
• Pla ra – Fermented fish and rice flour seasoning common throughout Southeast Asia
• Rakfisk – Norwegian fermented freshwater fish
• Shiokara – Japanese seafood fermented in highly salted viscera

Other strong-smelling foods

• Asafoetida – Indian spice; dried latex from the rhizome or root of several Ferula spp.
• Century egg – A Chinese egg product made by preserving eggs in a mixture of clay, ash, salt, quicklime, and rice hulls
• Durian – very pungent-smelling fruit from southeast Asia
• Kimchi – Traditional Korean side dish of salted and fermented vegetables
• Kiviak – fermented birds in seal skin from Greenland

• Ringblom, Fredrik and Westerlund, Örjan (2009) Surströmming: En handbok. Grenadine. ISBN 978-91-85329-81-6. (Swedish)

Wikimedia Commons has media related to Surströmming.

• Surströmming.se (in Swedish)