During the production of surströmming, just enoughsalt is used to prevent the raw herring fromrotting while allowing it toferment. Afermentation process of at least six months gives the fish its characteristic strong smell and somewhat acidic taste.[2] A newly opened can of surströmming has one of the mostputrid food smells in the world, even stronger than similarly fermented fish dishes such as theKoreanhongeo-hoe, theJapanesekusaya or theIcelandichákarl, making surströmming anacquired taste.[3]
At the end of the 1940s, surströmming producers in Sweden lobbied for aroyal ordinance (Swedish:förordning) that would prevent incompletely fermented fish from being sold. The decree that was issued forbade sales of the current year's production in Sweden prior to the third Thursday in August. While the ordinance is no longer in force, retailers still maintain the date for the "premiere" of that year's catch.[4]
Fermented fish is a traditional staple inEuropean cuisines. The oldest archeological findings of fish fermentation are 9,200 years old and originate from the south of today's Sweden.[5][6] More recent examples includegarum, a fermented fish sauce made by theancient Greeks andRomans, andWorcestershire sauce, which also contains fermented fish.
Preservation of fish through fermentation in weakbrine may have developed when brining was still expensive due to the cost of salt.[7] In modern times, the fish are initially marinated in a strong brine solution that draws out the blood, then fermented in a weaker brine in barrels prior to canning.
Thecanning procedure, introduced in the 19th century, enabled the product to be marketed in shops and stored at home, whereas formerly the final stage would have been stored in large wooden barrels and smaller, one-litre kegs. Canning also enabled the product to be marketed farther south in Sweden.
A can of Surströmming, with the top noticeably bulging due to fermented gases being released
The herring are caught in May and June, when they are in prime condition and about to spawn, and have not yet fattened. They are put into a strong brine for about 20 hours that draws out the blood, after which the heads and innards are removed and the fish is put into a weaker brine solution. The barrels are placed in a temperature-controlled room kept at 15–18 °C (59–64 °F). Canning takes place at the beginning of July and for three to four weeks thereafter. Ten days prior to the premiere the final product is distributed to wholesalers.[10] The fermentation of the fish relies on a lactic acid enzyme in the spine that is activated if the conditions, temperature and brine concentration, are right. The low temperature in Northern Sweden is one of the elements that contribute to the character of the final product.[citation needed]
Prior to the development of modern canning methods, surströmming was sold in wooden barrels for immediate consumption, as even the smaller kegs could leak.[11]
Fermentation continues in the can, causing it to bulge noticeably, which would usually be a sign ofbotulism or otherfood poisoning concern in non-fermented canned foods. Species ofHalanaerobium bacteria are responsible for the in-can ripening. These bacteria producecarbon dioxide and a number of compounds that account for the unique odor: pungent (propionic acid), rotten-egg (hydrogen sulfide), rancid-butter (butyric acid), and vinegary (acetic acid).[8] 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.[12][13]
Surströmming is commonly sold in grocery stores all over Sweden. According to the Surströmming Academy's statistics from 2009, about 2 million people eat surströmming annually. Sweden's export of surströmming is only 0.2 percent of all produced surströmming.[14]
Many people do not care for surströmming.[15] As with theNordic dried-fish dishlutefisk,[citation needed] it is a food that meets strong reactions. It is more popular in northern Sweden than in other parts of the country.[16]
As of 2023[update], over the past few years, the supply of Baltic and other herring caught by Swedish fishermen has dramatically declined. Baltic herring fisheries have been used unsustainably since theMiddle Ages, andoverfishing is pushing populations to the brink of collapse. With such low catch numbers, retailers are now selling out their entire supply within minutes of the annual surströmming release.[17][18][19][20]
Surströmming served ontunnbröd (a Swedishflatbread) with boiled potatoes and vegetablesSurströmming with potatoes and onion on butteredtunnbröd, served with a glass of milk
Swedes usually consume surströmming after the third Thursday of August, labeled as "Surströmming day", through early September.[21] 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 escaping gas from spraying brine.
Surströmming comes both ungutted with only the heads removed and asfillets. With the former, the fish isgutted prior to eating, and the backbone and sometimes the skin are removed. Theroe is commonly eaten along with the fish.
Surströmming is often eaten withtunnbröd, either soft or a crispy type of flatbread made of different kinds offlour, sometimes it also containsmilk and bread spices.[22] Crispy tunnbröd has a bubbly texture and is more brittle than typicalcrispbread made ofrye.[22][23] The use of tunnbröd originated in theHigh Coast area, where the tradition is to make a sandwich (known as asurströmmingsklämma) with two pieces of buttered hard tunnbröd. In addition to the fish, the two most common toppings arepotatoes (either sliced or mashed, oftenalmond potatoes) and finely dicedred onion. Surströmming is also commonly eaten without bread, with potatoes and red onion. To counterbalance the strong flavour of the fish,Västerbotten cheese is sometimes added.[24]
Surströmming is commonly served withsnaps,light beers likepilsner orlager,svagdricka (a type ofsmall beer), water, or coldmilk. What to drink with surströmming is disputed amongconnoisseurs. Surströmming is usually served as the focus of a traditional festivity called asurströmmingsskiva.
Germanfood critic and author Wolfgang Fassbender wrote that "the biggest challenge when eating surströmming is tovomit only after the first bite, as opposed to before".[26]
Due to being made from herring from theBaltic Sea, surströmming today contains higher levels ofdioxins andPCBs than permitted in theEU. Sweden was granted exceptions to these rules from 2002 to 2011 and then applied for a renewal of the exceptions. Producers have said that if the application is denied, they will only be allowed to use herring less than 17 centimetres (6.7 in) long, as those contain lower levels, which will affect the availability of herring.[27][needs update]
In 1981, a landlord evicted a tenant without notice after the tenant intentionally spread surströmming brine in the apartment building's stairwell on the night of 24–25 December. The matter was brought to court due to the tenant disputing the validity of the eviction's reasoning. In January 1984, theregional court ofCologne ruled that the termination was justified after the landlord's party demonstrated their case by opening a can inside the courtroom. The ruling cited a violation of the tenant agreement per § 573Bürgerliches Gesetzbuch, stating that the court "had convinced itself that the disgusting smell of the fish brine far exceeded the degree that fellow-tenants in the building could be expected to tolerate".[28][29]
In April 2006, several major airlines (such asAir France,British Airways,Finnair, andKLM) banned the fish,[30] claiming that the pressurised cans of fish are potentially explosive. The sale of the fish was subsequently discontinued atStockholm Arlanda Airport. Those who produce the fish have called the airlines' decision "culturally illiterate", claiming that it is a "myth that the tinned fish can explode".[15]
On 4 June 2005, the first surströmming museum in the world was opened in Skeppsmalen, 20 km (12 mi) south-east ofÖrnsköldsvik, a town at the northern end of the High Coast.[31] The name of the museum isFiskevistet (translated as 'The Fish Encampment').
^Koizumi, Takeo (2002).発酵は力なり: 食と人類の知恵 [Fermentation is power: food and human wisdom]. NHK Ningen Kouza.ISBN4-14-084183-4 – via honkawa2.sakura.ne.jp.Excerpt fromHakkou ha chikara Nari