Surströmming with potatoes,
onion on tunnbröd.
Surströmming ("soured (Baltic)
herring") is a northern Swedish dish consisting of fermented Baltic herring. Surströmming is sold in
cans, which often bulge during shipping and storage, due to the continued
fermentation. When opened, the contents release a strong and sometimes
The herring is caught in spring, when it is in prime
condition and just about to spawn. The herring are fermented in barrels for one
to two months, then tinned where the fermentation continues. Half a year to a
year later, gases have built up sufficiently for the once cylindrical tins to
bulge into a more rounded shape.
These unusual containers of surströmming can be
found in supermarkets all over Sweden. However, certain airlines have banned the
tins on their flights, considering the pressurized containers to be potentially
dangerous. Species of Haloanaerobium bacteria are responsible for the
in-can ripening. These bacteria produce carbon dioxide and a number of compounds
that account for the unique odour and the sour
(acidic) properties: pungent (propionic acid), rotten-egg (hydrogen sulfide),
rancid-butter (butyric acid), and vinegary (acetic acid).
Historically, other fatty fish like salmon and whitefish have been fermented not
unlike surströmming, and the original
gravlax has resembled surströmming.
Surströmming is often eaten with a kind of bread known as
tunnbröd, literally "thin bread".
The custom is to
make a sandwich, commonly known as a "surströmmingsklämma", using two pieces of
the hard and crispy kind of tunnbröd with butter, boiled and sliced or mashed
potatoes and sliced fish in between and
Left: Opened can of surströmming in brine.
In the south part of Sweden it is customed to use a variety
of condiments such as diced onion, gräddfil (fat fermented milk/sour cream) or
crème fraîche, chives and sometimes even tomato and chopped dill.
The surströmming sandwich is usually served with
snaps and light colored beers
like pilsener or lager. Some claims that cold milk
is the right and only choice to go along with the
Many people do not care for surströmming, and it is generally considered to be
an acquired taste. Conversely, it is a food which is subject to strong passions
(as is lutefisk), and occasionally people like the taste on first try. In fact,
there are usually no middle levels - you either love it or hate it.