Filmjölk

Filmjölk (also known as fil ) is a Swedish mesophilic fermented milk product that is made by fermenting milk with a variety of bacteria from the species Lactococcus lactis and Leuconostoc mesenteroides. The bacteria metabolize lactose, the sugar naturally found in milk, into lactic acid. The acid gives filmjölk a sour taste and causes proteins in the milk, mainly casein, to coagulate, thus thickening the final product. The bacteria also produce a limited amount of diacetyl, which gives filmjölk its characteristic taste. Filmjölk is similar to cultured buttermilk, kefir, or yoghurt in consistency, but fermented by different bacteria and thus has a slightly different taste. Compared with yoghurt, filmjölk tastes less sour. In Sweden, it is normally sold in 1-liter packages with live bacteria and has a stabilising effect on the stomach and intestines.

In Nordic countries, filmjölk is commonly eaten during breakfast or as a snack between meals (mellanmål) in the same manner as yoghurt, usually from a bowl with a spoon. It can be drunk but is not normally done so since the liquid is fairly thick. Filmjölk is often eaten with breakfast cereal, müesli or crushed crisp bread. Since plain filmjölk tastes sour, many people add sugar, jam, applesauce, cinnamon, fruits, and berries to make the taste more palatable.

During the 1960s, Swedes normally ate regular, unflavoured filmjölk containing 3% milkfat. Since the 1970s, a proliferation of different types of filmjölk has been marketed in Swedish grocery stores. In 1997, Arla introduced its first flavoured filmjölk: strawberry flavoured filmjölk. The flavoured filmjölk was so popular that different flavours soon followed. By 2001, almost one third of the filmjölk sold in Sweden was flavoured filmjölk. Since 2007, variations of filmjölk include filmjölk with various fat content, filmjölk flavoured with fruit, vanilla, or honey, as well as filmjölk with bacteria that is considered extra healthy, such as Arla Onaka fil which contains Bifidobacterium lactis (a bacteria popular in Japan) and Verum Hälsofil which contains Lactococcus lactis L1A in quantities of at least 10 billion live bacteria per deciliter.

In English
There is currently no accepted English term for fil or filmjölk. Fil and/or filmjölk has been translated to English as sour milk, soured milk, acidulated milk, fermented milk, and curdled milk, all of which are nearly synonymous and describe filmjölk but do not differentiate filmjölk from other types of soured/fermented milk. Filmjölk has also been described as viscous fermented milk and viscous mesophilic fermented milk, as well as incorrectly translated to junket. Furthermore, articles written in English can be found that use the Swedish term filmjölk, as well as the incorrect spellings filmjolk, fil mjölk, and fil mjolk.

In Finland Swedish
In Finland Swedish, a dialect of Swedish spoken by Swedish-speaking Finns, fil in Finland is the equivalent of filbunke in Sweden. With the exception of filbunke and långfil, all variants of filmjölk are not found in Finland and Swedish-speaking Finns do not use the term filmjölk. The most similar product to filmjölk in Finland is surmjölk (in Finland Swedish) or piimä (in Finnish), which is a fermented milk product that is thinner than filmjölk and resembles cultured buttermilk.

Types of filmjölk in Sweden
In Sweden, there are six Swedish dairy cooperatives that produce filmjölk: Arla Foods, Falköpings Mejeri, Gefleortens Mejeri, Milko, Norrmejerier, and Skånemejerier. In addition, Wapnö AB, a Swedish dairy company, and Valio, a Finnish dairy company, also sell a limited variety of filmjölk in Sweden. Prior to the manufacture of filmjölk, many families made filmjölk at home.

Fil culture is a variety of bacteria from the species Lactococcus lactis and Leuconostoc mesenteroides, e.g., Arla's fil culture contains Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. cremoris, Lactococcus lactis biovar. diacetylactis, and Leuconostoc mesenteroides subsp. cremoris.

Homemade filmjölk
To make filmjölk, a small amount of bacteria from an active batch of filmjölk is normally transferred to pasteurized milk and then left one to two days to ferment at room temperature or in a cool cellar. Pasteurized milk must be mixed with fil culture to create filmjölk because the naturally occurring bacteria in milk is killed during the pasteurization process.

A variant of filmjölk called tätmjölk, filtäte, täte or långmjölk is made by rubbing the inside of a container with plants of the genus Drosera (called sileshår in Swedish) or with leaves from plants of the genus Pinguicula (called tätört in Swedish). Lukewarm milk is added to the container and left to ferment for one to two days. More tätmjölk can then be made by adding completed tätmjölk to milk. Carl von Linné described in Flora Lapponica (1737) a recipe for tätmjölk and wrote that any species of Pinguicula could be used to make tätmjölk.

Drosera and Pinguicula are carnivorous plants that have enzymes that degrade proteins, which make the milk thick. How Pinguicula influences the production of tätmjölk is not completely understood; lactic acid bacteria have not been isolated during analyses of Pinguicula.

There is a common belief that tätmjölk can not be made when there is a thunderstorm.