Filmjölk

Filmjölk (Swedish: [²fiːlˌmjœlk]), also known as fil, is a traditional fermented milk product from Sweden, and a common dairy product within the Nordic countries. It is made by fermenting cow's milk with a variety of bacteria from the species and . The bacteria metabolize lactose, the sugar naturally found in milk, into lactic acid which means people who are lactose intolerant can tolerate it better than other dairy products. 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, a compound with a buttery flavor, which gives filmjölk its characteristic taste.

Filmjölk is similar to cultured buttermilk or kefir in consistency and has a mild and slightly acidic taste. It has a shelf-life of around 10–14 days at refrigeration temperature.

In the Nordic countries, filmjölk is often eaten with breakfast cereal, muesli or crushed crisp bread on top. Some people add sugar, jam, apple sauce, cinnamon, ginger, fruits, and/or berries for extra taste. In Norwegian it is called surmelk (Nynorsk: surmjølk) (sourmilk) but the official name is kulturmelk (Nynorsk: kulturmjølk). The drink is also popular in Latvian kitchens, where it is called rūgušpiens, rūgtpiens (fermented milk or sourmilk) and can be bought ready from stores but is more commonly made at home, additionally it can also be purchased and is popular in the neighboring country, Lithuania, where it is called rūgpienis or raugintas pienas (sour/fermented milk), due to its popularity it can be bought in majority of the stores alongside kefir.

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