Piimä

Piimä is a traditional Finnish fermented milk beverage characterized by a mild sour taste and thin, pourable consistency. It is produced by fermenting milk with mesophilic lactic acid bacteria that convert lactose into lactic acid; some strains also produce diacetyl, which contributes a buttery aroma. Historically piimä was made by allowing raw milk to sour at ambient temperature or by backslopping with a portion of the previous batch, and modern commercial production uses defined starter cultures and pasteurized milk.

The product is similar to cultured buttermilk found elsewhere in Europe and North America but differs from other Nordic fermented milks such as viili, which is more viscous and ropy. Piimä is usually consumed cold as a drink, poured over cereal, or used in baking and cooking to add acidity and tenderness to doughs and batters. It is available in full-fat and low-fat varieties and may be plain or flavored.

Nutritionally, piimä provides protein, calcium and B vitamins, and contains live lactic acid bacteria in unpasteurized or specially cultured forms, which are sometimes associated with gastrointestinal benefits. As a staple of Finnish food culture, piimä is commonly found in households and stores throughout Finland and in regions influenced by Finnish culinary traditions.