Viili (Finnish viili, Swedish fil) is a type of yogurt (a mesophilic fermented milk) that originated in the Nordic countries. It has a ropey, gelatinous consistency and a pleasantly mild taste resulting from lactic acid. This cultured milk product is the results of microbial action of lactic acid bacteria (LAB) and a surface-growing yeast-like fungus Geotrichum candidum present in milk, which forms a velvet-like surface on viili. In addition, most traditional viili cultures also contain yeast strains such as Kluveromyces marxianus and Pichia fermentans. The LAB identified in viili including Lactococcus lactis subsp. cremoris, Lactococcus lactis subsp. lactis biovar. diacetylactis, Leuconostoc mesenteroides subsp. cremoris. Among those mesophilic LAB strains, the slime-forming Lc. lactis subsp. cremoris produce a phosphate-containing heteropolysaccharide, named viilian. Viilian is similar to kefiran produced by kefir grains. The production of exopolysaccharides (EPS) by the strain forms the consistency character of viili and it has been claimed to have various functional benefits toward the rheological properties of milk products and the health improving potential.