Viili

A ropy strain of Lactococcus lactis subsp. cremoris produces a stretchy polysaccharide texture as the milk ferments. That bacterial starter is why viili looks stringy rather than like a firm, spoon-cut yogurt.

Viili is a mesophilic fermented milk, so it is traditionally cultured at a relatively cool room temperature rather than heated like many yogurt processes. Finnish household starters are often saved from one batch to seed the next.

Viili is mildly sour and creamy, with a thick, ropy body. Kefir is usually thinner and lightly fizzy because kefir grains contain a mixed culture, while viili's signature is the Lactococcus-created rope.

They are related Nordic fermented milks, but the names refer to different regional products and starter cultures. Viili is the Finnish one best known for long stretchy strands, while filmjolk is typically smoother and langfil is another ropy Swedish style.