Ymer is a Danish soured milk product which has been known since 1930. It is made by fermenting whole milk with the bacterial culture Lactococcus lactis. When producing fermented milk products such as yoghurt, ymer, filmjölk, skyr, qvark and A-38, and also when producing cheese, one can add lactic acid bacteria which convert milk sugar in the milk into lactic acid and other substances. Acidity makes the milk thicker, gives it a tart flavour, and increases the shelf life by several days.
Ymer is named after the primordial being Ymir in Norse mythology. In 1937, dairy farmer E. Larsen in Hatting registered his new soured milk product as ymer; the name was then used by other dairies that began making the product.
Ymer is made with the help of a starter culture, which is added to skimmed milk (milk whose fat content is typically 0.1% and generally no higher than 0.5%). It is kept at 18 °C until the pH drops to 4.6. The serum is broken down and drained after fermentation, and cream is added.
Unlike other fermented milk products, ymer is drained of its whey. That means that ymer has a higher content of solids, including protein, while the fat content stays at 3.5% as in whole milk.
Ymer is used in breakfasts, snacks, desserts, dressings and baking. The traditional breakfast topping is ymerdrys (“ymer sprinkle”), which is a mix of rugbrød breadcrumbs and brown sugar.