Lappologists have described in their writings how the Sámi used to preserve reindeer, sheep and goat milk by mixing them with plants. This method of preservation has been called “kombo” or “grass milk”. A variety of plants, both herbs and all the common berries, were in the old days used for such grass milk. The milk was kept in a wooden barrel or other wooden vessel, or in a pouch made from the stomach of a reindeer or a sheep.
According to the historian T. I. Itkonen, reindeer milk was mixed with French sorrel, crowberries and cloudberries and then preserved in the rumina of reindeer in Enontekiö. In Utsjoki, reindeer milk was mixed with French sorrel (Rumex acetosa) and mountain sorrel (Oxyria digyna) in the early 1800s. The milk could be frozen and used as “ice milk”, or hung from a wooden rail to curdle and dry into a cheesy mass that had the taste of smoke.
In Enontekiö, the milk was mixed with young leaves of Angelica that had been boiled, cut up and salted mildly. Then the milk was anchored in a stave vessel to a spring and eaten later. In Utsjoki, the French sorrel was reaped “half-grown, cut up and boiled and then added to reindeer or sheep milk which then soured, so that eating it was much more pleasant.”