Peat diggers sometimes stumble upon a white
substance called ‘bog butter’, which has the appearance and texture of paraffin
wax. It is thought to be the remains of food once buried in the bog to preserve
it. As peat is cool and contains very little oxygen, it can be used as a primitive
kind of fridge. The question remained what type of food was buried in the peat.
Local lore sometimes says that the waxy stuff is literally the remains of butter.
Also dead animals could be the source for the waxy material, however. Corpses
often contain adipocere, a substance also known as ‘grave-wax’. Therefore, bog
butter could also be the remains of carcasses rather than dairy products.
In order to find out, the fatty acids in bog butter were analysed. The hydrocarbon chains in the fatty acids derived from dairy products tend to be shorter than when derived from animal fat. There are also differences in the relative amounts of 12C and 13C. Artificial bog butters, made in the 1970s from mutton fat and butter mixed with soil and water respectively, were analysed on differences. Furthermore, nine samples of bog butter from the National Museum of Scotland, some of which are 2000 years old, were analysed. Conclusion: Six of the museum bog butter samples come from dairy products, and three are from animal fat. It seems that ancient Scots clearly used the peat to store both types of food, they say.
Some mystery remains. It is still not known whether the food was buried solely to preserve it. Maybe burying it in peat helped to transform the foods to more palatable products in a kind of primitive food processing. Next up is research on burying some modern fatty foods in peat to find out if anything interesting happens to them and their taste.
source: Berstan, R. et al. The
Analyst, 129, 270 - 275 (2004)http://www.nature.com/nsu/040315/040315-5.html