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Bog Butter

Unearthed after centuries in peat bogs, these blocks of aged dairy have an incredibly funky flavor.

Bog butter from the 15th or 16th century at the Ulster Museum in Ireland.

In rural Ireland, it’s not unusual for residents to come across a block of bog butter while digging up peat to heat their homes. Incredibly, this butter has often laid buried—in wooden containers, earthenware pots, or animal skins—for hundreds of years. Even after all this time, it can still have a notably buttery texture and aroma, although the taste tends to be a little too aged for modern palates.

So what exactly is bog butter? In the majority of cases, it’s exactly what it sounds like: cow’s milk butter that was buried in the peat bogs of Ireland or Scotland. It can also describe beef tallow that was buried in a similar manner. Bog butters are typically several hundred years old, but some have been around for multiple millennia. According to one archaeologist, their aroma is often pungent and “slightly offensive.” When he tried a 3,000-year-old bog butter, Andrew Zimmern described its flavor as having “a lot of funk” with “a crazy moldy finish.”

There have been several recent experiments with aging bog butter for shorter periods. In 2017, a journalist unearthed his batch after 17 months and found it had an earthy, parmesan-like flavor. In 2012, a food researcher and butter producer made a three-month-old version. Tasters described it as gamey and funky, with notes of moss and salami.

Why did people bury their butter in a bog in the first place? The most prevalent theory involves simple preservation. Being cool, low in oxygen, and high in acidity, these bogs were excellent at preserving perishable items (including the many examples of remarkably well-preserved ancient human remains that have been extracted from bogs across the globe).

Other theories argue that people buried the butter as an offering to the gods or as a method of protecting important stores from thieves and invaders. If your village was about to be occupied by hostile forces, where better to hide your valuable butter supplies than six feet down in a bog?

Bog butter from the 15th or 16th century at the Ulster Museum in Ireland.

Need to Know

If you have a bog nearby, wrap some butter in a cheesecloth and towel, bury it, and leave it there for at least a few months. Remember to make a note of your burial site: Many bog butters remained hidden for so long because their makers couldn’t find them again.