Honey is often credited as a multiuse wonder, known to soothe sore throats, heal burns, and add a little sweetness to drinks and desserts. But if a bottle in the back of your pantry has been collecting dust, you might be wondering if it’s safe to eat. Don’t worry: As long as it’s stored properly, honey will never expire. Honey has an endless shelf life, as proven by the archaeologists who unsealed King Tut’s tomb in 1923 and found containers of honey within it. After performing a not-so-scientific taste test, researchers reported the 3,000-year-old honey still tasted sweet.
Honey’s preservative properties have a lot to do with how little water it contains. Some 80% of honey is made up of sugar, with only 18% being water. Having so little moisture makes it difficult for bacteria and microorganisms to survive. Honey is also so thick, little oxygen can penetrate — another barrier to bacteria’s growth. Plus, the substance is extremely acidic, thanks to a special enzyme in bee stomachs called glucose oxidase. When mixed with nectar to make honey, the enzyme produces gluconic acid and hydrogen peroxide, byproducts that lower the sweetener’s pH level and kill off bacteria.
Despite these built-in natural preservatives, it is possible for honey to spoil if it’s improperly stored. In a sealed container, honey is safe from humidity, but when left open it can absorb moisture that makes it possible for bacteria to survive. In most cases, honey can be safely stored for years on end, though the USDA suggests consuming it within 12 months for the best flavor.
Finding food offerings inside burial chambers and tombs isn’t unusual in the archaeological world — and can be a useful tool for researchers to understand how people of the past ate. But not all ancient foods are found as grave goods. Take, for example, a barrel of 3,000-year-old butter found in an Irish bog. In 2009, workers in a peat deposit unearthed a wooden barrel in eastern Ireland; the barrel was revealed to be around 3,000 years old, with the butter inside perfectly preserved. While it was an unusual find, the 77-pound bucket of dairy isn’t the first — or possibly last — to be unearthed; nearly 500 similar containers have been found in Ireland. Historians have dubbed the preserved spreads “bog butter,” and believe they were likely packed and sunk into cool bogs to preserve or protect against theft at a time when butter was so valuable that it could be used to pay taxes.