Worried about using every last drop of your new jar of honey before it goes bad? Never fear, because unlike other grocery items that have expiration dates that seem to creep up on you before that recipe gets made, honey that’s been properly sealed doesn't spoil.
Yes, that’s right, pure honey has a perfect combination of characteristics that allow it to last indefinitely.
Let’s take a closer look.
Honey is mostly comprised of a mixture of water and sugars, namely sucrose and glucose. Bees make honey by gathering moisture-rich nectar from flowers, storing it in an extra “stomach” and returning to the hive. This specialized stomach has digestive enzymes and gastric acids that begin to break down the nectar, making it more suitable for long-term storage. The partially processed and still water-dense liquid (nectar) is deposited into honeycomb and then fanned by the bees. By fanning the liquid, its water content is reduced to below 18% before it is then capped with beeswax.
The result: airtight honeycomb filled with a low-moisture and perfectly sweet honey. But what makes it last forever?
Because of their extra stomachs, bees partially digest the flower nectar using an enzyme called glucose oxidase. This yields a key by-product, hydrogen peroxide, which acts a barrier to the growth of spoilage-inducing microbes.
But it doesn’t stop there.
Another byproduct of partial digestion: honey is acidic. With an average pH of around 3.9, its acidity level makes it a very inhospitable environment, eliminating nearly all bacteria and microorganisms. By comparison, coffee has an acidity level of around pH 4.5.
Thus, it’s this 1-2-3 combination of low moisture, presence of hydrogen peroxide and a relatively high acidity level that allow sealed honey to last for millennials.
Having said this, there is one caveat to keeping honey in such tip-top shape that it won't spoil even when found thousands of years later in Egyptian tombs: it must be sealed and stored properly. Because honey is made from sugars which are hygroscopic, it has a natural tendency to absorb water. When the moisture content of honey rises above 18%, it begins to lose its effectiveness at fending off bacteria that will feed on the sugars and cause it to ferment. Thus, when used in humid environment, return the cap to your honey jar after use.
But what about when honey crystallizes, is it still safe to eat then? Yes! Raw honey may crystallize, but this is completely natural. Honey contains a high concentration of sugar, and a low concentration of moisture, which can cause the glucose to separate from the water and remain in the form of crystals. This can easily be remedied by placing your jar of honey in a pot of warm water for 15-30 minutes. Make sure not to heat the honey over 110 F in order to maintain it's raw properties. To learn more about crystallized honey, check out our FAQs and this great article from Wired.
As an anecdotal sidebar, honey has been used in both ancient and modern times as a wound dressing because of these factors. It’s believed that the hygroscopic nature of honey helps to reduce inflammation by drawing moisture from a wound, while the hydrogen peroxide acts as barrier to bacteria growth, assisting in the healing process.