Can 3,000-year-old honey from ancient Egyptian tombs still be edible? Yes, and archaeologists have reported finding it.

• ✓Low water activity + acidity + glucose-oxidase-produced hydrogen peroxide preserve honey
• ✓Reports of ~3,000-year-old honey recovered from Egyptian tombs

Archaeologists cracked open ancient Egyptian tombs and found 3,000-year-old honey — and it was still edible. So how does honey never spoil? Honey's moisture content sits so low — typically around 17 percent — that bacteria and mould cannot draw enough water to survive. Its pH hovers between 3 and 4.5, about as acidic as tomato juice, killing most microorganisms outright. And glucose oxidase, an enzyme bees add during production, continuously generates hydrogen peroxide, a natural antimicrobial. Seal honey away from moisture, and you have essentially made a food that outlasts civilisations. The oldest jar of honey ever found sat undisturbed for three millennia, and it was still good to eat.