十万个为什么·科学启蒙30篇（4）

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为什么蜂蜜几乎不变质

Honey has very low water content, usually below 18%, which prevents most microbes from growing.
Its high sugar concentration creates osmotic pressure that pulls water out of bacterial cells.
Bees add an enzyme called glucose oxidase to nectar, which produces hydrogen peroxide slowly.
This mild antiseptic compound inhibits microbial growth without harming humans.
Honey is also naturally acidic, with a pH between 3.2 and 4.5, too low for many pathogens.
Even ancient honey found in Egyptian tombs remained edible after thousands of years.
Crystallization doesn’t mean spoilage—it’s just glucose forming solid particles over time.
Storing honey in airtight containers keeps moisture out and preserves its stability.
Unlike fruit juices or milk, honey lacks nutrients that fast-growing bacteria need.
Modern food scientists use honey’s preservation traits to develop natural food preservatives.