How does a natural food like honey never expire, unlike other natural foods like fruits or vegetables?
In: Chemistry
It’s not necessarily that honey is natural and fruit are unnatural. It has more to do with the moisture content.
Food goes bad when bacteria starts growing in the food and begins to leave behind nasty byproducts that make the food inedible. This is normally fueled by the presence of water Sunlight is another way that food becomes spoiled and that’s driven by the decay of compounds through UV light.
In contrast, honey almost has no water which leads to a very hostile environment for bacteria. If a bacterium is able to start growing, the honey will quite literally suck the moisture out of it through osmosis, effectively killing it. Honey is also known to have a number of antibacterial compounds in it which also inhibits bacterial growth. Additionally, the acidity of honey is not ideal for bacterial growth.
Honey contains so much sugar and so little water than any microbe that could try to spoil it gets all their moisture sucked out and they die. It’s basically the same reason that sugar or salt don’t spoil.
Fruits and vegetables are alive and can support other life…bacteria will eventually eat them (spoil them).
Honey has virtually no water in it and all animals (including bacteria) require water to survive and get a lot of water from the food they eat.
High sugar content is a preservative because of osmosis.
Osmosis is basically the movement of water from a area with a few dissolved molecules to an area with a lot of dissolved molecules. It basically wants to equalise the amount of water on either side.
So when a bacterium (that makes food go bad) lands on honey, the water inside it is pulled out and it dies.
Fruit and vegetables also have sugars, but they’re stored in different cells and parts of cells, so the bacteria can eat the sugar bit by bit without the water trying to equalise.
More generally, honey is made to store food for the bees, but fruit is made (by the plant) to protect its seeds until they’re ready to make new plants. So many ripe fruit want to be “eaten” by bacteria and fungi so that the seeds will be spread out.
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