Why Does Food Stay Fresh In Cans?

When canning was invented, no one knew why food that was packed and heated inside containers remained fresh for a long time.

campbell soup cans

Then, in 1860, French scientist Louis Pasteur discovered that food spoilage was due to bacteria present in all fresh food and in the air. These organisms breaks down substances in the food and make them useless or harmful to man.

Then it was understood how canning works: The heating kills bacteria in the food, and the sealing of the can prevents more bacteria from getting into the food. Food inside a can should stay fresh for as long as there is no opening in the can.

In the 1920s, American companies found that packing food in liquid kept it fresher and more nutritious. That’s why most canned foods are packed in water. And all cans today are vacuum-packed, which means that the air is sucked out of the can before it is sealed.

This prevents bacteria in the air from infecting the food.

About Karen Hill

Karen Hill is a freelance writer, editor, and columnist. Born in New York, her work has appeared in the Examiner, Yahoo News, Buzzfeed, among others.

2 thoughts on “Why Does Food Stay Fresh In Cans?”

  1. why don’t you talk a little more about the colloidal effects of silver? If bacteria initially touched the food while it was growing outside, i’m almost positive a little bacteria can seep through the actual product in the can and after it is vaccum sealed. Pharoas and kings drank out of silver cups and used silver dishware to keep their food from spoiling for weeks without sealing possibly months. Silver and Bacteria are antagonist compounds.

  2. They said they heat the food before canning it and vaccuming it. If the food is heated bacteria cannot grow on the surface nor can it thrive on the inside. Also silver does not have a colloidial affect on a bacteria but rather it binds and denatures bacteria. Silver shouldn’t even be discussed on a topic like this anyways and I think you’re just trying to be smart when it isn’t appropriate.

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