How do bagged potato chips stay good for so long? — Andrew, Brownwood, Texas
But in order for bacteria to do their thing, they have certain requirements. One of the things bacteria need is water. Most dry foods do not require refrigeration because of the lack of water, including dry sugar, dry flour, dry rice, dry breakfast cereal, dried potato flakes, etc. Vegetable oil does not need refrigeration either.
This is why potato chips stay good for so long. When they make potato chips, the cooking process removes all the water from the potatoes and coats the potatoes in oil. Neither dry potatoes nor oil spoil, so potato chips last a long time without any refrigeration.
For more info see: How Food Preservation Works