When you buy a bag of chips or whatever it will stay fresh for a long time but once you open the bag it will only last for a few days. How is this possible?

Question

Like there is air in the bag as well so how come it can last for longer period of time when sealed?

In: Earth Science

Answer 1

Humidity in the sealed bag is very specific and limited to the captured volume of air. This means the chips don’t absorb moisture from the surrounding air and go stale.

Once you’ve opened the bag, there’s significantly more moisture available for the chips to absorb (from the whole air supply around them in the house, even if you roll the bag tightly.