Perfectly-cooked popcorn kernels are light and fluffy. Properly storing uncooked popcorn improves the chance of all the kernels fully bursting by maintaining adequate moisture levels.
To properly pop, kernels must have a moisture content of 13.5 to 14 percent. If raw popcorn is left exposed for one day in warm temperatures, it can lose one percent of moisture; this will result in more half-popped or unpopped kernels. Popcorn that has lost three percent or more of its dampness will normally not pop.
Best Storage Methods
Glass or plastic vessels with tight fitting lids are best for popcorn storage. Store the containers should be stored in a cool place, away from sunlight and the stove.
The idea that popcorn keeps best in a refrigerator or freezer is not valid. These storage options actually tend to dry out the kernels more than room temperature storage.
Since it seems wasteful to discard the unpopped kernels often found at the bottom of the popcorn bowl, you can still try to pop the so-called “old maids.” Place these kernels in a jar, and add just enough water to barely moisten their surfaces. Shake the jar and let them sit for a few days; this will rehydrate them. Rehydrated kernels will often pop as well as fresh popcorn.