For my entire life, my mom has kept an array of grains, seeds and nuts in a mix-and-match assortment of jars that had once held marinara sauce, peanut butter and fruit juices. One of the most useful things she taught me about storing dry goods in jars (other than always make sure your jar is 100% dry before filling) is to rotate the contents.
This means that when you bring a fresh bag of popcorn home from the bulk section, take the time to pour what remains in the jar out into a bowl, so that the freshest product ends up at the bottom of the jar and the oldest is at the top. This way it gets used in order of age. Here are a few pictures to show you exactly what I’m talking about.
Empty the remaining contents of your popcorn jar into a bowl for temporary storage.
Then empty the fresh popcorn into the jar. You might notice that it’s appearing that I have more popcorn than is going to fit in this half gallon jar.
Top the jar off with the old popcorn. A wide-mouth funnel is a real help here, as it keeps your popcorn contained (unpopped kernels escape so easily).
The popcorn jar is filled. But what’s that? There’s still some corn left in the bowl.
That ends up in an overflow jar. I’ll make a point of using this one up first, since it holds entirely older popping corn.
See, I even label it as such, to ensure that I remember that it’s the one that should be finished off first. Sharpies are so handy for jar labeling, as they write on the glass smoothly and erase with a bit of rubbing alcohol (I learned that trick in 12th grade biology).