I found a store that sells leftover food items at a big discount. They had large boxes of Krusteaz cake and muffin mixes that I couldn't resist. They are not outdated. I want to make certain that I am not bringing any critters home to my cupboard. Somewhere I read that freezing will kill any bugs or eggs lurking in boxes. My question is this: If I freeze these boxes, can I then remove them from the freezer and store them in an airtight plastic container, or must they stay in the freezer to keep them pest-free?