Dear Straight Dope:
Every other cereal comes in a clear plastic bag, but not Corn Pops--it comes in a silver bag made of some kind of wax paper. Why?
The folk at Kellogg’s were slightly less than cooperative–perhaps they consider some of these things to be "trade secrets." But we’re scientists here. Using a bit of deduction and some good old common sense, it would appear the reasoning is as follows:
(1) Corn Pops and Smacks apparently are the only "puffed grain" cereals Kellogg’s makes. (Post also has Super Golden Crisp, which is a cheap Smacks ripoff.) So, they’re fundamentally different from the other cereal types, which typically are ground grains.
(2) This difference means that the cereal itself is unflavored (most cereals start as a pasty mix which is then turned into whatever shape cereal is desired), and also a bit prone to drying out, and therefore it must be sugar-glazed.
(3) Sugar glazing is hygroscopic (absorbs water), and if these cereals absorb water vapor, they stick together. You can do this experiment yourself by leaving one of these cereals open in an even slightly humid place.
(4) Evidently, the folks at Kellogg’s decided that these cereals got stale too quickly inside the normal bags, suggesting that water vapor can penetrate them. Therefore, they developed the foil-lined bags (which would indeed be impermeable) and solved the problems that way.
Doesn’t seem like much of a trade secret after all, does it?
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