Many communities now accept paperboard boxes from things like cereal for recycling. But they often refuse to take the same types of boxes if they have any food contamination on them (like frosting from a cake, or dried-on cheese from pizza). The reason is simple: When paperboard is recycled, it’s mixed with large amounts of water. Everything is separated during this pulping process, including the oil and fats in paper, but it is not removed, which means the new recycled paper can end up with oil splotches. So if you have paperboard with any food contamination -- no matter how small -- toss it out and don’t recycle it.
ANDREWS MCMEEL SYNDICATION