Why do processed cheeses only need refrigeration after the package is opened?

I'm thinking of the packages of cheese wedges (Laughing Cow), and also things like the cheese balls that come in holiday gift baskets. They don't need to be refrigerated until the package is opened, then they do. Why is that?

Why do processed cheeses only need refrigeration after the package is opened?
I think because you are letting air in and starting the bacteria growth.



just a guess.

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