We cycled our MREs about every three months in Iraq. KBR must've done the same at the Army Chow hall with their food too.
They had what they called milk in little cardboard containers like individual juice servings come in. I saw a pallet of them out back of the chow hall sitting in the summer sun all day long. Whatever they make that stuff out of, it doesn't taste a whole lot like milk, but it doesn't spoil easily either. I think it had a shelf life of 6 months or more at ambient temps.
I was damned glad the wife kept sending me a regular supply of milkman powdered milk mix. It is better than carnation, and a lot better than what was in those cartons. I bet you could use that carton milk stuff to whitewash a picket fence and it'd keep it in good shape for a decade.
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The ultimate result of shielding men from the effects of folly is to fill the world with fools.
-- Herbert Spencer, English Philosopher (1820-1903)