The longest I can keep it around is a couple months. It takes 4 cans to load up the dehydrator, and the wife won't leave it alone any longer.
I've left it in a Ziploc on top of the refrigerator during the summertime and it seems to be fine. The wife is picky enough that any off taste would put her off of it.
She does dob off a bit of oil when removing it from the dehydrator, but from a mass ratio perspective that is fairly negligible. She only likes the regular recipe.
It will literally dry to a brittle state if you process it long enough. I find that setting it like sole leather (stiff but still pliable), seems the most desirable.
I guess there's enough salt and other preservatives in Spam to keep it from spoiling. Go figure.
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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)