Sugar doesn’t go bad, since it’s a preservative (think jelly – all you need is a little parafin and it’s safe for years). As long as it’s kept dry, mold won’t attack it.
Refined sugar is a simple chemical compound and unless something is added (water, for instance) it doesn’t break down any more than salt does.
Sugar has even been used to treat infected wounds; the osmotic gradient causes the bacteria to literally shrivel up, I would imagine the same thing makes it quite difficult for bacteria to spoil it in storage.
I saw something on discovery (?) recently regarding Hammurabi’s code and early medical practices that said they smeared honey on open wounds as an antibacterial agent.
They’ve recovered honey from Egyptian tombs, 3000 years old, and still good. (But severely crystallized, I bet.) The stuff is so hygroscopic (I just love an opportunity to use the word “hygroscopic”!) that it just sucks all the moisture away from bacteria depriving them of life.
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Substitute “she” for “it;” “joy” for “moisture;” “Milo” for “bacteria;” and “him” for “them;” and Jomo Mojo has just perfectly summed up my now-defunct marriage.
And speaking of insects and sugar, while sugar does not necessarily go bad, there is no guarantee that some little bug hasn’t laid a few thousand eggs in your batch. Once I came across a jar of sugar that I had forgotten about in the basement. Turns out that it was a breeding ground for at least a little while considering the number of dead bugs (all seemingly the same species) inside the tightly-closed jar.
Despite the discovery of this new source of protein, I opted to throw it out.