I'm seeing a number of people asking about white powder, or white residue, collecting on their beef jerky. I've experienced this as well, and am not totally sure what it is. But I thought I'd start this thread and see if folks out there have answers.
My best answer is that most of this stuff is salt.
I've noticed with vacuumed sealed packages of jerky, the vacuum suction causes oils inside the meat to rise to the surface, giving the meat a shiny wet appearance. When the the seal is broken, the oils sink back into the meat, leaving behind salt deposits, which appear as a white powder, or residue. This stuff doesn't rub off, or scrape off, and doesn't seem to change the flavor of the jerky.
This is my best guess, based on eating numerous brands of jerky.
I think that other forms of "white stuff on jerky" could very well be mold. You might want to smell it first and see if reeks. If you can scrape it off with your fingernail, it's likely mold. Certainly you'll know right away if it's mold by tasting it.
Most jerky is shelf stable for a year or two, perhaps even longer. So, I tend to doubt that it's mold. The exception might be with an unopened package of moist jerky, where a tiny hole in the package exists, allowing for oxygen to enter.
I did a review of North Prairie Signature Bison Jerky, where after only 5 minutes of opening, white powder began growing across the pieces. After just 15 minutes, the jerky was more white than it was dark-brown. You can see photos in the review, which I took within minutes of opening, and already there's white powder spreading...
It looked pretty strange eating white bison jerky, but it didn't have a bad taste, it all seemed to taste just fine.
If you know something about the white stuff on jerky, post a comment.