I've been noticing this white, almost chalky residue on some parts of my jerky the last few times, though this by far is the worst. It doesn't seem to taste bad and on this batch it seemed to collect in the middle as if it's dripping from the vent. Only thing is, it wasn't the worst on the top rack. In fact, I don't think there was any on the top rack until I rotated. Is it fat dripping from the rack above? I cut my strips as lean as possible. Something in my marinade? This batch was pork, but I've seen it on beef as well.
(http://i1369.photobucket.com/albums/ag216/BoxcarBetts/0C773F95-E08B-4272-829F-14AA5A287D2A_zpsfmrofeaf.jpg) (http://s1369.photobucket.com/user/BoxcarBetts/media/0C773F95-E08B-4272-829F-14AA5A287D2A_zpsfmrofeaf.jpg.html)
Usually if you get drippings they are black which is why you get the term black rain. My guess is this may be some type of a salt residue. How much salt or cure are you using?
You don't have lots of Seagulls in your area do you. LOL Just kidding. That is pretty unusual. I have seen black stuff which is what they call Black rain from moisture dripping down around the vent. Yours being white is very odd and makes me think it is a mold/fungus but I don't believe it is since you say it was not on the top till you rotated the racks. It doesn't look like mold growth but more like something splashed on it. Very odd. Does your wife have a large insurance policy on you. LOL ok just kidding again. I am afraid I am no help. I have never seen anything like it.
Oooo watchdog beat me to it. Good call on the salt. I was just going to suggest that. Do you have any white build up around the vent.
What are the ingredients in your marinade? Is it a commercial brand? Are you doing anything different in your technique since you started having this white stuff on your jerky?
Doesn't look like it is dripping on it to me.
KyNola, I tend to agree. I think it's something pooling on the meet and then drying up. I did notice what seemed to be liquid fat/juice on some of them, but I can't be totally sure it was where this white stuff ended up. I'd hazard a guess that yes.
I haven't done anything new in my technique aside from I wasn't able to tend to the jerky as much as I'd have liked, so they didn't get rotated properly. That being said though, I cut the pieces very unevenly some were done way too soon so instead of rotating top/bottom, back/front, I just placed the most raw pieces closer to the element.
As for my marinade... Hmm. One thing I did do different was use apple cider vinegar because I didn't want to use up all my Worcestershire and thought it might go good. But I have noticed this phenomenon before even when not using vinegar. Could be the salt in the Worcestershire? The only other real source of salt would be a dusting of salt and pepper before the go in the smoker. I wonder if I'm accidentally putting too much in one spot...
The last thing that might contribute to the amount this time is that I did have a moisture problem. I cold smoked some cheese the day before and I forgot to drain the melted ice cubes out of the bottom pan.
Well I found this website that concisely describes possible sources of it. It's definitely not mould because it formed in the smoker. I know my marinade didn't set evenly in all the pieces and I seem to recall a couple of pieces pooling with a lot of juice (probably the ones pictured). I'm willing to bet it was something with my marinade combined with the excessive moisture I had.
http://meat.tamu.edu/2013/01/22/possible-causes-for-white-film-on-beef-jerky/
Looks a lot like salt and fat