Im a bit confused about this issue. So the point of going to all the laborious trouble of making pemmican is to separate the fat so it doesn't go rancid, render it to oil, and add it back.
But if the fat goes rancid in the first place, what difference does rendering it make, then adding it back? Why would it go rancid if dried along with the lean, but not when rendered and added back?
Lamb and beef fat is mostly mono and saturated fat, right? That's pretty stable and doesn't easily go rancid right? And once rendered to oil or tallow, it can be stored at cool room temperature without going rancid right? Well, again, why can't we just well-dry the marbled meat, lean and fat together?
I have a homemade jerky maker using a trash can, space heater, mini fan, and BBQ grills. Works like magic. I ground mutton today, fat n all, flattened it into thin sheets on the racks, and dried it for 10 hrs. I ended up with well-dried jerky sheets with a fair amount of clear oil pooled on them.
So what's the problem with taking this backpacking?
I think the problem is that the fat requires a higher temperature to render properly (around 240). Otherwise, there is still going to be water trapped in it that will make it go rancid sooner. If you tried to dry the meat at this temperature it would cook it, which you don't want to do. As you found out it's probably fine for a few days, but for long term storage I think rendering the fat is key.
If you've got drippings from your "jerky," you haven't dried it, you've cooked it.
To answer your question, the fat must be rendered (at as low a temperature as possible ... > 212F to purge the water but less than 240F) in order to remove the water from it, as one poster said. If there is any water in either the fat or the dried meat, the pemmican you make won't keep as it will be possible for mold and bacteria to grow. Rendered fat is not a substance that bacteria likes. Dry rendering is not using water, wet rendering is the same but has the added step of removing the water after the fat has hardened. Not a big deal, but it's an extra step. Either way, I've got fat in my cupboard 4 months old that still looks/smells/tastes like it did the day I put it in there.
The meat must be dried for the same reason. Since both need to be prepared at a different temperature range (don't dry the meat at more than about 104F!) they must be prepared separately.
As far as the mixture is concerned, weigh equal parts of the dried meat and rendered fat. crumble / powder the dried meat and melt the rendered fat separately (LOW LOW temp - it'll melt at about 104F, you can go maybe to 110) and the mix the two together. You don't want to deep fry the meat when you mix it in with the melted fat just like you didn't want to cook the fat when you rendered it.
Pack the mixture still warm into ziplocs or whatever you got to keep them dry. When it cools it'll solidify a bit. Eat as desired.
150 grams of pemmican made this way is worth about 1,000 calories. A pound is about 453 grams and a little over 3,000 calories, and about 70-80% fat calories.
If you use ONLY grass-fed beef and beef fat, you'll have an intensely nutritious substance that can sustain you for long periods. 10 pounds of it prepared properly can sustain a mountain hiker for a week. Or ruin your dinner something fierce.
So what's the problem with taking this backpacking?
Nothing. Why would it be a problem? Dehydrated meats are fantastic, and especially so for camping or hiking.
Pemmican is an interesting, if a bit anachronistic, method of preparing a dense, portable serving of protein and fat. It's also gross. "Traditional" pemmican doesn't have berries, nuts, or any of the flavoring that white settlers added after learning how to prepare pemmican from native Americans.
However, I've made it, and I like it (barely) enough to still take on some outings.
Regarding randcidity and spoilage, all rendering does is boil the water out from the fat. The (already lean) meat used is dehydrated into complete lack of moisture whatsoever, so that the meat can be powderized and added to the mixture. Once all the moisture is gone, bacteria cannot take a hold -- in fact, the fat acts as an anti-bacterial when moisture is removed (also e.g. confit). This is important, as the powdered meat could sustain a bacterial colony if one took hold.
To finish my rant, though ... the crap that passes as "pemmican" these days, commercially, is completely deplorable (yes, there's a couple authentic brands, too). Just like jerky - make it yourself for the best quality you can attest to! :-)
We make beef jerky with eye of round that has a nice edge of fat on it and even roast that have a good amount of fat in it. I do not trim off the fat and after slicing thin dehydrate in my dehydrator at 95 to 100 degrees for 8 to 12 (depending on how thick it is). I like to keep it simple and try to mimic natural dehydrating.
My family loves the taste of the fat on the jerky and it has never gone "off". Granted, we do store it in the fridge and it usually does not last long because it is so delicious. There have actually been small skirmishes when stocks get low. We have taken it camping many times but always in a cooler.
This jerky is the best medium we have found to transport homemade salsa, pico de gallo, and guacamole to our mouths. Forget chips!
I have made pemmican many times and I love the taste of it without the fruits, spice, honey, or whatever added. It is a pain in the you know what to make though. It is so much easier to slice the meat with the fat and dehydrate. Done.