really, one of the most important things about making pemmican for storage is to make sure that everything is VERY dry...render the fat to dewater it, dry the meat very dry (think like chipped beef kind of dry) make sure that any fruit you use is moisture free enough that you're capable of grinding it into a powder, nuts aren't really so much of a big deal, but for long term storage mind that the oils in untoasted nuts can go rancid, whereas roasted or cooked nuts just tend to go a bit ...stale.
if you see white on your pemmican and it's been in storage, there's two possibilities...if it's fuzzy, you have a science project, a mold chia-pet....your ingredients weren't dry enough (it's hard to get them TOO dry...about the only thing you can do is turn the meat into carbon...which, anything short of that, you should be ok). If it's white and greasy, it's simply like the fat-bloom on chocolate that's gotten warm and then cooled off. won't hurt anything.
my recipe is for a base, to which I can add nuts, fruits, hell, I've even added honey and peanut butter or a shot of maple syrup.
5 pound of the leanest, toughest beef you can find (minimal marbling, I usually use round, from low, close to the hock, usually called 'heel of round' 'pike's peak roast'). I cut the fat and meat apart, grind the meat 2-3 times if I have a grinder, otherwise I slice very thin (deli slicer shaving), dry it, and while it's drying, I render the fat. Makes about 1 1/4 pounds dry, which I throw into the blender of food processor to turn into a powder.
1/2-2/3 pound rendered beef fat- on this, I add a tablespoon or three of olive oil to the molten fat, to help balance the omega fatty acid profile. If you're desperate and don't have rendered beef fat, you can use lard, but the flavor might be slightly less than the best.
when mixed and chilled, this will have a consistency close to fudge. I've done it enough that I kinda know the feel of it. Go easy on the fat, and make sure it's warm, doing it with the fat cooling, it'll take more to soak into the meat, and make the pemmican very rich (hint on how to alter the fat content) and if you're eating for summer, it can easily be way 'too' rich. So make sure your fat's not trying to set.
that's the basic, and is ready to eat once it's moulded to shape and sets. with everything properly dry, keep the air out of it, and it'll last for several months in warm conditions, a year or two in temperate, and virtually indefinately if frozen or fridged, so long as it's kept airtight and dry.
If your'e going to add something like..say for my favorite...honey, dried cherries and blueberries, add these things to the meat, but before the fat. Fruit, make sure it's finely minced or at least a mealy powder. If you add honey, it'll reduce the amount of fat needed to bind it, and will give you a quick bit of energy when you first eat it, but go easy on it, or you'll reduce your fat so much that you wont' have a lot of 'lasting' energy from the fats.
if you want to add nuts, I would grind them into a creamy peanutbutter consistancy first, and because nuts are a high fat food, you can ease up on the rendered fat a bit without losing long lasting energy.
my recipe is meant to be flexible, and something to tinker with, to add things I may or may not be in the mood for. I had a mate that added dried red pepper flakes to his. I've seen blackstrap molasses added instead of honey, then there's maple syrup, sorghum syrup, karo, etc. It's a very flexible 'add what you like' food, as long as the ingredients are very low water.