delfuego has found a way to render fat at <104°F.
William,
Delfuego and I have corresponded on this topic and I've been following the thread closely. His oven temperature is actually slightly above 104°F and he's measuring the internal temperature of the fat with a meat thermometer. The the moisture doesn't boil off at such a low temperature so he has to remove the majority of it manually. It is not clear that enough moisture is removed from the liquid fat to allow for the exceptional room temperature keeping qualities that pemmican is famous for. If you are going to eat it right away then this may not be a problem, however, if you are looking for emergency rations that can be stored for long periods without refrigeration or freezing, then the point is critical. An everyday example of this is butter. It is mostly fat, but contains substantial water which over time causes the butter to go rancid and it must be kept refrigerated. To keep butter for long periods unrefrigerated, you must melt the butter and boil off the water and remove the milk solids (small amounts of protein and lactose). This has been done in the Middle Eastern countries for centruies and the end result is called Ghee. Like rendered animial fat it can be kept for long periods and requires no refrigeration.
The yield is not clear. Rendering fat above 200°F provides about 7 lbs of rendered fat for every 10 lbs of raw fat. At very low temperatures much of the fat may remain trapped in the cellular structure and the yield may only be 1/2 or 1/3 of normal. The saturated fat requires a temperature above 120°F to melt so this may not be released at all, thus altering the fatty acid profile of the completed pemmican. In other words it may be nutritionally deficient and not provide everything needed for a human to remain healthy.
The process takes many hours, (days actually), and though you don't have to watch it closely, you do have to skim the water off once or twice a day. The temperature is also perfect for culturing bacteria and mold. Unlike jerky where the moisture is driven off and the material becomes drier inhibiting the growth of critters, the fat actually traps nutrient rich water under it, and then keeps it nice and toasty for the critters to grow and multiply. In effect he's created a very nice incubator in his kitchen.
Delfuego hopes to keep the enzymes intact by keeping the temperature low. I have no idea if this is good or bad. Part of pemmican's amazing keeping qualities may rely on the destruction of the enzymes in the fat during the rendering process - we just do not know. Again, this may be a critical factor if pemmican is to be used as an emergency food. The problem is, we have no way of measuring the presence of enzymes so there is no way to know if the goal has been accomplished or even if there are significant enzymes to save in the first place.
Delfuego's "new" method introduces no fundamental change in process or technology. The process is exactly the same one that's been used for hundreds of years, with the single exception of lowering the fat rendering temperature. Unlike freeze drying which is very high tech and only been available in the last 50 to 75 years, just lowering the heat to render fat would have been available to the North American Natives who invented this stuff in the first place. From what research I've done, a heat level above the boiling point of water was always used. If the higher rendering temperature did not provide some advantage, then why didn't the process evolve to a low temperature model over the centuries? There must be a good reason, as lower temperatures take far less fuel and attention to maintain than higher temperatures.
Traditional pemmican has stood the test of time over many many centuries. I'm hopeful that Delfuego achieves what he's after, however, right now there are many unanswered questions.
Lex
