Apologies for the years-late reply
I have been making biltong for years, and the fat does sometimes go rancid. Reading online, I get the impression beef fat should not go rancid below 25c. Yes, you can dry meat above that temperature, but the fat will turn to the dark side.
There isn't one or two degrees or levels of food poisoning. I have had it dozens of times. It can vary from a mild single session of semi-squits on the toilet, to a few similar sessions, or queasiness lasting a few hours. The very worst I have had it (only once) did include stomach cramps, and it was a 48 hour bout, but no where near bad enough to require hospitalisation.
You could also have food poisoning and not realise it, it can be that mild. There are hundreds of degrees of how "bad" it can get.
Back to droewors, pork and pork fat are out of the question. But the beef (and lamb fat) should ideally be in a cool and dry location, NOT a hot location, despite the fact that yes people do make it when the temperature is soaring. It is possible that way back when in the day (and now) something was incorporated into the making of droewors which permitted the heat. Alcohol, saltpetre, natural or articial preservatives, the use of a cool or basement location during the heatwave, caves or shade, etc.
Bottom line... when making droewors, keep the temperature under 25 celsius. If you can access a fridge or buy a second one to use as a big cool biltong box, so much the better!
Regarding mixing the meat loosely, this is imperative. Ideally the mince and lamb (or just beef mince and lamb fat only) will be minced from a semi frozen state.
The process is
1) Mince coarsely
2) Loosely mix in spices with your hands, tossing the meat very lightly like a salad
3) Throw meat in freezer for 30 minutes to very lightly frost or deeply chill. This has the effect of hardening the fat ever so slightly, keeping the same coarsely ground texture.
4) Add vinegar and any final (wet) spices tossing very lightly
5) Mince again (spices are blended properly)
6) Case up your load!
7) Dip sausages in a tray with 5mm of a vinegar/hot water mix, remove immediately, hang to dry.
Going back to the mixing, if you mix your meat by hand, hard, and the tiny individual lumps of ground fat start to smudge, smear, melt, and blend in with the mince, you have ruined the texture of your droewors. The droewors will taste like... droewors paste.
Something else I have learned is that droewors should be cased lightly, not stuffed tightly. This helps preserve the ground textures in their individual globule format, so the meat can crumble (bits of fat, bits of lamb, bits of beef) in your mouth.You don't want to stuff your droewors sausage too tightly.
Ive only made droewors once (and didnt have any casings or a sausage stuffer!) and Ive never made sausages before, but Ive been eating the stuff all my life and have done a fair bit of reading. My first batch tasted good (all droewors does!) but suffered the over-mixed effect, which ruins the texture. I'd tasted that effect in other peoples droewors before, as well as the opposite (the lightly stuffed, lightly mixed) but hadn't put it into practise until now.
I say now, as Ive just made my second batch which is hanging up to dry!
It smells delicious!! Cant wait to eat it ALL!