The longer you cook any food the more the proteins in that food are denatured. In this case the longer you cook a steak, the longer it takes to digest as well, up to a point. The less done the steak the less the proteins are denatured and the less time it will take to digest. Now will these thing really matter that much in the big picture? Eh probably not enough to stress about them.
Steak should be cooked at a temperatue that allows the internal temp to reach 60°C for a few minutes. This way you are able to kill most bacteria and the like. The proteins are not really lost by cooking, but rather converted by heat to others. Enzyme processing is not changed that much, as most of the break down of steak is physical (chewing) and chemical (acids in the stomach) before enzymatic processing of proteins for aminos.
Basically considering a steak will take a couple of hours to fully digest, the actual time difference between the different stages of cooking is going to be minutes, thus negligible. The main reason you cook meat is to ward off parasites and bacteria. I can honestly say that anyone who doesn't cook their chicken properly is an idiot headed for food poisoning (I've disected "parasite free" chooks and they were riddled with worms). You cook your food for a reason, don't get side-tracked by fuzzy minuta.
BBC NEWS | Health | Rare steak 'is safe to eat'
It is bc the steak is a solid piece of meatand hamburger is not, it is ,loose, if youwill. Excusemy typing my space bar is eithernot working orputting 3-4 spacesbt each word.
But this doesn't address why you cook meat. You are cooking meat so that it reaches 60-69ºC so that you begin to denature the proteins of pathogens. The main concern is the external layers, but the internal layers can still harbour parasites and bacteria so the meat has to be cooked through. You also have to realise that "medium rare" would actually be well within my stated range of cooking, "rare" it may or may not depending on the thickness of the meat.
See my points above: meat can harbour all sorts of pathogens. In food preparation the majority are external from contaminated surfaces, etc. But the pathogens still exist within the steak or whatever.Quote
I looked for the original reference and have battled to find it. I place little faith in university trials (MuscleTech.......). Do you have a link to the original?Quote
See my first point. I'll reitterate that meat is often contaminated all the way through, the surface is just more aerobically active due to exposure to the air. Most contamination methods (grinding, ground, tenderising, etc, etc) also introduce air/O2 into the meat. The pathogens are still present internally, albeit in smaller concentrations.Quote
Also there has been 30yrs of research on this topic, so if anyone is interested: