Why does chicken need to be cooked more then beef?
So I was wondering about why beef can be cooked pretty rare without much problem but chicken needs to be cooked all the way through? Is there some kind of bacteria that can makes it's way to the center of chicken but not a steak for some reason?
Yep, Campylobacter and Salmonella are present throughout the meat of contaminated chicken.
E. coli 0157 H7, the main contaminant of beef, is only found in the feces of cows. It can get on the outside of the meat by contamination, but it doesn't penetrate the meat. Therefore, cooking the outside of the beef can kill the contaminating E. coli. (Keep in mind, ground beef is all surface meat, so you can't safely destroy E. coli in ground beef without cooking it all the way through).
Ok, I'm not claiming this is the absolutely correct answer but based on my reading of the USDA's FSIS website and applying some logic, here's what I am guessing: both chicken and beef are prone to picking up many of the same bacteria but most of the bacteria and contamination for animals tends to come from the skin of the animal or from their gastrointestinal tract. Now the butchering and processing part of the food chain try to minimize the possibility that bad bugs from both areas stay off the carcasses, but this isn't perfect or foolproof.
Ok so both beef and chik are recommended to be taken to temps of between 165-170 for optimal safety (maximum bug kill.) But beef are skinned entirely; the skin peeled off and away so the bacteria which might have been riding along on feces or manure from the farm are mechcanically removed early on. Chicken however are killed, scalded, sent through plucking machines and the skin is typically left on until the go through further processing. So there is more opportunity for the bugs to not get cleaned off. Chicken also have more nooks and crannies where bugs can hide: wings, legs, body cavity etc. There's just plain more surface area relative to total meat.
The biggest source is that gastro intestinal tract. It's a microbiological superhighway for pathogens. It's size relative to flesh is greater for a bird than a cow so more intestine to flesh = more opportunity that during the gutting, the contents might get on the bird and the workspace is so much smaller on a bird that it's a lot harder to do this cleanly.
The thicker the cut of meat, the further away it is from the surface the less chance for contamination. So the safest is to have high heat cooking on the surface that roast the bugs and meat. This, I think, is why the USDA says that you can do large roasts to only 145 but recommends 160-160 for other cuts and ground beef should definitely go to 160 or higher since you have now taken tons of surface area, ground and mixed it all up.
Finally all animals are processed by humans who can also be sources of contamination, so the processors, butchers, wrappers, etc. all have an opportunity to add a bug to the mix. Either by direct contact with the meat or on the prep surfaces. So if you get a bird with a bug on it, and you mishandle it, leave it out too long, cross contaminate etc. then your odds of getting sick from that bug go up especially if you don't cook it well enough to be done but not so well that it's dry.
Basically the contamination tends to be on the skin or surface of the meat and unless there are lots of nooks and crannies throughly cooking the surface of the meat should get you to a safe and happy place.