Is liver different from other meats (from the same animal) regarding cooking times and temperatures, for safety?

Question

As long as I can think (and speaking purely about my circle of family and friends), there seems to have been some stigma associated with liver (and possibly other organs, as differentiated from muscle flesh) and cooking times/temperatures. I.e., some people I know are fine eating steak done rare, but would not touch liver that hasn't been cooked through almost to shoe-sole consistency.

Is this founded on some real fact about the likeliness of liver carrying a higher amount (or more dangerous) pathogens, or is this more of a popular prejudice, maybe correlated to my assumption that liver was in the past probably somewhat of a "poor man's" food?

If you wish, as a secondary aspect, you could expound on whether the answer depends significantly on the type of liver (beef, pig, poultry, ...)

To focus this question a bit, I am not asking about the issue of whether "bad stuff accumulates in the liver" or whether liver in itself (i.e. it's iron content or other natural components) is to be considered healthy or whether it tastes better cooked in a certain way or other, or anything adjacent like that. I am strictly asking about anything that needs to be killed or neutralized by cooking. For the purpose of this question, assume a source animal kept and slaughtered to the highest standards of health and cleanliness, and an uninterrupted cold chain. Also assume a perfectly healthy consumer with no immune system deficiencies or anything like that.

Answer 1

First and foremost, USDA's Food Safety and Inspection Service recommends cooking all ground and "variety" meats (organs, tongue, etc) to 160°F/71°C (with the exception of poultry, for which they recommend 165°F/74°C). They state that that temperature is required in order to kill bacteria present in and on the meat.

When a cow is slaughtered (in the US, in a USDA approved facility) the organs are removed after the animal has been partially processed (ex: skin and head removed, among other things). The body cavity is opened and the digestive tract removed. Most carcasses are exposed to some low level fecal contamination at some point during these processes, in spite of cleanliness procedures intended to minimize such things. (Livestock are living creatures, after all, and there's no avoiding it). Edible organs are removed along with the remaining viscera at this point, which means that they are also exposed. Most organs need further processing to be used in modern cooking (membranes, veins, ducts, etc removed and the like). Any of these additional handling steps run the risk of introducing bacteria or spreading existing bacteria.

None of this would be a substantial problem if the organs were able to be washed in the way that the remaining carcass can be, but they are typically more delicate (liver, kidneys, pancreas) or effectively impossible to sanitize (ex: tongue). The carcass is later washed with a mild acid solution after is it cut into sides and prior to chilling in order to kill bacteria on the surface of the meat. Scalding water is used in some places for the same purpose. Neither of these is really possible for something like a liver.

So the long and the short of it is that if you were there when the cow was slaughtered, took the fresh, intact liver into your kitchen, prepared it for cooking and then cooked it, there were be almost no chance of bacterial contamination on the interior of the liver. However, if you're buying fresh liver at a butcher, it has sat around for a time at temperatures that allow bacteria to spread, if slowly, and will continue to do so in your refrigerator until cooked. If you're buying frozen liver from a source that freezes them shortly after harvest, and you thaw it (or partially thaw it) properly in a refrigerator and use it soon after it has thawed, then there is still risk of food poisoning from undercooked liver, but it would be reduced compared to fresh.

For culinary purposes, if you choose to follow USDA's guidelines, I would be sure to use a thermometer and stop cooking a couple of degrees short of the guideline so that carry-over heat finished the job (assuming thinly sliced beef liver, there's not much carry-over to be had). Though it will be well done, it should stop short of shoe leather at least. If, like me, you prefer it medium, enjoy your meal with the knowledge that it is possible that it could end badly.