eli5: Why you can safely cook meat in a slow cooker (approx 8 hours on low), if after 2 hours on the counter it needs to be tossed?

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Surely it’s in the “danger zone” for a long time before being fully cooked, right? Could you leave out meat for 4 hours THEN toss it in a slow cooker?

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No and no

The meat heats up to “kill germs” level on the outside pretty quickly. The long slow cook is to melt the collagen which makes it juicy and adds body.

If you leave it sitting out in the danger zone a long time you can a massive growth of the nasties that are more likely to survive in the deeper parts of the meat

A slow cooker on low in typically 190F/87C – If your kitchen is that temperature then both you and the meat are going to get cooked.

The key points are that even the coolest of cooking temperatures are high enough to kill microorganisms. So a slow cooked food still gets sanitized and is safe to eat.

The problem with “Danger Zone” foods is partially a living infection by microorganism but also the poisons and toxins they produce. So even if you cook a food that has sat out for a while and manage to kill off the colonizing organisms you are still left the toxins they produced while alive, those aren’t destroyed by cooking.

This is the reason why you need dispose of canned food you suspect was exposed to botulism. You can just cook the food and kill off the microbes but the toxin lingers and that’s actually the thing that can hurt you severely.

Meat in the danger zone allows bacteria to proliferate. Once it is raised above the danger zone (for the recommended time) enough bacteria have been killed to make it not infectious. IF you leave a roast for 4 hours at room temp and then eat it, it has an infectious load. If you have it in the danger zone for 4 hours and then it goes into the safe zone above the danger zone then it is eliminating the pathogens.

This is why sous vide is safe; bc different heats for different times kill pathogens. 2 min at 165f might do the trick while 2 hrs at 130f will also do it.

Slow cookers are not food holders. A food holder will keep food around 150-160F to stop bacteria growth. That’s what all the heat lamps due at fast food places.

A slow cooker *can*/*will* reach 212F. Even on low, my slow cooker slightly bubbles where the liquid touches the ceramic once it has come to temp.

When food goes bad, the *food* is not what makes you sick, its the poisons the bacteria create through their metabolic processes which make you sick. Cooking can’t remove those poisons.

I have left things out overnight by mistake, but it has never worried me since the food hits the container when its still well above 140F and once sealed, nothing else is getting in to set up shop. The chance of any growth is minimal. I’ve done that with bone stocks. Boiled 12 hours, turn it off, leave it still covered cause it bed time. At that point, the broth is sterile from 12 hours at 212F and being covered, nothing is really getting in to set up a colony and if something does, it is super minor and then next morning I bring it back to a boil again and keep going killing anything that did get in.

This is very different than leaving out a rack of ribs for 4 hours on your counter top.