Suppose I buy some beef, to make a stew with. This meat is contaminated with the E coli bacteria-the kind that made those people sick at Chipotle. I put my ingredients in a pressure cooker, and bring it to the boiling point for 2-3 hours-will this meat be safe to eat? Will boiling destroy the toxic by products of the bacteria?
Yes
This.
But 2-3 hours in a pressure cooker is definitely overkill. Though it will be tender, for sure.
160F for 15 seconds is enough to render your beef safe to eat.
The boiling point in a typical home-kitchen pressure cooker is about 250F. 2-3 hours at this temperature will make your beef soft enough to collapse under its own weight.
E coli bacteria are killed at temperatures much lower than boiling. 160 F for 15 seconds will safely kill E coli. The trick is that means every part of the contaminated material has to reach that temperature.
Note that there are lots of different pathogens that cause food poisoning and E coli is only one of them.
How deep into the meat will the e coli penetrate?
The surface for steak, the entire mass for hamburger.
I think it should be pointed out that in cases such as the E. coli outbreaks, the problem is bacterial infection, which can be dealt with by killing all the bacteria as mentioned above.
However, the shiga-like toxin/verotoxin that the pathgenic E. coli strain produces takes a little more to destroy. It is fairly heat stable and can’t be inactivated by standard pasteurization methods, but will be inactivated if treated for 5 minutes at 100C. So it certainly will be in a pressure cooker, which can reach standard autoclave pressure and temperatures (15 psi, 121C).
Is contamination of food with shigatoxin a significant public health issue? This seems unlikely, since food safety authorities say “160F for 15 seconds” is enough to render beef safe to eat. My guess is that if beef has been stored under conditions that are conducive to production of dangerous amounts of shigatoxin (i.e. at warm temps and/or for long durations), then various other bacteria will also have gotten busy decomposing the meat to the point that no one would even want to eat it.
Right, as far as I can tell the toxin itself isn’t produced in sufficient quantity in contaminated foods to be a concern, unlike in say, botulism. I did find one report that looked at toxicity of shiga toxins taken orally. One toxin (Stx1) was not lethal, and another (Stx2) had a 1000X higher LD50 compared to than when it was injected.
Too late to edit. By not lethal, I mean the authors stated that it was not practical to purify enough of the toxin for it to be a lethal dose.