My wife was travelling for a couple of weeks and I was home alone. I love cooking, but with just me at home I figured there were better things to do with my time (like finally finishing my Lost DVDs). So I made a huge pot of pasta sauce, with plans of making it last for a number of days. Well, after a week I still had lots of sauce, and it still looked and smelled pretty good, so I re-boiled the whole thing for 10-15 minutes to make sure that if had started to spoil anything would be killed off. A week later there was still some sauce left, so I re-cooked it again. I finished the sauce a few days later, but got to wondering, how many time could I have re-cooked the sauce and still been able to safely eat it? For information, it was a tomato-based sauce (a mix of both fresh and canned tomatoes) and also had a bunch of pork sausages in it. If I caught it before anything really took hold and kept it at a killing boil for a proper amount of time, could I keep doing this indefinitely?
In some cases, organisms produce toxins that aren’t killed by heat. Cooking properly or reheating doesn’t help.
I suppose by using liquid nitrogen to cool it, and some kind of high powered flash cooking technique that would turn the food into unrecogizable mush you could keep bacteria from growing in your food. But since you wouldn’t be doing that, then the total time spent between temperatures well over 100F and well below 32F allows bacteria to multiply, and eventually make you sick.
ETA: Telemark makes an good point. Of course those things can kill you on the first cooking.
Yup, there’s plenty of bugs that live through heating, and everytime you cool & reheat stuff, you’re putting it in the “danger zone” of 40-140 degrees F for a while. That’s the zone where all the baddies have parties and make more baddies.
If you really want to do this kind of stuff, freeze it in individual portions, and only take out and reheat the bit you want to eat. That way, you’re only reheating once and storing it properly in between, and your chances of being bit by a baddy go way down.
You’re probably lucky that it was tomato sauce and not, say, beef broth. Tomato sauce is acidic enough that it can help slow bacterial growth. Even so, eventually it’s going to accumulate enough toxins to make you sick.
freezing in meal sized quantities is the way to do it for safety. refrigerated meat might only be safe up to a week to two time period.
freezing in meal sized quantities also gives you more refrigerator capacity. smaller packages make better use of freezer space. also saves energy in that you only heat what needs heating for consumption.
refrigeration and freezing only slow spoilage. freezing could be good for a year for meat.
I kind of get the gist, but am not sure I entirely follow the logic. I understand that there are certain pathogens that won’t get killed by heating and could multiply during the period between 40 and 140F. But are people saying that these heat-resistant pathogens (or their toxins) will accumulate over time as I keep recooking the food? If that is the case, I get the argument.
But I would have thought of it as more of a binary thing: either your food is exposed to them or it isn’t (which is what I think **Tripolar **was saying). In which case you are equally at risk whether you cook the food once or cook it 10 times.
But every time you take a lid off of it, it gets exposed. It’s not like there’s one and only chance for the food to get exposed.
Every time you take it out of the fridge, or even when it’s in the fridge if it’s not sealed properly, it can accumulate spores that are floating in the air, or on that spoon that wasn’t washed good enough, etc…
There’s a reason that hospitals, labs, etc… have to keep sterile instruments in sealed containers/wraps after coming out of the sterilizer, because once it’s open to the air, it’s no longer sterile.
refrigeration and freezing only slow spoilage. home freezing could be good for a year for meat.
in a laboratory, industrially or commercially things can be frozen to lower temperatures. what it is and how cold will determine how long things will last. things will still deteriorate.
in a home refrigerator meat is good for up to a week or two (this is an all depends on what condition it is in). microorganisms still grow at refrigerator temperatures just that they do so slower than at a higher temperature.
toxins if produced by microorganisms will accumulate. taking the food to a killing boiling treatment will kill many microorganisms. new ones get introduced as the pot cools before putting in the refrigerator and while in the refrigerator.
Any time you expose your sauce to the outside world, whether it’s via dumping it in a pan, sticking a spoon in it, or even just opening it up and letting air get at it, you could potentially be recontaminating it. There are bugs everywhere.
Yes, this is the case.
Your food is exposed. All of it. Even your canned food is exposed as soon as you open it. Maybe not to a particularly virulent strain of something like the types of E. Coli you might see on the news, but you can be sure that it’s been exposed to something that, given time, will make you very sick, or worse.
It was exposed when you bought it. It gets more exposed in your kitchen. You kill most of these when you boil the food but no matter how clean you are your house isn’t sterile. As soon as your food cools a bit germs (from the air, from your utensils, from you touching the food, from everywhere) are going to recolonize it. The toxins from this second batch of bacteria are going to add to the toxins of the first. Given enough time the toxin level is going to get high enough to make you sick.
As other posters have said, it IS contaminated, most likely. What we don’t know is how much. It takes a certain number of bacteria to make you sick. So 1 salmonella bacteria isn’t a big deal, it won’t make you sick. But in a very short period of time, that one salmonella becomes 2, and 2 become 4 and 4 become 8 and 8 become 16 and 16 become 32 and 32 become 64 and 64 become 128 and 128 become 256…each generation will double in number. Every bacteria has a different division rate, but the food born ones tend to be very quick dividers, often measured in minutes, not hours. When it hits a certain threshhold (again, different number for different bacteria), then it will make you sick.
This is why reheating is bad - between the temps of 40 and 140 F, you’ve essentially got a bacteria breeding ground. To reheat, you cruise it through those temperatures, and to cool it off again, it goes through those temperatures in reverse. Those temps encourage the growth and division of the bacteria that most often give us food poisoning. Cool it under 40, and they slow division a lot. Get it hotter than 140, and many of them die and thus stop dividing. But in between, it’s like a Roman orgy in there! While many of those bacteria will be killed when you heat it hot enough, in the meantime they’re pissing out toxins that can make you sick all by themselves and which aren’t damaged by heat. Also, you don’t always kill every bacteria, especially if, like most people, you heat your sauce until it’s “hot enough”. Usually “hot enough” for most people’s taste in leftovers is not hot enough to kill most of the bacteria. Leave enough behind, and you will get sick.
For salmonella in particular, the “infective dose” - the amount that has to get in you to make you sick- is 1000000 bacterial cells. If you’re young, elderly or use a lot of antacids, you only need 1000 salmonella bacterial cells to make you sick.
It takes fewer than 1000 listeria bacteria to give you food poisoning, which may lead to meningitis and death in pregnant women and their fetuses. A 1000 cell colony of listeria is smaller than a period in 12 point Times Roman.