Leftovers and food safety
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mtaratoot
Posts: 13,567 Member
There are a number of good resources on how long it is safe to store foods including leftovers. The USDA is the go-to resource in the USA. The USDA is also pretty conservative because they really don't want anyone to get sick. They recommend keeping leftovers no more than three or four days in the refrigerator. Many foods are probably safe beyond that time, but let's just go with USDA's recommendation because it's solid.
Now let's say you have had some cooked food properly stored in the refrigerator for two or three days, then you use it as an ingredient in a new dish. An example would be smoking a pork shoulder to make pulled pork, freezing some, and leaving some in the refrigerator and then using some of the refrigerated pork to add to a pot of delicious mayocoba beans you just cooked. Does the new dish get a new start date for the 3-4 day safe food count, or does the original best-by date from the pork trump the dish and it needs to be eaten in one to two days.
I searched the USDA website and couldn't find an answer. I think I know the answer, and I've asked USDA. In the meantime, what do YOU think?
Now let's say you have had some cooked food properly stored in the refrigerator for two or three days, then you use it as an ingredient in a new dish. An example would be smoking a pork shoulder to make pulled pork, freezing some, and leaving some in the refrigerator and then using some of the refrigerated pork to add to a pot of delicious mayocoba beans you just cooked. Does the new dish get a new start date for the 3-4 day safe food count, or does the original best-by date from the pork trump the dish and it needs to be eaten in one to two days.
I searched the USDA website and couldn't find an answer. I think I know the answer, and I've asked USDA. In the meantime, what do YOU think?
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While thinking about this question, I recalled a time when I lived in an apartment with five other guys from all over the world. Two were from China, and one was from Taiwan. They would keep a pot on the stove and throw things in it each night. They often had things I wouldn't normally consider eating, but that's neither here nor there. Here's what they did after they ate:
They just left the pot on the stove. The stove was off, and the pot just sat on top. Each night, they'd add a little more meat and some fresh vegetables and re-cook it. I urged them to put the pot in the refrigerator rather than leaving it out all day. They said it was a traditional cooking style. Scared the heck out of me..... And I'm sure the USDA would have told them please don't do that. It's well past the two hours the USDA recommends before food becomes potentially unsafe.
They never got food poisoning.
So my question about recooking foods that have been stored properly SEEMS obvious that it SHOULD be ok... What am I missing?
Clostridum toxin can't be denatured by cooking. So if food is contaminated with Clostridum botulinum and has produced toxin, it already isn't safe to eat. Cooking would have no effect on the toxin, but it would kill the organism.
So am I missing something?0 -
165F seems to be the tipping point. Above 165F there are none of the common micro organisms present. Yes, there could possibly be some spores or encased eggs or some rare critters, but please, you don't have to show everyone how smart you are today.
For all practical purposes, food is sterile when it is cooked above 165F and not re-contaminated.
There is the fly in the ointment. Fooling around with the dish letting ambient air in, etc. will start a new breed of critters.
You can take the left over pot, bring it back up to temperature, slip oven resistant plastic wrap over it and put the lid on and refrigerate and definitely get 3 days out of it. I just freeze it unless it is pasta which doesn't freeze well.0 -
I do not recall the exact temperatures off the top of my head BUT I had a chat with a registered dietician about food safety for some college boys I knew. They used to leave the crocpot on warm FOR A WEEK and eat the pulled pork from said pot when it finished cooking on Monday. She said technically speaking, this was safe. But gross.0
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alexandramosenson wrote: »I do not recall the exact temperatures off the top of my head BUT I had a chat with a registered dietician about food safety for some college boys I knew. They used to leave the crocpot on warm FOR A WEEK and eat the pulled pork from said pot when it finished cooking on Monday. She said technically speaking, this was safe. But gross.
Kind of depends on what the temperature of "Warm" actually is. I don't think my crockpot would go below a temperature that I would actually consider pretty hot, even on the lowest setting. Restaurants are taught to keep things either hot or cold and avoid the "danger zone" between 40 and 140 deg F. I don't think there is a maximum time for holding above 140 from a food safety standpoint but the quality of the food will deteriorate faster at a higher temperature.0 -
There are a number of good resources on how long it is safe to store foods including leftovers. The USDA is the go-to resource in the USA. The USDA is also pretty conservative because they really don't want anyone to get sick. They recommend keeping leftovers no more than three or four days in the refrigerator. Many foods are probably safe beyond that time, but let's just go with USDA's recommendation because it's solid.
Now let's say you have had some cooked food properly stored in the refrigerator for two or three days, then you use it as an ingredient in a new dish. An example would be smoking a pork shoulder to make pulled pork, freezing some, and leaving some in the refrigerator and then using some of the refrigerated pork to add to a pot of delicious mayocoba beans you just cooked. Does the new dish get a new start date for the 3-4 day safe food count, or does the original best-by date from the pork trump the dish and it needs to be eaten in one to two days.
I searched the USDA website and couldn't find an answer. I think I know the answer, and I've asked USDA. In the meantime, what do YOU think?
I don't have great theory, but in the kind of scenario you describe, I mostly don't worry about food poisoning if the food has been reasonably handled (not left sitting at room-ish temps very long, maybe well-reheated between trips to frig/freezer, etc.). Quality decline may be an issue, maybe not so much food safety?
I'm sure I'm biased by being vegetarian, but mostly I figure that if such a food looks OK, smells OK, it's probably OK . . . though I might have a bias toward heating in the later stages. For veg foods, I feel OK with restarting the day count after a thorough re-heat. (That's for things under aerobic conditions. Anaerobic, dunno.) I literally have zero thoughts about meat, haven't had any food meat in the house since not having cats, no meat for humans that I can recall since 1998.
What do you think the answer is? What did USDA say (if they did)? Did you try your local extension service office or health department? (I admit I wouldn't try the health department now, mid-pandemic. They have their hands full.)While thinking about this question, I recalled a time when I lived in an apartment with five other guys from all over the world. Two were from China, and one was from Taiwan. They would keep a pot on the stove and throw things in it each night. They often had things I wouldn't nor? mally consider eating, but that's neither here nor there. Here's what they did after they ate:
They just left the pot on the stove. The stove was off, and the pot just sat on top. Each night, they'd add a little more meat and some fresh vegetables and re-cook it. I urged them to put the pot in the refrigerator rather than leaving it out all day. They said it was a traditional cooking style. Scared the heck out of me..... And I'm sure the USDA would have told them please don't do that. It's well past the two hours the USDA recommends before food becomes potentially unsafe.
They never got food poisoning.
So my question about recooking foods that have been stored properly SEEMS obvious that it SHOULD be ok... What am I missing?
Clostridum toxin can't be denatured by cooking. So if food is contaminated with Clostridum botulinum and has produced toxin, it already isn't safe to eat. Cooking would have no effect on the toxin, but it would kill the organism.
So am I missing something?
In the common situation, I don't think clostridium is the biggie, and that's not how I understand the stuff. Clostridium is anaerobic, and won't grow in an acidic environment. Also, WHO says the toxin is neutralized by sufficient heat, though the spores aren't:Though spores of C. botulinum are heat-resistant, the toxin produced by bacteria growing out of the spores under anaerobic conditions is destroyed by boiling (for example, at internal temperature greater than 85 °C for 5 minutes or longer).
From: https://www.who.int/news-room/fact-sheets/detail/botulism
I admit that there have been issues with botulinum toxin in some low-acid foods (minced garlic in oil comes to mind) under home conditions (I believe including refrigerated), but the common case is in preserved (canned, loosely) low-acid foods, because of the anaerobic conditions. That's IMU why water bath canning works for acidic foods, but need pressure canning (hotter) for low acid. (People screw up salsa sometimes, thinking it's acid, when it may not be due to non-tomato ingredients, low-acid tomatoes, unless there's vinegar or something to get the pH right.)
I think other pathogens are more common (if less fatal) worries. In the US, norovirus, salmonella, clostridium, campylobacter and staph are reportedly the biggies.0 -
What do you think the answer is? What did USDA say (if they did)? Did you try your local extension service office or health department? (I admit I wouldn't try the health department now, mid-pandemic. They have their hands full.)
I think the answer is that if you reheat it enough to pasteurize (time + temperature), you would invalidate any spoilage organisms. I think the date count should start over. The USDA won't even read my question until at least tomorrow. It's a holiday for Federal employees.In the common situation, I don't think clostridium is the biggie, and that's not how I understand the stuff. Clostridium is anaerobic, and won't grow in an acidic environment. Also, WHO says the toxin is neutralized by sufficient heat, though the spores aren't:
Indeed. Clostridium is an anaerobe. All the other spoilage organisms that I know of make you ill when you ingest the organism. That's why I think the answer is you get to restart. The food was still safe when you used it as an ingredient, then you cooked it.I admit that there have been issues with botulinum toxin in some low-acid foods (minced garlic in oil comes to mind) under home conditions (I believe including refrigerated), but the common case is in preserved (canned, loosely) low-acid foods, because of the anaerobic conditions. That's IMU why water bath canning works for acidic foods, but need pressure canning (hotter) for low acid. (People screw up salsa sometimes, thinking it's acid, when it may not be due to non-tomato ingredients, low-acid tomatoes, unless there's vinegar or something to get the pH right.)
I think other pathogens are more common (if less fatal) worries. In the US, norovirus, salmonella, clostridium, campylobacter and staph are reportedly the biggies.
Listeria, E. coli, and salmonella can do a body some pain. If the leftover ingredient was free of Listeria, I don't know how it would get contaminated other than from the new ingredients. The other two could be problematic, but cooking kills them.
Not sure why I even questioned it, just thought it might be an interesting topic to ponder. I'm keen on food safety, although I do like to let certain vegetables "rot" in some brine in my kitchen.1 -
You betcha. But botulism has that "most potent biological toxin" rep, and is neurotoxic, which is creepy.What do you think the answer is? What did USDA say (if they did)? Did you try your local extension service office or health department? (I admit I wouldn't try the health department now, mid-pandemic. They have their hands full.)
I think the answer is that if you reheat it enough to pasteurize (time + temperature), you would invalidate any spoilage organisms. I think the date count should start over. The USDA won't even read my question until at least tomorrow. It's a holiday for Federal employees.In the common situation, I don't think clostridium is the biggie, and that's not how I understand the stuff. Clostridium is anaerobic, and won't grow in an acidic environment. Also, WHO says the toxin is neutralized by sufficient heat, though the spores aren't:
Indeed. Clostridium is an anaerobe. All the other spoilage organisms that I know of make you ill when you ingest the organism. That's why I think the answer is you get to restart. The food was still safe when you used it as an ingredient, then you cooked it.I admit that there have been issues with botulinum toxin in some low-acid foods (minced garlic in oil comes to mind) under home conditions (I believe including refrigerated), but the common case is in preserved (canned, loosely) low-acid foods, because of the anaerobic conditions. That's IMU why water bath canning works for acidic foods, but need pressure canning (hotter) for low acid. (People screw up salsa sometimes, thinking it's acid, when it may not be due to non-tomato ingredients, low-acid tomatoes, unless there's vinegar or something to get the pH right.)
I think other pathogens are more common (if less fatal) worries. In the US, norovirus, salmonella, clostridium, campylobacter and staph are reportedly the biggies.
Listeria, E. coli, and salmonella can do a body some pain. If the leftover ingredient was free of Listeria, I don't know how it would get contaminated other than from the new ingredients. The other two could be problematic, but cooking kills them.Not sure why I even questioned it, just thought it might be an interesting topic to ponder. I'm keen on food safety, although I do like to let certain vegetables "rot" in some brine in my kitchen.
Yup, is. I hadn't really thought much about it before, but I probably over-rely on appearance/small/cautious taste, less on good rules. My fridge is set a little too cold, which I think tends to hold some things a little longer, too (some freeze!).
It does seem to me that meat is a little more challenging, but that may just be inexperience talking. Certainly, it's vegetables that have been causing most of the well-publicized food poisoning outbreaks in recent years, though more about farming & processing issues, rather than home storage ones.
The "garlic in oil" (or "herbs in oil") one is about home processing/storage, though. And I do follow the rules scrupulously if canning, like testing pH if I'm not sure that water bath is OK.
The one I've wondered about is the old practice of putting up jam/jelly in jars sealed with paraffin. I know it's no longer recommended, but I ate lots of it growing up that had been preserved that way. I know it's the sugar factor that helps make that semi-work.0 -
I heard back from USDA.
Let me first say that I'm impressed with the speed that they got back to me. I sent my question during a three-day weekend, and their replies came in their first morning back in the office. Sweet.
I got two replies. The first one may have been automated. It said that my request was being forwarded, and it gave some feedback that was essentially what already is available on their website - safe times to keep leftovers and appropriate temperatures.
Within one hour (ONE hour) I got a more detailed answer from an actual human being.
As we postulated, if the leftovers were cooled quickly and kept out of the danger zone for no longer than the recommended time and then reheated to 165 as they were cooked into another dish, the clock resets.
This makes sense, and it's what I would have done. It's actually what I did. It's still good to know that USDA agrees that this is a safe practice.
I may delete this discussion because it's kind of obscure and probably won't really help anyone.1 -
I heard back from USDA.
Let me first say that I'm impressed with the speed that they got back to me. I sent my question during a three-day weekend, and their replies came in their first morning back in the office. Sweet.
I got two replies. The first one may have been automated. It said that my request was being forwarded, and it gave some feedback that was essentially what already is available on their website - safe times to keep leftovers and appropriate temperatures.
Within one hour (ONE hour) I got a more detailed answer from an actual human being.
As we postulated, if the leftovers were cooled quickly and kept out of the danger zone for no longer than the recommended time and then reheated to 165 as they were cooked into another dish, the clock resets.
This makes sense, and it's what I would have done. It's actually what I did. It's still good to know that USDA agrees that this is a safe practice.
I may delete this discussion because it's kind of obscure and probably won't really help anyone.
Good to know. I'd encourage you not to delete it: It'll roll off into history pretty quickly if no one comments, and it's solid useful information . . . unlike a lot of those historical threads!1 -
I might just leave a big pot of stew or other leftovers in my kitchen, depending on the season. In summer it certainly goes into the fridge, in winter it's fine. never got sick. One thing I never do, and what I learned from people in Asia/India: never keep rice! It apparently develops a toxin that might make you sick. This also seems to be true for the fridge. So I always cook fresh rice.0
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@yirara
I think you are mistaken about rice. You can totally keep leftover rice for a few days in the refrigerator. It is a very good growth medium, though, so you should be sure to keep it hot until you chill it rapidly before saving it. One of the organisms that can grow does create a toxin that can cause food-borne illness.
I work in a sushi restaurant three days per year at an annual festival. Well, I used to. The festival hasn't been held for a couple years. At the end of the first and second day, we often have a little rice left over. We take it to the refrigerated truck to use the next day. The quality of chilled day-old sushi rice isn't as good as freshly made and chilled, but it works. In fact, I've seen commercially prepared sushi available at grocery stores that stays on the shelf a few days. At least a day or two.
At home if I have extra rice (unlikely; I only cook a little because otherwise I will EAT IT ALL), I like to mix it with spices and seasonings in the morning, maybe some vegetables, mix with an egg or two, and fry into a delicious rice pancake. Day old rice is also good to use to make fried rice.
But yes, rice IS a good growth medium, so it has to be treated appropriately.
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I never have any problem with leftover rice. I always cook a cup and then portion it in quarters for four rice-based meals. It goes straight from the rice pan to a Ziplock bag and into the Fridge.
Sometimes it takes a week. If I don't get it used in a week it goes in the freezer. Even better for fried rice. I make a dish imitating Nooroongji but much Americanized.0 -
I am very OCD about tossing anything leftover after the 3 day mark (unless it's frozen). I've never looked into it and don't have really any science on it...it's just a thing of mine and it frankly wouldn't matter to that part of my brain even if they said you can just keep this in the fridge for a month and it'd be ok.1
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