Leftover Food Dangers and How to Avoid Them


In early 2022, information retailers nationwide picked up the story of a school pupil in Massachusetts who needed to get his legs and fingers amputated after alleged food poisoning from leftover lo mein noodles. It turned out that the sickness was truly attributable to a meningococcal blood an infection and had nothing to do with spoiled meals. However the story reminded individuals in regards to the significance of leftover meals security.

What Micro organism Lurk in Your Leftovers?

Micro organism are tough to identify. Many occasions, the contaminated leftovers look, style, and scent wonderful, in accordance with Juan Leon, a researcher at Emory College. Listed here are some widespread bacterial culprits that may lurk in your meals and how one can forestall them:

Bacillus cereus: Raw pasta or rice might include spores of a micro organism known as Bacillus cereus. Spores are tiny protecting capsules that enable the micro organism to hibernate till they’re able to develop. These spores can survive at excessive temperatures, so cooking received’t kill them. After the rice is cooked and cools to room temperature, the micro organism “get up” and begin to develop.

Each the micro organism and its toxins could make you sick. The longer you permit cooked rice or pasta out, the extra doubtless it’s to have these micro organism and their toxins. In the event you eat the contaminated meals, you’ll begin to throw up or have diarrhea inside a couple of hours. These signs can final about 24 hours.

Eat pasta and rice instantly after cooking it. Afterward, cool it shortly by storing it within the fridge. Eat the leftovers inside 1 day. If you reheat it, examine that every one the rice is steaming. Don’t reheat it once more: You probably have any left if you’re completed, throw it out.

Clostridium botulinum: Baked potatoes wrapped in foil are a well-liked and straightforward aspect. However potatoes can include spores of Clostridium botulinum micro organism. These spores can survive oven temperatures. In the fitting circumstances, like when foil locks out oxygen, these micro organism can develop and make the lethal toxin that causes botulism. Paralysis and respiratory issues normally start 18-36 hours after consuming meals contaminated with these toxins.

In the event you roast potatoes in foil, be certain that to eat them or put them within the fridge inside 2 hours.

Clostridium perfringens: These micro organism are intently associated to the germs that may contaminate baked potatoes, however Clostridium perfringens prefers leftover meat. Often, C. perfringens impacts dishes like roast beef and entire turkey. If contaminated meat is cooked and left at room temperature for too lengthy, these spores can begin to develop. After you eat the contaminated meals, the micro organism begin to make toxins in your physique. These toxins trigger diarrhea in 6-24 hours.

All the time cook dinner meat, particularly giant batches of it, to a safe temperature. In the event you’re serving it buffet-style, use a heating machine to maintain it hotter than 140 F. Retailer leftovers within the fridge instantly at 40 F or beneath. Reheat your meals to 165 F during earlier than consuming.

Salmonella: You might need heard that you simply shouldn’t style uncooked cookie dough. That’s as a result of egg and flour can carry Salmonella micro organism. However what in regards to the frozen cookie dough left over from final Christmas? Sadly, freezing doesn’t kill micro organism. So frozen cookie dough nonetheless may carry Salmonella. This kind of micro organism could cause nausea, diarrhea, and fever inside hours or days.

Fortunately, it’s straightforward to take away this sort of micro organism from leftover cookie dough: refrigerate instantly and earlier than having fun with, merely cook dinner or reheat.

Staphylococcus aureus:Staphylococcus aureus micro organism can develop in meals that’s ignored for too lengthy. These micro organism are discovered practically in every single place, from our pores and skin to counter tops, so it’s very straightforward for meals to change into contaminated. Staphylococcus don’t type spores, however they do make toxins that trigger stomach ache and diarrhea. Reheating the meals will kill the micro organism, however the toxins will stay. The micro organism can develop in a wide range of meals, together with meat, eggs, salads, dairy merchandise, and baked items.

To assist forestall Staphylococcus poisoning, don’t go away leftovers unrefrigerated for greater than 2 hours.

The Significance of Hand-Washing

Even when your leftovers are refrigerated and saved safely, touching them with soiled fingers may introduce new germs, bacterial and in any other case.

“With some microorganisms, you want little or no to trigger a giant impact,” Leon says. For instance, solely 18 norovirus particles are sufficient to make somebody sick.

To place that in perspective, an contaminated particular person has “about 10 billion noroviruses per gram of stool [poop], and every of us defecates (poops) about 200 grams of stool,” in accordance with Leon. In the event you don’t wash your fingers earlier than grabbing that slice of chilly pizza, it might be very straightforward to unfold these germs.

When getting ready leftovers in his personal kitchen, Leon by no means skips the nice and cozy water and cleaning soap. “Fingers are typically the almost certainly automobile of meals contamination,” he says, “So when you care for hand hygiene, usually you’re wonderful.”

There’ll all the time be some threat, Leon highlights. “We are going to by no means get all the way down to zero threat, however what we are able to do is cut back the chance as a lot as potential by working towards good meals security habits.”

Suggestions for Leftover Meals Security

The method of storing, thawing, and reheating leftover meals gives many alternatives for micro organism to develop, in addition to different well being dangers. You possibly can assist defend your self from the 5 widespread varieties of micro organism (and different germs) in leftovers by following these tips. Keep in mind to scrub your fingers earlier than finishing any of those steps.


Micro organism develop quickest at 40 to 140 F, or anyplace between the temperature of your fridge and a scorching cup of tea. These temperatures are known as the “meals hazard zone.”

After you eat, cool your leftovers quickly so that they don’t keep within the hazard zone for too lengthy. Don’t go away meals in your countertop for greater than 2 hours (or 1 hour, if it’s 90 F or hotter). Put leftovers within the fridge instantly, even when they’re nonetheless scorching. You probably have loads of leftovers and are fearful about heating up your fridge, strive dividing the meal into smaller containers. Smaller parts cool extra shortly than bigger parts.

Correct storage will assist preserve moisture in and micro organism out. Wrap leftovers tightly or seal them in hermetic containers.

Most refrigerated leftovers are protected for 3-4 days. In the event you received’t be capable of eat the leftovers inside 4 days, freeze them. They’ll normally keep protected within the freezer for 3-4 months.


You possibly can thaw meals within the fridge, chilly water, or the microwave. The fridge technique is most secure as a result of it retains the complete dish at a protected temperature the entire time. In the event you use chilly water, defend the meals in a sealed bag. Make certain the bag doesn’t have any holes; if it leaks, micro organism out of your sink can splash onto the meals. In the event you thaw meals within the microwave, use a meals thermometer to examine that the leftovers are heated to a minimum of 165 F.

Eat or refreeze thawed meals inside 3-4 days. In the event you thaw meals with the chilly water technique, cook dinner the leftovers earlier than refreezing.


Search for containers which might be labeled as microwave-safe. Don’t reheat takeout containers or frozen dinner trays. Glass, paper, ceramic, and a few varieties of plastic are protected to reheat in a microwave. However some varieties of plastic include chemical substances that may leak into your meals whereas being microwaved. Reheating fatty meals like meat or cheese can increase your possibilities for contamination. These meals can shortly attain excessive temperatures, inflicting plastic to soften. In the event you use plastic wrap, don’t let it contact the recent meals.

When reheating meals within the microwave, cowl the dish and rotate it incessantly. Make certain the masking has holes so steam can escape. Microwaves can go away chilly spots, so let the meals relaxation a minute so the warmth can unfold. Then examine the temperature in a couple of totally different locations. It must be steaming during.

When reheating sauces, soups, and gravies on the stovetop, convey them to a rolling boil. Cowl the pot with a lid to protect moisture and assist the meals reheat evenly.

Whether or not you might be utilizing the microwave or the range, warmth leftovers till they’re 165 F during. Verify the leftovers’ inside temperature with a meals thermometer. Don’t reheat issues in a strain cooker, as a result of they don’t all the time get scorching sufficient to kill micro organism.

If in Doubt…

When unsure, throw it out. Don’t style iffy leftovers. You usually can’t style or scent harmful germs.


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