Holidays mean food, and lots of it. If you’ve ever dug into the back of your fridge a week after Christmas and wondered if that slice of turkey was still good, or been disturbed by a gurgling stomach after trying it despite your doubts, this story is for you.
To come up with a guide to leftover safety, Global News contacted two experts: microbiologist Jason Tetro, author of The Germ Files and host of the Super Awesome Science Show podcast, and Toni D’Ettorre, supervisor for safe food and water at Ottawa Public Health.
Neglecting food safety with your leftovers can mean nausea, vomiting, diarrhea, and sometimes even fever or chills.
Here’s how to handle your food properly.
How should you properly put away leftovers?
You’ve cooked a nice dinner and served it. Now what? The key is putting the food away quickly.
“Once you have it at room temperature, it essentially becomes a petri plate,” said Tetro.
“Anything that gets onto it is going to grow.”
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Leaving a hot pot of soup to cool slowly on the stove before putting it away is “the worst possible thing you could ever do,” D’Ettorre said. That soup will sit in what she calls “the danger zone” between four and 60 degrees for a long time, allowing bacteria to grow.
“All hazardous foods should not be left out at room temperature beyond two hours. If you’re leaving it beyond that then you’re asking for trouble.”
You should put the food quickly into clean containers, storing different foods in separate containers, and stick it in the fridge, Tetro said. It’s OK if the food is still hot.
How long will your leftovers last?
Generally, most leftovers will last about three days, said D’Ettorre. Health Canada says that cooked meats, poultry, egg, fish and vegetable dishes will last 3-4 days in the fridge.
There’s some judgment involved though, she said. “I don’t know if you’ve ever opened something in your refrigerator and it’s glistening or it’s slimy — those are spoilage organisms. They don’t necessarily cause illness but the product is not good.”
When in doubt, throw it out, public health agencies like to say.
Can you eat leftovers cold, or should you reheat them first?
“Turkey and chicken sandwiches are just awesome. You can’t take that away from people,” Tetro said.
If you’ve stored the food properly and it’s been less than three days, you should be fine to eat it cold, he said. “If after three days you still want to use it, then I would consider heating it so you’re bringing it up to 74 degrees Celsius.”
Re-cooking the food should kill bacteria that’s been growing in it. “As long as it gets over 74 degrees Celsius within the flesh then you’ve got no problems because you’re killing everything,” he said.
Will re-cooking the food ‘restart the clock’ on its spoilage?
Generally speaking, Tetro said, re-cooking food should kill harmful bacteria, meaning it will last longer. So if you’re making a soup out of three-day-old chicken, that leftover soup should, in turn, be good for another few days if it’s stored properly.
“As long as you brought it above 74 degrees Celsius, everything starts fresh,” he said.
But you probably wouldn’t want to do that repeatedly. Aside from gradually spoiling the taste and texture of your food, there are some bacteria, notably staphylococcus, that could get on your food if you touch it with your hands. These secrete toxins that aren’t destroyed by the cooking process and can make you sick.
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Do you have to freeze leftovers right away?
No, says D’Ettorre. It’s fine to have something in the fridge for three days, decide you’re not going to finish it before it spoils, and put the rest in the freezer.
How long do frozen leftovers last?
In one sense, indefinitely, said Tetro.
D’Ettorre agrees. “When a product is in the freezer, it could stay there if your freezer is -18 degrees Celsius. It’s all about the aesthetics of the product.”
Health Canada says cooked meat, egg and vegetable dishes last about two or three months in the freezer, and cooked poultry and fish last about four to six months.
While your food will last, you do have to worry about freezer burn, so it probably won’t taste as good if frozen for a long time.
How should you thaw frozen food?
Don’t let your leftovers thaw on the counter, D’Ettorre said. She recommends letting food thaw slowly in the refrigerator. Letting it sit on the counter once again leaves it in the “danger zone” for too long, allowing bacteria to grow.
Once thawed, you should eat that food within one or two days.
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Can you refreeze food?
Yes, from a food safety point of view, but you probably don’t want to. “The problem is that every time you do a freeze-thaw, you’re destroying the integrity of the meat,’’ Tetro said. Ice crystals that form during freezing will degrade your food further every time you freeze it and thaw it.
If cheese has gone mouldy, can you just cut off the mouldy bits?
“If the cheese is covered in mould, don’t do that. Just throw the thing out. It’s not worth it,” D’Ettorre said. “If there’s just a little area where there’s mould, you could cut about an inch behind that, cut an inch off, then you should be okay.”
Will repeatedly eating questionable foods make your stomach stronger, thereby making you less likely to get sick?
“No! No! That just doesn’t… nooo. It’s not like you can develop an immunity to it. No!” said D’Ettorre, before bursting into laughter.
“It’s not like chicken pox.”