Are those leftovers safe to eat?

Are those leftovers safe to eat?

Someday you’ll pull something from the fridge and wonder, is this okay to eat?

Sometimes the answer is obvious . . . but sometimes it’s not, and that’s because the organisms that cause food to rot and decay are different from the ones that cause illness. In the circle of life, things that used to be alive but aren’t anymore get broken down into smaller bits and recycled.

The obvious signs of bad food — off colors, bad smells, mushiness, mold — are generally due to natural enzymatic action and the business of microbes scavanging for nutrients. The bad actors like Salmonella E. coli don’t announce themselves.

So how can you tell?

The answer lies in whether the food was prepared safely, and whether it was stored properly both before and after.

Your food comes pre-inoculated with thousands of varieties of microbes and it picks up more around your house. You can’t get rid of them all and you can’t keep them from reproducing — the best you can do is keep them under control.

Have at least 3 thermometers. Keep one in your refrigerator and check it frequently to make sure the temperature is always below 40 F, never warmer. One goes in your freezer to be sure it maintains a frosty 0 F. And keep a food thermometer handy for those times when you need to make sure food is either cold enough or hot enough.thermometer

Keep hands and work surfaces clean. You may not feel sick, but you are still covered in germs that could affect someone else, so wash your hands frequently. Use separate cutting boards for animal products (especially raw meats) and produce, or sterilize them between uses. Transferring bacteria from a raw food you’re going to cook to a raw food you’re not going to cook (eg, turkey to salad) is just asking for trouble.

Keep cold foods cold and hot foods hot. The range of temperatures between 40 F and 140 F is known as the “danger zone,” because that’s where bacteria grow best. Limit the amount of time perishable foods spend there.

Refrigerate leftovers after 2 hours. Sure, you’ve left your Thanksgiving dinner sitting out all day while you had dessert and watched football and no one got sick then, but that was the time you got lucky. Don’t leave perishables marinating in the danger zone.

That thing about letting hot foods cool on the counter before putting them in the fridge? Once upon a time an icebox was literally a big block of ice in a box, and steamy foods caused the ice to melt faster. Your electric refrigerator can handle hot foods just fine.

Reheat leftovers to 165 F. Even properly handled food isn’t sterile, and bacteria will continue to grow. It’s fine to eat leftovers straight out of the fridge, as long as you’ve kept them at 40 F or lower.

Nothing lasts forever. If you want to really stay on top of your game, date your leftovers and clear them out before they age out. has a handy food storage chart. Cooked turkey and foods with meat in them can be kept in the fridge 3 to 4 days, cooked veggies about a week.

Btw, not all bugs are bad

Not chocolate yet.

Wikipedia, that vessel for all that is known, has an entire page listing the microbes used in food production. These are the germs that are put in there on purpose because they do good things. Take the first entry on the list: Acetobacter aceti. As you might guess from its name, this bacterium produces acetic acid as a metabolic byproduct. You likely have at least one bottle of diluted bacterial byproducts in your kitchen now. Balsamic, apple cider, distilled, doesn’t matter – however your vinegar started out in life, bacteria made it what it is today.

If that surprises you, check this out: A. aceti is just one of many microbes that are used to produce that food of the gods, chocolate. Before they can be turned into something fit for eating or drinking, cocoa beans must be fermented, dried and roasted. Acid-producing bacteria are essential to developing flavor, color and aroma during the fermentation process. Yum.

Also, your gut is loaded with bacteria that fight off hostile microbial invaders, synthesize critically important vitamins and aid in digesting your food — in fact, up to 30% of your feces is dead bacteria. You are a walking container for a microbial biome so vast you are likely more them than you. Scientists are still refining the numbers but the germs we carry around may far outnumber the cells that make up our bodies.


More information

USDA Leftovers and Food Safety

Storage times for the refrigerator and freezer

The Microbes We Eat

FDA Bad Bug Book

Microorganisms and food spoilage (lecture outline)

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