Is properly storing leftovers really important?

As long as you remember to close the pizza box to keep rodents out, you're good—right?

Perhaps unsurprisingly, that's not the best way to avoid food poisoning. In fact, even if you're fairly careful about how you store your leftovers, you're probably making a few mistakes. Ditto for your fruits and vegetables; chances are, your habits are wasting something, whether that’s flavor or edibility.

Julie Garden-Robinson, PhD, RD, is a professor and food and nutrition specialist at the North Dakota State University Extension Service. She gave us a few tips for avoiding some common pitfalls of food storage.

For instance...

Keep hot stuff hot (and cold stuff cold).

Garden-Robinson recommends the pneumonic device "FAT TOM" to remember the things bacteria need to flourish: food, acidity, time, temperature, oxygen, and moisture. Protein-rich foods, like meat and dairy, are particularly susceptible to bacteria growth, while pickles and other acidic foods have fewer bacteria issues. With that said, almost any food can harbor bacteria, given the right conditions.

The major factors you can control to reduce bacteria growth are time and temperature.

"Bacteria can double in number about every 10 to 15 minutes in the right circumstances, but if we control the temperature, we can slow the growth of bacteria," says Garden-Robinson. "We consider the temperature danger zone to be 40 to 140 degrees Fahrenheit."

As such, it's important to keep foods out of that danger zone, especially if they're cooking all day.

"We recommend no more than two hours in the temperature danger zone when preparing and serving perishable foods," she says.

If you're serving food at a summer picnic, the acceptable time for serving food drops to one hour. That's yet another reason to eat those pork chops as soon as they come off of the grill.

What if you need to wait longer? You can maintain safe temperatures longer by nesting salad bowls and other cold food in containers of ice. Likewise, you can keep hot foods above the 140-degree threshold by serving them in slow cookers.

Don't put your slow cooker directly into the refrigerator.

Cold food items can go directly into the fridge once the food has been served. Hot food requires a little more care; your goal is to bring the food from above 140 degrees to below 40 degrees as quickly as possible.

The key is to store food in small quantities. Avoid the temptation to stick a whole crock pot in the fridge (yeah, we've done it, too).

Crock pots are designed to hold heat, so they'll continue to (slowly) cook your meal. They'll also raise the temperature of the refrigerator itself, which could endanger the other cooled foods. Divide the food into smaller quantities as soon as you can—preferably right after you're finished cooking.

"For instance, cut a roast into thinner slices and place thick stew into shallow pans with no more than two inches of food," Garden-Robinson says.

This might seem like a lot of work, but it's safe and potentially quite efficient, since the small quantities make for easy meal prepping. We recommend picking up some cheap meal prep containers from a site like Amazon.

To bring the heat down as quickly as possible, Garden-Robinson also recommends placing leftover containers in an ice bath before putting them in the fridge. This helps to prevent your leftovers from heating up the other foods around it.

And this should be obvious, but we'll say it anyway: Leftovers should be covered to keep the food fresh and to prevent cross-contamination. If the food is still warm when you put it in the fridge, you can tent some aluminum foil over the top so that heat disperses more quickly. If you go this route, just be sure to tighten the foil once the food has cooled down.

When it's time to reheat your leftovers, use extra caution.

It's important to thoroughly heat your leftovers to get rid of any harmful bacteria in the food. That means cooking it to at least 165 degrees or to a rolling boil for liquids. If you're using a microwave, make sure to stir your food occasionally to get rid of cold spots.

What happens if you forget about your leftovers for a few days? Are they still safe to eat?

That's a complicated question, but the scientists at North Dakota State University (NDSU) have a helpful cheat sheet that shows how long different foods last in the fridge. Some of the recommendations are a bit surprising: Pasteurized blue crab meat can last up to six months in a refrigerator, while cooked beef or chicken ("in gravy") should be eaten within two days.

If you're used to storing leftovers for weeks at a time, we've got some bad news. According to NDSU's food storage guide, your refrigerator isn't quite the superpowered preservative tool you thought it was. However, freezing leftovers gives you a much larger window, provided that you freeze food fairly quickly after you cook it.

If you're freezing meat, be careful when thawing.

The most effortless thawing method—placing the meat into the refrigerator—isn't perfect. According to Garden-Robinson, a pound of meat thaws in a about a day. She recommends thawing meat in a pan or a bowl on the lowest shelf of the refrigerator. If raw meat juice accidentally drips out, you don't want it falling on top of other food.

For a quicker thaw, you've got to do some work.

"Place the meat in a leak-proof plastic bag, and place [it] in a container of cool water—70 degrees [Fahrenheit]," she says. "Change the water every 30 minutes. Completely cook cold-water thawed meat immediately. If you decide you do not need the thawed meat, cook it to the 'done state' before refreezing."

Finally, you can thaw meat in your microwave using the manufacturer's settings. Just be sure to cook the meat all the way before refreezing if you decide to eat something else.

You're probably making a few simple mistakes with your potatoes.

According to Don Odiorne (a.k.a Dr. Potato), the vice president of foodservice for Idaho Potatoes, storing potatoes in the fridge is a bad idea. The cold temperature causes their starch to convert to sugar, giving them a sweet taste.

This chemical reaction can also cause fried potatoes to blacken in an unappetizing way. Well, unappetizing to us—we're not going to speak for you, but we're not fans of spongy, black spuds.

The ideal place for storing potatoes is somewhere cool (between 42 and 55 degrees Fahrenheit), dark, humid, and well-ventilated. Potatoes need fairly specific conditions because they are still alive when they are picked.

In fact, if most of your potatoes seem to go bad before you use them, you can probably figure out what's causing the problem. Warm temperatures can cause spuds to sprout or develop disease; dry environments wither them; direct light can cause green spots that have a bitter taste. These spots can be cut off, but you can also avoid them by picking a better storage location.

Odiorne recommends keeping potatoes in your cellar, but if you don’t have one of those, you can always just toss them in a pantry closet. If you want to peel potatoes ahead of time for, say, a Thanksgiving feast, you can store them in chilled or ice water in the fridge for no more than 24 hours. Adding a teaspoon of lemon juice will keep them from turning black from oxidation.

Wonder why your tomatoes are tasteless?

The article "Chilling-Induced Tomato Flavor Loss is Associated With Altered Volatile Synthesis and Transient Changes in DNA Methylation" tells you everything you need to know. If you're short on time—or if you don't feel like deciphering phrases like "DNA methylation"—here's a one-sentence summary: refrigeration extends the life of a tomato but ruins the flavor.

The Washington Post has been following the problem of tasteless commercial tomatoes for years. Columnist Rachel Feltman explained that grocery-store tomatoes are generally picked while green, ripened with ethylene, and then refrigerated until they're ready for sale. This leaves them lacking the vibrant flavor of their homegrown counterparts.

In a perfect world, tomatoes would be picked while ripe and sold soon afterwards. Unfortunately, this process is not feasible for supermarkets. They sell produce year-round in mass quantities, which requires shipping tomatoes long distances (in the winter, most of them come from Florida).

However, during the summer and fall, a great option for freshly picked tomatoes is a farmers market. Of course, you can always grow your own if you're looking for something even fresher. Store them on the kitchen counter until you're ready to eat them. They won’t go bad—they used to live outside, after all.

Plan routines to avoid wasting your food.

The key to keeping food safe and tasting great is to plan for the short term. You may have to grocery shop twice per week, but you'll have better-tasting food without risking an illness. Try making a large batch of chili, lasagna, or soup on Sunday and freezing individual portions to reheat throughout the week.

Don't stock your fridge with fresh meat if you aren't sure you'll eat it within 48 hours. Don't buy the 10-pound bag of potatoes if it will take you a month to get through them. And always remember Garden-Robinson's go-to adage on determining whether to eat or toss an iffy item: "When in doubt, throw it out."

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