​One of the biggest issues with holiday meals, especially Thanksgiving or Christmas meals, is that the food tends to sit out all day, making it risky to consume later.
After about two hours at room temperature, quality starts to decline. The amount of potentially illness-causing bacteria in food can double in as little as 20 minutes. As a rule of thumb, bacteria grow rapidly between 40°F and 140°F — the danger zone, according to the U.S. Food and Drug Administration (FDA).​
Even though it may be fun to watch football and graze all day, unless you are keeping your cold food on ice or your hot food consistently hot, you run the risk of getting sick.​
Leftovers will generally last in the fridge for three to four days, but that’s not the case if the food has been sitting out all day.​
If anything sat out for hours or traveled long distances home with you after the meal, it is best to consume it within the next day or two,
Throw these items away
​Be especially suspicious of those grazing platters people nibble on all day long. Things like cheese plates, seafood platters and even crudités will have lots of hands touching them throughout the day, increasing the risk of contamination. Raw seafood and softer, more perishable cheeses like Brie or blue cheese should be disposed of, no matter what. Dips can oxidize or form a skin, and even if they are still safe to eat, they likely won’t taste as good when they are leftovers.​
Keep in mind that you can’t see or smell foodborne illnesses, so if in doubt, throw the food out.
Refrigerator storage tips
​Storing your leftovers properly will ensure that they last, taste good and are safe to eat. Make sure your fridge is set at 40°F or below. If you aren’t sure, an appliance thermometer can help.​
Put cooked proteins in the refrigerator as soon as the meal is over. Generally, items that are high in protein, moisture or acid are more prone to bacteria growth and have the tendency to spoil quicker,
Don’t be afraid to start packaging up the turkey before the meal is over — it could make a huge difference in terms of food safety.​
It’s also imperative to cool down your food before putting it in the fridge. According to the FDA, One of the most common causes of foodborne illness is improper cooling of cooked foods.
That’s because bacteria can be reintroduced even after the food is cooked. Cooling food down before refrigerating it “reduces the condensation that will form inside the container,” Roszkowski says, “which is helpful, because the added moisture can influence the amount of spoilage-causing bacteria that can grow in the coming days.” ​
What’s more, putting too many hot things in the refrigerator at once can warm it up. Temperatures inside the fridge need to stay at 40°F or below for safe food storage.​
To more quickly cool larger proteins, such as a whole turkey, ham or roast, break them into smaller portions and then refrigerate.​
Slice breast meat; legs and wings may be left whole. You’ll want to slice roasts too,
To cool vegetables faster, lay them on a sheet pan before packaging. Don’t worry about getting them to room temperature, because if they’re stored in small batches, they will quickly cool in the fridge.​
Food storage options
​Consider different storage options. A vacuum sealer is an excellent tool. Because it removes all the air from the bag, it deprives bacteria of the oxygen it needs to grow and helps food last longer.​
If you are using glass or stainless steel containers, consider placing food into small, shallow, two-inch-thick containers for faster cooling. That’s better than, say, one huge container of mashed potatoes. It also helps you reheat leftovers evenly.​
Glass containers and ones made of stainless steel hold on to coldness better because of the conduction properties of these materials,
If possible, place your leftovers toward the back of the refrigerator and on a lower shelf, where it’s generally cooler. Never store leftovers in the fridge’s doors — the temperature is warmer and inconsistent as people open and close them.​
Use the freezer for longer storage
​If you don’t think you’ll be eating the leftovers over the weekend, freezing is the best option. You can store food for up to three or four months in the freezer. ​
Foods That Last Longer Than You’d Think
“A lot of pies actually freeze well,” says Jupiter. He advises wrapping food carefully to prevent freezer burn. Ziploc bags are fine, but add an extra layer of plastic wrap or freezer paper.​
Some items don’t freeze well:​
Gravy, which can get icy and gritty (unless it’s stored in a vacuum-sealed bag).​
Some desserts like fruit tarts.​
Mashed potatoes, which won’t retain their texture if frozen.​ Some cooked casseroles, especially those with lots of vegetables, due to high water content.​
Foods made with mayonnaise.​
Repurposing leftovers ​
If you are going to take the time to store your leftovers, have a plan for how to use them. Label leftovers with the name of the dish and the date to help you remember what you have and when you need to use it by.​
Many people don’t love simply repeating the Thanksgiving meal the next day. Jupiter recommends researching creative repurposing options beyond turkey sandwiches, such as breading the mac and cheese and turning it into mac and cheese bites. Day-old pastries are great for bread pudding, and leftover dinner rolls can be used to make bread crumbs.​
How to reheat leftovers​
Most leftovers dry out a bit when reheated, so you’ll want to add a little stock (or water in a pinch). Reheat leftovers to at least 140°F degrees so they’re safe to eat. Your stovetop or oven will usually yield the best results, but you can use the microwave if that’s most convenient. Just make sure everything is heated through consistently.​
If you own a sous vide, a tool for thermal immersion cooking, you can take your vacuum-sealed bags and reheat them to the exact proper temperature. Plus, you won’t have to worry about your leftovers drying out.