Why shouldn't you use aluminum foil to wrap leftover food?

Don't use aluminum foil to store leftovers. Here's why there are safer ways to store leftovers.

 

What is silver paper?

Foil , as the name suggests, is mostly aluminum—98.5%, combined with iron and silicon to make it puncture-resistant, according to the United States Department of Agriculture (USDA). Manufacturers press it between rollers to thin it.

Aluminum foil comes on both glossy and matte sides, but it doesn't really matter which side you use. The exception: when using the " non-stick " kind to heat food, in which case you'll want to choose the matte side because it has the non-stick coating.

Why should you avoid using aluminum foil to store leftovers?

There are a few problems with wrapping leftovers in foil, and they all relate to food safety.

Is aluminum foil toxic? Which leftovers pose the greatest risk? Do you really need new food containers? We'll explore these topics, along with why you should avoid removing aluminum foil from containers to store leftovers.

Aluminum foil can cause bacteria to grow faster.

The foil itself doesn't promote faster bacterial growth, but the way it covers the plate might. After all, when you cover the plate with foil, even if it's folded carefully, it doesn't form a tight seal, so air can still get in, making it easier for some types of bacteria to grow faster.

 

Staphylococcus (sometimes found in meat and poultry) and Bacillus cereus (found in leftover rice and other starchy foods) are two types of bacteria that need air to grow and multiply. These two types of bacteria are not killed by reheating food at high temperatures, so they are especially dangerous.

Aluminum foil retains heat, causing food to spoil quickly.

We spread aluminum foil over hot fried chicken while vegetables cook because it keeps food warm. But what is good for that is not so good for keeping food safe.

Aluminum foil retains heat better than plastic wrap or wax paper, and that can cause leftovers to spoil faster. If you wrap dishes in aluminum foil before they're completely cool, the foil can trap heat, leaving the food at dangerous temperatures of 40 to 60 degrees Celsius, where bacteria thrive. If you use aluminum foil to store leftovers, use it for dishes that are completely cooled or have already cooled.

Aluminum foil can put you at risk for botulism. Here's a surprising case: Baked potatoes stored in aluminum foil have caused cases of botulism. The bacterium Clostridium botulinum releases a toxin that can damage the central nervous system and even cause death.

There are two problems with storing potatoes in foil. First, the bacteria Clostridium botulinum thrives in oxygen-deprived conditions. Wrapping potatoes in foil reduces oxygen, which is exactly what these harmful bacteria want. Another problem with second-day potatoes? Potato skins are dirty (even if you washed them before cooking), which encourages bacteria to grow. You should never store baked potatoes in their skins, as the skins contain dirt and therefore bacteria.

 

Aluminum can leach into your food.

Aluminum itself is a known neurotoxin. According to a 2023 report in the International Journal of Molecular Sciences, aluminum can accumulate in the brain and central nervous system. There is some evidence that people with Alzheimer's disease have more aluminum in their brains.

Before you panic, know this: The biggest concern comes from cooking acidic foods in foil ; there's no clear evidence that wrapping food in foil causes significant problems. Roberts says that as long as there's a small amount of food left on the plate and the foil doesn't touch it, it's not a health concern. But if there's a chance the foil might come into contact with your chili or chicken piccata, use plastic wrap or a container instead.

What happens if you wrap leftover food in foil?

You could get food poisoning. This is especially worrying for certain groups of people, such as children under 5, the elderly, pregnant women, and anyone with a weakened immune system.

Don't worry, though, if you need to grab some foil to take home from a party or need to quickly wrap a sandwich in foil because it's all you have on hand. It's fine to use it for a short time.