Why You Should Never Wrap Leftovers In Aluminum Foil

The not-so-shiny truth about using this kitchen staple for food storage.

We’ve all done it: used tinfoil to wrap dinner leftovers or to send guests home with the remainder of a meal. It’s certainly convenient, but is aluminum foil actually a safe way to store leftover food? According to experts, it’s usually not.

Unlike other popular methods of storing leftovers—like in plastic bags and Tupperware—foil cannot create an airtight seal. This means that no matter how tightly you manage to wrap your food with foil, some air will still get in.

Proper food storage decreases the risk of bacteria growth by limiting exposure to air and preventing moisture loss. Aluminum foil excels at neither.

“Aluminum foil alone cannot create a completely airtight seal because it’s not inherently adhesive and [it] doesn’t conform perfectly to surfaces,” explains Zachary Cartwright, Lead Food Scientist for AQUALAB by Addium and member of the Food Safety and Quality Management Division at the Institute of Food Technologists (IFT).

Meet Our Expert

• Zachary Cartwright is a lead food scientist for AQUALAB by Addium and a member of the Food Safety and Quality Management Division at the Institute of Food Technologists (IFT).

The Risk Of Bacteria Growth

The Centers for Disease Control (CDC) warns that the presence of air can help potentially dangerous bacteria such as staphylococcus (staph) and Bacillus cereus, which can thrive in the conditions created by tinfoil storage, grow faster.

The CDC estimates that about one in every four people carry staph on their skin and in their nose. Food can become contaminated with staph if people who carry the bacteria touch it without first washing their hands. Staph can multiply in food and even make a toxin that causes food poisoning even after cooking.

Cartwright said that improper aluminum foil storage also increases the risk of foodborne illnesses including Clostridium botulinum and Listeria monocytogenes. Though rare, both of these can result in serious illness.

Improper food storage can lead to other health hazards as well, including chemical reactions and contamination.

According to Cartwright, aluminum can react with acidic (think tomato sauce) or salty foods, causing leaching of aluminum into the food. This may alter the food’s taste and increase aluminum intake, which is linked to health concerns if consumed in large quantities over time.

If you must use aluminum to store food, limit it to short periods (no more than two days). Avoid wrapping hot or warm foods directly in foil. Instead, let food cool to room temperature or refrigerate quickly. Cartwright also recommends double wrapping with foil or starting by wrapping the food in a layer of plastic wrap.

Related: Should You Use Aluminum Foil With The Shiny Side Up Or Down?

The Right Way To Safely Store Leftovers

Cool Food Quickly

Cooling food quickly before storage prevents bacteria from multiplying in the “danger zone” (40°F to 140°F). You can do this by dividing large portions into smaller, shallow containers (two inches deep or less). Never leave food out for more than two hours.

Use Proper Containers

Airtight containers prevent contamination and reduce moisture loss. Cartwright recommends glass or BPA-free plastic receptacles, which are suitable for both refrigeration and reheating. Avoid metals like aluminum, which can react with acidic foods.

Label and Date

Use masking tape or labels to note the date and type of food in each container. This helps track how long leftovers have been stored.

Store in the Right Place

For short-term storage, your leftovers should last in your refrigerator (kept at or below 40°F) for up to four days. For long-term storage in the freezer, most leftovers are safe for two to three months but may lose quality over time.

Avoid Cross-Contamination

Keep leftovers away from raw foods, and cover containers tightly with lids or plastic wrap.

Reheating Leftovers

Heat to an internal temperature of at least 165°F (use a food thermometer for accuracy) and stir thoroughly to ensure even heating. Be sure to reheat the entire portion at once to avoid bacterial growth.

Discard If in Doubt

Off smell, unusual texture, and/or visible mold are all signs of spoilage. If stored longer than recommended, it’s safer to throw it out.

Safe Practices For Wrapping Food In Tinfoil

• Use aluminum foil primarily for short-term storage.

• Avoid wrapping acidic or salty foods directly in foil; consider using glass or BPA-free containers instead.

• For longer storage, use foil with an airtight container or plastic wrap.