7 Foods You Should Never Cook in Aluminum Foil

Anything You’re Microwaving

Aluminum foil and the microwave don’t mix, full stop. Aluminum foil exposed to microwave rays can lead to sparking and even fire, which can cause permanent damage to your microwave oven or worse. Leftovers shouldn’t typically be stored in aluminum foil, as it’s not airtight, so keeping leftovers in a glass or microwave-safe container can save you a step as you pop it right into the microwave to reheat. 

Tomatoes, Citrus and Acidic Marinades

Falling under the category of acidic foods, tomatoes, citrus fruits, and vinegar-based marinades are not safe to cook in aluminum foil. “Acidic foods can cause more aluminum to leach into your meal, increasing your aluminum intake, which can potentially lead to issues if consumed over time in large amounts,” Wood explains.

Salty Dishes

Just like acid, salt can cause aluminum to leach into foods. Any dish that has a substantial amount of salt in it (think homemade savory baked goods or cured meats, like ham and sausages), shouldn’t be cooked in aluminum to prevent the sodium chloride (i.e. salt) from reacting with aluminum ions.

Slow-Roasted Dishes

Wrap your ribs in foil before slow-cooking them for hours? You may want to think again. “You want to avoid using foil for anything that is baked for a long time, like slow-roasted meats or casseroles,” Wood says. “This can cause more aluminum to be released in your meal.” If you’re used to slow-roasting dishes in foil, this is a great time to switch to ceramic or glass cookware, or if you must, use a layer of parchment paper between the aluminum so it’s not directly touching the food.

Research in the International Journal of Environmental Research and Public Health demonstrated that the exact same dish cooked in oven-proof cookware versus aluminum foil was much higher in aluminum after being cooked in foil, proving that the element leached into the cooked food.  

Foods Cooked at High Heat

The good news is that aluminum typically doesn’t start to melt until it’s over 1,000 degrees Fahrenheit, but you’ll still want to avoid cooking with aluminum for any foods baked at over 400 degrees. Above this temperature, the metal can leach into the food. Skip the aluminum-wrapped baked potato, and coat it with a thin layer of neutral cooking oil, or wrap it in parchment paper instead. This also goes for campfire cooking—wrapping foods in aluminum foil and cooking them via open flames isn’t recommended.  

Seafood

Seafood packets are a popular way to easily cook fish, but research published in Food Science and Nutrition shows that aluminum foil can leach deeper into fish than cuts of meat from mammals or birds, making fish probably the worst protein to cook in foil. Fish cooked in parchment paper, or en papillote, is a popular (and similar) way to steam filets. 

Cookies

Cookies typically cook quickly at a relatively low temperature, so technically they could be safely baked on aluminum foil, but to questionable results. The material will make the bottoms of your cookies hard and crispy, and the treats will potentially stick to the aluminum, causing them to crumble on removal.