The shiny or matte side of aluminum foil: what changes when baking

The difference between the two sides is not due to any special properties, but rather to the production technology. To make the sheet thin enough without breaking, it is laminated in two layers at once. The side that touches the polished rollers becomes smooth and shiny, while the side that does not touch that surface remains matte.

In terms of heat conduction and safety, there is no difference between the two sides. Aluminum conducts heat equally well from any surface and does not release metallic particles into food. The myth that the matte side leaves metallic residue is not scientifically proven.

The shiny side reflects slightly more infrared radiation, while the matte side absorbs it a bit better. In a conventional oven, where the heat comes from hot air, this difference is practically imperceptible: dishes wrapped with one side or the other taste and have a similar texture. The only noticeable difference is that the matte side is somewhat rougher, so food sticks more easily, while the smoother shiny side allows grease and sauces to drain more easily.

For wrapped meat, chicken, fish, or vegetables, the paper side doesn't matter; the essential thing is to seal the edges well so the juices don't escape. If the food is going on an open tray, it's best to place it with the shiny side down, which prevents sticking and makes it easier to remove. Fish, being delicate, especially benefits from this side. For a crispier crust, the paper can be removed at the end of cooking.

When grilling or cooking over direct heat, it is recommended to wrap the food with the shiny side facing outwards, so that it reflects some of the heat from the coals and prevents it from burning.

The paper can be reused if it hasn't been in contact with acidic foods, such as tomatoes or lemons, and if it isn't very dirty, warped, or torn. Greasing it isn't necessary, although a light coating of oil helps with foods that tend to stick, especially if using the matte side.