You can put the aluminum pack in the freezer before you open it, let it freeze for 30-60min and the material will become completely solid, which helps the aluminum to separate more easily.

If you want to use ethanol to dissolve the material left on the aluminum, make sure all the materials are cold (fridge cold), because at higher temperatures ethanol and aluminum react to form aluminum triethoxide, which is caustic and damaging to the eyes. (its just better to Avoid this.)