We've all covered leftovers in aluminum foil at one point or another in order to keep food fresh for longer. However, did you know that you can use aluminum foil to prevent the entire ripening process from even happening when it comes to bananas? Try covering the stems of the bananas tightly in aluminum foil and they should stay fresh for longer and now brown as quickly as they would without foil.
This occurs because aluminum foil traps the gases released by bananas that would normally cause them to ripen and brown. The same happens if you wrap them in plastic wrap.