Though aluminium is a quite reactive metal,the food in aluminium pot doesn’t react with the pot, why?

Though aluminium is a quite reactive metal it doesn’t react with the food.This is due to the presence of an inert aluminium oxide layer on its surface which if formed when an aluminium pot is produced, the surface is oxidized instantly (aluminium combine with the oxygen of air).

This thin but strong layer prevents the reaction of aluminium with food.