They don't lose vitamin C.
It loses vitamin C after a period of time.
They will decay after a long period of time and might lose the vitamin C inside.
When we slice the oranges into smaller pieces, it loses its vitamins.
It does not lose vitamin C after picked but will if salt is present.
It loses vitamin C when we add fertilizers to it when it is growing.
It loses vitamin C when it is heated.
Vitamin C is lost when the orange skin is removed.
When we squeeze the oranges to make orange juice, it loses vitamin C.