Silica Gel

This is an excellent dehumidifiers without the costly electric bill, excellent moisture absorber, its colour will be changing from deep blue (when dry) to light pink (when it had absorbed moisture from its surroundings). 
Usually used by photographers to keep moisture away from their camera gears.  

Reusable, after it had turned light pink, microwave it using a safe microwaveable dish for 3 minutes (for 250 gr weight in blue coloured condition) then it will turn blue again.

Not to be eaten.  Desiccant.