Pipistrellum no había leído tu última entrada hasta ahora mismo no sé por qué.
Para no enrrollarme yo mucho y que quede más claro te pego la explicación de wikipedia
"Methylene blue is widely used a redox indicator in analytical chemistry. Solutions of this substance are blue when in an oxidizing environment, but will turn colorless if exposed to a reducing agent. The redox properties can be seen in a classical demonstration of chemical kinetics in general chemisty, the "blue bottle" experiment. Typically, a solution is made of dextrose, methylene blue, and sodium hydroxide. Upon shaking the bottle, oxygen oxidizes methylene blue, and the solution turns blue. The dextrose will gradually reduce the methylene blue to its colorless, reduced form. Hence, when the dissolved oxygen is entirely consumed, the solution will turn colorless"
Edit: añado imagen:
![$m[1]](http://genchem.rutgers.edu/MK-MB.gif)