Explanation:
The rotting of fruit is a chemical reaction. When fruit rots, the molecules of the fruit actually change through an enzymatic reaction. This process is called ENZYMATIC BROWNING. This process occurs over several steps. First, the PPO enzyme changes phenolic compounds (through oxidation) into quinones, which then react with other compounds to form melanin (the same pigment that makes your hair brown!).
There is also the process of PHOTODEGRADATION, which happens when fruit is exposed to light. The fruit loses its color, flavor, vitamins, etc.
Most fruit rots occur because of fungal organisms and bacteria, which cause fruit lesions and/or rots.