Describe the process of enzymatic browning in fruits and vegetables, including its causes and methods to prevent it.

Enzymatic browning in fruits and vegetables is caused by the oxidation of phenolic compounds by the enzyme polyphenol oxidase (PPO) when the tissue is damaged or exposed to air. This reaction results in the formation of brown pigments. To prevent enzymatic browning, techniques such as blanching (briefly immersing in boiling water), using ascorbic acid (vitamin C) or citric acid to inhibit PPO activity, and storing fruits and vegetables in acidic or low-temperature environments can be employed.