FRUIT PRESERVATION
Dear HIW,
When I put lemon juice on a cut avocado it stays green longer. What is in lemon juice that prevents browning?
Jess Burns
Avocados have an enzyme called polyphenol oxidase (PPO) underneath the skin. When these enzymes are exposed to oxygen, they alter compounds in the avocado and turn it brown. As soon as the avocado’s protective skin is broken, the air makes contact with its flesh and this process begins. PPO is only active when in certain pH conditions, between 6 and 7.5. By adding lemon juice, the pH becomes more acidic and prevents the
