My husband and I are trying out a Fitness Magazine eating planner called 31 Days of Superfoods. All meals are nutritious, well proportioned and for the first time since we have been married we are eating avocados. Last night we were enjoying a lemony lentil soup and salad with some of the green fruit (yes, avocado is a fruit). If you have seen avocados and guacamole a while after being plated, you know that after a while they turn brown. Do you know why? My husband’s answer to my question was “air.” That’s correct. Eh, sort of.
Air in itself doesn’t cause the avocado to brown. Air or the oxygen molecules react with the catechol, contained in the fruit cells, and are catalyzed by an enzyme, also contained in the avocado, called polyphenol oxidase or PPO. The chemical reaction leads to the formation of long chains of o-benzoquinone which is why you see the streaks of brown melanin pigmentation on the avocado’s surface. The same PPO enzyme is contained in other fruits and vegetables such as apples, potatoes and bananas. For the nerds out there (I love chemistry!), here is what happens to the avocado:
Now, many don’t necessarily care why the fruit turns brown but how to prevent it. Here is a great About.com video that gives you some avocado-preserving options along with the results: