Reducing the browning of avocados
Excerpts taken from a 12/20/10 blog post from DesiGrub When exposed to air, avocados turn brown. The oxygen in the air reacts with enzyme polyphenol oxidase (PPO) to form brown pigmentation called melanoidin.
There are many theories on how to reduce this browning, such as: squirting lime or lemon over the avocado, adding oil, adding part of the avocado pit to guacamole (or leaving the pit in a whole avocado) and adding salt.
This blogger has done an impressive amount of testing to figure out that the most effective way to avoid browning is to add lime or lemon to the avocado. It's this act of adding ascorbic acid and citric acid - found in lemon and limes - that decreases the rate of browning. It does it by lowering the pH of tissue. Browning is most active in the neutral pH range of 6 to 7 while there is no browning, below pH of 3.
To make guacamole, the blogger suggests that you do the following:
- Cut open and mash the avocados as the last step in making guacamole, have all the other ingredients ready to combine with the avocados.
- Add lime or lemon juice right after mashing avocados. Cover with plastic wrap.
- Don't add salt until you're ready to serve
