Can an Avocado Pit Really Keep Guacamole From Turning Brown? http://shar.es/1gTXwM via @LiveScience
So how does leaving the pits in the bowl mitigate this process? It is
not because the pits exude an ineffable, protective aura that reminds
the guacamole where it came from, or because they emit chemicals that
counteract the oxidation process. As anyone who’s tried the method can
attest, the pits are really effective at preventing browning only on the
part of the guacamole’s surface they touch.
The pit protects the guac simply because it shields a portion of the
dip’s surface from exposure to air. You'd be just as well off plopping a
few hardboiled eggs or some golf balls or an iPhone into your
guacamole.
http://www.epicurious.com/archive/blogs/editor/2014/01/keeping-avocados-guacamole-green.html
Avocado 4: Avocado with Pit, Lemon Juice, and Plastic Wrap
Combining lemon juice and plastic wrap was by far the winning solution.
In fact, this avocado looked almost freshly cut. These results, as well
as my own anecdotal experience, lead me to believe that guacamole, made
with lemon or lime juice and with plastic wrap pressed directly onto
its surface, will keep, chilled in the fridge, for at least a couple
hours.
The Guacamole Test: Guacamole Topped with Water
This idea came from The Kitchn
and is a little bit of kitchen genius.
http://www.thekitchn.com/the-best-way-to-keep-guacamole-green-tips-from-the-kitchn-193462
Here's how it works: Start by
putting your freshly made guacamole in a container with a tight-fitting
lid then push the guacamole down into the container to get rid of any
air pockets. Next, pour 1/2 inch of lukewarm water on top, seal the
container, and pop it in the fridge. When you're ready to eat the
guacamole, pour out the water and stir the guacamole to incorporate any
surface moisture. That's it. My guacamole was still bright and green
after a full 24 hours, but the Kitchn reports this method keeps your
guac good to go for three days