Open avocados and guacamole brown due to oxidation (exposure to oxygen).
Prevent an open avocado from browning
Just submerge the avocado in water and put it in the fridge. I did this to half an avocado and after 4 days, it still looks good.
Prevent an open container of guacamole from browning
If you have a container of guacamole that you don’t want to brown, add water to cover the top surface.
