“Though it may look unappetising, it is still safe to eat.
“The lemon or lime juice prevents browning because the citric acid acts as a natural preservative by reacting with the oxygen instead of the avocado itself reacting.
“Some suggest placing it in water, some douse the avocado flesh in lemon juice, others place it in an air-tight container, or use clingfilm.
“We also recommend leaving the pip, or stone, in the cut avocado as this will prevent all of the flesh from browning, just be sure to remove it before eating.”
So if you buy an unripe avocado, which then ripens in seven days, before storing it in the fridge for another three days, before then dousing it in lemon juice, you could expect a cut avocado to last for around 12 days.