Add lemon juice

A helpful alternative to oxygen for preventing the browning of avocados is pH level modification. Targeting other factors that have an impact on PPO's activity because PPO is essential for regulating browning may also help avoid it.

Since PPO is active between pH 6 and 7.5 and inactive below pH 3, one way to affect PPO is by adding acidulants, which are chemical compounds that help lower pH levels. Avocados' pH is lowered by acidulants such as citric and ascorbic acid, which may be found in lemon juice, and their enzyme activity is reduced, preventing browning. Furthermore, strong antioxidants found in citrus fruits work against oxygen to prevent some foods from spoiling or turning brown. Squeezing some lemon or lime juice over the flesh of sliced avocados before storing them in an airtight container should prevent browning for about a day.