How will apples with lemon juice still turn to brown?

Apples turn brown because of a chemical reaction called enzymatic browning. This happens when the enzymes in the apple, called polyphenol oxidases (PPOs), react with oxygen in the air. Lemon juice helps slow down this process, but it doesn't stop it completely. Here's why:

* Lemon juice is acidic: The acid in lemon juice helps to inhibit the activity of the PPO enzymes. However, it doesn't completely deactivate them.

* Oxygen is still present: Even though the lemon juice helps slow down the browning, it doesn't remove the oxygen from the apple's surface. Eventually, oxygen will still reach the PPO enzymes and cause browning.

* Time is a factor: The browning process will still happen over time, even with lemon juice. It just takes longer.

Here's what you can do to prevent browning:

* Use a lot of lemon juice: More acid means more inhibition of the PPO enzymes.

* Submerge the apple in water: This will block oxygen from reaching the apple and help slow down browning.

* Store the apple in an airtight container: This will also reduce the amount of oxygen available to cause browning.

* Use a combination of these methods: The best way to prevent browning is to use a combination of all of the above methods.

Ultimately, lemon juice will significantly delay the browning process, but it won't prevent it entirely.