What is it called when air hits a bit apple and it turns brown?

When air hits a bitten Apple and it turns brown, the process is called enzymatic browning. This occurs when the enzyme polyphenol oxidase reacts with oxygen in the air, leading to the oxidation of phenolic compounds in the Apple. The result is the brown discoloration that can affect the fruit's appearance and taste. To slow this process, you can apply lemon juice or another acidic substance, which inhibits the enzyme's activity.