It is commonly known that freshly cut fruits turn a brownish color when exposed to the air for a number of minutes. This is due to the action of the enzyme polyphenoloxidase. It is also well known that the formation of the brown color can be prevented or slowed by chilling the fruit, boiling it or rubbing it with lemon juice (which contains ascorbic acid). Explain why

Question

each of these methods works to slow down the browning process.

Answer 1

Chilling reduces the rate of the reaction.
Boiling removes the enzyme.
Oxygen reacts with both the enzyme and the citric acid but it reacts with citric acid first and will keep the browning away as long as the lemon juice is in excess.