2006-07-04 02:52:21 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
Browning of apples is caused by an enzyme (polyphenol oxidase) which acts on various phenolic compounds in the apple in the presence of oxygen from the air. The activity of the enzyme is dependent on the pH. A very low pH (lemon juice) for example inhibits the enzyme and the browning it causes. Adding an alkaline substance will partly neutralize the apple's acidity and will shift the pH to a higher value, more favorable for the enzyme's activity. Hence the increased browning.
2006-07-06 12:10:20 · answer #1 · answered by sehling99 2 · 3⤊ 0⤋
it's an oxidation reduction reaction with the sugar in the apple. adding acid like lemon juice protects agaist browning. An alkaline medium will promote the reaction with the "free ions" in solution.
hope this helps
2006-07-04 13:34:36 · answer #2 · answered by shiara_blade 6 · 0⤊ 0⤋
This is because the alkali reacts with the acid in the apple, thus resulting in a neutralization reaction.Thereby forming a salt which imparts the brown colour.
2006-07-04 10:07:20 · answer #3 · answered by govi 2 · 0⤊ 0⤋
It has to do with an oxidation - reduction taking place at the surface of the exposed interior of the apple.
2006-07-04 10:09:50 · answer #4 · answered by Darryl E 2 · 0⤊ 0⤋