Final answer:
Potatoes that have been boiled at 100°C and then sliced do not turn brown because the heat denatures the enzyme responsible for the browning reaction.
Step-by-step explanation:
Potatoes that have been boiled at 100°C and then sliced do not turn brown because the heat denatures the enzyme responsible for the browning reaction. This enzyme, called polyphenol oxidase, is deactivated when exposed to high temperatures.
When potatoes are cooked, the heat causes the polyphenol oxidase to denature, preventing it from catalyzing the oxidation of phenolic compounds present in the potatoes. As a result, the potatoes do not turn brown.
Additionally, the hot water used to boil the potatoes can cause leaching of phenolic compounds, reducing their availability for oxidation and further preventing browning.