Catecholase is an enzyme found in potatoes. This enzyme works to turn the catechol in the potato to benzoquinone. Benzoquinone is a reddish brown color. Based on this information, read the following prompt and answer the question. A freshly cut potato turns brown when left standing. Why do mashed potatoes stay white? (Choose all that apply)
The catecholase in the fresh potato turned catechol into benzoquinone
The catecholase in the fresh potato became denatured and as a result was not able to turn catechol into benzoquinone
The catecholase in the mashed potato became denatured and as a result was not able to turn catechol into benzoquinone
The catecholase in the mashed potato turned catechol into benzoquinone
The catecholase in the fresh potato was able to lower the activation energy of the chemical reaction
The catecholase in the mashed potato was able to lower the activation energy of the chemical reaction
The Correct Answer and Explanation is :
Correct Answers:
- The catecholase in the mashed potato became denatured and as a result was not able to turn catechol into benzoquinone
- The catecholase in the fresh potato turned catechol into benzoquinone
Explanation:
When a fresh potato is cut and exposed to air, it undergoes a browning reaction due to the enzyme catecholase (also known as polyphenol oxidase). This enzyme catalyzes the oxidation of catechol (a naturally occurring compound in potatoes) into benzoquinone, which is reddish-brown in color. This reaction is similar to how apples and bananas turn brown when cut and exposed to oxygen.
However, mashed potatoes do not turn brown like fresh-cut potatoes. This is because the cooking process used to prepare mashed potatoes involves boiling or steaming, which exposes the potatoes to high temperatures. High temperatures cause the enzyme catecholase to denature, meaning that its protein structure is altered in such a way that it can no longer function. Since the enzyme is no longer active, it cannot catalyze the reaction that converts catechol into benzoquinone, preventing browning.
In contrast, in a freshly cut, raw potato, catecholase remains active because the potato has not been exposed to heat or other denaturing conditions. As a result, when the cut surface is exposed to oxygen, the enzyme facilitates the conversion of catechol into benzoquinone, leading to the characteristic brown discoloration.
Therefore, mashed potatoes stay white because the catecholase enzyme is denatured during cooking and cannot catalyze the reaction, while fresh-cut potatoes turn brown because the enzyme remains active and completes the oxidation process.
Image Generation:
I will now generate an image illustrating the enzymatic browning process in fresh-cut potatoes and the absence of browning in mashed potatoes.
Here is the generated scientific illustration comparing a fresh-cut potato (which turns brown due to enzymatic oxidation) and mashed potatoes (which remain white due to enzyme denaturation). Let me know if you need any modifications!
