Question

During the process of ripening of fruits, the transition of pectic substance occurs in the following order:
(A). Protopectin
(B). Pectin
(C). Pectinic acid
(D). Pectic acid
Choose the most appropriate answer from the options given below:

• A. (A), (B), (C), (D)
• B. (B), (A), (C), (D)
• C. (B), (C), (D), (A)
• D. (C), (B), (D), (A)

Hint:

Remember the progression from hard to mushy: Starts with the large, insoluble \textbf{Protopectin} (unripe). This breaks down into soluble \textbf{Pectin} (ripe), which is then further degraded into \textbf{Pectinic acid} and finally \textbf{Pectic acid} (overripe/mushy).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Pectic substances are complex carbohydrates that act as a cementing agent in the cell walls of plants, contributing to the firmness of fruits. As a fruit ripens, enzymes progressively break down these substances, leading to softening. This transition follows a specific biochemical pathway.
Step 3: Detailed Explanation:
The correct order of transformation of pectic substances during ripening is as follows:
1. (A) Protopectin: This is the water-insoluble form of pectin found in unripe, hard fruits. It is a large polymer bound to the cellulose in the cell wall.
2. (B) Pectin: As the fruit begins to ripen, the enzyme protopectinase starts to break down protopectin into smaller, soluble pectin molecules. This is what causes the fruit to begin to soften.
3. (C) Pectinic acid: With further ripening, the enzyme pectin methylesterase (PME) removes some of the methyl groups from the pectin molecules. This results in the formation of pectinic acids.
4. (D) Pectic acid: In the final stages of ripening and over-ripening, the enzyme polygalacturonase (PG) breaks down the polymer chains, and any remaining methyl groups are removed. This results in the formation of pectic acid (polygalacturonic acid), leading to a very soft or mushy texture.
The correct sequence is therefore (A) \(\rightarrow\) (B) \(\rightarrow\) (C) \(\rightarrow\) (D).
Note: None of the multiple-choice options provided in the question [(A), (C), (B), (D), etc.] match this scientifically correct sequence. There appears to be an error in the question's options.
Step 4: Final Answer:
The correct sequential order for the transition of pectic substances during fruit ripening is Protopectin \(\rightarrow\) Pectin \(\rightarrow\) Pectinic acid \(\rightarrow\) Pectic acid. As none of the provided options reflect this, the question is flawed.