Question

Pectin is a polysaccharide which is a polymer of ________________.

• A. Fructose
• B. Glucose
• C. Maltose
• D. Galacturonic acid

Hint:

Pectin is functionally characterized by its galacturonic acid backbone.
The acid groups on these units allow pectin to form gels in the presence of sugar and acid, or calcium ions.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Pectin is a structural heteropolysaccharide found in the primary cell walls and middle lamella of terrestrial plants, particularly fruits.
It is widely used in the food industry as a gelling agent, thickener, and stabilizer in jams, jellies, and dairy desserts.

Step 2: Detailed Explanation:
Let us analyze the chemical structure of pectin:
Pectin is not a polymer of simple hexose sugars like glucose, fructose, or maltose.
Instead, its backbone consists primarily of \(\alpha\)-(1,4)-linked D-galacturonic acid units (a sugar acid derived from galactose).
This linear chain of galacturonic acid is partially esterified with methyl groups.
The degree of esterification determines whether it is high-methoxyl or low-methoxyl pectin, which dictates its specific gelling mechanism.
Therefore, pectin is a polymer of galacturonic acid.

Step 3: Final Answer:
Pectin is a polymer composed primarily of Galacturonic acid units.