Question

In high methoxy pectin, the amount of methylation is…….

• A. 25%
• B. 30‐35%
• C. 40‐46%
• D. 50‐60%

Hint:

Pectin Gelling: - HM ($>50$ DE): Needs Sugar + Acid (Classic Jam). - LM ($<50$ DE): Needs Calcium (Diet Jams).

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The question asks for the degree of esterification (DE) or the percentage of methoxyl groups in High Methoxy (HM) Pectin. Pectin is a structural heteropolysaccharide found in the primary cell walls of terrestrial plants.

Step 2: Detailed Explanation:

• Pectin Classification: Pectin is classified based on the percentage of galacturonic acid units that are esterified with methyl alcohol.

• High Methoxy (HM) Pectin: By definition, HM pectin is pectin where more than 50% of the carboxyl groups are methylated ($DE > 50\%$). Commercial HM pectins typically range from 50% to 75%.

• Low Methoxy (LM) Pectin: Pectin with a degree of esterification less than 50% ($DE < 50\%$).

• Gelling Mechanism: HM pectin requires high sugar ($> 65\%$) and low pH ($2.8 - 3.5$) to form a gel. LM pectin can form gels in the presence of divalent cations like calcium ($Ca^{2+}$) even without high sugar.

• Choice Analysis: Option (D) 50-60% is the only choice that places the value in the "High" category ($> 50\%$).

Step 3: Final Answer:
High methoxy pectin is characterized by a degree of methylation exceeding 50%. Option (D) represents this range.