Question

The Jelmeter test for determining pectin content gives accurate result in the temperature range

• A. 12-20°C
• B. 21-38°C
• C. 40-45°C
• D. 48-55°C

Hint:

Fruit extract must be cooled to room temperature ($21\text{--}38^\circ\text{C}$) before running the Jelmeter test to avoid viscosity measurement errors.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The Jelmeter test determines the pectin grade and required sugar proportion of fruit extracts based on capillary flow rate.

Step 2: Detailed Explanation:
The Jelmeter is a calibrated capillary tube that measures the viscosity of fruit juice extract as a direct proxy for pectin concentration.
Because kinematic viscosity is highly temperature-dependent, standard Jelmeter tables are calibrated for accurate flow timing at ambient temperatures between $21^\circ\text{C}$ and $38^\circ\text{C}$ ($70\text{--}100^\circ\text{F}$).

Step 3: Final Answer:
Therefore, the Jelmeter test provides accurate results in the temperature range 21-38°C.