Question

Which among the following methods are used for determination of moisture content of agricultural produce
(A) Brown-Duvel fractional distillation method
(B) Dielectric method
(C) Chemical method
(D) Infra-red method
Choose the correct answer from the options given below:

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

Hint:

Direct methods (distillation, chemical) are highly accurate but destructive and time-consuming, while indirect methods (dielectric, infra-red) are rapid and non-destructive, making them ideal for field use.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Moisture content determination in agricultural commodities is essential for safe storage, processing, and commercial trading.
These methods are broadly classified into direct methods (removing and measuring water) and indirect methods (measuring physical or chemical properties related to water).

Step 2: Detailed Explanation:
Let us evaluate each of the given moisture determination methods:
- (A) Brown-Duvel fractional distillation method: This is a direct physical method where a weighed sample of grain is heated in a non-volatile oil.
The moisture is vaporized, condensed, and collected in a graduated cylinder to measure the volume of water directly.
- (B) Dielectric method: This is an indirect electrical method that measures the dielectric constant of the grain mass, which varies significantly with water content since water has a much higher dielectric constant than dry grain.
- (C) Chemical method: This includes direct chemical reactions like the Karl Fischer titration, where iodine reacts quantitatively with water, which is highly accurate for measuring low moisture levels.
- (D) Infra-red method: This is an indirect optical method that measures the absorption of near-infrared light by water molecules in the grain, providing a rapid, non-destructive moisture measurement.
Since all four methods (A, B, C, D) are established techniques for measuring moisture in agricultural products, option 2 is correct.

Step 3: Final Answer:
The methods used are (A), (B), (C) and (D).