Agricultural/Bioengineering Post-Harvest Technology

Question 1

What is the primary purpose of grain drying in post-harvest management?

Accepted Answer

Reduce moisture to safe storage levels and prevent spoilage

Answer

Drying reduces grain moisture below the threshold (typically 13–15%) at which mold, insects, and bacteria thrive.

Question 2

Equilibrium moisture content (EMC) of grain is defined as the moisture level at which:

Accepted Answer

Grain neither gains nor loses moisture to the surrounding air

Answer

EMC is reached when the vapor pressure of grain moisture equals that of the surrounding air, resulting in no net moisture transfer.

Question 3

Which type of grain dryer passes heated air upward through a moving grain column?

Accepted Answer

Cross-flow dryer

Answer

In a cross-flow dryer, heated air moves horizontally through a vertically moving grain column, which is the most common commercial design.

Question 4

Controlled atmosphere (CA) storage of fresh fruits and vegetables involves modifying which gases?

Accepted Answer

Oxygen and carbon dioxide

Answer

CA storage reduces O₂ and increases CO₂ levels to slow respiration and delay ripening of fruits and vegetables.

Question 5

The process by which fresh produce continues to consume oxygen and release CO₂ after harvest is called:

Accepted Answer

Respiration

Answer

Post-harvest respiration is the metabolic process that consumes stored carbohydrates and generates heat, reducing shelf life.

Agricultural/Bioengineering Practice Test