Agricultural/Bioengineering Agricultural/Bioengineering: Food Engineering 2

Question 1

Which heat transfer mechanism is primarily responsible for cooking food in a microwave oven?

Accepted Answer

Dielectric heating

Answer

Microwaves cause polar molecules like water to rotate rapidly, generating heat internally through dielectric heating.

Question 2

The 'z-value' in thermal processing refers to:

Accepted Answer

The temperature increase needed to reduce D-value to 1/10th

Answer

The z-value is the temperature change required to achieve a 10-fold (one log) change in the D-value of a microorganism.

Question 3

Which of the following is NOT a colligative property exploited in food preservation?

Accepted Answer

Surface tension reduction

Answer

Surface tension is not a colligative property; colligative properties depend on solute concentration, not identity.

Question 4

In extrusion processing of food, the 'specific mechanical energy' (SME) input affects:

Accepted Answer

Starch gelatinization, protein denaturation, and product expansion

Answer

SME drives the thermomechanical transformation of ingredients, affecting starch gelatinization, protein structure, and the expansion ratio of the extrudate.

Question 5

What is the primary purpose of blanching vegetables before freezing?

Accepted Answer

To inactivate enzymes that cause quality deterioration

Answer

Blanching inactivates enzymes such as peroxidase and lipoxygenase that would otherwise cause color, flavor, and texture degradation during frozen storage.

Agricultural/Bioengineering Practice Test

Agricultural/Bioengineering Practice Test

Agricultural/Bioengineering Agricultural/Bioengineering: Food Engineering 2