250+ TOP MCQs on Unit Operations – Microwave Heating and Answers

Food Engineering Multiple Choice Questions on “Unit Operations – Microwave Heating”.

1. Which of the following is a synonym for loss factor of food?
a) Loss tangent
b) Dielectric loss
c) Loss tangent & Dielectric loss
d) None of the mentioned

Answer: c
Clarification: Loss factor of food is called loss tangent and dielectric loss.

2. Which of the following is true about loss factor of food?
a) It is desirable quality of food
b) It is the ability of food to absorb waves
c) It is represented by Ɛ
d) All of the mentioned

Answer: d
Clarification: All the given factors are true about loss factor.

3. Penetration depth of food refers to the depth inside the food inside which the heat generation drops to 37%.
a) True
b) False

Answer: a
Clarification: Penetration depth of food refers to the depth inside the food inside which the heat generation drops to 37%.

4. Which of the following is untrue?
a) It is difficult to predict the electric field intensity inside a food material
b) Design of oven plays an important role in determining the electric filed intensity in a food material
c) Orientations of microwaves is an important role
d) None of the mentioned

Answer: d
Clarification: It is difficult to predict the electric field intensity inside a food material. Design of oven plays an important role in determining the electric filed intensity in a food material. Orientations of microwaves is an important role.

5. Any food item should be subjected to micro frequencies such that, the dielectric constant is _____ and loss factor is _____
a) Maximum, minimum
b) Maximum, maximum
c) Minimum, minimum
d) Minimum, maximum

Answer: c
Clarification: Any food item should be subjected to micro frequencies such that, the dielectric constant is minimum and loss factor is minimum.

6. Hannah heats refrigerated rice which has been devoid of moisture and become dry. She heats it in a microwave. It gets unevenly heated. What should she do?
a) Water should be added for even heating
b) She should heat it using equipment that offers conduction or convection
c) None of the mentioned
d) All of the mentioned

Answer: a
Clarification: Water has a low dielectric constant due to the generation of friction due to rotation of dipoles. Hence, water should be added for even heating.

7. Statement 1: In microwave heating, heat is not applied to the food item.
Statement 2: Radiation doesn’t gives even drying whereas microwave heating does.
a) True, False
b) True, True
c) False, False
d) False, True

Answer: b
Clarification: In microwave heating, heat is not applied to the food item. Instead, heat is made to generate within the food item. Radiation doesn’t gives even drying whereas microwave heating does by addition of water. Water has a low dielectric constant due to the generation of friction due to the rotation of dipoles. Hence, water should be added for even heating.

8. Statement 1: The factor F₀ shows the microbial safety in the food item at the coldest point.
Statement 2: F₀ takes the time-temperature data at that particular point and compares conventional heating to microwave heating.
a) True, False
b) True, True
c) False, False
d) False, True

Answer: b
Clarification: The factor F₀ shows the microbial safety in the food item at the coldest point. F₀ takes the time-temperature data at that particular point and compares conventional heating to microwave heating.

9. One disadvantage of microwave cooking is that the energy efficiency in this process is less.
a) True
b) False

Answer: b
Clarification: Microwave cooking has very high energy efficiency.

10. Statement 1: Microwave heating helps save electricity.
Statement 2: The quality of product in microwave heating is good hence rejections are lesser.
a) True, False
b) True, True
c) False, False
d) False, True

Answer: b
Clarification: Microwave cooking has very high energy efficiency. Hence, it helps save electricity. The quality of product in microwave heating is good hence rejections are lesser.

11. Although microwave heating can be used for drying of food containing uneven water content, it is isn’t done for certain food products like garlic. Why?
a) No pasteurization
b) Essential oils being stripped off
c) None of the mentioned
d) No pasteurization & Essential oils being stripped off

Answer: d
Clarification: For drying of garlic, the essential oils which are the volatile components of the garlic are stripped off from it.

12. Microwave heating is good for puffed products. Why?
a) The rate of heat transfer is less than the rate of moisture loss
b) The heat transfer in these food items takes place so fast that instead of shrinking of the food items due to loss of moisture content, they stay intact and hence puffed
c) None of the mentioned
d) All of the mentioned

Answer: b
Clarification: The heat transfer in these food items takes place so fast that instead of shrinking of the food items due to loss of moisture content, they stay intact and hence puffed.

13. Which of the following is NOT a part of the microwave heating system?
a) Magnetron
b) Anode
c) Cathode
d) None of the mentioned

Answer: d
Clarification: All the given above are parts of a microwave heating system.

14. Recently, cancer causing effects, nutritional destructions of food and biological effects of exposure of microwave heating has come into light.
a) True
b) False

Answer: a
Clarification: Recently, cancer causing effects, nutritional destruction of food and biological effects of exposure of microwave heating has come into light.