Food Engineering Questions and Answers – Principles of Food Preservation by Drying-1

This set of Food Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Principles of Food Preservation by Drying-1”.

1. Evaporation, desiccation and dehydration all mean the same thing.
a) True
b) False
View Answer

Answer: b
Explanation: Evaporation and desiccation denote the same thing. Dehydration has a slightly different meaning.

2. Statement 1: Dried foods from a dehydration unit have better quality than sun dried components.
Statement 2: The color of dehydrated food under optimum conditions is superior to that by sun drying.
a) True, False
b) True, True
c) False, False
d) False, True
View Answer

Answer: a
Explanation: Dried foods from a dehydration unit have better quality than sun dried components. The color of sun dried food is superior to dehydrated food under optimum conditions.

3. Statement 1: In cooking quality, sun dried foods are better than dehydrated foods.
Statement 2: Sun dried animal flesh and fish can be highly acceptable.
a) True, False
b) True, True
c) False, False
d) False, True
View Answer

Answer: d
Explanation: In cooking quality, dehydrated foods are better than sun dried foods.
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4. Which of the following is NOT an advantage of dehydration under controlled conditions over sun drying?
a) Cost
b) Time of drying
c) Quality of drying
d) None of the mentioned
View Answer

Answer: a
Explanation: Dehydration under optimal conditions is more expensive than sun drying.

5. Which of the following is NOT a method of controlling biological forces on food supply?
a) Packaging and chemical additives
b) Reducing free water content
c) Increasing osmotic pressure
d) None of the mentioned
View Answer

Answer: a
Explanation: Packaging and chemical additives is a method of controlling chemical forces.
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6. Which of the following is an advantage/use of dried food items?
a) Lesser cost and minimum labor required
b) Limited processing equipment and minimum food storage requirements
c) Reduction in distribution costs
d) All of the mentioned
View Answer

Answer: d
Explanation: The entire mentioned are advantages/uses of dried food items.

7. Statement 1: The volume of gas at standard pressure increases _____ in volume for every _____ rise in temperature.
Statement 2: Each 15 deg C raise in temperature, _____ the holding capacity of air.
a) 1/273, 5 deg C, doubles
b) 273, 1 deg C, halves
c) 1/273, 1 deg C, doubles
d) 273, 5 deg C, halves
View Answer

Answer: c
Explanation: The volume of gas at standard pressure increases 1/273 in volume for every 1 deg C rise in temperature. Each 15 deg C raise in temperature doubles the holding capacity of air.
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8. Statement 1: Case hardening is controlled by _____ and _____
Statement 2: Drying time _____ rapidly as the final moisture content approaches its equilibrium value.
a) Increases, humidity, temperature
b) Decreases, humidity, concentration
c) Increases, temperature, concentration
d) Decreases, temperature, concentration
View Answer

Answer: a
Explanation: Case hardening is controlled by humidity and temperature. Drying time increases rapidly as the final moisture content approaches its equilibrium value.

9. Statement 1: In drying, the vapor pressure of water in the solid is more than outside.
Statement 2: For wet bulb, the greater the velocity, the more rapid is the rate of drying.
a) True, False
b) True, True
c) False, False
d) False, True
View Answer

Answer: b
Explanation: In drying, the vapor pressure of water in the solid is more than outside. The difference in the two determines the rate at which water vapor is absorbed by air. For wet bulb, the greater the velocity, the more rapid is the rate of drying.
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10. Statement 1: Foaming a liquid exposes enormous surface area for quick moisture removal and hence permits low drying temperatures.
Statement 2: During the constant drying time, the rate is determined by the rate at which water at the centre of the food diffuses outside.
a) True, False
b) True, True
c) False, False
d) False, True
View Answer

Answer: a
Explanation: Foaming a liquid exposes enormous surface area for quick moisture removal and hence permits low drying temperatures. During the falling rate period drying time, the rate is determined by the rate at which water at the center of the food diffuses outside.

11. It is possible to maintain conditions of temperature and pressure whereby the physical state of food substrate can be maintained at a critical point for the successful removal of water. This is called _____
a) Freeze dehydration
b) Freeze rehydration
c) Freezing
d) None of the mentioned
View Answer

Answer: a
Explanation: It is possible to maintain conditions of temperature and pressure whereby the physical state of food substrate can be maintained at a critical point for the successful removal of water. This is called freeze dehydration and freeze drying.

12. Statement 1: At _____ and _____of mercury, water is at triple point.
Statement 2: For drying of meat, the last few percentage of water is removed by _____
a) -273 k, 76 mm, conventional methods of heating
b) 273 k, 14.7 mm, non-conventional methods of heating
c) 273 k, 14 mm, conventional methods of heating
d) -273 k, 14 mm, non-conventional methods of heating
View Answer

Answer: b
Explanation: At 273 k and 14.7 mm of mercury, water is at the triple point. For drying of meat, the last few percentage of water is removed by non-conventional methods of heating.

13. Statement 1: Moisture vapor obtained from sublimation needs to be evacuated to keep the system below the critical pressure level.
Statement 2: Deterioration of muscle protein occurs in a salt solution above 5%.
a) True, False
b) True, True
c) False, False
d) False, True
View Answer

Answer: b
Explanation: Moisture vapor obtained from sublimation needs to be evacuated to keep the system below the critical pressure level. Deterioration of muscle protein occurs in a salt solution above 5%.

14. With the _____ in temperature and _____ in ice percentage, the percentage of soluble solids _____
a) Increase, decrease, increases
b) Decrease, increase, decreases
c) Increase, decrease, decreases
d) Decrease, increase, increases
View Answer

Answer: d
Explanation: With the decrease in temperature, majority of water converts into ice, hence, the ice percentage increases. Since the percentage of soluble solids is with respect to water and the water content has decreased and the solid concentration is constant, the percentage of soluble solids increases.

15. Which of the following is NOT a characteristic of freeze-dehydration?
a) Moisture loss by sublimation from boundary of ever receding ice crystal zone
b) Continuous process
c) Temperatures sufficiently low to prevent thawing used
d) None of the mentioned
View Answer

Answer: b
Explanation: Freeze dehydration is a batch process.

Sanfoundry Global Education & Learning Series – Food Engineering.

To practice all areas of Food Engineering, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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