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Drying of Fruits and Vegetables

1. The efficiency of the dryer is in range of:

a. 85-90%

b. 95-100%

c. 90-95%

d. 65-75%

Ans. d

2. Fluidized bed dryer is used for drying:

a. Milk

b. Tea leaves

c. Fruit juices

d. Vegetables

Ans. b

3. In freeze drying the removal of moisture takes place due to:

a. Boiling

b. Condensation

c. Sublimation

d. Pressure reduction

Ans. c

4. If the addition of heat does not change temperature it is known as:

a. Latent heat

b. Sensible heat

c. Super heat

d. Saturated heat

Ans. a

5. Constant rate of heating takes at:

a. 1000 degree C

b. 1200 degree C

c. 1150 degree C

d. All temperatures

Ans. d

6. EMC of a product changes with ………… of the environment:

a. Temperature

b. RH

c. Temperature and RH

d. Pressure

Ans. b

7. The vapour pressure of the moisture in the materials due to addition of heat:

a. Decreases

b. Increases

c. Decreases initially and increases

d. Does not change

Ans. b

Drying Food Preservation Examples

8. If the moisture content on dry basis is 25%, then what would be moisture content on wet basis?

a. 18%

b. 20%

c. 22%

d. 25%

Ans. b

9. Volatile compounds are retained in:

a. Spray dryer

b. Impringement dryer

c. Cabinet dryer

d. Rotary dryer

Ans. d

10. The safe moisture for storing the grains is:

a. 14%

b. 20%

c. 4%

d. 25%

Ans. a

11. In cabinet dryer the product attains…… temperature than the used air:

a. Higher

b. Same

c. Lower

d. 10 times higher

Ans. c

12. The average particle size in spray dryer is:

a. 10pm

b. 100pm

c. 0.01pm

d. 50pm

Ans. b

13. 20% M.C. (w.b.) is equal to ……… M.C. in dry basis:

a. 10%

b. 15%

c. 20%

d. 25%

Ans. d

14. The recommended temperature of drying of grains for seed purpose is about:

a. 40 degree C

b. 50 degree C

c. 60 degree C

d. 70 degree C

Ans. a

15. 100kg of grain is dried from 18% (w.b) to 13% (w.b). The amount of water removed is:

a. 4.8 kg

b. 5 kg

c. 5.7kg

d. 6.2kg

Ans. c

16. Natural air-drying needs dehumidification if atmospheric humidity is:

a. Very less

b. Low

c. Intermediate

d. High

Ans. d

17. In drying, end of constant rate period and start of falling rate period is known as:

a. Critical moisture content

b. Equilibrium moisture content

c. Constant drying rate period

d. Falling rate period

Ans. a

Difference between Drying and Dehydration MCQs

18. Dryers utilizing high gas temperatures of 500 degree C or more, but for short exposure of time are called as:

a. Fluidized bed dryers

b. Flash dryers

c. Turbol dryers

d. Drum dryers

Ans. b

19. The water activity of the surface of a food product at the end of constant drying rate:

a. Remains constant at 1

b. Drops below 1

c. Equals to zero

d. Drops below 2

Ans. b

20. In single effect evaporator the economy is:

a. Equal to 1

b. More than 1

c. Less than 1

d. More than 10

Ans. c

21. The process of removal of moisture from moist ar known as …… process:

a. Humidification

b. Cooling

c. Dehumidification

d. Drying

Ans. c

22. When dry bulb and wet bulb temperature are same the RH of air will be:

a. 0%

b. 50%

c. 100%

d. 70%

Ans. c

23. Thermal radiation emitted by a body is proportional to of its absolute temperature:

a. Fourth power

b. Square

c. Square root

d. Cube root

Ans. a

24. The heat which causes increase or decrease in the temperature of a body without changing its state is known as:

a. Latent heat

b. Specific heat

c. Sensible heat

d. Total heat

Ans. c

25. A property used to measure the gravity of energy or irreversibility of the process is called as:

a. Enthalpy

b. Entrop

c. Diffusivity

d. Conductivity

Ans. b

What is Dehydration of Food in What way is this technique useful

26. The universal moisture meter measures ………. of the grain at given comparison:

a. Electrical conductivity

b. Electrical resistance

c. Diffusivity

d. Thermal conductivity

Ans, b

27. BET equation is used for measuring the…….. of food:

a. Moisture humidity

b. EMC

c. Water activity

d. Dry matter

Ans. c

28. The ratio of kg of water vapour and kg of dry air is:

a. Relative humidity

b. Percentage humidity

c. Absolute humidity

d. Humid volume

Ans. c

29. In the process where there is change from one condition to other condition without transfer of heat between system and atmosphere or surrounding during the entire process is known as:

a. Isothermal

b. Isoentropic

c. Adiabatic

d. Isobaric

Ans. c

30. During sensible heating or cooling there is no change in the values of:

a. Relative humidity

b. Humidity ratio

c. Specific humidity

d. Absolute humidity

Ans. b

31. The vapour pressure of the water in grain lower than the vapour pressure of free water surface is known as:

a. Bound water

b. Unbound water

c. Free water

d. Surface water

Ans. a

32. In thin layer drying, the thickness of grain is normally up to:

a. 15-20 cm

b. 20-25cm

c. 25-30cm

d. 30-35cm

Ans. a

Methods of Dehydration of Fruits and Vegetables

33. Method of drying used for heat sensitive produce is:

a. Spray drying

b. Tray drying

c. Flow drying

d. Freeze drying

Ans. d

34. Due to moisture migration the spot of moisture accumulation takes place at….. of storage structure during winter:

a. Top

b. Bottom

c. Centre

d. Side

Ans. a

35. The factors influencing the diameter of drying chamber in the spray dryer design are:

a. Velocity of drying air

b. Atomizer speed

c. Density of air

d. Temperature of inlet air

Ans. b

36. LSU drier is a type drier:

a. Continuous mixing

b. Non mixing

c. Thin layer

d. Deep bed

Ans. a

37. The optimum moisture content for paddy harvesting is …..%:

a. 20

b. 22

c. 24

d. 26

Ans. b

38. Parboiling of paddy is treatment:

a. Hydration

b. Dehydration

c. Thermal

d. Hydrothermal

Ans. d

39. Two fluid nozzle is used in a:

a. Spray drier

b. Drum drier

c. Fluidized bed drier

d. Freeze drier

Ans. a

40. At 100% RH, wet bulb temperature is…. dew point temperature:

a. More than

b. Less than

c. Same as

d. Less or more

Ans. c

41. Sensible cooling of air….. RH of air:

a. Increases

b. Dereases

c. Does not change

d. Both a and b

Ans. a

Dehydration Methods of Food Preservation pdf

42. Holding a grain between two drying passes is termed as:

a. Stabilizing

b. Tempering

c. Cooling

d. Equalizing

Ans. b

43. Density of air at normal conditions is approximately ……. kg/m3:

a. 1.0

b. 1.2

c. 1.4

d. 1.6

Ans. b

44. Isobaric process are those in which…… is maintained constant:

a. Temperature

b. Volume

c. Pressure

d. Humidity

Ans. c

Sun (Solar) Drying of Fruits and Vegetables

45. The RH will be reduced to half of its original value if the temperature of air is increased by:

a. 21 degree C

b. 15 degree C

c. 11 degree C

d. 8 deggree C

Ans. c

46. When the temperature of air increases, the RH:

a. Increases linearly

b. Decreases

c. Does not change

d. Increases exponentially

Ans. b

47. In spray dryer, the pressure nozzle requires…… pressure:

a. 200kg/cm2

b. 25kg/cm2

c. 50kg/cm2

d. 75kg/cm2

Ans. a

48. In drying process the moisture removal takes place by:

a. Radiation

b. Conduction

c. Diffusion

d. Convection

Ans. c

49. Energy required for removal of bound moisture from the materials is….. free moisture:

a. More than

b. Half of the

c. Equal to

d. 10 times higher than the

Ans. a

50. Mixing type columnar dryer is used for:

a. Liquid materials

b. Granular materials

c. Leafy materials

d. Powder materials

Ans. b

Drying and Dehydration Books

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