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ABE 2 Second Exam > Module 3: Moisture Content > Flashcards

Module 3: Moisture Content Flashcards

1
Q

moisture content as a percentage of fresh weight of the sample

A

moisture content wet basis

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2
Q

moisture content is commonly used in the ____ industry

A

grain

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3
Q

moisture content as a percentage of bone dry weight of the sample

A

moisture content dry basis

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4
Q

moisture content of the grain is one of the most important indexes in determining the following

A
  • whether the crop is ripe for harvest
  • dry enough for safe storage
  • ready for milling to prevent breakage
  • seed certification
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5
Q

representing moisture on dry basis rather than on wet basis is more convenient

true or false

A

true

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6
Q

method that is usually used in expressing moisture of soils and other inert matter

A

moisture content dry basis

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7
Q

rule of thumb in mc reduction

a weight change of _____ kg per bag per ___ % decrease in moisture content

A

0.5 kg; 1%

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8
Q

factors affecting the choice of method

A
  1. form of water present
  2. nature of product
  3. relative amount of water present
  4. rapidity of determination
  5. accuracy desired
  6. cost of equipment
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9
Q

methods of determining moisture content

A
  1. primary or direct method
    a. oven methods
    • vacuum oven
    • air-oven
    • water oven
      b. distillation method
    • brown-duvel
    • toluene
      c. drying with desiccants
      d. hygrometric methods
      e. chemical method
  2. secondary or indirect method
    a. electrical resistance
    b. die-electric or capacitance method
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10
Q

why is it incorrect to state that a certain percentage or amount of water has been removed from a given weight of grain when the moisture content is lowered on a wet basis?

A

it is incorrect to state a specific percentage or amount of water removed because the moisture content percentage is based on the total weight of the grain. as water is removed, the total weight of the grain changes, altering the proportion of water to the total weight. this principle means that the removal of water cannot be directly translated into a fixed percentage or weight without considering the change in the total weight of the grain.

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11
Q

methods of determining moisture content

used by researchers to obtain highly accurate moisture measurements

A

primary or direct method

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12
Q

methods of determining moisture content

used to calibrate the secondary type of moisture measuring devices

A

primary or direct method

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13
Q

methods of determining moisture content

steps used are too cumbersome and time-consuming for use in the field or warehouse

A

primary or direct method

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14
Q

in the primary method, representative sample of the bulk is dried in the vacuum oven for __ to __ hours at 100 degree Celsius

A

72 to 96

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15
Q

in primary method, the drop in weight is measured to know that water displaced in the method

true or false

A

true

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16
Q

methods of determining moisture content

types of oven method

A
  1. vacuum oven method
  2. air-oven method
  3. water-oven method
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17
Q

methods of determining moisture content

oven method

the pressure is reduced (25-100 mmHg) to allow a more complete moisture and volatiles removal removal without decomposition within 3-6 hours of the drying time

A

vacuum oven method

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18
Q

methods of determining moisture content

oven method

2-3 grams for one hour at 226 degree F

A

one stage air-oven method

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19
Q

methods of determining moisture content

one stage air-oven is for grain with more than 13% moisture

true or false

A

false; that is two stage air-oven method

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20
Q

methods of determining moisture content

two-stage air-oven method dry 25-____ grams until the moisture drops to ________ (less/more than) 13%

A

30; less than

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21
Q

methods of determining moisture content

in water-oven method, 25-30 grams is heated to 211-212 degree Celsius for 72 to 96 hours

true or false

A

false; Fahrenheit

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22
Q

methods of determining moisture content

types of distillation methods

A
  1. Brown-Duvel fractional (BD)
  2. Toluene distillation method
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23
Q

methods of determining moisture content

BD distillation

_____: 212 degree Fahrenheit
corn: ____ degree Fahrenheit

A

rice : 212 degree Fahrenheit
corn: 190 degree Fahrenheit

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24
Q

methods of determining moisture content

in BD distillation, a 100 g samples is mixed with 150 mL of ________ oil

A

mineral oil

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25
Q

methods of determining moisture content

BD distillation collects condensed water, which is equal to the moisture content of the sample

true or false

A

true

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26
Q

methods of determining moisture content

in BD distillation, the sample is heated for 190 degree Celsius for milled rice

true or false

A

false; 190 degree F is for corn

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27
Q

methods of determining moisture content

in BD distillation, sample is heated to 200 degree Celsius for milled rice for ___-45 minutes

A

30-45 minutes

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28
Q

what is the IUPAC name of toluene?

A

methyl benzene (C6H5CH3)

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29
Q

methods of determining moisture content

uses toluene

A

toluene distillation method

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30
Q

boiling point of toluene is 110 degree Celsius

true or false

A

false; 111 degree Celsius

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31
Q

in toluene distillation, a 25 g samples is mixed with ___ mL of toluene

A

75

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32
Q

the sample in toluene distillation method is boiled up to 2 hours

true or false

A

true

33
Q

methods of determining moisture content

finely ground sample is placed near an efficient drying agent, called _______, in a closed container

A

desiccants

34
Q

methods of determining moisture content

in drying with desiccant, what is maintained at very low levels within the container?

A

vapor pressure

35
Q

methods of determining moisture content

give an example of a desiccant

A

anhyndrous sulphuric acid

36
Q

methods of determining moisture content

reason why moisture moves from the sample to the desiccant

A

the vapor pressure of the desiccant is lower than the vapor pressure in the sample

37
Q

methods of determining moisture content

the sample is place in a sealed container which will allow the sample to equilibrate with the atmosphere in the container with known RH and temp

A

hygrometric methods

38
Q

methods of determining moisture content

in hygrometric methods, how is the MC of the sample measured?

A

the RH of the air in equilibrium with the sample

39
Q

methods of determining moisture content

chemicals are added which combines with water

A

chemical method

40
Q

methods of determining moisture content

in chemical method, how is the MC of the sample measured?

A

the chemical reaction produces gases which can be measure volumetrically or which decreases the original weight of the sample

41
Q

methods of determining moisture content

involves the measurement of properties of the materials including electrical, mechanical, or thermal property related to its actual MC

A

secondary or indirect method

42
Q

which is/are NOT true about secondary or indirect method?

a. results can be determined faster
b. it is more accurate
c. can be used in field works
d. expressed in dry basis

A

B; it is less accurate
D; usually expressed in wet basis

43
Q

methods of determining moisture content

the elec resistance of the grain varies with temp, moisture, degree of ________ and __________ of the grain

A

compaction and cleanliness

44
Q

methods of determining moisture content

moisture meters that studies the elec resistance of water in grains

A
  • Kaneko
  • Shega III
  • Dole
45
Q

as moisture content increases, the electrical resistance decreases

true or false

A

true

46
Q

higher temperatures _______ (reduces/increases) electrical resistance

A

reduces

47
Q

higher density materials have higher electrical resistance

true or false

A

false; have lower elec resistance

48
Q

methods of determining moisture content

samples is places between two capacitor plates

A

die-electric of capacitance method

49
Q

methods of determining moisture content

in die-electric or capacitance method, the capacitance of grain is dependent on?

A
  • grain MC
  • degree of compation
  • temp
50
Q

methods of determining moisture content

capacitance-type moisture meters are accurate over the range of moisture 12% to 30%

true or false

A

true

51
Q

most important point in determining moisture content in grading work

A

accuracy with rapidity

52
Q

it is not okay to use quick testing methods since it is not a hundred percent accurate

true or false

A

false; it’s necessary! even if it’s not 100% accurate, provider the error is small and constant

53
Q

methods of determining moisture content

motomco moisture meter measures the capacitance of moisture in the grain

true or false

A

true

54
Q

as moisture content increases, electrical capacitance _______ (increases/decreases)

A

increases

55
Q

as temperature increases, electrical capacitance decreases

true or false

A

true

56
Q

higher density materials have _______ (higher/lower) electrical capacitance

A

higher

57
Q

capacitance-type moisture meters are accurate over the range of moisture from ___-___ % w.b.

A

12-30%

58
Q

according to the Rice Postproduction Technology, the electrical capacitance meters are generally more accurate

true or false

A

true

59
Q

four stages of paddy where MC is important to be determined

A
  1. on the field
  2. on the farm
  3. during storage
  4. during milling
60
Q

four stages of paddy where MC is important to be determined

to control the degree of drying (natural or artificial)

A

on the farm

61
Q

four stages of paddy where MC is important to be determined

to determine the proper time of harvesting

A

on the field

62
Q

MC of paddy during dry season harvesting

A

20-22%

63
Q

a mature paddy with ___% MC is ready to be harvest on a wet season

A

26%

64
Q

four stages of paddy where MC is important to be determined

to ascertain the basic req for safe storage and to determine possible evaporation losses

A

during storage

65
Q

MC is determined during milling to prevent excessive ________ and _____

A

breakage and heat

66
Q

the threshold value for safe storage is 11%

true or false

A

false; it’s 14%

67
Q

the threshold value for milling is 12%

true or false

A

true

68
Q

these two methods are necessary for calibrating elec moisture meters

A
  1. distillation method
  2. thermostatic ovens
69
Q

this determines’ the grain’s quality and susceptibility to deterioration

A

MC

70
Q

MC is one of the most important indexes in determining the ff

A
  • whether the crop is ripe for harvest
  • dry enough for safe storage
  • ready for milling with optimum recovery
71
Q

how do experienced rice dealers qualitatively determine whether palay is wet or dry enough for milling

A

they crack the grain with their teeth

72
Q

there is about ___kg change in weight in one bag of paddy of __ kg for every percent change in MC

A

1kg; 44kg

73
Q

optimum MC at harvest for palay is between 21-28% MC wb

true or false

A

false; it’s 21-24% MC wb

74
Q

optimum MC for safe storage and milling is between 13-15% MC wb

true or false

A

true

75
Q

amount of water that must be removed to desired moisture content level per kilogram of wet grain

A

moisture load

76
Q

choice of methods to use for a specific product will depend upon several factors

A
  • form in which water is present
  • nature of product analyzed (whether easily oxidized or decomposed)
  • the relative amount of water present in the product, rapidity of the determination
  • the accuracy desired
  • the cost of the equipment required
77
Q

the moisture content of rice has a bearing on the ff:

A
  • shattering loss on the field
  • keeping properties of paddy, milled rice and by products
  • loss of weight by evaporation during storage and processing
  • milling output
  • cooking characteristics of milled rice
78
Q

REVIEW QUESTION (no answer in the flashcards)

  1. Determine the moisture load of 100 kg grain with initial moisture content of 20% and final moisture content of 13%.
  2. Convert 10 % MCwb to %MCdb.
  3. Determine the change in weight in one cavan palay (44 kg at 14% MCwb) if its moisture content increases to 15% MCwb.
A

COMPUTE

ABE 2 Second Exam (6 decks)

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