Module 3: Moisture Content

Question 1

moisture content as a percentage of fresh weight of the sample

Answer 1

moisture content wet basis

Question 2

moisture content is commonly used in the ____ industry

Answer 2

grain

Question 3

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

Answer 3

moisture content dry basis

Question 4

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

Answer 4

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

Question 5

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

true or false

Answer 5

true

Question 6

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

Answer 6

moisture content dry basis

Question 7

rule of thumb in mc reduction

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

Answer 7

0.5 kg; 1%

Question 8

factors affecting the choice of method

Answer 8

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

Question 9

methods of determining moisture content

Answer 9

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

Question 10

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?

Answer 10

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.

Question 11

methods of determining moisture content

used by researchers to obtain highly accurate moisture measurements

Answer 11

primary or direct method

Question 12

methods of determining moisture content

used to calibrate the secondary type of moisture measuring devices

Answer 12

primary or direct method

Question 13

methods of determining moisture content

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

Answer 13

primary or direct method

Question 14

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

Answer 14

72 to 96

Question 15

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

true or false

Answer 15

true

Question 16

methods of determining moisture content

types of oven method

Answer 16

1. vacuum oven method
2. air-oven method
3. water-oven method

Question 17

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

Answer 17

vacuum oven method

Question 18

methods of determining moisture content

oven method

2-3 grams for one hour at 226 degree F

Answer 18

one stage air-oven method

Question 19

methods of determining moisture content

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

true or false

Answer 19

false; that is two stage air-oven method

Question 20

methods of determining moisture content

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

Answer 20

30; less than

Question 21

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

Answer 21

false; Fahrenheit

Question 22

methods of determining moisture content

types of distillation methods

Answer 22

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

Question 23

methods of determining moisture content

BD distillation

_____: 212 degree Fahrenheit
corn: ____ degree Fahrenheit

Answer 23

rice : 212 degree Fahrenheit
corn: 190 degree Fahrenheit

Question 24

methods of determining moisture content

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

Answer 24

mineral oil

Question 25

methods of determining moisture content BD distillation collects condensed water, which is equal to the moisture content of the sample true or false

Answer 25

true

Question 26

methods of determining moisture content in BD distillation, the sample is heated for 190 degree Celsius for milled rice true or false

Answer 26

false; 190 degree F is for corn

Question 27

methods of determining moisture content in BD distillation, sample is heated to 200 degree Celsius for milled rice for ___-45 minutes

Answer 27

30-45 minutes

Question 28

what is the IUPAC name of toluene?

Answer 28

methyl benzene (C6H5CH3)

Question 29

methods of determining moisture content uses toluene

Answer 29

toluene distillation method

Question 30

boiling point of toluene is 110 degree Celsius true or false

Answer 30

false; 111 degree Celsius

Question 31

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

Answer 31

75

Question 32

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

Answer 32

true

Question 33

methods of determining moisture content finely ground sample is placed near an efficient drying agent, called _______, in a closed container

Answer 33

desiccants

Question 34

methods of determining moisture content in drying with desiccant, what is maintained at very low levels within the container?

Answer 34

vapor pressure

Question 35

methods of determining moisture content give an example of a desiccant

Answer 35

anhyndrous sulphuric acid

Question 36

methods of determining moisture content reason why moisture moves from the sample to the desiccant

Answer 36

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

Question 37

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

Answer 37

hygrometric methods

Question 38

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

Answer 38

the RH of the air in equilibrium with the sample

Question 39

methods of determining moisture content chemicals are added which combines with water

Answer 39

chemical method

Question 40

methods of determining moisture content in chemical method, how is the MC of the sample measured?

Answer 40

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

Question 41

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

Answer 41

secondary or indirect method

Question 42

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

Answer 42

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

Question 43

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

Answer 43

compaction and cleanliness

Question 44

methods of determining moisture content moisture meters that studies the elec resistance of water in grains

Answer 44

- Kaneko - Shega III - Dole

Question 45

as moisture content increases, the electrical resistance decreases true or false

Answer 45

true

Question 46

higher temperatures _______ (reduces/increases) electrical resistance

Answer 46

reduces

Question 47

higher density materials have higher electrical resistance true or false

Answer 47

false; have lower elec resistance

Question 48

methods of determining moisture content samples is places between two capacitor plates

Answer 48

die-electric of capacitance method

Question 49

methods of determining moisture content in die-electric or capacitance method, the capacitance of grain is dependent on?

Answer 49

- grain MC - degree of compation - temp

Question 50

methods of determining moisture content capacitance-type moisture meters are accurate over the range of moisture 12% to 30% true or false

Answer 50

true

Question 51

most important point in determining moisture content in grading work

Answer 51

accuracy with rapidity

Question 52

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

Answer 52

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

Question 53

methods of determining moisture content motomco moisture meter measures the capacitance of moisture in the grain true or false

Answer 53

true

Question 54

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

Answer 54

increases

Question 55

as temperature increases, electrical capacitance decreases true or false

Answer 55

true

Question 56

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

Answer 56

higher

Question 57

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

Answer 57

12-30%

Question 58

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

Answer 58

true

Question 59

four stages of paddy where MC is important to be determined

Answer 59

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

Question 60

four stages of paddy where MC is important to be determined to control the degree of drying (natural or artificial)

Answer 60

on the farm

Question 61

four stages of paddy where MC is important to be determined to determine the proper time of harvesting

Answer 61

on the field

Question 62

MC of paddy during dry season harvesting

Answer 62

20-22%

Question 63

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

Answer 63

26%

Question 64

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

Answer 64

during storage

Question 65

MC is determined during milling to prevent excessive ________ and _____

Answer 65

breakage and heat

Question 66

the threshold value for safe storage is 11% true or false

Answer 66

false; it's 14%

Question 67

the threshold value for milling is 12% true or false

Answer 67

true

Question 68

these two methods are necessary for calibrating elec moisture meters

Answer 68

1. distillation method 2. thermostatic ovens

Question 69

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

Answer 69

MC

Question 70

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

Answer 70

- whether the crop is ripe for harvest - dry enough for safe storage - ready for milling with optimum recovery

Question 71

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

Answer 71

they crack the grain with their teeth

Question 72

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

Answer 72

1kg; 44kg

Question 73

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

Answer 73

false; it's 21-24% MC wb

Question 74

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

Answer 74

true

Question 75

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

Answer 75

moisture load

Question 76

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

Answer 76

- 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

Question 77

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

Answer 77

- 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

Question 78

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.

Answer 78

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