MC Determination Flashcards

1
Q

It is the amount of water present in the grain, and is expressed in percentage (%).

A

Grain Moisture Content

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2
Q

Grain is ______, where moisture content may increase
or decrease depending on ambient temperature and
relative humidity.

A

Hygroscopic

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3
Q

When grain is exposed to air with low temperature
and high relative humidity (RH) the grains will absorb
water from the air.

A

Re-wetting

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4
Q

When grain is exposed to air with high temperature

and low RH the grains will release water to the air.

A

Drying

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5
Q

Recommended MC for Drying

A

< or equal to 14%

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6
Q

Recommended MC for Drying

A

< or equal to 14%

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7
Q

Recommended MC for milling

A

13-14%

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8
Q

Recommended MC for seed storage

A

< or equal to 12%

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9
Q

Recommended MC for long term storage

A

< or equal to 9%

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10
Q

Primary losses for drying

A

Spoilage, fungal damage, discoloration

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11
Q

Primary losses for milling

A

breakage
grain cracking
over-milling

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12
Q

Primary losses for storage

A
  • Fungal, insect damage (grain storage)

* Loss of vigor (seed and long term storage)

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13
Q

Moisture content is determined by removing moisture and then measuring weight loss.

A

Direct method

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14
Q

measuring moisture using the
change in electrical or structural characteristic of a
material as a relationship of its moisture content

A

Indirect Method

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15
Q

methods such as biting,
shaking, and crunching are commonly used by both producers
and small traders.

A

Empirical Measurement

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16
Q

MC is determined with the use of

convection oven.

A

Air-oven Method

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17
Q

moisture is determined by fractional

distillation.

A

BROWN DUVEL Method

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18
Q

Moisture is determined by
evaporation using infrared
heaters as heat source.

A

Infrared method

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19
Q

This method measures the electrical properties (resistance and
capacitance) in relation to the moisture content in the grain.
Most commonly known in this method is the use of moisture
meters.

A

Secondary or Indirect method

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20
Q

measures how the material reduces the electrical

current flow. (value increases with moisture)

A

Resistance

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21
Q

measures dielectric constant of grains.(value decreases with moisture)

A

Capacitance

22
Q

the ability of any substance to

store electrical energy

A

dielectric constant

23
Q
• Removal of excess moisture
for safe storage
• Delay leads to damage
• Too rapid result to stress
cracks
• Over-drying results to
economic loss
A

Drying

24
Q

is one way of increasing farmers’ income

by reducing quantity and quality losses

A

drying

25
Q

expands farmers opportunities enabling
them to temporarily store and seek better markets
without quality deterioration

A

drying

26
Q

Forms of losses due to delay or

improper drying

A
  1. Discoloration
  2. Loss of seed viability
    (seed growers)
  3. Reduced milling recovery
  4. Altered texture/
    appearance and taste
  5. Spillages/other physical losses
  6. Price reduction
27
Q

DRYING PRINCIPLE

A

heat transfer

mass transfer

28
Q

Heat energy from the sun

A

radiation

29
Q

transfer of thermal energy through direct contact

A

conduction

30
Q

transfer of thermal energy through the movement of

liquid or gas

A

convection

31
Q

VPg > VPa

A

desorption

32
Q

VPg < Vpa

A

absorption

33
Q

VPg = Vpa

A

Equilibrium Moisture Content (EMC)

34
Q

transport heat to grain

A

air

35
Q

to hasten evaporation of moisture

A

heat

36
Q

TOO MUCH
HEAT will result
to ______

A

stress crack

37
Q

TOO LOW
AIRFLOW – will result
to _____

A

moisture gradient

38
Q
Occurs when:
• Evaporation is faster than
diffusion
• When there’s uneven shrinkage
between surface and inner grain
•When grain is rewetted, surface
expands abruptly due to absorption
of moisture
A

stress cracks

39
Q

TRO OR POLS. IT REQUIRES LESS ENERGY TO REMOVE

MOISTURE AT THE FALLING RATE PERIOD THAN AT THE CONSTANT RATE PERIOD

A

POLS

40
Q

flue gas and other products of

combustion goes into the dryer

A

DIRECT-FIRED

41
Q

a heat exchanger is used to
prevent smoke and other products of combustion to
go with the drying air

A

INDIRECT-FIRED

42
Q

Grain is stationary during drying

A

batch type

43
Q

Grain moves across the drying
chamber continuously and are equipped with
tempering bins

A

continuous flow

44
Q

Grain is continuously

recirculated during drying

A

BATCH-TYPE RECIRCULATING

45
Q

Types of Mechanical Dryers

A
  1. BATCH TYPE
  2. CONTINUOUS FLOW
  3. BATCH-TYPE RECIRCULATING
46
Q

Basic Parts of a Flatbed Dryer

A

burner, blower, bin/bed

47
Q

Occurs when there is moisture difference
between grain at the bottom and top of the
flatbed dryer

A

moisture gradient

48
Q

this where combustion
gases (flue gas) is
released to the
atmosphere

A

chimney

49
Q

this is where the heat is
transferred from
combustion gases
to the process air

A

heat exchanger

50
Q

this is where the ricehull fuel

is burnt

A

combustion chamber