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ABE 2 Second Exam > Module 6: Milling > Flashcards

Module 6: Milling Flashcards

1
Q

postproduction processes for rice

A
  1. threshing
  2. cleaning
  3. drying
  4. milling
  5. storage
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2
Q

rice milling losses

A

5.5% of 16.47%

wait lang di ko gets yan hahaha

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3
Q

objectives of rice milling

A
  1. remove the husk and bran layers from paddy rice
  2. produce white rice kernels that are sufficiently milled and free of impurities
  3. high head rice recovery; contain a minimum number of broken grains
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4
Q

milling yield and quality is affected by?

A
  • quality of the raw paddy
  • milling equipment
  • skill of the operator
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5
Q

most rice varieties are composed of

A
  • 20% rice hull or husk
  • 80% brown rice
  • 8-10% bran layers
  • 70-72% starchy endosperm, also called as the total milled rice
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6
Q

outermost part covering of the paddy

A

hull

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7
Q

pericarp, testa, aleurone layer

A

bran

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8
Q

brain is low in oil and protein, but high in vitamins and mineral

true or false

A

false; brain is high of all that

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9
Q

living organism in the grain capable of development into a new plant

A

embryo

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10
Q

starch with a few protein, minerals, vitamins, and oil and high energy because of carbs

A

endosperm

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11
Q

intertwined covering removed in milling

A

palea and lemma

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12
Q

ideal milling recovery

A
  • 20% husk
  • 8-12% bran depending on the milling degree
  • 68-72% milled rice or white rice depending on the variety
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13
Q

milling systems

A
  1. one-step milling system
  2. two-step milling system
  3. multistage milling system
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14
Q

milling systems

husk and bran removal are done

A

one-step milling system

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15
Q

in a one-step milling system, paddy passes between a __________ ____ shaft and a cylindrical shaped ______ ______

A

revolving steel shaft and a cylindrical shaped mesh screen

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16
Q

white head recovery of a one-step milling system is <30%

true or false

A

false; it’s 50-55%

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17
Q

one-step milling system results to low head rice which is less than 30%

true or false

A

true

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18
Q

a steel mill or Engelberg mill is an example of what type of milling system?

A

one-step milling system

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19
Q

milling systems

has a rubber roller husker and a friction whitener

A

two-step milling system

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20
Q

capacity of a two-step milling system

A

0.5 to 1 ton per hour paddy input

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21
Q

milling recoveries in a two-step milling system is above ?

A

above 60%

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22
Q

give an example of two-step milling system (based on PPT)

A

compact mill

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23
Q

milling systems

this is used to reduce mechanical stresses and heat buildup in the grain

A

multistage milling system

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24
Q

in a _________ ______ _______, grain breakage is minimized, therefore producing uniformly polished grain

A

multistage milling system

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25
Q

steps in rice milling

A
  1. pre-cleaning
  2. dehusking
  3. husk aspiration
  4. paddy separation
  5. whitening/polishing
  6. sifting and grading
  7. mixing
  8. mist polishing
  9. weighing and bagging
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26
Q

advantages of a rubber-roller

A
  • reduce breakage of milled kernels
  • high hulling efficiency (85-90%)
  • by-products are free from sand and silicon
  • very compact in comparison to disc huller
  • less vibration
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27
Q

disadvantages of a rubber-roller

A
  • cost to purchase
  • cost of rubber rollers
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28
Q

this is produced when the bran layer of the the brown rice is removed

A

white rice

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29
Q

white rice is produced by applying friction the grain surface either by

A
  • rubbing the grains against an abrasive surface
  • rubbing against each other
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30
Q

type of whitener

A
  1. abrasive
  2. friction
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31
Q

type of whitener

grain is whitened by passing the rice kernel between a moving abrasive surface and stationary screen

A

abrasive

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32
Q

type of whitener

rice kernels are forced against each other and a metal screen by a steel-ribbed cylinder rotating inside a metal-plated cylinder

A

friction

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33
Q

friction polishers can vertical or horizontal in design

true or false

A

false; they are always horizontal, abrasive can be vertical

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34
Q

a friction polisher applies more pressure on the grain than an abrasive whitener

true or false

A

true

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35
Q

good practices conducted in rice milling

A
  • good MC
  • preclean paddy before husking
  • do not mixed varieties
  • use rubber-roll husker and paddy separator
  • consider two-stage whitening
  • grade the milled rice and do maintenance
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36
Q

grain or grade factors

A
  1. MC
  2. purity
  3. cracked grains
  4. varietal characteristic
  5. immature grains
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37
Q

relationship of milling recovery to moisture content

A

inversely proportional

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38
Q

presences of foreign matter decreases MR and quality

true or false

A

true

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39
Q

___________ (Japonica): as low as 15%
long grains (________): as high as 23%

A

short grain (Japonica): as low as 15%
long grains (_Indica): as high as 23%

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40
Q

husk content of immature paddy

A

as high as 40%

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41
Q

operation factors considered in rice milling

A
  1. skill and attitude of the operators
  2. mode of payment in milling fee
    a. payment in cash
    b. payment in kind
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42
Q

milling fee is based on weight input, mill operator does not care so much of the quality and quantity

true or false

A

true

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43
Q

paying in kind

operator would ensure _______ is attained if payments is milled rice

A

max MR

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44
Q

percentage of milled rice (including brokens) obtained from a sample of paddy

A

milling recovery

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45
Q

a measure of the percent bran removed from the brown rice kernel

A

milling degree

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46
Q

rice after milling which includes removing all or part of the bran and germ from the husked rice

A

milled rice

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47
Q

milled rice with length greater or equal to three quarters of the average length of the whole kernel

A

head rice

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48
Q

similar term for paddy, or rice retaining its husk after threshing

A

paddy or rough rice

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49
Q

paddy from which the husk has been removed

A

brown rice or husked rice

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50
Q

percentage of head rice (excluding brokens) obtained from a sample of paddy

A

head rice recovery

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51
Q

by products of rice milling can be used for

A
  • fuel
  • building materials
  • high-end materials
  • animal production (beddings)
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52
Q

factors that increases MR

A
  • drying and storage
  • other practices
  • equipment
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53
Q

process of transformation of a product into a form suitable for either human or livestock consumption

A

milling

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54
Q

process of converting paddy into rice which involves the removal of the husk and bran to produce milled rice for human consumption with maximum percentage of whole grain

A

rice milling

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55
Q

rice milling

A

obtaining whole grain rice involves preserving most kernels’ original shape, producing well-milled white rice free of impurities with minimal broken grains

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56
Q

three essential factors that directly affect milling yield and quality of rice

A
  • quality of the rice paddy
  • efficiency of the milling equipment
  • skill of the rice mill operator
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57
Q

paddy rice grain comprised of the ff

A
  • a brown rice kernel enclosed by the husk
  • a bran layer
  • a germ/embryo; a
  • starchy center
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58
Q

mature paddy rice consists of roughly __% by weight of hull, __% of bran and ___% of endosperm.

A

22%; 6%; 72%

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59
Q

outermost covering of the paddy

60
Q

hull is formed by the leaves of the spikelet namely

A
  1. palea
  2. lemma
61
Q

part of the hull which covers the ventral parts seed

62
Q

part of the hull which covers the dorsal portion

63
Q

these leaves are longitudinally joined together

A
  1. palea
  2. lemma
64
Q

mainly consists of cellulose and fibrous tissue and is covered with very hard glass-like spines or trichomes

65
Q

this part of the grain protect the grain against insects, microorg, moisture and gases

66
Q

this becomes visible when the hull is removed

A

pericarp or frequently known as silver skin

67
Q

thin fibrous layer that is usually translucent or grayish in color and is an essential component of the brown rice grain

68
Q

considered as the outermost layer of the bran because of its oil content

69
Q

grain is called ___ _____ when the pericarp is reddish instead of a translucent layer.

70
Q

the pericarp is formed by three layers

A
  1. pericarp
  2. mesocarp
  3. cross layer
71
Q

pericarp layer is the _____ which is rich in oil and protein but low in starch content

72
Q

this part of grain serves as an additional protective layer against molds and causes

73
Q

this part of grain located immediately under the testa

A

bran layer

74
Q

portion of rice which is removed in the whitening stage of milling

A

bran layer or aleurone

75
Q

this part of grain which is characterized by its very low starch content; and high percentage of oil, protein, vitamins and mineral

A

bran layer or aleurone

76
Q

this part of grain is easily affected by oxidation due to its high oil content

A

bran layer or aleurone

77
Q

this part of grain is located on the ventral part

78
Q

living organism in the grain capable of development into a new plant

79
Q

the embryo respires by taking in ________ in the air; consumes food particularly the ______ of the grain; and simultaneously gives off ______ and ____

A

oxygen; starch; moisture and heat

80
Q

the indented shape of the milled rice is caused by the removal of which part during milling operations?

81
Q

most important part of the grain

82
Q

remainder after the removal of the husk, pericarp, bran and embryo in grain

83
Q

mainly comprised of starch with a few percentages of protein, minerals, vitamins and oil

it is characterized by high energy value due to the high percentage of carbohydrates

84
Q

the starchy cells in the core of the grain are nearly __________ (shape), tend to become elongated and even have long walls radiating outwards from the ________ in the portion between the center and the outside part

A

hexagonal; center

85
Q

an ideal milling equipment should be able to do what? what is its milling recovery?

A
  • remove the hull
  • scrape off the bran
  • produce the milled rice

has a milling recovery of 72%

86
Q

total weight of milled rice to the total weight of palay

A

milling recovery

87
Q

if the milling recovery is greater than 72% it is considered overmilled rice

true or false

A

false; it is considered undermilled rice

88
Q

if the milling recovery is ____ (less, more) than 72%, thus overmilled rice

89
Q

upon harvest, paddy or “palay” is being dried to the recommended storage and milling moisture content of ___ % wet basis

90
Q

rice milling operations

A
  1. pre-cleaning
  2. hulling
  3. husk aspiration
  4. paddy separation
  5. whitening or polishing process
  6. grading

***other additional processes
1. rice mixing
2. mist polishing
3. rice weighing

91
Q

rice milling operations

initial operation to remove foreign materials consisting of
- large impurities
- small impurities
- impurities as big as the size of the grains

A

pre-cleaning

92
Q

rice milling operations

foreign materials

includes rice straw panicles, bag strings, soil particles, stones, iron parts

A

large impurities

93
Q

rice milling operations

foreign materials

dust, sand, soil particles, weed seeds, insects, stones

A

small impurities

94
Q

rice milling operations

foreign materials

includes empty grains, stone, iron parts

A

impurities as large as the size of the grains

95
Q

rice milling operations

grain pre-cleaners can be classified according to their cleaning mechanism, which are

A
  1. oscillating sieve type
  2. aspiration cum oscillation type
  3. rotary cleaner
  4. de-stoner with aspiration
96
Q

grain pre-cleaners classification according to their cleaning mechanism

consists of two sieves of different sizes depending on the size and shape of the grain

A

oscillating sieve type

97
Q

grain pre-cleaners classification according to their cleaning mechanism

this cleaner removes lighter impurities such as dust, dirt, chaff and straw by blowing or sucking air through the mass of falling grain

A

aspiration cum oscillation type

98
Q

grain pre-cleaners classification according to their cleaning mechanism

consists of one or two drums; each drum is fitted with mesh of different sized hexagonal or square perforation and oscillating sieve

A

rotary cleaner

99
Q

grain pre-cleaners classification according to their cleaning mechanism

two types of rotary cleaner

A
  1. single drum with aspirator and oscillation sieve
  2. double drums with aspirator
100
Q

grain pre-cleaners classification according to their cleaning mechanism

two types of rotary cleaner

utilizes a single drum to separate large, light and heavy impurities

A

single drum with aspirator and oscillation sieve

101
Q

grain pre-cleaners classification according to their cleaning mechanism

two types of rotary cleaner

has two rotation drums with each drum having a different size hole on the wire mesh

A

double drums with aspirator

102
Q

rice milling operations

removal of the hull from the palay to produce brown rice

103
Q

rice milling operations

this is traditionally done using mortar and pestles

A

de-husking

104
Q

percentage of paddy that is de-hulled to produce brown rice during hulling

A

hulling efficiency

105
Q

an efficient husker will remove ___% of the husk in a single pass

106
Q

types of husking machines

A
  1. steel huller
  2. under-runner disc
  3. rubber roll
107
Q

types of husking machines

removes the husks and whitens the rice in one pass

A

steel huller

108
Q

types of husking machines

use of two horizontal abrasive stones; the upper surface is stationary, while the lower surface rotates

A

under-runner disc

109
Q

types of husking machines

type of huller makes use of a pair of rubber rolls arranged side-by-side

A

rubber roll

110
Q

in a rubber roller, one rotates __% faster than the other

111
Q

most efficient hulling machine

A

rubber roll

112
Q

rice milling operations

suggests two rubber rollers of the different diameter are operated at different speeds to remove the husk from the paddy

true or false

A

false; same diameter

113
Q

clearance adjustment between the two rollers must be maintained at about ___ thickness

A

1/2 thickness

114
Q

________ ______can achieve hulling efficiencies of 85% to 90% with minimum broken or cracked grain

A

rubber roller

115
Q

rice milling operations

separation of husk (and light materials) from the brown rice by blowing air and directing the husk into a cyclone for final discharge

A

husk or hull aspiration

116
Q

rice milling operations

separation of unhulled palay from brown rice after hulling and husk aspiration

A

paddy separation

117
Q

two types of paddy separator

A
  1. compartment
  2. tray separator
118
Q

two types of paddy separator

separator uses the difference in specific gravity and the buoyancy to separate paddy and brown rice

A

compartment separator

119
Q

two types of paddy separator

differences in specific gravity, grain length and the co-efficient of friction to separate paddy and brown rice

A

tray separator

120
Q

product of the coefficient of hulling and the coefficient of wholeness of grains, expressed in percent

A

hulling efficiency

121
Q

rice hulling operations

it produces brown rice by removing the bran layer and the germ and this process is called whitening or polishing process

A

whitening or polishing process

122
Q

type of whitener that makes use of steel knife roller and screen

A

friction pearler

123
Q

the extent by which the bran layer of the brown rice is removed as a result of whitening

A

milling degree

124
Q

types of milling degree

A
  1. undermilled
  2. regular milled
  3. well milled
125
Q

ratio of the weight of milled rice to the total weight of palay

A

milling recovery

126
Q

ideal milling recovery

127
Q

rice milling operations

done by separating whole rice from broken rice by using a rotating indented drum

128
Q

a kernel or a piece of kernel with its length equal to or greater than 8/10 of the average length of the unbroken kernel

129
Q

ratio of the weight of head rice to the total weight of milled rice, expressed in percent

A

head rice recovery

130
Q

main byproducts of rice milling are rice hulls or husk, rice bran, and brewer’s rice

A
  1. rice hulls are generated during the first stage of rice milling, when rough rice or paddy rice is husked
  2. rice bran is generated when brown rice moves through the whiteners and polishers
  3. brewer’s rice is separated produced when milled rice is sifted
131
Q

one hundred kilogram (100 kg) of paddy rice will generate approx ___ kg of husk

132
Q

which gives the rice hulls and abrasive character?

A

ash composition and structure

133
Q

one hundred kilogram (100 kg) of paddy rice will generate approximately __-___ kg of bran

134
Q

a mixture of substances, including protein, fat, ash, and crude fiber

135
Q

often used as ingredient for beer brewing, hence the name

A

brewer’s rice

136
Q

small-capacity single pass machine rice mills

A
  1. japanese rice mill
  2. kiskisan rice mill/Engelberg rice mill
  3. UPLB improved village rice mill
137
Q

small-capacity single pass machine rice mills

use of rubber roll for hulling and horizontal abrasion for whitening

A

japanese rice mill

138
Q

small-capacity single pass machine rice mills

use of knife-edge roller and screen to do hulling and whitening simultaneously

A

kiskisan rice mill/Engelberg rice mill

139
Q

small-capacity single pass machine rice mills

use of rubber roll for hulling and kiskisan for whitening

A

UPLB improved village rice

140
Q

large-capacity single pass machine rice mills

use of underrunner disk for hulling and vertical abrasion for whitening

A

cono rice mill

142
Q

REVIEW QUESTIONS (no answer in the flashcard)

  1. What is the importance of optimum recovery in rice milling operations?
  2. Identify the products and by-products of the different rice milling operations.
143
Q

conditions as affected by production and post-production operations

A

grade factors

144
Q

maximum head rice recovery is obtained when the paddy harvested has ___ % moisture content

145
Q

major causes of grain breakage during milling

A

hulling and whitening operations

146
Q

these are critical for optimum milling results

A
  • proper selection
  • adjustments
  • operation of the milling equipment
  • knowledge and kills of operations or technologies
147
Q

(NOT A QUESTION, THESE ARE JUST RECOMMENDATIONS)

  • good quality milled rice can only be produced from good quality paddy (uniform size grain, sound grains starts from certified seeds and good agronomic practices
  • general darkening of the endosperm is also caused by delays in threshing and drying that cannot be corrected in the milling process
  • during drying of paddy process, care should be taken to prevent a heat or temperature stress that causes fissuring of the grain. dried paddy should be protected from reabsorbing moisture, such as getting rained on, or prolonged exposure to humid atmospheres. moisture reabsorption in storage causes the paddy grain to develop fissures.
  • as much as possible, do not mix different varieties of paddy. ensure to clean paddy before milling to remove half filled or empty grains.

ABE 2 Second Exam (6 decks)

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