Module 6: Milling Flashcards
(146 cards)
1
Q
postproduction processes for rice
A
- threshing
- cleaning
- drying
- milling
- storage
2
Q
rice milling losses
A
5.5% of 16.47%
wait lang di ko gets yan hahaha
3
Q
objectives of rice milling
A
- remove the husk and bran layers from paddy rice
- produce white rice kernels that are sufficiently milled and free of impurities
- high head rice recovery; contain a minimum number of broken grains
4
Q
milling yield and quality is affected by?
A
- quality of the raw paddy
- milling equipment
- skill of the operator
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
6
Q
outermost part covering of the paddy
A
hull
7
Q
pericarp, testa, aleurone layer
A
bran
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
9
Q
living organism in the grain capable of development into a new plant
A
embryo
10
Q
starch with a few protein, minerals, vitamins, and oil and high energy because of carbs
A
endosperm
11
Q
intertwined covering removed in milling
A
palea and lemma
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
13
Q
milling systems
A
- one-step milling system
- two-step milling system
- multistage milling system
14
Q
milling systems
husk and bran removal are done
A
one-step milling system
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
16
Q
white head recovery of a one-step milling system is <30%
true or false
A
false; it’s 50-55%
17
Q
one-step milling system results to low head rice which is less than 30%
true or false
A
true
18
Q
a steel mill or Engelberg mill is an example of what type of milling system?
A
one-step milling system
19
Q
milling systems
has a rubber roller husker and a friction whitener
A
two-step milling system
20
Q
capacity of a two-step milling system
A
0.5 to 1 ton per hour paddy input
21
Q
milling recoveries in a two-step milling system is above ?
A
above 60%
22
Q
give an example of two-step milling system (based on PPT)
A
compact mill
23
Q
milling systems
this is used to reduce mechanical stresses and heat buildup in the grain
A
multistage milling system
24
Q
in a _________ ______ _______, grain breakage is minimized, therefore producing uniformly polished grain
A
multistage milling system
25
steps in rice milling
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
26
advantages of a rubber-roller
- 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
27
disadvantages of a rubber-roller
- cost to purchase
- cost of rubber rollers
28
this is produced when the bran layer of the the brown rice is removed
white rice
29
white rice is produced by applying friction the grain surface either by
- rubbing the grains against an abrasive surface
- rubbing against each other
30
type of whitener
1. abrasive
2. friction
31
type of whitener
grain is whitened by passing the rice kernel between a moving abrasive surface and stationary screen
abrasive
32
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
friction
33
friction polishers can vertical or horizontal in design
true or false
false; they are always horizontal, abrasive can be vertical
34
a friction polisher applies more pressure on the grain than an abrasive whitener
true or false
true
35
good practices conducted in rice milling
- 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
36
grain or grade factors
1. MC
2. purity
3. cracked grains
4. varietal characteristic
5. immature grains
37
relationship of milling recovery to moisture content
inversely proportional
38
presences of foreign matter decreases MR and quality
true or false
true
39
___________ (Japonica): as low as 15%
long grains (________): as high as 23%
short grain (Japonica): as low as 15%
long grains (_Indica): as high as 23%
40
husk content of immature paddy
as high as 40%
41
operation factors considered in rice milling
1. skill and attitude of the operators
2. mode of payment in milling fee
a. payment in cash
b. payment in kind
42
milling fee is based on weight input, mill operator does not care so much of the quality and quantity
true or false
true
43
paying in kind
operator would ensure _______ is attained if payments is milled rice
max MR
44
percentage of milled rice (including brokens) obtained from a sample of paddy
milling recovery
45
a measure of the percent bran removed from the brown rice kernel
milling degree
46
rice after milling which includes removing all or part of the bran and germ from the husked rice
milled rice
47
milled rice with length greater or equal to three quarters of the average length of the whole kernel
head rice
48
similar term for paddy, or rice retaining its husk after threshing
paddy or rough rice
49
paddy from which the husk has been removed
brown rice or husked rice
50
percentage of head rice (excluding brokens) obtained from a sample of paddy
head rice recovery
51
by products of rice milling can be used for
- fuel
- building materials
- high-end materials
- animal production (beddings)
52
factors that increases MR
- drying and storage
- other practices
- equipment
53
process of transformation of a product into a form suitable for either human or livestock consumption
milling
54
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
rice milling
55
rice milling
obtaining whole grain rice involves preserving most kernels' original shape, producing well-milled white rice free of impurities with minimal broken grains
56
three essential factors that directly affect milling yield and quality of rice
- quality of the rice paddy
- efficiency of the milling equipment
- skill of the rice mill operator
57
paddy rice grain comprised of the ff
- a brown rice kernel enclosed by the husk
- a bran layer
- a germ/embryo; a
- starchy center
58
mature paddy rice consists of roughly __% by weight of hull, __% of bran and ___% of endosperm.
22%; 6%; 72%
59
outermost covering of the paddy
hull
60
hull is formed by the leaves of the spikelet namely
1. palea
2. lemma
61
part of the hull which covers the ventral parts seed
palea
62
part of the hull which covers the dorsal portion
lemma
63
these leaves are longitudinally joined together
1. palea
2. lemma
64
mainly consists of cellulose and fibrous tissue and is covered with very hard glass-like spines or trichomes
hull
65
this part of the grain protect the grain against insects, microorg, moisture and gases
hull
66
this becomes visible when the hull is removed
pericarp or frequently known as silver skin
67
thin fibrous layer that is usually translucent or grayish in color and is an essential component of the brown rice grain
pericarp
68
considered as the outermost layer of the bran because of its oil content
pericarp
69
grain is called ___ _____ when the pericarp is reddish instead of a translucent layer.
red rice
70
the pericarp is formed by three layers
1. pericarp
2. mesocarp
3. cross layer
71
pericarp layer is the _____ which is rich in oil and protein but low in starch content
testa
72
this part of grain serves as an additional protective layer against molds and causes
pericarp
73
this part of grain located immediately under the testa
bran layer
74
portion of rice which is removed in the whitening stage of milling
bran layer or aleurone
75
this part of grain which is characterized by its very low starch content; and high percentage of oil, protein, vitamins and mineral
bran layer or aleurone
76
this part of grain is easily affected by oxidation due to its high oil content
bran layer or aleurone
77
this part of grain is located on the ventral part
embryo
78
living organism in the grain capable of development into a new plant
embryo
79
the embryo respires by taking in ________ in the air; consumes food particularly the ______ of the grain; and simultaneously gives off ______ and ____
oxygen; starch; moisture and heat
80
the indented shape of the milled rice is caused by the removal of which part during milling operations?
embryo
81
most important part of the grain
endosperm
82
remainder after the removal of the husk, pericarp, bran and embryo in grain
endosperm
83
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
endosperm
84
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
hexagonal; center
85
an ideal milling equipment should be able to do what? what is its milling recovery?
- remove the hull
- scrape off the bran
- produce the milled rice
has a milling recovery of 72%
86
total weight of milled rice to the total weight of palay
milling recovery
87
if the milling recovery is greater than 72% it is considered overmilled rice
true or false
false; it is considered undermilled rice
88
if the milling recovery is ____ (less, more) than 72%, thus overmilled rice
less
89
upon harvest, paddy or “palay” is being dried to the recommended storage and milling moisture content of ___ % wet basis
14%
90
rice milling operations
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
rice milling operations
initial operation to remove foreign materials consisting of
- large impurities
- small impurities
- impurities as big as the size of the grains
pre-cleaning
92
rice milling operations
foreign materials
includes rice straw panicles, bag strings, soil particles, stones, iron parts
large impurities
93
rice milling operations
foreign materials
dust, sand, soil particles, weed seeds, insects, stones
small impurities
94
rice milling operations
foreign materials
includes empty grains, stone, iron parts
impurities as large as the size of the grains
95
rice milling operations
grain pre-cleaners can be classified according to their cleaning mechanism, which are
1. oscillating sieve type
2. aspiration cum oscillation type
3. rotary cleaner
4. de-stoner with aspiration
96
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
oscillating sieve type
97
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
aspiration cum oscillation type
98
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
rotary cleaner
99
grain pre-cleaners classification according to their cleaning mechanism
two types of rotary cleaner
1. single drum with aspirator and oscillation sieve
2. double drums with aspirator
100
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
single drum with aspirator and oscillation sieve
101
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
double drums with aspirator
102
rice milling operations
removal of the hull from the palay to produce brown rice
hulling
103
rice milling operations
this is traditionally done using mortar and pestles
de-husking
104
percentage of paddy that is de-hulled to produce brown rice during hulling
hulling efficiency
105
an efficient husker will remove ___% of the husk in a single pass
90%
106
types of husking machines
1. steel huller
2. under-runner disc
3. rubber roll
107
types of husking machines
removes the husks and whitens the rice in one pass
steel huller
108
types of husking machines
use of two horizontal abrasive stones; the upper surface is stationary, while the lower surface rotates
under-runner disc
109
types of husking machines
type of huller makes use of a pair of rubber rolls arranged side-by-side
rubber roll
110
in a rubber roller, one rotates __% faster than the other
25%
111
most efficient hulling machine
rubber roll
112
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
false; same diameter
113
clearance adjustment between the two rollers must be maintained at about ___ thickness
1/2 thickness
114
________ ______can achieve hulling efficiencies of 85% to 90% with minimum broken or cracked grain
rubber roller
115
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
husk or hull aspiration
116
rice milling operations
separation of unhulled palay from brown rice after hulling and husk aspiration
paddy separation
117
two types of paddy separator
1. compartment
2. tray separator
118
two types of paddy separator
separator uses the difference in specific gravity and the buoyancy to separate paddy and brown rice
compartment separator
119
two types of paddy separator
differences in specific gravity, grain length and the co-efficient of friction to separate paddy and brown rice
tray separator
120
product of the coefficient of hulling and the coefficient of wholeness of grains, expressed in percent
hulling efficiency
121
rice hulling operations
it produces brown rice by removing the bran layer and the germ and this process is called whitening or polishing process
whitening or polishing process
122
type of whitener that makes use of steel knife roller and screen
friction pearler
123
the extent by which the bran layer of the brown rice is removed as a result of whitening
milling degree
124
types of milling degree
1. undermilled
2. regular milled
3. well milled
125
ratio of the weight of milled rice to the total weight of palay
milling recovery
126
ideal milling recovery
72%
127
rice milling operations
done by separating whole rice from broken rice by using a rotating indented drum
grading
128
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
head rice
129
ratio of the weight of head rice to the total weight of milled rice, expressed in percent
head rice recovery
130
main byproducts of rice milling are rice hulls or husk, rice bran, and brewer’s rice
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
one hundred kilogram (100 kg) of paddy rice will generate approx ___ kg of husk
20 kg
132
which gives the rice hulls and abrasive character?
ash composition and structure
133
one hundred kilogram (100 kg) of paddy rice will generate approximately __-___ kg of bran
5-10 kg
134
a mixture of substances, including protein, fat, ash, and crude fiber
rice bran
135
often used as ingredient for beer brewing, hence the name
brewer's rice
136
small-capacity single pass machine rice mills
1. japanese rice mill
2. kiskisan rice mill/Engelberg rice mill
3. UPLB improved village rice mill
137
small-capacity single pass machine rice mills
use of rubber roll for hulling and horizontal abrasion for whitening
japanese rice mill
138
small-capacity single pass machine rice mills
use of knife-edge roller and screen to do hulling and whitening simultaneously
kiskisan rice mill/Engelberg rice mill
139
small-capacity single pass machine rice mills
use of rubber roll for hulling and kiskisan for whitening
UPLB improved village rice
140
large-capacity single pass machine rice mills
use of underrunner disk for hulling and vertical abrasion for whitening
cono rice mill
142
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.
EXPLAIN
143
conditions as affected by production and post-production operations
grade factors
144
maximum head rice recovery is obtained when the paddy harvested has ___ % moisture content
20%
145
major causes of grain breakage during milling
hulling and whitening operations
146
these are critical for optimum milling results
- proper selection
- adjustments
- operation of the milling equipment
- knowledge and kills of operations or technologies
147
(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.
ANSWER
