Rice milling transformed from
early man-power and animal-power to hydraulic operation. Later,
mechanical milling emerged. By then, rice milling yield greatly
exceeded the quantity attained in the previous stages. Now, rice
milling factories have entered “computerized and one-line operation
stages.” Other than higher rice milling yield, quality is also
better controlled. Lian-Fa Rice Milling Factory in Houbi Town is a
new type of rice milling factory. It has the latest equipments and
cleanliness is observed. It is the place for many agricultural
groups to visit. With Lian-Fa Rice Milling Factory as an example,
let us take a look at the new rice milling factory operation
methods.
◆《Quality Classification
Testing, Weighing, and Temporary Storage》
Peasants had either dried rough rice/paddy under the sun after
harvest or sought outsource peasants with driers in the past. Rice
was then sent to a rice milling factory. However, most new rice
milling factories now have drying equipments so rough rice/paddy is
delivered directly to the rice milling factory after harvest.
After rough rice/paddy is taken to the rice milling site, the rice
milling factory first conducts batch rice/paddy quality testing
using Rice Quality Tester and Water content tester. Lian-Fa Rice
milling is also equipped with a “Residual Pesticide Rapid Testing
Station Pesticide Residue Rapid Test Station” which strictly
monitors quality. After rough rice/paddy testing, trucks enter the
factory for weighing. They then enter the material unloading opening
to unload. Rough rice/paddy dropped on the ground will be sent to a
wet barrel (wet grain temporary storage barrel) using an elevator
for temporary storage.
|
|
Weighing |
Drying
by heat |
◆《Drying under low
temperature》
The rough rice/paddy in the wet barrel is transported to the drier
by the elevator where drying operations are initiated. During which
time, rough rice/paddy first passes through the precleaner to remove
impurities such as twigs, leaves, and stones. According to General
Manager (GM) Chen of Lian-Fa, drying temperature is regulated as to
the temperature of the day. Drying is usually done at 40 ℃. If the
temperature is too high, rough rice/paddy will be burnt. In
addition, rough rice/paddy turns up and down inside the drier like
frying rice in a pan. It has to be constantly turned over to ensure
even distribution of heat. After drying, samples are tested using
the Rice Quality Tester to confirm quality.
Generally speaking, private grain and public grain drying level
vary. Private grains are not stored over extended periods of time
and are sold to the public, so, there are demanding requirements for
the taste. For this reason, the water content of rough rice/paddy is
dried to 14.5 degrees. This not only ensures the best taste, it is
less likely to crack during rice milling. As for public grains, they
are normally stored for over a year; the water content should not be
in excess. Therefore, it is usually dried to 12-13℃ for easy
storage.
◆《Freezing under low
temperature》
After drying by heat, rough rice/paddy is sent to respective
freezing barrels for storage. The temperature inside each barrel is
maintained at 10-12℃. A freezing barrel is a storehouse with
air-conditioning. The entire equipment is made of large temporary
storage barrels and air-conditioning. You may wonder why rough
rice/paddy is not just stored inside storehouses. Instead, large
sums of money are spent to purchase freezing barrels to store it.
There is a reason behind this. Dried rough rice/paddy is first
stored. It is milled whenever needed. The longer rough rice/paddy is
stored, the less tasty it becomes. In order to maintain rice
quantity, storage at low-temperature is a better method as food
freshness can be preserved.
|
|
Freezing barrel under low temperature |
Computerized temperature control |
Although a freezing barrel has great capacity, the problem of space
inadequacy may still be faced during peak season. In times like
these, jumbo bags” are used to store rough rice/paddy. The capacity
of a jumbo bag is normally 1 ton. Since, the preservation results of
“jumbo bags” are less ideal than freezing barrels, rough rice/paddy
is usually milled and stacked in bags. Lian-Fa Rice Milling Factory
places importance of storehouse ventilation in order to maintain
public grain quality. There are also ventilation holes in grain
stacks to dissipate heat. After all, storehouses and freezing
barrels are different, thus, public grain usually tastes less
delicious.
|
|
jumbo
bag |
Public
grain storehouse |
Milled rice/polished rice
should be kept at room temperature at best》
Low-temperature
helps preserve rough rice/paddy freshness. This principle
also applies to milled rice/polished rice. If stores place
packaged rice under high-temperature (places in direct
contact with the sun), it is better not to buy it. Also,
after buying rice, it should be consumed as soon as
possible. The longer it is left unattended, the lower the
degree of freshness. It is best refrigerated to maintain
taste and prevent rice worms. |
◆《Temperature regeneration》
Rough rice/paddy inside the freezing barrow should be temperature
regenerated before milling it into brown rice or milled/polished
rice. Factory staffs first transport rough rice/paddy inside the
freezing barrel in amounts required into the temperature
regeneration barrel. This way, rough rice/paddy is less likely to be
subject to breaking during the rice milling process. Temperature
regeneration usually takes about 6 hours. If rice milling is
conducted in early morning, temperature regeneration has to start in
the middle of the night. It is convenient to measure rough
rice/paddy needed through a “flow meter.”
◆《Grain hulling》
After rough rice/paddy is temperature regenerated, it is ready for
dehulling. By this time, rough rice/paddy first passes through a
precleaner [to remove cords, coarse substances, and waste substances
etc.], and a destoner [to remove sand, stone, cement, metal, and
plastic etc] where foreign substances are further removed. It then
enters the huller to remove hulls. Dehulling usually takes several
milling sessions to complete to complete remove hulls. Hulls are
separated in the “Grain separator”, and transported by an elevator
to a chaff barrow for storage. As for brown rice, the impurities are
further removed and sent by an elevator to the brown rice storage
barrow.
|
|
Ddehusker/dehuller |
Vibrator |
◆《Rice refining》
Dehulled brown rice then enters rice refining procedures. First,
brown rice enters the rice refining machine for rice refining. Then
a vibrator is used to sieve fine bran. In conventional rice milling
factories, the rice refining procedure ends here but modern rice
milling not only places emphasis on yield, it also takes note of
quality. Therefore, there are other follow-up sieving and selection
actions taken.
Milled rice/polished rice after sieving fine bran is sent to the
rice washing barrow where fine crumbs and adhered fine bran on rice
surfaces are washed off. Milled rice/polished rice after rice
washing is quickly sent to a “Color sorter” for sieving and
selection. The Color sorter selects rice grains by means of optical
principle [undesirable looking rice or rice worm-bored rice] and
eliminates them. This way, milled rice grains appear lustrous and
rich which guarantee sales.
|
|
Rice
refining machine |
Color
sorter |
After color sorting, milled rice/polished rice passes through the
“sorter”, the “roller”, and the “rice washer” again. Then, the
“vibrator” will sieve broken rice. The entire process is repeated
sieving using different machines. Perhaps you wonder why there are
so many sieving procedures. In fact, they are there to ensure each
milled rice grain is both delicious and good-looking.
◆《automatic meter packaging, vacuum packaging, product freezing》
“Vibrator” sieved broken rice falls into a broken rice barrel.
Finished products (milled rice/polished rice) is sent to the
finished product barrel ready for packaging. Modern packaging is
controlled by an” automatic meter.” The computer precisely sets
quantity output unlike conventional rice milling factories that have
scales at exit points to weigh.
For 1kg or 2kg small packages, Vacuum Procedure is frequently
performed. This procedure is simple. Packaged rice is placed inside
a “vacuum packaging machine.” The machine automatically pumps air
inside the bag out and seals it. This way, the rice in the bag is
kept under oxygen-free condition. It not only prevents dampness,
oxidation, products are also kept for longer periods of time without
being spoilt.
|
|
automatic meter packaging |
Vacuum packaging |
|
|
Product freezer |
Product transported in a freezer vehicle |
◆《New type of rice milling factories that place importance on
quality》
From the descriptions above, it is found that both the new and old
types of milling adopt similar processes. However, new type of rice
milling place importance on quality. As a result, both rough
rice/paddy and packaged rice are kept under low temperatures to
maintain taste. The rice polishing process repeatedly “sieves” rice
to mill intact and consistent finished product. It is no wonder old
type of rice milling factories are no competition.
|