Process for preparation of starch from cassava
The process for preparation of starch from cassava is a physical
separation process, that is, the starch in the cassava raw material
is separated from other substances such as cellulose, protein,
inorganic substances and the like. In the preparation process,
according to the insoluble starch and the specific gravity of the
starch, water and special mechanical cassava starch preparation
equipment are used to separate the starch from the water
suspension, thereby achieving the purpose of recovering the starch.
The production process is divided into transportation, cleaning,
crushing, separating, (bleaching), sand removal, concentration,
dehydration, drying, sieving, packaging and other processes.
Cassava starch is mainly used as raw materials in food, sugar,
medicine, feed, textile, paper, chemical and other industrial
2. Raw materials for preparation of starch from cassava:
The raw materials for for preparation of starch from cassava
include fresh cassava and dried cassava chips. The quality of raw
materials must be ensured. Fresh cassava is required to be fresh,
it is purchased on the same day, processed on the same day, without
mud, sand, roots, whiskers, wood parts and other impurities. Dry
cassava chips require dry, no mildew, no deterioration, no insects.
The average composition of fresh cassava is as follows: starch 27%,
cellulose 40%, protein 1%, other 3%, moisture 65%
The average composition of dried cassava chips is: starch 68%,
cellulose 89%, protein 3%, other 8%, moisture 13%
Due to the difference in cassava variety, harvest time, natural
conditions, etc., the starch content of cassava raw materials
Sulfate 2kg/t starch; bleaching powder 0.5kg/t starch; potassium
permanganate 0.1kg/t starch
4. The process brief:
The wet processing process for preparation of starch from cassava
includes paddle washing, secondary crushing, thick slurry
separating, countercurrent washing, (redox bleaching), cyclone sand
removal, thick slurry separation, dehydration, and air flow drying.
Note: If fresh cassava is used as a raw material to prepare starch,
the excipients mentioned above and the bleaching process are not
5. The processing steps for preparation of starch from cassava:
Raw material prepare: Raw materials are the material basis of
production, and the quality of cassava is directly related to the
quality of the products. The raw materials of the cassava starch
plant include fresh cassava and dried cassava chips. After
harvesting fresh cassava, the soil, roots, whiskers and wood parts
should be removed in time and piled on clean ground to avoid mixing
with iron blocks, nails, stones, wood and other debris. It is
required to be harvested and processed on the same day to ensure
the freshness of raw materials, thereby improving the extraction
rate and product quality of preparation of starch from cassava. The
dried cassava chips should be dry, not mildewed, not degraded, and
free of insects to ensure product quality.
Cleaning cassava: The conveyor uses a belt conveyor to transport
the cassava to the washing machine, and it is required to ensure
the normal supply of raw materials. In the process of
transportation, it is necessary to prevent the inclusion of iron,
nails, stones, wood and other impurities. If impurities is found,
it should be picked up in time. The cleaning adopts cage type
cleaning machine and paddle type washing machine. Graded cleaning
to make a good cleaning effect. The cassava raw material is rolled
along with the wall of the cylinder, and is sprayed, washed,
bathed, frustrated, cleaned and washed with water as a medium. It
is required to clean the sediment by washing, during the process
can remove cassava outer peels and the peeling rate is over 80%.
Then cassava can sent to the cutting machine and sent to the rasper
machine for crushing.
The role of the crushing process for preparation of starch from
cassava is to destroy the structure of the cassava, so that the
tiny starch granules can be freed and separated from the cassava
roots. The rasper machine relies on high-speed operation, so that
the saw blade and sieve plate on the drum can be crushed in the
machine for continuous feeding of cassava, so that the cassava is
disintegrated and the starch granules are continuously freed. The
separated cassava starch is processed into a starch slurry by using
water as a medium. The pulverized starch slurry can passes through
a 1.2-1.4 mm mesh.
The crushed and stirred thin starch slurry is sieved to separate
the starch milk from the fibers. At the same time, the starch milk
needs to be sieved to remove the fine residue, and the fiber needs
to be subjected to detergent recovery starch. The separating
process for preparation of starch from cassava is sieved to achieve
the purpose of separating and purifying the starch. At present, the
centrifugal sieve and fine fiber sieve is mainly used to remove
fine fibers. Multiple screening or countercurrent washing processes
are commonly employed. After separation, starch residue contains
less than 35% starch, wherein the free starch contains less than
5%; the fiber impurity content of the starch milk slurry is less
than 0.05%; and the concentration of the milk slurry reaches 5-6Be.
Bleaching: This is an important part of ensuring the quality of
dried cassava chips produced starch products. Its function is:
adjust the pH value of the milk emulsion to control the microbial
activity and fermentation, saccharification; accelerate the
separation of starch and other impurities; bleach the outer layer
of the starch granules to make the starch granules last and white.
Sand removal: According to the principle of gravity separation, the
starch slurry is pumped into the cyclone by a pressure pump, the
bottom stream is sand removed, and the top flow is passed through
the slurry to achieve the purpose of sand removal. After sand
removal process for preparation of starch from cassava, impurities
such as fine sand can be removed, and the disc separator can be
Concentration: The concentrate function is to separate insoluble
protein and residual soluble protein and other impurities from the
starch slurry, thereby achieving the purpose of washing, refining
and concentrating the starch milk. SIDA company uses the 12-stage
hydrocyclone unit to wash, refine and concentrate starch slurry. It
is separated according to the specific gravity of water, starch and
yellow pulp protein. A 12-stage hydrocyclone is typically used in
series and requires a slurry concentration of 20-22Be.
Dehydration: The concentrated emulsion obtained by the separation
and purification process is generally 20-22 Baume, still contains a
large amount of water, and must be dehydrated to improve the drying
efficiency. Through the high-speed rotation of the peeler
centrifuge, most of the water is thrown out from the gap of the
filter cloth of the screen, and the wet starch accumulated on the
filter cloth is continuously scraped off with a scraper, and falls
straight into the hopper of the dryer, and is sealed conveying. The
screw feeder is fed wet starch to the dryer. Wet starch has a
moisture content of less than 36.5% to save energy, reduce costs,
and increase production and quality requirements of preparation of
starch from cassava.
In the modern cassava starch factory, vacuum dewatering machine is
also widely used. When vacuum dewatering machine working, the speed
regulating motor drives the rotating drum to rotate in the slurry
tank. Solid matter (wet starch) is adsorbed on the filter cloth of
the drum, and when it reaches a certain thickness, the fixed
scraper scrapes off the solid matter(starch), and the filtrate
enters the steam separator to achieve the purpose of separating
starch, water and gas, and the energy consumption is three-thirds
of similar equipment. However, by vacuum filter, the starch
moisture content is slightly higher than the peeler centrifuge,
Drying: The dehydrated wet starch is transferred to the flash dryer
for drying. The steam pressure is controlled at 0.8 MPa. It is
required to pass the drying, and the moisture content of the
finished starch is about 13.5%. The dried cassava starch is sieved
and packed into the warehouse. After this, the preparation of
starch from cassava processing is completed.
6. Preparation of starch from cassava process requirements:
(1) The freshness of cassava raw materials must be guaranteed to
ensure product quality and improve recovery.
(2) The amount of water used in the cassava starch processing
process is large, and the processing water is required to meet the
(3) Do not use iron equipment and pipes, because cyanide will
combine with blue ferrocyanide to make the starch color, which
affects the quality of starch. In addition, the entire preparation
of starch from cassava production process is basically slightly
acidic, therefore, the equipment and pipe fittings used are
preferably made of stainless steel.
(4) In the production process for preparation of starch from
cassava, the amount of material conveyed is large, so more pumps
are needed. The various pumps not only serve as a transport, but
also require a certain pressure to power the material to achieve
separation when the equipment is rotated at a high speed.
(5) Because the starch has easy sedimentation properties, the fiber
is uneven material, so the pipe elbow and other parts should have
flanges or unions, which can be disassembled and cleaned once
(6) In order to ensure the quality of the products, it is necessary
to pay attention to the frequent cleaning of equipment and sites
during the production process for preparation of starch from
cassava to keep them clean and hygienic. Since the starch slurry is
acidic, all the pulp pools should be treated with anti-corrosion
treatment. In the drying process, various flammable sources such as
smoking, electric welding, static sparks, etc. should be controlled
and eliminated to prevent dust explosion and ensure production
7. Process features:
① The production process floor space is small, the pipeline is used
less, the pump is used less, save investment, and the energy
consumption is reduced.
② The production process is short, only 30 minutes from the feeding
to the production of finished products.
③ The production process is continuous and the equipment efficiency
④ In addition to the drying process, the entire production process
for preparation of starch from cassava is carried out under normal
temperature and pressure conditions.
⑤ By adopting new technologies, the production level of the process
can be further improved, the equipment capacity can be fully
utilized, the number of equipment can be reduced, the energy
consumption and production cost can be reduced, the output can be
increased, and the product quality can be improved.
8. Main process parameters:
(1) cleaning water proportion 1:4.
(2) Crushing process water proportion 1: 1.
(3) The starch slurry can passes through a 1.2-1.4 mm mesh.
(4) After sieving and washing, the starch residue contains less
than 35% starch, wherein the free starch contains less than 5%; the
fiber impurity content in the milk slurry is less than 0.05%.
(5) The separation slurry concentration is 5-6 Baume, and the pulp
concentration is 20-22 Baume.
After dehydration, the moisture content of the wet starch is less
than 38%, and the moisture content of the finished starch after
drying is about 13.5%.
9. The main technical indicators:
① starch recovery rate: > 96%;
② water consumption: <15m3 / t starch;
③ coal consumption: <0.1t / t starch;
④ power consumption: <160kwh / t starch;
⑤ product quality: first-class product rate of 98% or more.