The reason why the produced cassava starch has impurities

1. Raw material cleaning is not thorough

Impurities(sand,dirt,etc) in cassava raw materials is the main source of impurities in starch. The reason why the produced cassava starch has impurities is mainly due to the lack of strict cleaning process, insufficient cleaning power, and an increase in the amount of impurity entering the starch.

① When the roots or tubers of cassava roots are harvested, the soil is too wet and sticky, and the surface of the cassava is rich in mud. When the wet mud is not dry, it is cleaned and processed, which is difficult to clean and has a large residual amount after washing. When using sweet potato, cassava, potato, etc. as the raw material of starch, the screening of the clods and sands contained in the raw materials is not strict, so that some impurities enter the rasping system.

DOING cassava cleaning machine - dry sieve

② Cassava roots are not thoroughly cleaned, not serious, and the water consumption is small. At present, the processing of cassava starch is mostly manual and semi-mechanized processing, and the cleaning process is mostly manual cleaning. During cleaning, some lack the soaking process, direct cleaning, it is difficult to clean in a short time; some use less water, and there is no more cleaning after the initial cleaning, still with a certain amount of impurity; some only use water on the cassava heap sprinkle a few times or rush with a tap, and start to crush; more, see the surface of the cassava skin seems to be relatively clean, simply do not wash, a large amount of impurity, residual soil and other pollutants into the follow-up section, it is more difficult to clean up and endanger human health.

DOING cassava paddle washer

2. The container used for standing sedimentation and the method of stirring are improper (this method refers to the production line of simple cassava starch processing equipment, the processing method of homemade sedimentation tank or the processing mode of hand workshop)

In the case of sedimentation, it is generally preferred to use a container with a slightly concave center at the bottom of the circle, such as a large cylinder, a yellow bucket, a round pool, etc. If a square pool is selected, it is inconvenient to collect sediment at the bottom layer. If the starch is stirred up during stirring, it is continuously stirred in one direction to form a vortex in the middle of the slurry, which is conducive to concentrated sedimentation and collection of the sediment. However, after disorderly stirring or stirring, a vortex cannot be formed in the center of the slurry in the container, which causes the sediment to be disordered and excessively mixed in the starch layer, which is disadvantageous for separation.

DOING fine fiber sieve

3. The filter mesh is large and lacks the second filtration.

In the cassava starch production process, when the pulp is separated, some manufacturers use only about 60 mesh, which causes a lot of fine slag (coarse fiber) to leak into the sieve together with the starch milk, and the same is used for the second precipitation. The coarse screen is filtered, or there is no secondary filtration at all, so that the fine slag is easily mixed with the small granular starch, resulting in an increase in the amount of impurities such as crude fibers in the cassava starch. Doing Company recommends that 80 mesh be used for the first separation, and about 120 mesh for the second separation.

Doing Filtration Equipment - Fine Fiber sieve - 2 channel fine filtration, 120-140 mesh screen, dedicated to the production of high-purity refined white cassava starch, can also be used for crude starch filtration. Ultra-low speed rotation to remove fine impurities in starch, fully guarantee the filtration fineness.

Cassava starch processing

4. Protein separation is not thorough

① Acid slurry method: When the acidity of the acid slurry reaches the isoelectric point of the protein, the protein adduct precipitates between the small granular starch in the upper layer of the starch, which makes the separation difficult.

② Automated machinery (starch hydrocyclone station): When using a hydrocyclone to separate proteins, some of the mechanical properties are poor or the operation is not accurate, so that the protein is mixed into the casava starch slurry into the dehydration system caused the produced cassava starch has impurities.

Sealed transfer tank(storage starch milk)

5. Machine operation is not standardized

The reason why the produced cassava starch has impurities caused by improper operation is mainly manifested in the following aspects:

① When the machine is crushing cassava, the machine is too close to the sedimentation tank and there is no protective measure. The potato or cassava slag in the machine splashes out and falls into the separated sedimentation tank to cause the increase of coarse fiber.

② The separation sieve has holes that have not been repaired in time to make the cassava residue leak.

③ Containers or utensils used to contact starch milk are not cleaned, with cassava dregs and sediment, contaminating starch.

④ When washing starch, the yellow powder and sediment layer are not cleaned seriously.

⑤ When the drying field is unclean or the wind is blowing during the cassava starch drying process, no dust-proof measures are taken to contaminate the starch. In addition, in the production process, the use of unclean water, etc. will cause excessive impurities in starch.

Therefore, in production, according to the cause of excessive impurities, take appropriate control measures to ensure that the cassava starch produced is white and pure.