The production principle of cassava starch
Cassava starch production process is actually a physical separation process, is the raw material of cellulose, protein, inorganic salt and other substances and starch separation.In the process of production, according to the starch insoluble in cold water and specific gravity is greater than the nature of water, water as a medium, the use of special mechanical efficiency, starch from water suspension separated.
The production process is divided into four main sections: crushing, screening, separating and drying.It is divided into transportation, cleaning, crushing, impregnation, screening, sand removal, separation, dehydration, drying, air cooling, packaging eleven control points.
1. Principle of cleaning
The role of cleaning: mainly remove the cassava surface layer with sediment, and wash away the cassava root tuber skin.Cleaning fresh cassava or cassava dry slice, as the raw material of starch production, is the basis to ensure the quality of starch. The cleaner the cleaning, the better the quality of starch.At the same time, in the cleaning process can also remove a part of the root tuber of hydrocyanic acid.
2. Principle of fragmentation
Role of fragmentation: cassava starch is mainly stored in the fleshy part of root tubers, and only a small amount is stored in the endothelium.The goal is to break down the structure of the cassava so that the small starch particles can be easily separated from the root tuber.The starch released from the cell is called free starch.The starch remaining in the cells inside the dregs is called binding starch.The purpose of breaking is to release as much free starch as possible.
3, the principle of screening
Cassava dregs is long and thin fiber, the volume is greater than the starch granules, expansion coefficient is greater than the starch granules, and the proportion of light in the starch granules, virgin pulp beating, with water as medium, stir well, and then to evenly feeding screening equipment, slurry pump in mechanical oscillation, rolls, centrifugal, under the action of hydraulic flushing, to repeated washing of protoplasm, and through the screen mesh, 80 ~ 120 respectively make slag and starch separation.
4. Principle of separation
The proportion of mud and sand is greater than that of water and starch granule.And the proportion of yellow slurry, close to the water, and lighter than the proportion of starch granules, its shape is palm, the longer the processing cycle of emulsion performance, the greater the viscosity sieve, sticking to the starch grain, very difficult to separate, the principle of disc separator is according to the specific gravity separation, cassava starch, generally require two separate, just can make the product quality to achieve the ideal effect.
5. Principle of centrifugal dehydration
Generally, the concentrated whey separated from the dish separator is 20 pom c, which needs to be centrifuged again to improve the drying efficiency and save energy.
Through high-speed rotation of the scraper centrifuge, the solid phase and the liquid phase are separated, and most of the water is thrown out from the gap of the cloth on the screen. The moisture content of the wet starch obtained is lower than 35%, so as to achieve the requirements of saving heat energy and improving output and quality.
6. Principle of drying
At present, airflow drying (also known as flash drying) is generally used in the starch plant. The whole process time is completed in a flash, so the water inside the starch granules has been dried before it has time to gelatinize, so gelatinization or degradation will not occur.
Airflow drying is a concurrent process, that is, the concurrent process of wet material and hot gas flow, which is composed of heat transfer and mass transfer.When the wet starch is in contact with the hot air, the hot air will transfer the heat energy to the surface of the wet starch, and then from the surface to the internal, this process is the heat transfer process;At the same time, the moisture in the wet starch diffuses from the inside of the material to the surface of the starch in the form of liquid or gas, and then diffuses from the surface of the starch to the air through the gas film, which is a process of mass transfer.It is to balance heat exchange between high-temperature airflow and wet starch in the drying tube, so that the dry starch is in powder form and can be packed into the storage after cooling.