Potato starch is starch extracted from potatoes. To extract the starch from potato in potato starch production plant, the potatoes are firstly crushed so that the starch grains can be released from the destroyed cells. The starch is then washed out, refined and dried to powder potato starch. Potato starch contains typical large oval spherical granules. Potato starch is a very refined starch, containing minimal protein or fat. This gives the powder a clear white color.

Potato starch production plant process by Doing Company are as below:

The process of potato starch production plant comprises the steps such as delivery and unloading potatoes, cleaning and washing, potato milling, potato starch slurry separation, starch extraction, starch milk refining, dewatering of refined starch milk and starch drying.

Potato starch production plant

1.Delivery and unloading potato process

Potatoes are delivered to the potato starch production plant via road or rail transport.

2.Cleaning and washing process

Cleaning and washing of potatoes takes place during the transport of potatoes to the crushing or milling machinery. The main cleaning is conducted in dry sieve whose main function is to remove the sand, stone and other debris attached on the potato. The remaining dirt, sludge and light wastes are removed by washing step in potato starch production plant. Water used for washing is then purified and recycled back into the process.

3.Potato wet milling process

Most often the rasping of potato tubers is carried out with a rasper. The purpose of this stage in potato starch production plant is disruption of cell walls, which therefore release the starch. In practice, potato cells are not entirely destroyed and part of the starch remains in the mash. Potato starch slurry rapidly turns dark, because tyrosine presented in the potato is oxidised by polyphenol oxidase, which is located in the cellular juice. Therefore, cellular juice must be separated as soon as possible.

Potato milling machine

4.Potato starch slurry separation process

In potato starch production plant, this process allows the recovery of starch and remove of the fibers. The potato starch slurry is directed to the centrifuge sieve to isolate the starch. In this machine starch slurry diluted with water is washed with a strong stream of water to flush out the milk starch. The mash smuggling with water is a waste product –dewatered potato pulp. Starch milk is contaminated by small fiber particles (potato tissue fragments) and the remaining components of the potato juice – that’s why it is called raw starch milk.

5. Starch milk refining process

Raw starch milk is purified in the refining process in potato starch production plant. This involves the removal of small fibers from the starch milk and then the removal of protein and cell sap and starch milk condensation. For this purpose, the hydrocyclone station is commonly used. Hydrocyclone station due to the low output (approximately 0.3 cubic meter per hour) are connected in parallel and works as multiple hydrocyclones. For the starch milk desanding bihydrocyclones are used. In order to prevent enzymatic darkening of potato juice, the chemical refining of starch is carried out using sulfurous acid. Refined starch milk has a density of about 22° Be, which is about 38% of starch.

Potato starch refining machine

6.Dewatering of refined starch milk and starch drying process

It is a suspension of starch in water, which needs dewatering up to 20% of moisture. This is equivalent to the moisture content of commercial starch when stored in potato starch production plant. High temperature cannot be use in this process because of the danger of starch gelatinization which destroys granular structure. It may result in significant changes of the functional starch properties. Therefore, removal of excess water from milk shall be done only under conditions that prevent the gelatinization of starch.

Dewatering of refined starch milk is carried out in two stages in potato starch production plant. In the first stage the excess water is removed by means of a vacuum filter. Secondly moist starch is dried, without starch pasting. For this purpose a pneumatic flash dryer is used. In this device moist starch (with water content 38 – 40%) is floating in strong and hot air flow and then dried during 2-3 seconds. Then, the starch is separated from hot air in cyclones. Due to short time of high temperature drying and intensive water evaporation from the starch granules, its surface is heated only to 40 °C. Dried starch contains about 18%-20% of water.

7. Sieving and packing process

Potato starch after drying will be sent to sieving machine to get the required size potato starch in potato starch production plant. Then the potato starch will be packed into bags for storage or for sale.