Production of native potato starch
- Potatoes are delivered to the factories throughout the season, which usually runs from August to mid-December.
- Loose dirt and stones are separated by dry-screening followed by a stone trap. The potatoes are then washed using rotating washing drums. All objects that are lighter than the potatoes are removed. The final washing step of the potatoes is by using a high-pressure spray.
- The potatoes are then opened by rasping in order to separate the starch from the potato cell walls. This is done using blades similar to saw blades fixed to rotating drums.
- The rasped potato pulp or slurry is then moved into so-called centri-sieves where the starch and fruit juice are separated from the fibre.
- The starch and juice are separated in two steps. Step 1 uses a hydrocyclone unit to concentrate the starch. Step 2 is a horizontal filter where the juice is drawn off and the starch cake is washed in pure water.
- The final wash is done in a hydrocyclone block with counter-current. The wash continues until the desired cleanliness is attained.
- The clean starch is the dewatered on a rotating vacuum filter to a moisture content of about 40 %. The starch is then dried to a balanced moisture content of about 80 % using a hot-air drier.