Potato starch technology
1999
Bergthaller, W. | Witt, W. | Goldau, H.-P.
Potato starch production encountered drastic changes during the last years, in particular in economics and substrate supply. Because of economically required reductions in subsidisation, production of potato starch will decrease. Changes in technology are characterised by savings in wash water and process water streams that are effected by increased efficiency introduced with new machinery and changed technological concepts. From an ecological point of view, an early and maximum fruit water separation (up to 95%) based on dilution of gratings with process water and decanter separation allowed to reduce the fresh water supply to 0.4 to 0.5 m(3)/t of processed potatoes. For economical isolation of potato protein a correspondingly high protein recovery rate (up to 90%) is essential. Concerning starch extraction, a minimum of 95% is reached in modern potato starch plants, but optimum engineering (rasping, decanting, sieving) gives recovery rates of 97 to 98%. In starch refinement, three-phase nozzle separators equipped with wash water supply and constructed for efficient displacement washing allow to achieve a fine fibre removal of 98% within three separation stages and a final concentration of purified starch milk of 22 to 23 degrees Be. Potato protein isolates (protein content 83 to 85%) are produced by isoelectric precipitation combined with heat coagulation while stringent solutions for treatment of de-proteinised fruit water are still lacking.
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