A total of 7.0 × 10 6 and 7.3 × 10 6 t starch was produced in 1996 and 1997, respectively, in the European Union, consisting of 15 member states [1,2]. The trend of a steadily increasing starch production is obvious. During a long period, potato starch played an important role in covering approximately 25 % of the available shares; the situation changed in 1995 by the decision of the European Commission to limit subsidies connected with the production of potatoes and their utilisation in starch factories. The instrument used to limit costs became a quota system issued to each potato starch producing member country; in fact, 8 of the 15 member states. A maximum potato starch production has been fixed at approximately 1,864 × 10 3 t/a. The main share is covered by four member states: Germany (696.3 × 10 3 t), Netherlands (538.3 × 10 3 t), France (281.5 × 10 3 t) and Denmark (178.5 × 10 3 t). Smaller quotas (49 to 64 × 10 3 ) are held by Sweden, Finland and Austria, while Spain owns a quota of 2,000 t ( Fig. 1) [3]. Recent resolutions, in connection with the development of EU's Agenda 2000 system, resulted in further reduction of starch production limits by 100 × 10 3 t. The relevant decreases in production will be approx. 40 × 10 3 t for Germany and 31 × 10 3 t for The Netherlands as the main potato starch producing countries. As result of these regulations, potatoes will not be used increasingly as substrates of starch production. Maize and wheat will cover future growth, with more important prospects for wheat.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°Bé. 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. * Publication No. 7075 of the Federal Centre for Cereal, Potato a...

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Da die Anforderungen an eine scharfe Klassierung von Stärke durch bekannte Verfahren nicht erfüllt werden, wurde eine Klassiermethode zur Gegenstromtrennung im Zentrifugalfeld entwickelt. Mit diesem neuartigen Verfahren können enge Stärkefraktionen gewonnen werden, die sich in ihren viskosen Eigenschaften, ihrer Zusammensetzung (Asche, Protein, Fett) und anderen relevanten Stärkeeigenschaften unterscheiden. Die Korngröße, bei der die Trennung erfolgt, kann bei diesem Zentrifugalverfahren durch eine Variation der Betriebsparameter (Durchsatz und Drehzahl der Zentrifuge) beeinflußt und mittels einer angegebenen Gleichung bestimmt werden. Die Qualität der Klassierung hängt von Stoffeigenschaften (Stärke‐ und Pentosananteil in der Suspension) und Betriebsparametern (Wasserverhältnis) ab. Nach der Vorstellung eines typischen Klassierergebnisses (Grobgut 3%< 10μm; Feingut 70%< 10μm) werden der Einfluß der Betriebsparameter auf die Klassierung sowie die Eigenschaften der Produkte diskutiert.