Bei der Untersuchung der Frage, ob über die mineralische Düngung eine gezielte Kartoffelstärkequalität bereits auf dem Felde hergestellt werden kann, zeigte sich zunächst die besondere Bedeutung der Jahreswitterung, des Anbaustandortes und der Sorte für die Verkleisterungstemperatur, die Heißviskosität und die Kaltviskosität der Kartoffelstärke. Gegenüber diesen Einflüssen war derjenige der mineralischen Düngung minimal. Es zeigte sich, daß die Stärkequalitätsfaktoren nur langfristig über eine Anhebung des P2O5‐Gehaltes des Bodens in geringem Maße positiv beeinflußt werden können. Gezielte Stärkequalitäten lassen sich über die Düngung der Kartoffel somit nicht erzeugen. Daraus resultiert, daß Anbauer von Stärkekartoffeln die mineralische Düngung auf einen optimalen Knollen‐ und Stärkeertrag ausrichten sollten.

Influence of Sort, Tuber Size, Specific Weight and Fertilizing on Viscosity Properties of Potato Starch. From the example of three different potato cultivation tests the sort is shown to have a highly significant influence on ash and phosphorous acid content as well as viscosity properties of potato starch in case the environmental factors of year of cultivation and locality are not taken into consideration. Tuber size and specific weight, however, do not take effect. Moreover, it became apparent that starch quality cannot be influenced by way of fertilizing — be it organic or mineral. Hence the recommendation for cultivation of starch potatoes to adjust fertilizing to optimum yield with highest possible starch content is given.

Special Problems of Chips Manufacturing. This investigation deals with the problems manufacturing potato chips referring to the quality. A manufacturer o f chips has realized some experiments in order to enlarge the spectrum of potato varieties, which are suitable for producing chips of good quality. Beside the results of these experiments some other problems have been solved, for example the degree of damage.T w o o f the most important characteristics of chips quality are the colour and the oil content. I t is reported about tests showing that within the single classes of specific gravity the d r y matter content, and depending on this d r y matter content, the reducing sugar content is spreading very much within one potato variety. T h e data f r o m these experiments show a correlation between dry matter content and chips colour within one variety. The increasing of dry matter content implies brightening up of the chips colour. Furthermore it is reported about the important correlation between d r y matter content and relation of starch to nonstarch material and the quality characteristics like oil content and yield of chips. T h e influence of the manufacturing process on the quality characteristics has been examined.(Zusammenfassung Seite 16; Rksuml 2 la page 16)

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