Lagerzeitabhängige Veränderungen von Kapazität und Leitfähigkeit bei Weißbrotkrumen

Changes in Capacity and Conductivity of Wheat Bread Crumbs Depending on Storage Times . The present paper describes a method for tracing changes depending on storage time in bread crumbs of wheat bread (toast bread) by means of measuring electric parameters. Comparing results thus obtained with data obtained from tests carried out simultaneously in order to gather sensoric and mechanical texture parameters, significant conformity of the course depending on storage time shows high suitability of the method. The method allows interpretation of relativ changes.     

Kaltquellfähige Kartoffelstärke-Derivate

Cold-Swelling Potato Starch Derivatives . By means of reaction with ethyl cyanide as well as grafting polymerization of acrylic acid ester on potato starch followed by saponification of reaction products cold-soluble respective cold-swelling potato starch derivatives were produced. The intrinsic viscosity as demanded by many fields of application is to be found especially with aqueous solutions of potassium salts of partially saponified acrylic nitrile-potato starch grafting polymerizates.     

Charakteristik der Stärke ausgewählter Kartoffelsorten Teil 1. Änderung des Stärkegehalts und der Stärkekorngröße während der Lagerung

Characteristics of Starch of Selected Potato Varieties. Part 1. Change of Starch Content and Starch Granule Size During Storage . Selected varieties of potatoes of the Czechoslovakian assortment were tested as to their contents of dry matter and starch, as well as to quality of their starch in three-years storage tests. Potatoes were stored in airconditioned boxes at temperatures of + 2 and + 10 °C. Analyses were carried out after harvesting and after storage. It was found that the content of dry matter was higher near the end of storage time. This increase was depending on temperature. Yet, related to dry matter the starch content had not diminished near the end of storage time. During storage of potatoes changes in the share of individual starch granule sizes do also occur. Larger granules were degraded to smaller ones, thereby increasing the latter's share. Higher temperature would also lead to an increase in these changes. The tests were supposed to show, wether during potato storage a change in size of starch granules takes place, and wether storage temperature may influence this change. Work on this problem will be continued.     

Untersuchung gefriergetrockneter Stärkekleister und Stärkeschwämme im Rasterelektronenmikroskop

Examination of Freeze-Dried Starch Pastes and Starch Sponges by Means of Scanning Electron Microscope. Pastes of potato and corn starch as well as various starch derivatives were examined by means of scanning electron microscope (SEM). As preparation method freeze fixation followed by freeze-drying were used. Special attention was directed to changes occuring in pastes after slow freezing and defrosting. Sample preparation which is more complex for the SEM than for light microscope has the advantage of its picture giving more accurate information on paste structure than those obtained by light microscopy. On the one hand, tests confirm results obtained by other authors on the structure of starch pastes by means of light microscopic photography, furthermore, new information was gathered especially regarding non-frozen pastes and pastes of starch derivatives. Illustrations of starch sponges as obtained by means of SEM are far more expressive than those obtained by conventional methods.     

Einfluß von Spurennährstoffen auf den Stärkegehalt von Kartoffeln und die Qualität von Kartoffelstärke

The influence of Trace Element Fertilizers on Starch Content of Potatoes and Quality of Potato Starch. The influence of added trace element fertilizers on starch content and yield of potatos was examined, and among other things the size of starch granules was determined. The trace element fertilizers influence the increase in tuber weight and starch yield and they do not impair starch quality which is expressed in granule size. Boron, manganese and zinc have an optimum effect at certain amounts, whereas copper does not show favourable effects on sand cultures.     

Schweflige Säure und Stärkehydrolyse

Sulfurous Acid and Technical Hydrolysis of Starch. The decrease of SO₂ content which can be observed during the storage of starch sirups is not only based on simple oxidation to sulfate but also on the formation of different organic sulfur compounds. The reaction possibilities for SO₂ in technically produced hydrolysates are greater than in pure sugar solutions because of the presence of colored materials, their precursors and amino nitrogen containing compounds. Thus, the amount of analytically ascertained SO₂ content is not a satisfactory criterion for the purity of starch sirups. The proposed modification of the starch hydrolysis process by using SO₂ in the starch slurry gives a chance to eliminate the formed sulfur compounds extensively. Furthermore the products manufactured in this way show less tendency to discoloration, and higher storage stability especially with increased temperatures.     

Änderung des Zuckergehaltes ausgewählter Kartoffelsorten während der Lagerung

Change of Sugar Content in Selected Potato Varieties During Storage . Ten Czechoslovakian potato varieties of different vegetation lengths were stored at +2°C and +10°C. Changes of glucose, fructose and saccharose content were examined in the years of 1972–1974. Results show the greatest changes of sugar content to occur in the period of November to January. This period of time is a certain limit in the dynamics of changes of sugar content. Tubers stored at +10°C show a different speed of change of content and share of the various sugars than tubers stored at +2°C. Influence of variety and year of vegetation is clearly confirmed, the influence of the year of vegetation being greater than that of variety. This leads to the conclusion that the physiological state of the tuber also affects dynamics of sugar transformation significally.     

Über die Phosphorsäure der Kartoffelstärke

On the Phoshoric Acid in Potato Starch. Potato starch contains chemically linked ortho-phosphoric acid (30 to 175 mg% P). Among the physico-chemical properties of potato starch effected by the phosphoric acid the most important are ion exchange and selfhydrolysis. By the ability of ion exchange it is possible to produce the salts of the pure esters of amylo-phosphoric acid (cationic starches). Sodium, potassium, ammonium, calcium and magnesium starches differ in rheological properties. The hydrogen ions of amylophosphoric acid are able to effect the hydrolytic splitting of the starch. This hydrolysis consists of two different processes: the splitting of the glucosidic linkages and the splitting of the ester linkage between the phosphoric acid and the glucose unit. Velocity of self-hydrolysis is dependent on the hydrogen ion concentration. The self-hydrolysis of hydrogen starch offers the possibility of producing degraded starch products with different technical properties without any addition of chemicals and/or enzymes.