Untersuchungen über die Retroaradation der Stärke in konzentrierten Weizenstärkegelen. Einfluß von Stärkeabbauprodukten auf die Retrogradation der Stärke

Investigations on the Retrogradation in Concentrated Wheat Starch Gels. Part 2. Effect of Starch Degradation Products on the Starch Retrogradation . In the present work the influence of added starch degradation products on the rigidity and retrogradation of 50% wheat starch gels was investigated. The gels prepared with the addition of maltodextrin were extracted with 40% ethanol, the extracts were analysed for glucose oligomers. The effect of the added starch degradation products was dependent on the degree of degradation. Weakly degraded, acid modified starches take part in the retrogradation process as do white and yellow dextrins as well as maltodextrins with dextrose equivalents (DE) <30. Maltodextrins and glucose sirups with a DE ≧ 30 act as plasticizers: in concentrations of 5-30% (based on starch d. s.) they reduce gel strength without affecting the retrogradation velocity. The plasticizing effects are particularly evident with maltose and maltotriose as well as maltotetraose and pentaose. Even so the extractibility of oligomers with a degree of polymerisation (DP) ≥ 6 was reduced, the hexamer and octamer might still have a plasticizer effect. With glucose, concentrations ≥ 26% were needed to observe plasticizing. The relation of these findings to bread staling is discussed.     

Einfluß der Düngung von Kartoffeln auf das Molekulargewicht der Stärke

Effect of Fertilization of Potatoes on Molecular Weight of Starch. In the years of 1977 through 1979 cultivation tests with gradated N-, P-, K-doses and additional doses of Ca and Mg were carried out on potatoes. Starch content depended upon fertilization doses and conditions of the vegetation year. Highest starch content was found with fertilization N₁P₁K₁Mg₁ and with the variants without Ca and Mg under conditions of the variant N₂P₂K₂. Optimum molecular weight appeared with variants N₂P₂K₂ through N₃P₂K₂. Highest molecular weight in a 3 year average was found with all variants at N₁P₁K₁Mg₁. Apparently, the tendency of raising of the molecular weight is parallel to that of starch content. Calcium and magnesium had their effect in close connection with N-, P-, K-doses and the vegetation years.     

Einfluß der Art der Energieübertragung auf strukturelle und funktionelle Merkmale von Stärke

Effect of the Form of Energy Transfer on the Structural and Functional Characteristics of Starch. The effect of the form of energy transfer on the structural and functional characteristics of starch was investigated. The changes in the molecular structure and functional properties of the starch resulting from vibration milling, drum-drying and extrusion cooking were established. These findings were compared with one another according to process specific characteristics. It could be shown that main and secondary valency bonds were broken due to vibration milling and extrusion cooking. On the other hand, drum-drying did not result in any molecular breakdown. The changes in the molecular structure resulted in an increased solubility of the starch. These changes in structure did not affect amylose and amylopectin to the same degree. The differences in the molecular structure were influenced by the form of energy transfer. Thus the mechanical energy transfer played a prominent role in the molecular breakdown during extrusion cooking and vibration milling. Those functional properties which depended on the molecular structure of modified starches were therefore developed according to the processes used. Extrusion cooking was by far the most flexible process in this respect. However, it was not possible to exclusively effect either mechanical or thermal energy transfer during extrusion cooking. Thus no extrusion cooked product possessed the water-binding properties typical of drum-dried starches.     

Einfluß der Düngung auf die Viskosität von Kartoffelstärke

Effect of Fertilization on the Viscosity of Potato Starch. In three years of field tests with graduated doses of calcium and magnesium for the potato cultivar Radka it was shown that starch content during particular growing phases is influenced by calcium and magnesium doses in conjunction with N-, P-, K-doses. Viscosity is also depending on addition of calcium and/or magnesium. Addition of these both fertilizers, however, effects also in connection with the N-, P-, K- doses. Highest starch content was found under the condition of variant N₁P₁K₁ · Mg₁. On the other hand highest viscosity was observed with variant N₃P₂K₂ · Ca₁.     

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.     

Untersuchungen über die Retrogradation der Stärke in konzentrierten Weizenstärkegelen. Teil 1. Herstellung konzentrierter Gele,Einfluß der Stärkekonzentration und Herstellungsbedingungen auf die Retrogradation der Stärke

Investigations on the Retrogradation in Concentrated Wheat Starch Gels. Part 1. Preparation of Concentrated Gels, Influence of the Starch Concentration and Conditions of Preparation on the Starch Retrogradation . A method for the preparation of homogenous, concentrated wheat starch gels is described. The influence of the starch concentration and conditions of gel preparation has been investigated by determination of gel strength (Avrami-analysis) and solubilized starch. An increase in starch concentration from 40 to 55% caused a corresponding increase in gel strength of the fresh gels, an enhanced increase in gel strength during storage and a reduction of soluble starch. The time of heating during gel preparation had little influence on retrogradation. The influence of the temperature of heating (130° and 100°C) was dependent on the starch concentration: with 40 and 50% gels a strong increase in water soluble starch is observed with the higher temperature, whereas the gel strength is increased with the 50% gels only. The amylose content in the gel extracts shows that both starch fractions take place in retrogradation. The water binding capacity of the insoluble starch is decreased during storage demonstrating that the retrogradation also occurs in the insoluble starch and significantly contributes to the increase in gel strength. Retrogradation in concentrated starch gels therefore proceeds inside and on the surface of the swollen starch granules as well as in the solubilized starch leached out during the heating process.     

Kernresonanzuntersuchungen zum Einfluß der technischen Aufarbeitung auf die Wasserbindungsfähigkeit von Kartoffelstärke

Nuclear Resonance Investigations Regarding the Influence of the Preparation on the Water Binding Capacity of Potato Starch . In a preceding paper we stated that an increased content of more tightly bound water has been observed in a sample of industrial potato starch in comparison with a sample of starch which has been isolated under carefully controlled conditions. Now it can be shown that the conditions of drying and also the size of the starch granules have no influence on the above mentioned difference, in spite of the fact that the portion of more tightly bound water distinctly depends on the granule size. The differences in the behaviour of the bound water can be explained by the ion content of the water used during the isolation of the starch. The mechanism of this effect, however, is not yet clear.     

Einfluß der Extrusionsparameter auf funktionelle Eigenschaften von Weizenstärke

The Influence of Extrusion Parameters on the Functional Properties of Wheat Starch. The functional properties of native starch can be altered by regulating the technical parameters in the extrusion cooking process. The influence of specific variables on the resultant starch properties can be differentiated by means of system analysis. To make this clear, a model has been put forward which divides individual factors into those which influence the process and those which are influenced by the process, as well as examining their interrelationships. As a result of the experiments, it was possible to use regression analysis to examine the relationships between the various system analysis components. Thus it is possible either to predict the properties of the resultant starch knowing the extrusion and system parameters, or to suggest suitable extrusion conditions in order to obtain a particular starch product.     

Einfluß von Sorte und Standort auf die Viskositätseigenschaften von Kartoffelstärke

Influence of Sort and Locality on Viscosity Properties of Potato Starch. Regarding its rheological properties potato starch holds a special position compared with all other starches, which is mainly due to the phosphoric acid, resp. phosphate groups bound ester-like to the amylopectin. The present work was carried out in order to find out, whether rheological properties of potato starch are also affected by outer influences such as year of cultivation, locality and sort. A marked influence of year of cultivation and locality as well as a less marked influence of the sort on phosphate and ash content of the starches became apparent. Locality exerts the strongest influence on viscosity. An influence of the sort can be stated, but it is mostly obliterated by superimposition.     

Einfluß der Klärmittel und ihrer Menge auf die polarimetrische Bestimmung der Stärke nach Ewers bei Weizen-, Mais- und Kartoffelstärke

Influence of Clearing Agents and their Amount on the Polarimetric Determination of Starch According to Ewers with Wheat, Maize and Potato Starch According to chemical analysis and statistical evaluation the clearing agent by Carrez will seem the most suitable. Lowest suitability is shown by phosphotungstic acid of 4 percent, as increasing dosis lowers starch content statistically significantly with all analyzed samples. Ammonium and sodium acetate cause a moderate lowering of the optical activity of starch. This lowering is not dependent upon the amount of the clearing agent. Probably, a sedimentation of starch comes into consideration. Normal as well as basic lead acetate (by Horn) cause a decrease of polarization and thus a decrease of the determined starch content.     

Einfluß des Verhältnisses von Stärke zu anderen Inhaltsstoffen auf den Geschmack von Kartoffeln

Influence of the Ratio of Starch to Other Substances on the Taste of Potatoes. The influence of the ratio of total nitrogen, proteinic nitrogen, ash, potassium, phosphorus, sugars and free amino acids to starch on the taste of boiled potatoes has been investigated. It was stated that the ratio of total nitrogen, potassium and sugars to starch influences the taste on the most part. Referring to this especially the variety and storing temperature are of highest importance.