Hydrothermische Behandlung von Stärke in Gegenwart von α-Amylase Teil 2: Einfluß einer hydrothermischenzymatischen Modifizierung auf die Quellungstemperatur von Weizenstärken

Hydrothermal Treatment of Starch in the Presence of α-Amylase. Part 2: Effect of a Hydrothermal Enzymatic Modification on the Swelling Temperature of Wheat Starches. The hydrothermal treatment of wheat starch in the presence of bacterial-α-amylase is directed to the production of modified residual starches with a maximal shift of swelling temperature T_max (measured by DSC) at high yields. The annealing of granular starch at temperatures below the swelling temperature (50°C) in presence of α-amylase gives no difference regarding the shift of T_max. Because of the hydrolysis of swollen material it is possible to use higher reaction temperatures and the process becomes more effective. The formed maltose syrup retards the shift of T_max and protects the granules. Within 24h wheat starch can be modified with a yield of 70% and a shift of T_max of 8K.     

Hydrothermische Behandlung von Stärke in Gegenwart von α-Amylase. Teil 3. Veränderung der rheologischen Eigenschaften von Weizenstärke durch hydrothermisch-enzymatische Behandlung

Hydrothermal Treatment of Starch in Presence of α-Amylase. Part 3: Changes of Rheological Properties of Wheat Starch by Hydrothermal Enzymatic Treatment . In order to change functional properties of wheat starch the feasibility for a hydrothermal enzymatic modification under conditions of excess water (annealing) has been tested. The granular structure of the starch should remain unchanged at the same time. Since wheat starch may be changed negligiblely at usual conditions of annealing (T=50°C) as a consequence of its rather low swelling temperature a bacterial α-amylase has been used for partial degradation of these portions of starch granules which gelatinize irreversiblely at higher levels of annealing temperatures. The resulting spectrum of saccharides consisting mainly of maltose (approx. 50%) allows the protection of the wheat starch matrix even at higher annealing temperatures (54°C). However, the gelatinization and gelation behaviour is changed in a characteristic way, in particular by a serious increase of the hot paste consistency at 95°C. In the following, the obtained consistency collapses significantly and arrives by cooling a level below the corresponding figures of the native starch. With respect to yield of annealed starch the reaction time at elevated temperature is of main importance. In order to demonstrate the protecting activity of the produced saccharides in particular with higher concentrations of maltose samples have been annealed in maltose sirups of varied concentration (6, 12, 25%m/m). Up to concentrations of 12%m/m and reaction temperatures of 50°C the Brabender consistency curves could be raised by 300 to 500BU. The application of 54°C limited the effect of modification. Using a 25%m/m maltose syrup allowed, of course, successfully the annealing at 54°C. As expected, yield losses remained low (< 10%). In applying a temperature-time-regime by steps together with a treatment by α-Amylase or alternatively 25%m/m maltose syrup the expected shifting of consistency curves could be observed as well, however, to a limited amount. Finally, pronounced differences could be found for the yield of modified starches.     

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.     

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.     

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.     

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.     

Einfluß der Stärke auf die Textureigenschaften von Kartoffelknollen

Interaction of Starch and Textural Properties of Potato Tubers. By a two years glas-green-house test the influence of starch content on texture of raw and boiled potatoes was studied. Results show that only at certain conditions the starch content can affect a tendency of influencing the texture. Physical properties of starch play as well an important role referring to the texture of tubers. With reference to the influence of starch on texture of potato tubers other factors seem to play a role which still must be investigated.     

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 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 der Klärmittel und ihrer Menge auf die polarimetrische Bestimmung von Kartoffelstärke nach Ewers

Influence of Clearing Agents and their Amount on Polarimetric Determination of Potato Starch According to Ewers. According to the results of chemical analysis and its statistical evaluation the Carrez clearing agent at an amount of 1 ml appears to be the most suitable for determination of starch in potatos. Use of sodium molybdate or ammonium molybdate led to lower values in average. Among these two sodium molybdate, as during examination of starch samples, appeared more suitable than ammonium molybdate. Phosphortungstic acid proved the least suitable. Normal as well as basic lead acetate after Horn did not show fully clear results upon revision. This is why they were not used.     

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 von Calcium auf Gehalt und Ertrag an Trockensubstanz und Stärke bei Kartoffeln

Effect of Calcium on Content and Yield of Dry Substance and Starch in Potatoes. During three years of glasshouse experiments with the late potato variety Kamyk the doses and different applications of Calcium have been tested. It was stated that tuber weight is high significantly influenced by the calcium dosage. Calcium decreased the dry substance content while the starch content was increased. The yield of dry substance and starch was also influenced. Besides of the tuber yield the content of dry substance and starch contributes to this influence. Depending on the way of application calcium fertilizing increased also the amount of reducing sugars.     

Zur Wirksamkeit verschiedener Metallsalzinitiatoren auf die Pfropfpolymerisation von Acrylnitril auf Kartoffelstärke

Efficiency of Different Metal Salt Initiators on Graft Polymerization of Acrylonitrile on Potato Starch. The activity of Cer(IV)-, Fe(II)-, Fe(III)- and Mn-salts were investigated as initiators for graft polymerization of acrylonitrile on potato starch. It was found that viscosity of aqueous kalium salt solutions of hydrolyzed acrylonitrile-potato starch-graft polymers is strongly dependent on the different initiators.     

Verarbeitung von Kartoffelstärke auf Kunststoff-Verarbeitungsmaschinen

Processing of Potato Starch on Plastics Processing Machines. Starch as an organic material with macromolecular structure has many properties comparable to usual plastic materials. Therefore, it is possible to manufacture starch products with polymer processing machines by the same methods as synthetic polymers. In addition of special plasticizer native potato starch has been processed to granules and films with different extruders. The granules were taken as feed material for experiments of the production of samples with an injection moulding machine. The mechanical properties of the produced specimens proved to be on a satisfactory level. By the suitability of the widely distributed screw machines for starch processing it is possible to substitute synthetic polymers by starch for special applications without high inital costs. Detailed knowledge about the suitable processing methods is an important condition for that.