| Abstract: | CONCLUSION. By studying cationic starch samples with graded DS prepared by four different processes, it was possible to show that their physical and chemical properties were determined mainly by the cationisation process and less by the DS. Each process resulted in products with a certain morphology and, in accordance with this supramolecular structure, their molecular composition, swelling, solubility and viscosity varied. The slurry process leaves the starch granular structure virtually unchanged. Consequently, swelling and solubility behaviour, viscosity, and molar mass closely resemble the data for native potato starch. The paste process caused complete destructuring of the starch granules. This led to samples that exhibited cold-water swelling, hot-water solubility, low viscosity and slightly degraded molar mass. In extrusion and semi-dry cationisation, an additional crosslinking reaction presumably occurred alongside introduction of the cationic substituents. This resulted in an unusual behaviour, in which the increasing influence of derivatisation was counteracted by the effect of crosslinking. Consequently, the solubility of the extruded samples decreased with increasing DS, while their viscosity increased. The crosslinked portion of the derivatives could not be separated by HPSEC, so that the molar mass of the extruded and semi-dry samples could only be determined for part of the sample. The results obtained in the present study indicate that the choice of process for the production of cationic starch derivatives largely predetermines their physical and chemical properties and consequently their range of application. Within the individual processes, changes in the physical and chemical properties of the derivatives are associated with a change in DS. |
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