| Abstract: | Contribution on Waxy Maize Starch and High Amylose Starch Modified under the Influence of Temperature. The starches of the two genetic varieties of the corn grain, waxy maize starch and high amylose starch, were subjected to the influence of different temperatures. Subsequently, the physico-chemical properties of the modified starches were examined. Waxy maize starch which mainly consists of amylopectin, and high amylose starch which contains a high portion of linear chains of polymerized glucose units are interesting test materials because of their properties which are different by nature. Waxy maize starch with its high viscosity values, great swelling power and good solubility in hot water shows no tendency to settle or retrograde. While the process of freezing the starch granules hardly changes the properties mentioned, the influence of a temperature of 100°C causes morphological changes of a small proportion of grains, including the loss of birefringence. These changes are particularly pronounced after treatment of native starch at 120°C. The properties of the starch pastes were also strongly changed. The native high amylose starch characterized by unusual, oblong starch granules without birefringence, a low viscosity, low swelling power and low solubility showed only minor changes after freezing, whereas a temperature of 100°C resulted in reduced values of solubility and aggregation of the starch granules. A temperature treatment at 120°C and at 125°C brought about changes in the swelling properties, the viscosity and limiting viscosity, settling, swelling power, and solubility of the starch pastes. Attempts were made to conform the changes in the different properties observed with the expected influence of temperature treatment on the intermolecular forces (hydrogen bonds, crossbonding). |
