| Abstract: | 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. |
