Starch is used as a rheology modifier in many foodstuffs. As a raw material, it is normally supplied in the form of approximately spherical granules, with diameters between about 1 µm and 100 µm. To be used as a rheology modifier, starch must undergo gelatinization, which occurs when the granules are disrupted in aqueous environments, to swell and eventually release the constituent molecules. The temperature at which this process commences will depend on the nature of the starch, but it is usually approximately 60°C. The process is thermally irreversible, and when the temperature is reduced, the system remains gelatinized, although some slow de-gelatinization (retrogradation) may occur.
The precise gelatinization temperature, the time taken for the process to go to completion, and the rheological properties of the gelatinized starch, will depend on the source of the starch, any physical and chemical modifications made, the pH of the aqueous phase, and so on. Test methods have been developed in the starch industry allowing the rapid testing of starches. The general procedure is as follows:
Stirring is carried out during the entire process. The stirring is necessary in the pre-gelatinization stage to prevent the starch particles from sedimenting. In the post-gelatinization stages, it is used to ensure good mixing.
For detailed information related to the Starch Pasting Cell, refer to the DHR/AR Series Starch Pasting Cell Getting Started Guide.
See Also
Setting the Cooling Water Parameters for the DHR/AR Starch Pasting Cell
Creating the Starch Pasting Cell Geometry in TRIOS
Calibration of the Measuring System Factor