Starch gelatinisation in Couette-Taylor flow apparatus
In this paper starch gelatinisation in Couette-Taylor flow (CTF) apparatus (equipped with a water heat jacket) has been investigated. CTF (characterised by the presence of Taylor vortices) provides good environment for gelatinisation, e.g. effective mixing, fast heat transfer, positive influence on starch rheological properties. During experiments starch gelatinisation degree and starch swelling has been studied. It was accompanied by temperature measurements performed along the apparatus. Additionally, starch gelatinisation was investigated by computer simulation. A complete starch gelatinisation was obtained for the shortest investigated residence time in the apparatus when the temperature in the heat jacket was above 85 °C. Nevertheless, it seems that it is still possible to reduce a residence time value, as well as, the value of Thj, but it may require some acceleration of rotor rotation. The swelling degree of gelatinised starch increased with growing values of residence time, rotor rotation and process temperature. Heat transferred could be affected by the structure of the Taylor vortex flow. No significant destruction of starch granules was observed during the treatment in Couette-Taylor flow apparatus. A quite satisfactory agreement between computer simulation and experiments results was achieved.