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Couette-Taylor flow (CTF), which is characterized by the presence of Taylor vortices, ensures effective mixing, fast heat transfer and improved rheological properties of starch slurry. Therefore, this type of flow can be expected to provide favorable conditions for starch processing. In order to check how to intensify the process, starch gelatinization has been studied experimentally and using computer simulation in two CTF apparatuses of different volumes. The results show that, when the volume of apparatus was small, high value of degree of starch gelatinization could be achieved at relatively low temperature or at relatively low rotor rotation frequency. The increase in the apparatus volume ensures higher rate of gelatinized starch production and the reduction in dissipation of mechanical energy connected with rotor rotation, however, it also amplifies the detrimental inlet and gravitation effects. To overcome both of these negative effects, the increase in the rotor frequency is required. PRACTICAL APPLICATIONStarch gelatinization is a process frequently encountered in food industry, e.g., food sterilization or starch hydrolysis. Therefore, a new way of starch processing could be interesting in the context of growing consumer interest in natural food. It is expected that CTF apparatus could enable to process much more concentrated starch slurry than a jet cooker or coil heater typically used in industrial setting. Starch granules should also be less damaged during treatment in CTF apparatus than in an extruder. The results presented in this paper are relevant for process intensification and scale-up of starch gelatinization in CTF apparatus and will be extended to simultaneous starch gelatinization with enzymatic hydrolysis in the future work. bs_bs_banner Journal of Food Process Engineering ISSN 1745-4530 STARCH PROCESSING IN COUETTE-TAYLOR FLOW R. HUBACZ, N. OHMURA and E. DLUSKA

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 T hj , 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.