Power-law foods in continuous coiled sterilisers

Starch gelatinisation in Couette-Taylor flow apparatus

“…Such numerical calculations require knowledge of a model describing rheological properties of wheat starch slurry during the entire process of gelatinisation. We could find a sufficiently developed model only for cross linked waxy maize (Kelder et al, 2004). This model was not valid in our case where gelatinisation of unmodified wheat starch was investigated.…”

“…This model was not valid in our case where gelatinisation of unmodified wheat starch was investigated. Additionally, even this rather sophisticated model needed an artificial assumption about the initial value of starch apparent viscosity in order to ensure laminar flow regime along the whole apparatus (Kelder et al, 2004). It stems from the fact that starch apparent viscosity grows significantly during gelatinisation, which may cause a transition of flow regimes from turbulent vortex flow to laminar flow with or without vortices along the apparatus.…”

“…The most significant advantage of using Couette-Taylor flow for starch gelatinisation seems to be a positive influence of shear stress field (generated by rotor rotation) on starch slurry rheological properties by causing a significant reduction of starch slurry apparent viscosity. Taylor vortices (similar to Dean vortices in Kelder, 2004) also ensure good heat transfer conditions, uniform heating and an effective (but gentle) mixing of the suspension. Additionally, there is a possibility of almost independent adjustment of mixing intensity and residence time of reactants in the apparatus (by controlling rotor rotation and axial flow).…”

Modeling of continuous thermal processing of a non-Newtonian liquid food under diffusive laminar flow in a tubular system

“…The advantages of using continuous processing units for fluid foods, instead of batch processing, are the increase in production rate, the reduction in energy consumption and the improvement on the sensorial and nutritional attributes of the product [5][6][7][8][9].…”

“…Since the flow is laminar, there is a significant spread on the residence time distribution in the equipment and the heat transfer through the food is slower than in turbulent flow. Consequently, different parts of the fluid are exposed to different timetemperature profiles and the output of the process is the mixture of these parts [8,13].…”