Arnesh Palanisamy1, Jingyi Mo2, David Cox2, Tan Sui2, Paul Menut1, and Marco Ramaioli1
1AgroParistech, France, 2University of Surrey, UK
Abstract: Starch is one of the most omnipresent materials found in plants. Starch is also largely used in industry as a viscosity and texture enhancer. Understand the mechanisms dominating its rheology and the role of the microstructure is of paramount importance from an industrial perspective, both in terms of processing cost and in terms of product development.
In this work, we characterize the variation of mechanical properties of the starch granules, namely Young’s modulus at the two extreme cases of the fully swollen (gelatinized) case1 and unswollen case. Nano-indentation is used to measure Young’s modulus of hard unswollen starch granules. Bulk rheology and osmotic compression are used to estimate Young’s modulus of soft swollen granules. The results show that starch granule strength changes drastically with the gelatinization degree. Quantifying these characteristics is of paramount importance as material properties determine the nature of particle-particle interactions. This can have profound effects on the rheology of suspensions such as shear thickening for native unswollen starches and shear-thinning for soft particle rheology.
Finally, a fully coupled CFD-DEM-Heat transfer model with particle swelling kinetics is used to show the significance of particle-particle interactions in the context of starch gelatinization inside a small gap Couette rheometer2.
 Palanisamy, A., Gabrielle, M., Ramaioli, M., Plana-Fattori, A., Flick, D. and Menut, P. 2021. Determination of the mechanical properties of gelatinized starch granule from bulk suspension characterization. Rheologica Acta.
 Palanisamy, A., Ramaioli, M., Menut, P., Plana-Fattori, A. and Flick, D., 2021. Multiscale modelling of flow, heat transfer and swelling during thermo-mechanical treatment of starch suspensions. Food Structure, 29, p.100211.