Water desorption of cassava starch granules: A study based on thermogravimetric analysis of aqueous suspensions and humid powders

• Analyzes the dehydration of starch granules at laboratory scale.
• Shows the differences between the drying and desorption process in starch granules.
• Relates desorption energy and frequency to hydration level and granule structure.
• Provides a new approach for quantitative evaluation of the bound and structural water in biological granules.

This work reports on water desorption from cassava starch in relation with the structure and conditioning of granules in suspensions or after equilibration in desiccators. The experimental work is performed by thermogravimetric analysis with isothermal and non-isothermal protocols and interpreted to derive the activation energies and desorption frequencies according to the humidity range with no adjustable parameter. The analysis points out the different types of water interacting with the starch granules and relates the drying coefficients to their microscopic structure. The work helps clarifying contradictory and partial results from the literature.