Modelling of transient moisture concentration of semolina pasta during air drying

Drying model for cylindrical pasta shapes using desorption isotherms

“…The drying process of cylindrical-shaped pasta is assumed to be one-dimensional along the pasta radius, while the process is assumed to be isothermal (De Temmerman et al, 2007). The mass transfer balance is expressed by Fick's law with an effective diffusion coefficient D and evaporation of moisture at the surface of the drying pasta.…”

“…The effective diffusivity of pasta was already determined in another study (De Temmerman et al, 2007). The effective diffusivity is expressed as a function of the moisture concentration X and the pasta temperature T (De Temmerman et al, 2007):…”

“…The use of such a model can be helpful for control design. This study is performed in addition to De Temmerman et al (2007), which was focused on the determination of the model parameters. This research however deals with the determination of drying curves based on moisture desorption isotherms, while this study can also be considered as a validation research for the model structure discussed in De Temmerman et al (2007).…”

Impact of the number and sampling time of water content measurements on the identifiability of a concentration-dependent water diffusivity

“…For hygroscopic products, including many polymers and food products, the water diffusivity decreases during drying as the ratio of bound to free water increases [14][15][16][17]. The dependence of the water diffusivity for the water content is generally expressed using an exponential function:…”

Effect of the water content measurements on the estimation and identifiability of water diffusion and convection mass transfer coefficients

“…The identifiability of the coefficients for mass transfer models differs from heat transfer models by the type of measurements available where only global water content measurements are generally available, the evolution of the mass of the product during processing, because internal water content measurements are difficult to obtain or inaccurate [15,16]. The measurement of the mass of the product allows for the calculation of the global water content but does not provide information about the internal water content of the product and it remains unclear how this affects the reliability of the estimation of the mass transfer coefficients from experimental measurements.…”