Desorption isotherms of flaxseeds (Linum usitatissimum L.) and thermodynamics parameters of the process

Authors

  • Maria da Conceição Valente Federal University of Pará/Graduate Program in Chemical Engineering (PPGEQ)
  • Rafael Nascimentro Federal University of Pará/ Natural Resources Engineering, PRODERNA/ITEC/UFPA
  • Elza Santana Federal University of Pará/Graduate Program in Chemical Engineering (PPGEQ)
  • Lênio José Faria Federal University of Pará/Graduate Program in Chemical Engineering (PPGEQ)
  • Cristiane Maria Costa Federal University of Pará/Graduate Program in Chemical Engineering (PPGEQ)

Keywords:

Equilibrium moisture content, Drying, Isosteric heat

Abstract

Sorption isotherms of flaxseeds were determined by static gravimetric method at temperatures 40; 60; and 80 ºC, over a relative moisture range of 10-95%. Six mathematical models were applied to analyze the experimental data. The modified GAB model showed the best fitting to the experimental data. The isosteric heat and differential entropy were determined by applying Clausius-Clapeyron and Gibbs-Helmholtz equations, respectively. The isosteric heat and the entropy of desorption isotherm presented similar behavior, with a sharp change in an equilibrium moisture content of 10%. The enthalpy-entropy compensation theory was applied to the isotherms, indicating that they are enthalpy-controlled.

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Published

2020-02-20

Issue

Section

Food Engineering