Modelling the Water Sorption Isotherms of Quinoa Seeds (Chenopodium quinoa Willd.) and Determination of Sorption Heats

Margarita Miranda, Antonio Vega-Gálvez, Mariela Sanders, JESSICA CAROLINA LOPEZ PASTEN, Roberto Lemus-Mondaca, Enrique Martínez, Karina Di Scala

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13 Scopus citations

Abstract

Adsorption and desorption isotherms of quinoa seeds (Chenopodium quinoa Willd.) were measured using the static gravimetric method at three temperatures (20, 40 and 60 °C). Water activity ranged from 0. 118 to 0. 937. The moisture sorption behaviour of quinoa was temperature dependent, as indicated by a decrease in equilibrium moisture content, at all levels of a w, with increasing temperature. Eight mathematical equations available in the literature were used to model the experimental data, namely, GAB, BET, Caurie, Henderson, Oswin, Halsey, Smith and Iglesias-Chirife. All the equations showed generally a good fit; however, the Iglesias-Chirife and Oswin equations were considered the best to predict the experimental data for both isotherms. Effect of temperature on model parameters was analysed and studied through an Arrhenius-type equation. The net isosteric heats of desorption and adsorption were determined by applying the Clausius-Clapeyron equation resulting in 69. 24 kJ mol -1 for desorption and 61. 26 kJ mol -1 for adsorption. The experimental heat data were satisfactorily modelled by Tsami's equation.

Original languageEnglish
Pages (from-to)1686-1693
Number of pages8
JournalFood and Bioprocess Technology
Volume5
Issue number5
DOIs
StatePublished - 1 Jul 2012

Keywords

  • Isosteric sorption heat
  • Mathematical modelling
  • Quinoa
  • Sorption isotherms

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