Sorption characteristics of amaranthus stems under storage conditions and water activity prediction
2010
Stencl, Jiri | Fajman, Martin | Sedlák, Pavel | Janstova, Bohumira | Kleparnik, Jan | Stencl, Jiri
Stems of amaranthus are considered as prospective biofuel in the Czech Republic. The study presents results of water sorption tests of this biomass in the range of 10-30°C and water activity (aw ) ranging from 0.4 to 0.99. The experimental procedure used was a gravimetric dynamic method. Four sorption models (Chung-Pfost, Halsey, Henderson, Oswin) were evaluated. The modified Henderson's equation was the best model for moisture adsorption and desorption of amaranthus stems. Critical values of equilibrium moisture content, corresponding to the aw =0.6, were 11.45% and 13.28%(wb) for water adsorption and desorption respectively, at the temperature of 20°C. Heat of sorption (qst ) was calculated using the chosen sorption model and Clausius-Clapeyron equation. An exponential function was found to fit the experimental qst values of amaranthus stems at moisture contents ranging from 7% to 40%(wb) for adsorption and desorption.
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