title: Sorption characteristics of Amaranthus stems under storage conditions and water activity prediction.
abstract: 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 degrees C and water activity (a(w)) 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 a(w)=0.6, were 11.45% and 13.28%(wb) for water adsorption and desorption respectively, at the temperature of 20 degrees C. Heat of sorption (q(st)) was calculated using the chosen sorption model and Clausius-Clapeyron equation. An exponential function was found to fit the experimental q(st) values of amaranthus stems at moisture contents ranging from 7% to 40%(wb) for adsorption and desorption.
authors.affiliation: Mendel University in Brno, Zemedelska 1, 613 00 Brno, Czech Republic. stencl@mendelu.cz
authors.forename: Jiri
authors.initials: J
authors.lastname: Stencl
authors.forename: Martin
authors.initials: M
authors.lastname: Fajman
authors.forename: Pavel
authors.initials: P
authors.lastname: Sedlak
authors.forename: Bohumira
authors.initials: B
authors.lastname: Janstova
authors.forename: Jan
authors.initials: J
authors.lastname: Kleparnik
authors.forename: Jiri
authors.initials: J
authors.lastname: Stencl
mesh_terms: D000327:Adsorption; D027721:Amaranthus / Q000378:metabolism*; D008954:Models, Biological; D018547:Plant Stems / Q000378:metabolism*; D013696:Temperature; D014867:Water / Q000378:metabolism*
chemical_list: D014867:Water