Modeling the equilibrium moisture content of desorption and adsorption of yam (Dente)

Amankwah, E.A.; Dsizi, K.A.; Straten, G. van; Boxtel, A.J.B. van


The experimental equilibrium moisture content of yam (Dioscorea rotundata; cultivar: Dente) at temperatures of 25°C and 50°C were determined at relative humidity from 0% to 95% employing the dynamic vapor sorption analyzer. Wet yam samples with about 68% initial moisture content were used, first for desorption and subsequently for sorption. Water activity decreased with increased temperature at constant equilibrium moisture content. The desorption and adsorption isotherms were fitted by the Guggenheim-Anderson-de Boer (GAB), Henderson, Halsey, Oswin, Smith, Brunauer-Emmett-Teller (BET) and Peleg models. On the basis of the fit the Peleg, GAB and Oswin models were most suitable for describing the observed data. When the focus is on drying, the GAB (3 parameters) and empirical Peleg model (4 parameters) performed best. Of these, GAB is preferable because it has fewer parameters, which, moreover, have a physical meaning.