1. Adsorption isotherm and heat of sorption of osmotically pretreated and air-dried pineapple slices.
- Author
-
K. O. Falade, I. Olukini, and G. O. Adegoke
- Subjects
ADSORPTION (Chemistry) ,SURFACE chemistry ,PINEAPPLE ,OSMOSIS - Abstract
Slabs (1 Ö1.5 Ö5 cm) of pineapple were immersed in sucrose solutions of 52°B, 60°B and 68°B (w/w) at 25 °C for 12 h. Osmosed pineapple slices were subsequently air-dried at 60 °C for 72 h. Adsorption isotherms of osmo-dried pineapple slices were determined at 20 °C and 40 °C, using the gravimetric-static method. Isotherms were modeled using Brunnauer, Emmet and Teller (BET) and Guggenheim Anderson de Boer (GAB) models. Heat of moisture adsorptions were calculated from adsorption data using the Clausius-Clapeyron equation. Adsorption isotherms of osmo-oven-dried pineapple followed the characteristic type III (J-shape) isotherms. Equilibrium moisture contents at constant water activity decreased with increasing temperature, but crossing of the isotherms occurred at a
w ~ 0.86. GAB and BET monolayer moisture decreased with increased temperature. The net isosteric heat increased with decreased moisture content, and decreased with increased sucrose pretreatment concentration of pineapple slices. [ABSTRACT FROM AUTHOR]- Published
- 2004