Enthalpy-entropy compensation in sorption phenomena of starch materials

The enthalpy-entropy compensation theory was applied to the experimental moisture adsorption and desorption isotherm data (water activity (a(w)) range 0.006-0.982) of raw potato, potato starch gel, potato starch powder, highly amylopectin corn starch powder and highly amylose corn starch powder in the temperature range 30-60 degrees C. A linear relation existed between differential enthalpy (Delta H) and differential entropy (Delta S) for all the experimental data considered, thus satisfying the enthalpy-entropy compensation theory. Further analysis of the data indicated an enthalpy-controlled (isokinetic temperature (T-beta) > harmonic mean temperature (T-hm)) and spontaneous (-Delta G) sorption process. (c) 2004 Elsevier Ltd. All rights reserved.