Sorption isotherms of Turkish delight

Moisture sorption isotherms of Turkish delight were determined using the gr avimetric static method of saturated salt solutions at 10, 20 and 30C. Isot herms were found to be of type Ill, typical of high sugar foods. The effect of temperature on moisture content was not significant (P>0.05). The sorpt ion isotherms exhibited hysteresis at low water activities (a(w) < 0.5). At higher water activities the moisture content increased sharply as the temp erature was increased, resulting in crossing of the isotherm curves at 0.65 water activity. Six models namely the BET, the GAB, the Halsey, the Hender son, the Chung & Pfost and the Iglesias di. Chirife were evaluated to deter mine the best fit for the experimental data. The GAB and the Iglesias & Chi rife models fitted well the data of Turkish delight in the temperature and water activity range investigated. However, the GAB model was not appropria te for the estimation of monolayer value. The Clausius-Clapeyron equation w as used to examine the isosteric heats of sorption.