Influence of sugar composition on water sorption isotherms and on glass transition in apricots

Sorption behaviour of papayas as affected by compositional and structural alterations from osmotic pretreatment and drying

“…This difference in moisture sorption behaviour between the untreated and pretreated papayas at the same temperature can be ascribed to the induced effect of osmosis and drying process, which caused modifications in composition and structure in the fruit. As expected, the equilibrium moisture content increased with an increase of a w and the characteristic shape of the type-III pattern sorption isotherm was observed as reported for high sugar fruits (Djendoubi Mrad et al, 2012. Sorption behaviour in such products can be explained by the fact that water can only be adsorbed into surface -OH sites of crystalline sugar at low a w , and thus the equilibrium moisture content remains low.…”

“…An intersection point was not evident for the pretreated and dried samples, presumably due to the comparably low sugar content of the fresh papaya (10°Brix) and sucrose solution applied (30°Brix). Djendoubi Mrad et al (2012) stated that the concentration and exposure time of the osmotic pretreatment are responsible for the occurrence of crossing isotherms at higher temperatures. Conflicting results concerning the ''crossing'' phenomenon have been reported for several fruits, mainly because the value of a w that the inversion point occurs depends on chemical composition as well as sugar type, content, hydration numbers and solubility properties.…”

“…In addition, it seems that osmosis altered the interaction between the sorption sites and molecules of water vapor, probably due to the changes in sugar composition as previously mentioned. Djendoubi Mrad et al (2012) found that the sugar concentration in the osmotic solution had a positive influence on the isosteric heat of sorption for apricot. The heat of desorption can provide a theoretical estimation of the minimum heat requirements for drying.…”

“…More specifically, Djendoubi Mrad et al (2012) found that desorption isotherms of osmo-dehydrated apricots were affected by the sugar composition and concentration due to the biopolymer binding at low a w values and the dissolution of sucrose at high a w values. Sugars may occur in different phases, i.e.…”

Thermal and Textural Changes of Turkish Delight with Storage Relative Humidity

“…Similar decreasing trend was also determined for the other thermal properties of lokum with increasing a w . The same results were reported in several sugar-based food products [9,11]. T g values of lokum found in the study were comparable with the literature values that sucrose, fructose, glucose, lactose and maltose were 62-70, 5, 31, 101, and 87 °C, respectively, and that of starch as within a range of 55-75 °C [1].…”