Moisture desorption isotherms and glass transition temperatures of osmo-dehydrated apple and pear

Effect of osmotic dehydration on desorption isotherms and glass transition temperatures of mango

“…() for persimmons and Djendoubi Mrad et al . (, ) for apricots, apples and pears. The equilibrium moisture content of fresh mango was significantly higher than that of the osmo‐dehydrated samples at a w > 0.33.…”

“…Within the a w range of 0.12–0.75, the thermograms of the samples exhibited one transition and showed no formation of ice and no ice melting peak in the DSC thermogram, meaning that only unfreezable water was found in the samples. Similar thermograms were also observed for osmo‐dehydrated fruits (Djendoubi Mrad et al ., , ). Several authors reported that water crystallisation in fruits occurred at a w values more than 0.80 (Telis & Sobral, ; Moraga et al ., ).…”

“…The glass transition temperature decreased from −1.1 to −58.7 °C when the moisture content of untreated mangoes increased from 0.034 to 0.280 g water g −1 sample (w.b.). Similar results were observed in osmo‐dehydrated samples (Baroni et al ., ; Djendoubi Mrad et al ., , ). Water is a well‐known plasticiser and has a low‐molecular‐weight and glass transition temperature (−135 °C) compared to the mango solids, and generally, the higher moisture content is accompanied by the lower glass transition (Guizani et al ., ; Syamaladevi et al ., ; Zhao et al ., ).…”

“…A change from rubbery to glassy state can also occur as a result of the decrease in food moisture contents during processing or storage. To the best of our knowledge, very few studies have focused on the impact of different solutes (molecular weight) of osmotic dehydration on the glass transition temperature in fruits (Telis & Sobral, ; Baroni et al ., ; Bchir et al ., ; Djendoubi Mrad et al ., , ).…”

Modelling the effect of temperature on the water sorption isotherms of chitosan films

“…This might result in a reduction in the total number of active sites in which the water molecules interact as a consequence of the physical changes in the polymeric material. Therefore, an increase in temperature results in a reduction in the amount of moisture adsorbed at a given water activity value (Li, 2012;Mrad et al, 2013;Muzaffar & Kumar, 2016;Souza et al, 2015). Water molecules also have the capability to increase the free volume in the polymer matrix, thus increasing the mobility of the polymer chains and the permeability of the material (Schmid et al, 2015).…”