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

Abstract

Summary The influence of different osmotic solution pretreatments (sucrose and glucose with concentration of 45%) on desorption isotherms and glass transition temperatures (Tg) of mango was investigated. The Peleg model satisfactorily described the relationship between water activity (aw) and moisture content of all samples (0.992 < r2<0.997). The equilibrium moisture content of mangoes osmotically pretreated in sucrose was higher than that of samples pretreated in glucose. Differential scanning calorimetry was used to measure the Tg of samples equilibrated with different aw (0.12–0.75). The dependence of Tg on moisture content was adequately fitted by Gordon–Taylor model (0.946 < r2<0.949). The osmo‐dehydrated mangoes showed lower Tg than fresh samples at the same moisture content. Additionally, the samples osmotically pretreated in glucose showed the lowest Tg value.

Thermal properties of Corinthian currant pastes as affected by storage

“…The plasticizing effect of water and/or glycerol was evident for all samples and Tg was well described by the proposed equation. The Tg depression with increasing moisture content has been observed for similar food products, including dried figs, freeze‐dried kiwifruit, and osmo‐dehydrated mango (Badii et al., 2014; Moraga, Martínez‐Navarrete, & Chiralt, 2006; Zhao et al., 2018). The Tg values of kiwifruit ranged approximately from +20 to −50°C, for relative humidities from 0.11 to 0.675, and for osmo‐dehydrated mango Tg depressed approximately from +0 to −70°C, for relative humidities from 0.11 to 0.75.…”

Changes in water state, distribution, and physico‐chemical properties of preserved kumquats during different processing methods

“…A DSC (Q2000‐DSC, TA instruments, New Castle, DE) was used for the T g characterization of the preserved kumquats following the method described by Zhao et al (2018) with slight modifications. Briefly, samples were frozen completely at −80°C and then freeze dried for 48 h. Approximately 5 mg lyophilized sample was sealed in an aluminum pan with a lid.…”

“…Removed water and sugar intake, as well as the increase in soluble solid, could influence texture properties and structural state, thereby affecting preservation features. Differential scanning calorimetry (DSC) is a normal method used to measure glass‐transition temperature ( T g ) in characterizing internal changes and stability in osmotically dehydrated fruits, such as in pomegranate seeds (Bchir et al, 2009), apricots (Djendoubi Mrad et al, 2012), apple and pear (Djendoubi Mrad et al, 2013), and mango (Zhao et al, 2018). Meanwhile, few studies have focused on the changes in water, T g , microstructure, texture, and color in the process of preserving kumquats.…”

Osmodehydrofreezing: An Integrated Process for Food Preservation during Frozen Storage

“…When osmotic pre-treatment is applied prior to conventional freezing, the water content decrease causes a depression of the freezing point and a significant decrease of the amount of water to be subsequently frozen. The moisture content decrease combined with a solute impregnation leads to an increase of the glass transition temperature, which makes formulated tissue much more stable during subsequent frozen storage [ 19 , 20 , 21 , 22 ]. As stated in Goula et al, 2012 [ 23 ], the reduction in moisture content, induced by the osmotic step, results in significant advantages, regarding the freezing process per se, including (1) improved retention of structure and other quality attributes; (2) reduced costs of packaging, distribution, and storage; and (3) energy savings during freezing of the remaining water and a decrease in the refrigeration load.…”