Glass transition changes during osmotic dehydration

The changes in Ataulfo mangoes (Mangifera indica L.) osmotically dehydrated were evaluated through Modulated Temperature Differential Scanning Calorimetry (MTDSC) in order to determine their thermodynamic behavior due to water loss (WL) and solid gain (SG) during the process. These values were related with the effective diffusion coefficients for water (D-ew) and solids (D-es) into the fruit. The samples were analyzed under frozen conditions. The glass transition temperature (Tg) corresponding to sucrose in concentrated solution, and the value referred as Tg' for freeze sucrose solutions were founded. Mango Tg variation was in increasing with the WL decrement, and the melting enthalpy increase with the soluble solids increment into the fruit. As moisture content decrease by dehydration, the food matrix became more viscous and the water and solids transfer are delayed; these changes were reflected in the decrease of effective diffusion coefficients, D-ew and D-es, while Tg in mango samples increase. All these results show the useful with the MTDSC analysis to follow the osmotic dehydration inside the product. (c) 2011 Published by Elsevier B.V. Selection and/or peer-review under responsibility of 11th International Congress on Engineering and Food (ICEF 11) Executive Committee.