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|Type:||Artigo de periódico|
|Title:||Thermal transitions of osmotically dehydrated tomato by modulated temperature differential scanning calorimetry|
|Abstract:||Modulated temperature differential scanning calorimetry (MTDSC) was employed to examine thermal transitions of osmotically dehydrated tomato (Lycopersicon esculentum, var. Deborah). Tomato halves, soaked in sucrose solution (60% sucrose), sodium chloride (10% NaCl) and mixtures of salt-sucrose solution (60% sucrose-10% NaCl/40% sucrose-15% NaCl) for 3 h at 40 degreesC, were comminuted, freeze-dried for 48 It and kept in desiccator over saturated salt solutions at 25 degreesC until equilibrium was reached. A MTDSC 2920 (TA Instruments) was used in all tests. A cyclic modulation of +/- 0.5 degreesC/40 s was superimposed on a constant scanning ramp of 2.5 degreesC/min. Thermo-analytical curves of both osmotically dehydrated and untreated tomato allowed the determination of the glass transition data and the plot of state diagrams. Furthermore, a peak of enthalpy relaxation in the glass transition region that partially disappears on rescanning was detected. Structural recovery was modelled by Williams-Watts equation and glass transition temperature by Gordon and Taylor and Kwei equations. (C) 2002 Elsevier Science B.V. All tights reserved.|
enthalpy of relaxation
|Editor:||Elsevier Science Bv|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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