Phase transitions of bovine hide gelatin plasticized by water | [Phases de transition de gelatine de cuir de bovin plastifiee par l'eau]
1999
Sobral, P.J.A. (University of Sao Paulo, Pirassununga (Bresil). Department of Animal Science) | Menegalli, F.C. | Guilbert, S.
It is well known that physical-chemical properties of gelatin are strongly dependent of its origin. The aim of this work is to study the thermal phase transitions of a particular gelatin sample plasticized by water, on the hygroscopic domain. Samples of a bovine hide gelatin were equilibrated, by adsorption or desorption, under various water activities (Aw = 0.11 - 0.84) at 25 degrees, for the DSC study in a DSC TA 2010 equipped with a TA4000 controller, at 5 degrees/min. Before first and second scans, the DSC cell was quench cooled, with liquid N2. The first DSC scans obtained with the sample, conditioned by absorption in low Aw displayed a well visible baseline shift, followed by a large endothermic peak. In high Aw, another endothermic peak appears (after glass transition and before the other peak), that becomes more important as moisture content increases. In the case of samples conditioned by des orption , this phenomenon was observed in all domain of Aw. In the second scan , only Tg was visible, shifted left. All Tg values plotted versus moisture content (X) displayed a practical glass transition curve and only values of second Tm displayed a monotonic curve versus moisture content
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Эту запись предоставил National Institute for Agricultural Research