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more evident with the increasing of sample hydration. At the same time, the growing of a second relaxometricwater population characterized by a longer T 2 was detected.2) Venturi L., Rocculi P., Cavani C., Placucci G., Dalla Rosa M., Cremonini M.A. (2007) Waterabsorption of freeze-dried meat at different water activities: a multianalytical approach usingsorption isotherm, differential scanning calorimetry, and nuclear magnetic resonance. Journalof Agricultural and Food Chemistry 55, 10572-10578.Hydration of freeze-dried chicken breast meat was followed in the range a w = 0.12 – 0.99 by a multianalyticalapproach comprising sorption isotherm, differential scanning calorimetry (DSC) and nuclear magnetic resonance(NMR). The amount of frozen water and the shape of the T 2 -relaxogram were evaluated at each water content byDSC and NMR, respectively. Data revealed an agreement between sorption isotherm and DSC experimentsabout the onset of bulk water (a w = 0.83-0.86), while NMR detected mobile water starting at a w =0.75. The originof the short-transverse relaxation time part of the meat NMR signal was also reinvestigated through deuterationexperiments and proposed to arise from protons belonging to plasticized matrix structures. It is proved both byD 2 O experiments and gravimetrically that the extra protons not contributing to the water content in the NMRexperiments are about 6.4 % of the total proton NMR CPMG signal of meat.3) Pittia P., Sacchetti G., Rocculi P., Venturi L., Cremonini M., Dalla Rosa M. (2008) Waterstate and mobility as affecting mechanical properties of coffee beans. Proceedings of the 10thInternational Symposium on the Properties of Water ISOPOW 10, Water Properties in Food,Health, Pharmaceutical and Biological Systems, Bankok, Thailand, 2-7 September 2008, pp I-17, 91.Water is the most effective plasticizer in food matrices, decreasing glass transition temperature (T g ) and mechanicalresistance and determining a softening effect with the increasing of its concentration. However, uponwater sorption, coffee beans showed an opposite effect (i.e. antiplasticization) up to a certain hydration degree,corresponding to a specific a w value or moisture content, different for raw and roasted product. Aim of this studywas to investigate the importance of water-food matrix interactions as well as the water state and mobility in affectingantiplasticization and plasticization effect of water on textural properties of coffee beans. Sorption isothermof raw and roasted coffee beans was obtained in the 0.24-0.95 a w range and fitted by GAB equation. Mechanicalproperties of samples equilibrated at different a w were studied by uniaxial compression. The water mobilitywas investigated by differential scanning calorimetry (DSC) and low resolution nuclear magnetic resonance(LW-NMR) through the analysis of the transverse relaxation time (T 2 ). By comparing the results of themechanical analysis and the sorption isotherms parameters, a critical moisture content corresponding to a criticala w value, was identified as starting point for the plasticization effect of water in beans. These values were differentfor raw (a w : 0.75 ± 0.02) and roasted (a w : 0.86 ± 0.02) beans and in the second case corresponded to the startingpoint of the upward concavity of the sorption isotherms where the bulk phase water is physically entrappedin the cellular structure. In principle, DSC and NMR results showed as the re-hydration process could be divedinto two different stages. The first one (a w 0.24-0.73 for raw samples and a w 0.22-0.88 for roasted ones) couldrepresent the solid matrix hydration where water acts as antiplasticizing agent as confirmed by the mechanicalanalysis. This hypothesis is supported by the very short T 2 values obtained by NMR as well as the concomitantabsence of any endothermic peak in the DSC pattern. In the second one, (a w 0.73-0.94 for raw samples and a w0.88-0.95 for roasted ones) after the completion of the solid matrix hydration, water behaves as bulk-like as confirmedby the appearance of an endothermic melting peak, more and more evident with the increasing of samplehydration, and by a significant increase in the T 2 measured by NMR. The presence of bulk-like water can accountfor the plasticizing effect in agreement with mechanical and isotherm parameters results.SISTAL - SOCIETA’ ITALIANA DI SCIENZE E TECNOLOGIE ALIMENTARIDipartimento di Scienze e Tecnologie Agroalimentari, Università degli Studi della TusciaVia San Camillo de Lellis, 01100 ViterboTel.: 0761- 35 74 94/7 , Fax: 0761- 35 74 98, e-mail: mmoresi@unitus.it40