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4) Pittia P., Sacchetti G., Rocculi P., Venturi L., Cremonini M.A., Dalla Rosa M. Water state andmobility as affecting mechanical properties of coffee beans. In: Water properties in relation tostabilisation of food, pharmaceutical and biological material: ISOPOW 10. CRC Press, BocaRaton, FLA, In Press.Plasticization and antiplasticization effect of water in raw and roasted coffee beans were investigated and discussedconsidering water-matrix interactions as described by sorption isotherms as well as water ‘freedom’ andmobility. Sorption isotherms were obtained in the 0.24 – 0.94 a w range and fitted by GAB equation. Mechanicalproperties of samples equilibrated at different a w were studied by uniaxial compression. Freezable water and watermobility were investigated by differential scanning calorimetry (DSC) and Low Resolution Nuclear MagneticResonance (LW-NMR) through the analysis of the transverse relaxation time (T 2 ), respectively. DSC and NMRresults showed that re-hydration process in coffee beans could be divided into two different stages. The firststage, (a w from 0.24 ± 0.01 up to 0.76-0.78 and to 0.86 for raw and roasted samples, respectively) where sorbedwater acts as antiplasticizer with an increase of fracture force at increasing moisture level, represents the solidmatrix hydration. In the second stage, at increasing levels of hydration (above a w 0.78-and 0.86 for raw androasted samples, respectively), after the completion of the monolayer hydration, water behaves as a bulk-likeagent as confirmed by the appearance of an endothermic melting peak and by a significant increase of T 2 . Onlyin this stage water acts as plasticizer. These results suggest that bulk-like water accounts for the plasticization effectas described by mechanical analysis.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.it41