A FTIR study on low hydration saccharide amorphous matrices: Thermal behaviour of the Water Association Band

We report a study on the thermal behaviour of the infrared Water Association Band (WAB) in dry binary saccharide-water systems (containing trehalose, sucrose, maltose, and raffinose). This is a follow-up of preceding studies on analogous carboxymyoglobin-saccharide-water ternary systems, which pointed out a mutual protein-matrix influence (coupling). A comparison between binary and ternary systems, for all the saccharides studied, evidences a reduction in the residual water content in the latter and, except for trehalose, a sizable modification in the thermal behaviour, which is discussed in terms of structure and hydrogen bonding properties of the sugars. The study allowed us also to improve the definition of Spectra Distance, which is useful to roughly evaluate the system thermal evolution.