The aim of the present work is to link the bioprotective effectiveness to the dynamic properties of a class of homologous disaccharides, that is, trehalose, maltose and sucrose, and their mixtures in water. The findings obtained by elastic neutron scattering point out a harmonic-anharmonic transition for all the three disaccharide mixtures. Using a new operative definition of 'fragility', the different degrees of 'strength' of the investigated systems are determined. The links existing between the degree of fragility and the cryptoprotective action are also discussed.