To investigate whether a heat-labile macromolecule could be
loaded into a solid sugar glass using the novel methodology, a
model protein macromolecule, β-galactosidase (β-gal) enzyme, was
incorporated into dehydrated TRA/SUC (75:25% w/w) sugar glasses.
Fig. 4 shows that whilst β-gal enzyme activity diminished over the endothermic region between 130 and 150 °C (Fig. 2A). The weight
loss profile with temperature (TGA) for the same material is superimposed
in Fig. 2A and shows a total weight loss of approximately 10%
w/w over the heating range. This water loss was greatest over the
temperature range 90–140 °C and hence the endothermic peaks observed
over this range correspond to dehydration of the dihydrate
crystal. This suggests that the hydrated form of the sugar was formed
during the process and that residual water remained within the glass
following dehydration