Before dehydration, the polysaccharide chains in the model food
systems are all hydrated with water molecules filling the spaces of
the pores to their highest Z positions, which for simplicity can be labeled
as having 100% water content in the pore spaces. Other than
the first two monomers, the polysaccharide chains are not rigid but
exhibit significant structural flexibility in their responses to the
interactions among themselves and with water. Shown in Fig. 4
are the side views of the porous structures formed by the amylose
and dextran chains with 100% water content but no water molecule
is included for visual clarity. It can be seen that the porous structures
with 20 polysaccharide chains that represent food systems
with a higher density of polysaccharide chains have smaller pores.
To probe the effects of pore structures on the water–water and
water–macromolecule interactions, the energetics of water molecules
as a function of their Z position and of their distance to the
nearest macromolecule are examined and shown in Figs. 5 and 6,
respectively. Compared with Fig. 3 that shows the energetics of
water molecules in very large pores or in bulk phase, it is apparent
from Fig. 5 that the porous structures have reduced the waterwater
interactions by about 2–3 kBT per water molecule and the level
of reduction is more significant with smaller in size pores in the
higher density systems. This effect of pore structures can be attributed
with certainty to the reduction of water–water hydration
numbers due to the presence of the polysaccharide chains. However,
the polysaccharide chains provide new water–macromolecule
interactions in return that make the water overall potential energy
stronger than that of bulk water. This energetic aspect could be