Different states of water molecules in food porous structures
can be further elucidated by the distribution of water energetics
as a function of distance to the food macromolecules and the
results are presented in Fig. 6. Again, it is observed that the magnitude
of the water-water interactions in the porous food structures
is weaker than that in the bulk phase (cf. Fig. 3) and that the water
molecules adjacent to the polysaccharide chains acquire strong
water–macromolecule interactions, which cause them to be
strongly bound, less available for other activities, and related to
smaller aw values. Such phenomena are more noticeable in the
food structures constructed with amylose chains (cf. Fig. 6) and
in particular when the pores decrease in size due to higher polysaccharide
density (cf. Figs. 3 and 6). As indicated by the stronger
water–amylose interactions in Fig. 6, the amylose-based porous
structures tend to accommodate water better than the dextranbased
porous structures. In accordance with this differentiation is
the finding that the amounts of water molecules in the first hydration
shells (within a distance equivalent to the effective water
diameter, 3.77 Å) around the amylose chains are larger than those
around the dextran chains by approximately a factor of three. It is
thus reasonable to conclude here that, in addition to the effects of
pore structures on water energetics and water activity, food
macromolecules with different molecular architectures can impart
their influences into different aspects of food properties and food
dehydration.