The swelling behavior of alginate/gelatin mixture beads after
air-drying is exemplified in Fig. 2. The data shown is for the beads
prepared at pH 10.5. The beads prepared at pH 7, pH 4, and pH
3.5 showed the same dependence of swelling on NaCl concentration.
Neither the control beads nor the alginate (1.0%)/gelatin (0.5%)
beads swelled in pure water, apart from a wetting process at very
beginning of the rehydration. The increase of NaCl concentration
up to 0.05% was insufficient for the control beads to swell, whereas
it led to a considerable swelling of the mixture beads. It manifested
that the presence of gelatin helps and improves the swelling
of Ca2+-crosslinked alginate beads. At a further higher concentration
of NaCl of 0.5%, both the control beads and the mixture beads
swelled significantly. The mixture beads swelled relatively faster
at initial stage, while slowed down at late stage, in comparison
with the control beads. The control beads however reached a higher
plateau of equilibrium swelling.