Unique shape, surface and porosity of dried electrified alginate gels

Alginate gels after electrification and freeze-drying produced moieties (cellular solids) exhibiting major increases in surface area and porosity. Gel size and gum concentration were not limiting factors. The spherical spaces created by the freezing, drying or electrification were round and paralleled the circumference of the gel, forming circles within the circle. The phenomenon was dependent on shape and did not occur on the outer surfaces of alginate beads. In contrast, cut beads, even if only a thin layer had been removed, changed character with the observed space formation. Before drying, a steeper pH gradient (∼2 near the anode and ∼12 near the cathode) was observed in the alginate gels. Agarose gels yielded similar pH values as the alginate gels if they included CaCl₂ added by diffusion, but no spaces were produced on their outer surface. Alginate gels that contained no extra ions (having previously diffused out) did not produce surface pores after electrification. pH was another factor involved in the formation of the new structures. Low methoxy pectin (LMP) gels resemble alginate in their cross-linking mechanism, and produced similar shapes upon electrification. If gels (alginate or LMP) were manufactured in a cubic shape, the created spaces were parallel to the rectangular base and ran along the prism's axis. Combinations of increased pH, gel composition, electrification and freezing caused these changes in structure and porosity, which could potentially be beneficial in many uses that involve the release of ingredients into different types of mediums.