Effects of Inorganic Salts and Phytate on Gelling Properties of the Seaweed Amikusa (Ceramium boydenii)

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Igisu-ryôri was prepared with the seaweed Amikusa (Ceramium boydenii). Amikusa was boiled and dissolved in the rice bran water extracts, and the sol was coagulated by cooling. Major inorganic ions contained in the rice bran water extracts were K⁺, Mg²⁺, Ca²⁺, and PO₄^3-. The effects of metallic cations on the gelling properties of Amikusa were examined by dissolving Amikusa in a solution of KCl, MaCl₂ or CaCl₂ containing 0.06% acetic acid during the boiling process. The increases in the concentration of KCl correlated with the increased Amikusa gel strength, but MaCl₂ and CaCl₂ had no significant effect. Amikusa was readily dissolved by NaH₂PO₄ or Na-phytate solution, which are compounds of phosphoric acid, but a gel did not form unless KCl was added to it. These results indicated that during the process of boiling the seaweed in the rice bran water extracts, the phosphoric acid radical of phytic acid affected the solubility of the seaweed, and the sol changed to a gel by cooling in the presence of K⁺.