The effect of alkali treatment on the rheological and ionic gelation characteristics of different species of Iranian gum tragacanth
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1Department of Chemical and Polymer Engineering, Yazd University, Yazd, Iran
2Department of Chemical and Polymer Engineering, Faculty of Engineering, Yazd University, Yazd, Iran
In this study, the effect of alkaline treatment on the rheological properties and ionic gelation behavior of gum tragacanth (GT), exudates from three species of Astragalus, including Astragalus gossypinus, Astragalus rahensis and Astragalus fluccosus, and the characteristics of prepared hydrogels have been investigated. Ionically crosslinked beads were prepared by dropping of polymer solution into solutions of Fe3+ ions (FeCl3). Afterwards, morphology and swelling behavior of the beads were evaluated. Fe3+ ions successfully crosslinked alkali treated GT (AGT) by formation of stable hydrogel beads but the beads prepared with raw gums lost their shape and integrity during preparation steps. All beads showed lower swelling degree and higher stability at pH 7.4 compared to pH 1.5. Fe-AGT beads remained stable in pH 7.4 for at least days. The beads prepared with alkali treated gum exudate from A. rahensis have lowest swelling degree and highest stability in both media. According to the results, prepared AGT beads could be considered as a promising candidate for cell/bacteria encapsulation or sustained drug release in neutral/basic media.