Comparative characterisation analysis of composite films fabricated from agar and alginate extracted from Gelidiella acerosa and Sargassum tenerrimum combined with Arrowroot Starch

Abstract

Biopolymers such as Sodium Alginate (SA) and Agar (AG) were extracted from Sargassum tenerrimum spp and Gelidiella acerosa spp. respectively. Extracted agar yielded a molecular weight of 110 kDa, higher than that of extracted alginate, i.e 53 kDa. Further, Arrowroot Starch (AR) was incorporated into SA and AG to develop various compositions of SA/AR and AG/AR films. The compatibility of arrowroot starch with agar and alginate was assessed by measuring physico-mechanical, barrier, and thermal properties. XRD analysis revealed that the extracted agar exhibited a high degree of crystallinity (CI ? 55 %), which decreased to 35–45 % in AG/AR composites, reflecting an increased amorphous phase and the formation of a continuous polymer matrix. Incorporation of arrowroot starch (AR) into sodium alginate (SA) and agar (AG) further enhanced the thermal stability, tensile strength, and whiteness index of the resulting films. In terms of barrier properties, the SA/AR composite exhibited a lower WVP than the AG/AR composite relative to their respective control films. Additionally, the solubility index of SA/AR composites (? 65–75 %) demonstrated high aqueous solubility, underscoring their suitability for edible coatings and dissolvable packaging applications. Overall, this study highlights the potential compatibility of arrowroot starch with agar and alginate polysaccharides, demonstrating strong potential for innovation in sustainable packaging materials. © 2025 Elsevier Ltd