<![CDATA[Phosphorylated sago starch-based edible films are promising environmentally friendly alternatives to conventional food packaging; however, their mechanical strength and water vapor barrier properties remain limited. This study aimed to optimize the formulation of phosphorylated sago starch-based edible films by varying the pectin-to- carboxymethyl cellulose (CMC) ratio. A completely randomized design with six formulations and three replications was employed: A1 (4 g starch), A2 (2 g starch + 2 g pectin), A3 (2 g starch + 2 g CMC), A4 (2 g starch + 1 g pectin + 1 g CMC), A5 (2 g starch + 0.5 g pectin + 1.5 g CMC), and A6 (2 g starch + 1.5 g pectin + 0.5 g CMC). Film thickness, tensile strength, elongation at break, water solubility, and water vapor transmission rate (WVTR) were evaluated and analyzed using one-way analysis of variance, followed by Tukey’s test (α = 0.05). The result shows that variations in the pectin-to-CMC ratio had no significant effect on film thickness, water solubility, or elongation at break but significantly affected tensile strength and WVTR. The optimum formulation (A5) exhibited the highest tensile strength (33.702 MPa) while maintaining a relatively low WVTR (1.632 g H₂O/m²·h), with a thickness of 0.116 mm, water solubility of 0.091%, and elongation at break of 3.060%. The superior performance of A5 was attributed to synergistic interactions among phosphorylated sago starch, pectin, and CMC, which promoted a denser three-dimensional polymer network through intermolecular hydrogen bonding, thereby enhancing matrix cohesion and reducing water vapor diffusion. These findings demonstrate the potential of the optimized composite film as a biodegradable packaging material for dry foods and other products requiring moderate moisture control.]]>
