Application of a Two-Level Full Factorial Design for the Synthesis of Composite Bioplastics from Durian Seed Flour and Yellow Konjac Flour Incorporating Ethanolic Extract of Syzygium myrtifolium Leaves and its Characterization

Increasing environmental problems related to synthetic plastics for food packaging encourage the creation of more environmentally friendly plastics from Indonesia’s local natural resources, such as durian seed, yellow konjac, and Syzygium myrtifolium leaves, which are abundant in nature. The purpose of the study was to evaluate the effect of the durian seed flour (DSF) mass, yellow konjac flour (YKF) mass, and the concentration of ethanolic extract of S. myrtifolium leaves (5-25%) on the tensile strength, elongation, and inhibition zone area of composite bioplastics. The two-level full factorial design was conducted for this experiment with 3 independent factors: DSF mass (0.5-1 g), YKF mass (0.5-1 g), and the concentration of ethanolic extract of S. myrtifolium leaves (5-25% b/v), and 3 responses were observed: tensile strength, elongation, and inhibition zone area. The physicomechanical characteristics were then used to further describe the best combination. The results showed that the DSF mass had only affected tensile strength, whereas the YKF mass had affected tensile strength and elongation of composite bioplastics. Meanwhile, the concentration of ethanolic extract of S. myrtifolium leaves only affects the inhibition zone area. The best combination was found in the DSF mass of 0.5 g, YKF mass of 1 g, and the concentration of ethanolic extract of S. myrtifolium leaves of 25%, with the tensile strength of 3.30 MPa, elongation of 50.00%, and inhibition zone area of 15.33 mm. Moreover, these combinations also had a thickness of 0.115 mm, modulus young of 0.066 MPa, density of 1.37 g.cm-3, moisture content of 17.14%, and water solubility of 76.91%.