Preparation and Characterization of Bioactive and Sustainable PHB Colored Film Incorporating Ginkgo biloba Autumn Leaves Extract

The bioplastic polyhydroxybutyrate (PHB) has great potential for sustainable food packaging applications, but its application is still limited by several factors, including brittleness, narrow functionality, and dependence on synthetic colorants. This study aimed to investigate the natural source of autumn leaves of Ginkgo biloba as a natural yellow pigment for the production of PHB films with antimicrobial activity. For pigment extraction, the leaves were ground at a ratio of 1:10 (w/v) with distilled water, 50% ethanol, 70% ethanol, and chloroform. UV–Vis analysis of 1.25 g/L extracts showed absorbance maxima at 314 nm (dH₂O, Abs 2.432), 315 nm (70% EtOH, Abs 3.895), and 319 nm (50% EtOH, Abs 3.878), confirming efficient pigment solubilization. Two gram-positive bacterial strains (RCF1 and RCS) were isolated from red capsicum rot. The antimicrobial activity, indicated by the inhibition zone of 9 ± 0.25 mm (RCF1), 3.3 ± 0.12 mm (RCS), and 1 ± 0.06 mm (control), showed strong antibacterial activity, especially against RCF1. Ethanol-derived dye concentration of 1–2 mg/mL and chloroform-derived dye concentration of 2.6–6.66 mg/mL (40–100 mg dye in 15 mL chloroform) were used to prepare the PHB–dye composite films. The chloroform extracts gave uniformly colored films with complete dissolution of the dye, whereas the ethanol-based films had undissolved particles with high crystallinity. These findings indicate the promising applications of G. biloba pigments for coloring and the antimicrobial properties of PHB films. Mechanical tests, biodegradation studies, and identification of 16S rRNA, as well as valorization of the leaf biomass from the post-extraction stage for producing PHB are still needed.