Fabrication of pH‐Sensitive Bacterial Cellulose Films by Acetic Acid Fermentation of Anthocyanin‐Rich Roselle ( Hibiscus sabdariffa L.) Extracts for Real‐Time Monitoring of Chicken Meat Spoilage

This study developed pH-sensitive bacterial cellulose (BC) films incorporated with anthocyanins from roselle (Hibiscus sabdariffa L.) extract as a sustainable and facile approach for real-time monitoring of chicken meat freshness. The films were fabricated through a one-step fermentation process using Komagataeibacter saccharivorans in anthocyanin-rich roselle extract (ARRE) at two concentrations: undiluted (ACN_1) and two-fold diluted (ACN_2), enabling simultaneous cellulose biosynthesis and pigment incorporation without additional processing steps. SEM analysis revealed that both films retained the characteristic three-dimensional nanofibrous network of BC, with bacterial cells embedded on the surface due to the absence of alkaline purification to preserve pH-sensitive pigments. FTIR and XRD analyses confirmed the preservation of cellulose chemical structure and crystalline form after anthocyanin incorporation. TGA-DSC analysis demonstrated enhanced thermal stability in anthocyanin-containing films due to the antioxidant properties of phenolic compounds. When applied as freshness indicators for chicken meat stored at 4°C, both ACN_1 and ACN_2 films exhibited distinct color transitions from red to dark purple-blue, corresponding to the progressive increase in total volatile basic nitrogen and total plate count resulting from microbial protein degradation. Notably, ACN_2 demonstrated comparable indicator effectiveness to ACN_1 despite containing half the anthocyanin concentration, suggesting that lower pigment levels are sufficient for reliable freshness detection. This finding enhances the economic feasibility and sustainability of the developed indicator films by reducing raw material requirements while maintaining functional performance, demonstrating their promising potential as cost-effective intelligent active packaging materials for the meat industry. PRACTICAL APPLICATIONS: The anthocyanin-incorporated bacterial cellulose films developed in this study can be used as color-changing freshness labels for meat packaging. These labels naturally change from red to bluish-purple when meat begins to spoil, allowing consumers to visually assess product freshness without opening the package. This simple, eco-friendly indicator could help reduce food waste and improve food safety in the meat industry.