MICROBIAL VALORIZATION OF POULTRY FEATHER WASTE INTO KERATIN-BASED BIODEGRADABLE FILMS FOR POTENTIAL ACTIVE FOOD-PACKAGING APPLICATIONS

Poultry feather waste generated by the poultry processing industry is an abundant keratin-rich by-product whose disposal presents significant environmental challenges. Valorization of this waste into biodegradable films with functional properties offers a sustainable approach to waste management while supporting circular bioeconomy and the development of environmentally friendly food-packaging materials. This study investigated the microbial conversion of poultry feather waste into keratin-based biodegradable films and evaluated their physicochemical, antioxidant, and biodegradation properties.

Feather-degrading bacteria were isolated from poultry waste and screened for keratinolytic activity using keratin azure medium. The most active isolate was selected for feather degradation in feather broth, after which the resulting keratin hydrolysate was processed into biodegradable films using the solvent-casting method. Keratin degradation and film functional groups were characterized by Fourier Transform Infrared (FTIR) spectroscopy. Mechanical properties, water solubility, water absorption capacity, antioxidant activity (DPPH radical scavenging assay), and biodegradability were evaluated to determine the suitability of the films for sustainable food-packaging applications.

The most efficient keratinolytic isolate was identified as Pseudomonas aeruginosa, achieving 90.3% feather degradation within 7 days and reducing feather mass from 2.00 g to 0.19 g, demonstrating its strong keratinolytic potential. Keratin azure decolorization showed a 78% reduction in absorbance at 595 nm, while soluble protein concentration increased from 0.42 to 3.85 mg/mL, confirming extensive keratin hydrolysis. FTIR spectra revealed characteristic amide I (1652 cm⁻¹) and amide II (1543 cm⁻¹) bands, verifying the formation of peptide-rich keratin hydrolysates suitable for film production. The resulting keratin-based films exhibited a tensile strength of 8.6 MPa and an elongation at break of 21.4%, indicating satisfactory mechanical performance. The films also showed low water solubility (10%) and a water absorption capacity of 25%, suggesting adequate structural stability while retaining moisture interaction desirable for biodegradable packaging materials. Furthermore, the films demonstrated strong antioxidant activity, with a DPPH radical scavenging capacity of 85.23 ± 1.15%, equivalent to 0.502 ± 0.014 mg/mL gallic acid, indicating their potential to retard oxidative deterioration in active food-packaging systems. The films also underwent 63% biodegradation after 21 days under soil burial conditions, demonstrating their environmental compatibility and potential to reduce persistent plastic waste.

These findings demonstrate an effective strategy for converting poultry feather waste into biodegradable keratin-based films through microbial bioconversion. The combination of favorable mechanical properties, antioxidant activity, controlled water solubility, and biodegradability highlights the potential of the films as sustainable materials for active food-packaging applications while promoting waste valorization and circular bioeconomy within the food production chain.