Enhancing poultry byproduct valorisation through efficient and sustainable extraction of collagen and keratin

Collagen extraction using acetic acid and pepsin enabled recovery of >90% of collagenous proteins without structural damage and showed no dependence on farming system. Feathers were found to comprise >90% keratin by dry mass. Two extraction methods—sulphitolysis and alkaline treatment—were optimised, yielding 54–65% keratin.

Extracted keratins were processed into films, with mechanical and barrier properties influenced by extraction and formulation parameters. Optimised films showed excellent flexibility (74–114% elongation at break), UV blocking (≤0.4%), and oxygen barrier performance (as low as 13 × 10⁻⁶ cc×mm/m²×day×Pa), though tensile strength and moisture resistance remained lower than conventional polymers. Life Cycle Analysis highlighted chemicals and thermal processes as the main contributors to environmental impacts and costs, underscoring the need for improved chemical recovery and energy efficiency.

Overall, this work demonstrates that chicken feet, wingtips, and feathers can serve as sustainable sources of collagen, gelatine, and keratin, offering poultry producers opportunities for higher-value utilisation of waste streams.<br><br><i>Thesis is embargoed until 31 December 2030.</i><br>