Extraction of Keratin from Waste Chicken Feathers Using Sodium Sulfide and L-cysteine

Keratin was extracted from different segments of disposable waste chicken feathers (CF) including the whole feathers, calamus/rachis (β-sheet) and barbs/barbules (α-helix), using sodium sulfide and L-cysteine. The yield of extracted keratin from sodium sulfide and L-cysteine was ˜88 % and ˜66 % respectively. The mass ratio of feathers to reducing agent was 1:20 and the reaction temperature was 40 °C for 6 h. Concentration of keratin extracted by each chemical was measured using the Bradford assay. The protein extracted from each feather section was characterised using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, vibrational spectroscopy including FTIR and Raman, nuclear magnetic resonance, and thermogravimetry. These results confirmed the keratine structures in each extraction methods. The study showed that α-helix and ß-sheet based keratin could be extracted from CF using sodium sulfide and L-cysteine with good yeields. This is the first report of CF keratin extraction using L-cysteine.