Investigation of the effect of oxidation on keratin obtained from chicken feathers

Purpose: To investigate excipient properties of oxidized extracted keratin (OEK) compared to extracted keratin (EK) obtained from chicken feathers. Methods: Keratin from whole chicken (Gallus gallus domesticus) feathers was extracted under conditions of optimum yield. Oxidation was carried out with hydrogen peroxide (H2O2) for 15 mins, washed, filtered, dried and stored in airtight containers. Organoleptic properties, chemical tests, pH, true density, hydration capacity, swelling capacity, flow properties and chemical functionalities using UV/visible spectroscopy, Fourier transform-infrared spectroscopy (FT-IR) and High-performance liquid chromatography (HPLC) were investigated. Results: The yield of EK was 28 % while that of OEK was 89.2 % (obtained from EK). The EK was dark brown, fine and powdery with a characteristic odour. However, OEK was pale brown, smooth texture and odourless. Furthermore, OEK had significantly lower hydration capacity, and true density as well as significantly higher pH, swelling capacity, and improved flow compared to EK (p < 0.05). UV and FTIR spectra were superimposable. The wavelength of maximum absorption was 244.50 to 306.50 nm (EK) and 269 to 335.50 nm (OEK). The transmission band was attributed to CH3, C=O, N-H, C-H, C-S, and N-H stretching. Furthermore, HPLC analysis revealed varying amounts of amino acids and total amino acid content was higher in EK compared to OEK. Conclusion: Oxidation of EK from chicken feathers enhances appearance, and flow, and reduces protein content with a significant reduction in cysteine residues. Drug release modulation properties of OEK would need to be investigated in further studies.