Melanin Extraction from Human Hair by Ultrasound-Assisted Alkaline Hydrolysis
Till date, the extraction of melanin in pure form from human hair has been a challenge due to several side
reactions that occur in this process. Various methods have been put forth for solubilization of keratin, one such method is
hydrolysis using strong acids; the drawbacks of using these acids are difficulty in handling, complete solubilization of the
hair fiber and structural damage of melanin. Enzymatic hydrolysis has also been performed using proteolytic enzymes such
as proteases and keratinases from different sources but has not been successful due to the strong resistant nature of keratin,
weak penetration and its slow degradation. In this study, a method for isolating melanin from human hair using ultrasoundassisted
alkaline hydrolysis has been attempted. It involves two steps to enhance the digestion of hair with minimum damage
to the biological structure of melanin; 1) soaking human hair in strong alkali under shaking conditions and 2) ultra-sonication
of the soaked hair solution. Effect of alkali concentration, incubation temperature, pH and time of exposure to sonication is
determined. The extracted melanin was purified acid hydrolysis and characterized using UV-Spectroscopy, Fourier
Transform Infrared Spectroscopy, TGA, X-Ray Diffraction, solid-state13C-CPMAS spectra and SEM. The presence of
residual protein or amino acid was studied using ninhydrin and folin-lowery method. Thus the attempt is made to
demonstrate the isolation of melanin in its purest form and also indicate the potential use of the ultrasound-assisted alkaline
hydrolysis in degradation of human hair waste.
Keywords- Melanin, Hair degradation, Ultrasonication, Alkaline hydrolysis.