Keratin extraction and production of keratoses/polyvinyl alcohol blend films

Abstract Keratins represent a group of fibrous proteins abundantly present in nature; in fact they constitute the major part of hair, wool, horns, nails, feathers and stratum corneum of the skin. They are characterised by a high sulphur amount and by the presence of strong disulphide bonds which make keratin water insoluble and resistant to different chemical agents. Keratin from wool fibers was extracted with different extraction methods, e.g. oxidation (using peracetic acid), reduction (using dithiothreitol), sulphytolysis (using sodium metabisulphite) and superheated water hydrolysis (170°C for 30 min using water). Different samples of extracted keratin were characterized by amino acids analysis, molecular weight determination, FT-IR spectroscopy. Extracted keratoses (KOx) were blended with polyvinyl alcohol (PVA) using water as common solvent and cast into films. The following mixing ratio were used: 0/100, 10/90, 30/70, 50/50, 70/30, 90/10, 100/0 w/w KOx/PVA. PVA is a well-known biodegradable polymer with a wide range of applications in the food and pharmaceutical industries [3]. Blended films were characterised by spectroscopic and tensile properties. It is to be noted that increasing the amount of keratoses in the blend up to 50% increases the tensile strength of the films and decreases the elongation at break, while blends containing 90% of keratoses become too brittle for films production.