Characterisation of keratin biomass from butchery and wool industry wastes

The chemical and structural characteristics of wool and horn–hoof were compared with the aim of better addressing possible exploitation of protein biomasses available as waste from textile industry and butchery. Amino acid analysis showed that wool has a higher amount of cystine and a lower amount of the amino acids that favour α-helix formation than horn–hoof. The difference in the α-helix content is confirmed by FTIR spectroscopy. Electrophoresis separation patterns showed two characteristic protein fractions related to low-sulphur proteins (between 60,000 and 45,000 Da) in wool, while different low-sulphur proteins are present in horn–hoof. These data are partially confirmed by DSC analyses that showed different endothermic peaks at temperatures higher than 200 °C in the horn–hoof thermograms, probably due to denaturation of α-keratins at different molecular weights. Moreover, wool keratin was more hygroscopic and showed a higher extractability with reducing agents than horn–hoof. On the basis of these results, waste wool is a more suitable source than horn–hoof for uses involving protein extraction, but application can be envisaged also in surfactant foams for fire extinguishers and slow-release nitrogen fertilizer.