Optimization of keratin protein extraction from waste chicken feathers using hybrid pre-treatment techniques

Abstract

This study modeled and optimized the operational conditions for the extraction of keratin from waste chicken feathers via alkaline hydrolysis method. Response Surface methodology using Box-Behnken design was used to investigate the effect of time, temperature and the concentration of both sodium hydroxide and sodium bisulphite as an extraction solvent on the keratin hydrolysate and protein yield. The coefficients of determination (R2) of 0.77 and 0.74 were obtained for keratin hydrolysate and protein yield models, respectively demonstrating the fitness of the models to navigate the optimization space. The optimum parameters were temperature (87 °C), time (111 min), sodium hydroxide (1.78%) and sodium bisulphite (0.5%). The yields of keratin hydrolysate and protein after validation were 68.3% and 65.2% respectively. Protein analysis via the CHNS analyser showed the elemental composition of 13.85% N, 47.25% C, 6.90% H and 2.8% S. The molecular weight of the extracted keratin ranged between 10-15 kDa and 3–10 kDa. Ultimate analysis by FTIR and NMR confirmed the presence of amide, carboxylic groups and alkyl side chains of amino acids. The results of this study proved that chicken feathers, typically disposed of by the poultry slaughterhouses, would be able to serve as a great sustainable source of keratin protein for the manufacture of value-added products like bio-adhesives.