An Optimal Designed Experiment for the Alkaline Hydrolysis of Feather Keratin
Abstract Feathers, burdensome waste from the poultry industry, can be a cheap source of keratin, a protein with excellent physicochemical, biological and mechanical properties. The high yield of the keratin isolation is ensured by alkaline hydrolysis. This study aimed at assessing the statistically significant effect of input variables in the alkaline hydrolysis of keratin from chicken feathers on the process yield and on the molecular weight of peptides obtained. The volume ratio of 1M NaOH to the feathers mass, the hydrolysis time and the shaking speed of the reaction mixture were analyzed. The use of statistical analysis at the design step of experiment allowed to reduce of the trials number from 27 to 9. Among the input variables analyzed, only the volume ratio of 1M NaOH to the feathers mass had a significant effect on the process yield, while none of them significantly affected the molecular weight of the peptides obtained. All hydrolysates were dominated by two peptides fractions, with molecular weights of ca. 130 and 250 kDa, and mixture of many peptides of weight close to 10 kDa and smaller. Alkaline hydrolysis of feather keratin yielded protein hydrolysates soluble over a wide pH range.