Analysis of the amino acid and protein composition of feather keratin hydrolyzed using alkali and sodium hydrosulfite

Abstract

This study aimed to investigate the possibility of extracting protein from chicken feathers. We conducted our research in a controlled laboratory environment, where we carefully washed feathers collected from white broiler chickens. The feathers were ground and hydrolyzed using a 1:10 ratio of 0.2 eq/L of standard sodium hydroxide (NaOH) solution and 28.5 % sodium hydrosulfite (NaHSO3) solutions. The hydrolyzed solution was further processed in a 90 °C water bath for 6 h using a rotor stirrer. After this, the solution was neutralized with 99 % acetic acid (CH3COOH) and filtered. The filtrate was dialyzed with distilled water in a cellophane membrane bag for 24 h. Following dialysis, we obtained two samples of the dried and ground protein. The first sample was subjected to physicochemical analysis, while the second sample was treated with 5 % H2O2 before analysis. Our analysis, conducted using the Kjeldahl and liquid chromatography methods, revealed that 68–78 % of proteins were synthesized. The study of free amino acids found that the highest indicator, which belongs to 38–40 % of cysteine, asparagine, glutamine, and tryptophan in the protein, failed because of alkaline hydrolysis. However, samples 1 and 2 of the protein containing 17 free amino acids were comparable, further validating our findings.