Antioxidant activity and in vitro protein digestibility of chicken feather protein hydrolysates

Abstract Objective The hydrolysis of chicken feather waste was carried out using sodium hydroxide and the hydrolysed feather solution precipitated using different acids (nitric acid, sulfuric acid, hydrochloric acid and trichloroacetic acid). Hydrolysates of the different acids were evaluated for antioxidant activity via 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, ferric reducing power and metal chelating activities. In addition, the in vitro protein digestibility of the respective acid hydrolysates was carried out. Results: Data obtained showed that nitric acid-precipitated hydrolysate had the highest DPPH scavenging activity while the hydrolysate precipitated with trichloroacetic acid exhibited the highest ferric (Fe3+) reduction potential. On the other hand, trichloroacetic acid-, sulfuric acid- and nitric acid-precipitated hydrolysates showed similar metal chelating potential compared to hydrochloric acid-precipitated hydrolysate with the least chelating potential. The in vitro protein digestibility of the different hydrolysates ranged from 62.30 ± 1.0% (nitric acid) to 73.10 ± 1.3% (trichloroacetic acid) and were significantly (p < 0.05) higher compared to 23.80 ± 0.5% (raw feather). These results indicate that alkaline-hydrolysed chicken feather hydrolysate may be useful as supplementary protein and antioxidants in animal feed formulations.