Valorization of Chicken Feather Waste: Role of Pre-treatment Prior to Alkaline Hydrolysis

Chicken feathers, an abundant poultry by-product rich in keratin, remain underutilised due to their recalcitrant structure. The combined effects of feather pre-treatment and room-temperature alkaline hydrolysis conditions on keratin extraction efficiency, degree of hydrolysis, and antioxidant activity were systematically studied. Two pre-treatment methods were compared: a typical method, involving feather grinding and defatting (T-method) and a simplified one based on detergent washing only (S-method). Feather solubilisation ranged from 27 to 72%, and protein recovery from 11 to 56%, depending on hydrolysis conditions. The T-method achieved higher feather solubilisation and protein recovery, particularly at higher feather mass to NaOH volume ratios (1:6 and 1:9), whereas the S-method yielded hydrolysates with comparable or higher antioxidant activity. Regardless of pre-treatment method and hydrolysis parameters, the degree of hydrolysis ranged from 6.5 to 22.3%, with peptide molecular weight after dialysis mainly within the 5–7 kDa range. Dialysis caused a 60–80% loss of low molecular weight peptides, responsible for strong antioxidant activity; however, medium-sized peptides partly compensated for this loss. Overall, simplified feather pre-treatment effectively reduced process complexity without compromising hydrolysate quality. When combined with room-temperature alkaline hydrolysis, this provides a more practical and potentially scalable alternative for keratin valorization, while also indicating the need to optimise the purification of keratin hydrolysates to retain bioactive peptide fractions.