Feather Meal as a Source of Peptides with Antioxidant Activity from Enzymatic Hydrolysis

Feather is the most abundant keratinous material in nature. This by-product of animal origin has about 80–90% of crude protein. This work aimed to maximize the enzymatic hydrolysis of feather meal using the proteolytic enzyme from Bacillus sp. P45 and evaluate the antioxidant capacity of different fractions of the hydrolysate. Enzymatic hydrolysis was maximized using a central composite rotatable design (CCRD) 2 4 , where the effects of the variables CaCl 2 concentration (0–100 mmol/L), temperature (35–55 °C), enzyme/substrate ratio (600–6000 U/g-protein), and substrate protein concentration (10–40 g/L) were estimated on the responses degree of hydrolysis (DH) and protein recovery (PR). The highest values of DH and PR were obtained when the hydrolysis was performed with 50 mmol/L of CaCl 2 , 50 °C, 6000 U/g-protein, and substrate protein concentration of 10 g/L. Hydrolysate presented DH of 8.4% and PR of 37.5% at 6 h of reaction. The obtained peptides were separated by molecular weight through a sequential ultrafiltration process in the membranes of 10 and 3 kDa, and the antioxidant activities of the different fractions were analyzed. The fraction