Biotransformation of free-range chicken feather into functional protein hydrolysates using microwave alkaline pretreatment

Chicken feathers has great potential to produce functional peptides. However, due to the highly rigid structure of keratin, the biotransformation of feathers is hindered. In this study, we aimed to evaluate the influence of microwave-alkaline pretreatment (MAP) on enzymatic hydrolysis of free-range chicken feathers using two distinct enzymes in functional and technological terms. Four protein hydrolysates were prepared from the feathers treated in microwaves using the enzyme Flavourzyme® (PHFW) and Alcalase® (PHAW) and from untreated feathers using Flavourzyme® (PHF) and Alcalase® (PHA). A two-way ANOVA revealed a significant interaction effect between MAP and enzyme type on the antioxidant activity of the hydrolysates. The DPPH and ABTS radical scavenging capacities were higher in PHFW. Our findings suggest that the MAP enhances the action of the enzyme in hydrolytic cleavage, with Flavourzyme® demonstrating a superior ability to produce hydrolysates with high antioxidant capacity. For emulsifying capacity and emulsifier stability, only MAP had a significant effect, with higher values observed in hydrolysates obtained from treated feathers regardless of enzyme type. It can be concluded that the hydrolysates obtained from MAP feathers underwent conformational modification of proteins, promoting better enzyme action during hydrolysis, resulting in higher antioxidant activity and technological properties.