Impact of hydrolysis duration and discoloration on peptide profiles and antimicrobial properties in chicken cruor hydrolysates: Identification of five novel antifungal peptides

Chicken cruor (Ch-cru), a protein-rich slaughterhouse by-product, has potential as a sustainable source of antimicrobials. This study investigated the impact of peptic hydrolysis duration (up to 24 h at pH 3) and a subsequent chemical discoloration step on the degree of hydrolysis, peptide profiles, and antimicrobial activities of hydrolysates adjusted to pH 4.0 or 9.0. Hydrolysates obtained after 0.5 h showed notable antifungal activity (9.31-19.10 mm). Crude hydrolysates at pH 9 after 6-24 h inhibited Listeria ivanovii, whereas discoloration induced a bioactivity shift toward Gram-negative bacteria, with discolored hydrolysates at pH 9 after 0.5 h active against Escherichia coli. PLS-DA linked antimicrobial activity to peptide populations, identifying 23 candidate peptides, five showing antifungal activity after synthesis. One peptide exhibited the highest activity (MIC 0.0098 ± 0.00 mM). Overall, hydrolysis duration and discoloration strongly influenced antimicrobial properties, supporting Ch-cru valorization as a natural bio-preservative within a circular economy approach.