Chicken blood, a protein-rich by-product of slaughterhouses, is produced in large quantities, with 48 million liters annually in Canada. It offers significant potential as a sustainable alternative to synthetic preservatives linked to health concerns. Despite its abundance, the potential of chicken cruor, solid part of blood, for generating antimicrobial bioactive peptides remains underexplored. This study investigated the production of antimicrobial peptides through 24-hour enzymatic hydrolysis at optimal pH for pepsin activity (pH 3), followed by a discoloration step to facilitate application on white meat such as chicken. The degree of hydrolysis (DH), number of peptides, and peptide population were analysed as a function of hydrolysis duration (0, 0.5, 1, etc …24h). The antifungal and antibacterial activities of crude hydrolysates at pH 9 and discolored hydrolysates at two pH (4 and 9) were evaluated against three fungal strains (Paecilomyces spp., Rhodotorula mucilaginosa, and Mucor racemosus) and four problematic bacterial strains in the poultry industry (Salmonella enterica, Campylobacter coli, Listeria ivanovii, and Escherichia coli). Additionally, a regression-based machine learning approach, Partial Least Square Discriminant Analysis (PLS-DA), was used to identify peptides potentially responsible for the bioactivities. Results showed that DH increased progressively, reaching 23.4 ± 1.9 at end of hydrolysis, with no significant difference compared to DH at 12 hours, 20.4 ± 0.9 (p > 0.05). Similarly, the number of peptides increased over time, with no significant difference observed between crude and discolored hydrolysates (p > 0.05). Hydrolysates obtained after 30 minutes exhibited best antifungal and antibacterial activities against tested strains, with inhibition zones up to 19.10 mm diameter. Discolored hydrolysates at pH 9 showed activity against E. coli with 11.33 mm diameter, while crude hydrolysates over 6 hours exhibited anti-Listeria activity (11–12 mm). Furthermore, PLS-DA analysis enabled identification of 61 potential antimicrobial peptides and 2 known ones. 23 unknown new sequences were synthesized and are currently tested individually for antimicrobial activities. These findings highlight chicken cruor’s potential as a sustainable source of bio-preservatives, contributing to valorization of by-products within a circular economy framework by applying natural antimicrobial hydrolysates on chicken meat to increase shelf-life.

Zain Sanchez-Reinoso

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