Poultry Cruor Hydrolysate is a New Potential Source of Hemoglobin: Obtaining of Active Peptides

The hydrolysates of animal proteins from Agri-Resources have been the subject of numerous studies for their potential which makes it possible to produce molecules with high added value thanks to their richness in bioactive peptides obtained after enzymatic hydrolysis. The poultry cruor represents an important co-product from slaughterhouses. The aim of this study is to characterize this new source of peptides to be valorized as feed additives. In this work, the conditions of peptides production were fist studied, and revealed that hydrolysis using pepsin as enzyme and discoloration are both optimal at pH 3, and that the optimal initial substrate concentration is at 9% (w/v). The potential of poultry cruor to contain bioactive peptides was then studied in silico by comparing poultry with bovine hemoglobin derived peptides using bioinformatic tools. The blast results showed the presence of high similarities between poultry hemoglobin and bovine hemoglobin sequences with identities of 71.13% and 64.34% for α and β chains respectively. Prediction of cleavage sites of poultry hemoglobin was also carried out using Peptidecutter software and compared to bovine hemoglobin peptides. The results revealed the presence of similar peptides of poultry cruor hydrolysates comparing to bovine hemoglobin hydrolysates with generation of many new peptides. Mass spectrometry analysis was carried out to investigate the presence of bioactive peptides in poultry cruor hydrolysate based on those identified in previous studies. Results revealed the presence of 28 bioactive peptides with mainly opioid and antibacterial peptides. The antibacterial activity against 6 different strains was then assayed. Results revealed bacterial growth inhibition with interesting MIC values (10 mg/mL against M. luteus E. coli and S. aureus, 1.25 mg/mL against K. rhizophilia and 20 mg/mL against S. entirica and L. innocua ). The antioxidant activity was also evaluated using different tests. The β-carotene bleaching inhibition activity revealed a relative antioxidant activity (RAA) of 79.23 ± 1.4%. The DPPH •+ trapping assay an antiradical activity of poultry cruor hydrolysate of 829.35 ± 21.12 µmol/mL and 708.85 ± 0.66 µmol/mL at 40 mg/mL and 20 mg/mL of hydrolysate, respectively which is greater than BHT at 0.1 mg/mL and neokyotorphin at 1 mg/mL. The ABTS radical scavenging method revealed inhibition percentages are higher than 90% for hydrolysate concentration above 10 mg/mL which are higher than those obtained with BHT at 0.5 mg/mL. Finally, the Total antioxidant capacity (TAC) assay showed that the studied hydrolysate have a TAC comprised between that of BHT at 0.3 mg/mL and 0.1 mg/mL. Consequently, these important biological activities found in poultry cruor hydrolysate make it a new interesting alternative natural additive in food industry. Graphical Abstract