High Added-Value Co-Product: the Porcine Cruor is an Attractive Source of Active Peptides

Abstract

The porcine cruor represents a co-product from slaughterhouses. It mainly contains hemoglobin which is rich in bioactive peptides obtained by hydrolysis by porcine pepsin. The aim of this study is to valorize this new source rich of bioactive peptides to be used as feed additives. An in silico study on the potential of porcine cruor to contain bioactive peptides was studied by comparing it with peptides derived from bovine hemoglobin. The blast results showed a high similarity between porcine cruor hydrolysate peptides and bovine hemoglobin hydrolysates for both α and β chains with identities of 87% and 83% respectively. Cleavage sites of porcine cruor were also predicted using Peptide Cutter software and compared with bovine hemoglobin. Results reveal the preservation of most of peptides of porcine cruor hydrolysates comparing to bovine hemoglobin hydrolysates. The presence of bioactive peptides was then determined by mass spectrometry analysis. Results showed the presence of 37 bioactive peptides defined by their sequences found in previous study with mainly antibacterial and opioid peptides. The antibacterial activity was then verified by in vitro analysis against 4 bacterial strains. Results showed interesting MIC values comparing with tested synthetic peptides (4.53 µM for M.luteus and L.innocua, 35.94 µM for E.coli and 312 µM for S.newport). The antioxidant activity was also verified by studying DPPH•+ trapping and results showed an antiradical activity for porcine cruor hydrolysate greater than neokyotorphin which was previously validated as a natural preservative to substitute synthetic additives against food alteration (14% and 10% respectively). These similarities of porcine cruor hydrolysate in peptic profiles as well as biological activities make it a new interesting source of bioactive peptides.

Effect of pH on the Antimicrobial Activity and Peptide Population of Pepsin Hydrolysates Derived from Bovine and Porcine Hemoglobins

“…40,41 In addition to this, the reduction of the pH fosters the enzyme accessibility to cleavage sites as a consequence of the hemoglobin denaturation (pH < 3.5). 24,42 On the contrary, the DH for porcine hemoglobin was not significantly different between pH 3 and 4 at 30, 60, 120, and 180 min (Figure 1b). The final values of the DH for pH 3 (8.4 ± 0.2%) and pH 4 (8.8 ± 0.2%) were not statistically different.…”

“…The porcine hemoglobin sequence has 89% of similarity to Hb-B, and 10 different cleavage sites have been predicted when hydrolysis with pepsin is performed at pH > 2.0. 24 On the contary, the peak areas in UV chromatograms were different between pH values. As the pH was lower, the peptides fractions presented a higher area and vice versa, which can be explained by a higher release of peptides appearance when the pH was close to the pepsin optimal pH (pH 2.0).…”

“…41,43 Hemoglobin is denatured at pH 3.5 (even in the absence of urea), fostering a zipper mechanism that generates a rapid conversion of hemoglobin into intermediate peptides as it could happen to pH 2 and pH 3. 24,42 Conversely, the one-by-one mechanism is characterized by hydrolyzing hemoglobin mainly in small size peptides since a pepsin molecule can hydrolysate only one hemoglobin molecule at a time. 20,41,43 Apart from this, the remaining peak of β subunit in porcine hemoglobin at pH 4 can be due to sequence differences between Hb-B and Hb-P.…”

“…Bovine hydrolysates showed the presence of nine peptides previously reported in the literature with a strong antimicrobial activity: α(1−23), α(34−46), α(37−46), α(84−98), 47 α(99− 105), α(99−106), α(137−141), β(126−145), and β(140− 145). 24 Peptide α(1−23) has been the object of multiple studies. Froidevaux et al 25 evaluated the antimicrobial activity and reported a MIC of 1.5 mg•mL −1 for Micrococcus luteus.…”

“…16 On the contrary, some differences were observed in the peptides produced from porcine hemoglobin due to differences in amino acid sequence with Hb-B (Figure 5). It can be observed that the peptides α(99−105) and α(99−106) can be only formed in the Hb-B, 24 ) present some differences in the sequences that antimicrobial peptides derived from Hb-B, but a great similarity can be observed when they are compared by the basic local alignment search tool (BLAST). A total of 20 potential antimicrobial peptides with a high identification percentage were both hydrolysates from Hb-B and Hb-P (Table 3).…”