Valorization of porcine blood, coproduct of slaughterhouses, through the production of antifungal peptides
A. Cournoyera,b*, L. Ben Saida,b, J. Thibodeaua,b, Z. Sanchez Reinosoa,b, S. Mikhaylina,b, I. Flissa,b, L. Bazineta,b
a Département de sciences des aliments et Laboratoire de transformation alimentaire et procédés électromembranaires, Université Laval, Quebec, G1V 0A6, Canada
b Institut sur la Nutrition et les Aliments Fonctionnels (INAF), Université Laval, Quebec, G1V 0A6, Canada
Pork processing plants in Québec currently collect approximately 21 million liters of blood annually. The corresponding Canadian volume is approximately 68 million liters1. Porcine blood can be easily separated into plasma and cruor, the latter containing blood cells, and therefore, a high concentration of hemoglobin. Cruor hydrolysis by pepsin yields a wide variety of peptides, some of which are biologically active. Studies on the antibacterial activities of hydrolyzed hemoglobin peptides have mostly been conducted on bovine hemoglobin, whereas porcine hemoglobin has attracted very little attention. A peptide called Neokyotorphin (NKT), also found in the porcine sequence, possesses strong antibacterial and antioxidant activities2. The goal of the present study was to hydrolyze porcine cruor under conditions that favor NKT production and to characterize the overall peptide population obtained. Moreover, since coloration by heme can limit the potential uses of the hydrolysate in situ, decolorizing techniques were applied, and their effects on hydrolysate composition and antibacterial and antifungal activities were compared. The degree of hydrolysis of the hydrolysates was measured, and the peptide population was determined using UPLCMS/MS. Antimicrobial activities were evaluated using agar diffusion tests and Minimal Inhibitory Concentrations (MICs) determination. Important differences were found between the obtained peptide profiles. Heme precipitation resulted in a decrease in the concentration or the disappearance of at least 38 peptides. Antifungal activity against some yeast and mold strains decreased by up to 10-fold post hydrolysates decolorization. No antibacterial activity was detected, despite the presence of active peptide sequences. This study shows that hydrolysis duration and the decolorization step have considerable impacts on the population of obtained peptides. This is also the first demonstration of the antifungal activity of this type of hydrolysate. New peptide sequences were identified and synthesized to confirm and quantify these activities. These hydrolysates will be processed to obtain two enriched fractions: one with antifungal properties and one antibacterial fraction rich in NKT. Our overall aim is to produce new active ingredients from porcine blood that can be utilized for meat preservation within a circular economy framework.
1. Agriculture et Agroalimentaire Canada, 2021. URL: agriculture.canada.ca/fr/secteurs-agricoles-du-canada/production-animale/information-marche-viandes-rouges/porc
2. Przybylski, R., Firdaous, L., Châtaigné, G., Dhulster, P. and Nedjar, N. (2016). Production of an antimicrobial peptide derived from slaughterhouse by-product and its potential application on meat as preservative. Food Chemistry, 211, 306‑313. doi.org/10.1016/j.foodchem.2016.05.074