Slaughterhouse blood is considered a valuable by-product of the meat industry that is mainly derived from the slaughter of cattle and pigs. Its cruor fraction is mainly constituted of hemoglobin, which has been widely described as an important source of several antimicrobial peptides that can be released by hydrolysis with pepsin. Despite the high sequence similarity between bovine (Hb-B) and porcine (Hb-P) hemoglobins, the release of antimicrobial peptides may be affected by varying hydrolysis conditions. This study presents, for the first time, the impact of pH (pH 2, 3, 4, and 5) on the antimicrobial peptide population of hydrolysates derived from the main hemoglobin sources by using pepsin (bovine and porcine). In the same way, their antibacterial, antifungal, and antiyeast activities are compared, as well as their type of mechanism of action (static or cidal effect). These characteristics have not been described previously in the literature. A total of 29 peptides from Hb-B and 35 peptides for Hb-P with potential antimicrobial peptides were identified by reversed-phase ultrahigh-performance liquid chromatography with tandem mass spectrometry (RP-UPLC–MS/MS) and bioinformatics tools. Similarities in the peptide population between Hb-B and Hb-P hydrolysates were observed by PCA, mainly in the enzymatic hydrolysis at pH 2 and pH 3. Both bovine and porcine hydrolysates produced at pH 2 and pH 3 showed antibacterial activity against L. ivanovii (MIC = 0.62–1.25 mg·mL–1) and antiyeast activity against R. mucilaginosa (0.31–1.25 mg·mL–1). Conversely, only antifungal activity against M. racemosus in the porcine hydrolysate at pH 3 was observed (1.25 mg·mL–1). This study confirms the similarities of Hb-B and Hb-P in terms of peptide profiles and antimicrobial activity, which indicates they are suitable sources of antimicrobial peptides with antibacterial, antifungal, and antiyeast activities that could be employed in the preservation of food products.

Wastewater and by-product treatments are substantial issues with consequences for our society, both in terms of environmental impacts and economic losses. With an overall global objective of sustainable development, it is essential to offer eco-efficient and circular solutions. Indeed, one of the major solutions to limit the use of new raw materials and the production of wastes is the transition toward a circular economy. Industries must find ways to close their production loops. Electrodialysis (ED) processes such as conventional ED, selective ED, ED with bipolar membranes, and ED with filtration membranes are processes that have demonstrated, in the past decades and recently, their potential and eco-efficiency. This review presents the most recent valorization opportunities among different industrial sectors (water, food, mining, chemistry, etc.) to manage waste or by-product resources through electrodialysis processes and to improve global industrial sustainability by moving toward circular processes. The limitations of existing studies are raised, especially concerning eco-efficiency. Indeed, electrodialysis processes can be optimized to decrease energy consumption and costs, and to increase efficiency; however, eco-efficiency scores should be determined to compare electrodialysis with conventional processes and support their advantages. The review shows the high potential of the different types of electrodialysis processes to treat wastewaters and liquid by-products in order to add value or to generate new raw materials. It also highlights the strong interest in using eco-efficient processes within a circular economy. The ideal scenario for sustainable development would be to make a transition toward an eco-circular economy.

Porcine blood is an important by-product from slaughterhouses and an abundant source of proteins. Indeed, cruor, the solid part of blood, is mainly composed of hemoglobin. Its enzymatic hydrolysis with pepsin generates a diversity of peptides, particularly antimicrobials. One of the downsides of using these hydrolysates as food bio-preservatives is the color brought by the heme, which can be removed by discoloration. Nonetheless, the effects of this procedure on the antimicrobial peptide population have not been completely investigated. In this study, its impacts were evaluated on the final antibacterial and antifungal activities of a cruor hydrolysate. The results demonstrated that 38 identified and characterized peptides showed a partial or total decrease in the hydrolysate, after discoloration. Antifungal activities were observed for the raw and discolored hydrolysates: MICs vary between 0.1 and 30.0 mg/mL of proteins, and significant differences were detected between both hydrolysates for the strains S. boulardii, C. guilliermondii, K. marxianus, M. racemosus and P. chrysogenum. The raw hydrolysate showed up to 12 times higher antifungal activities. Hence, peptides with the highest relative abundance decrease after discoloration were synthesized and tested individually. In total, eight new antifungal peptides were characterized as active and promising. To our knowledge, this is the first time that effective antifungal peptide sequences have been reported from porcine cruor hydrolysates.

No abstract