How Discoloration of Porcine Cruor Hydrolysate Allowed the Identification of New Antifungal Peptides.

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.

Impact of Pulsed Electric Fields and pH on Enzyme Inactivation and Bioactivities of Peptic Hydrolysates Produced from Bovine and Porcine Hemoglobin.

The production of bioactive peptides from hemoglobin via peptic hydrolysis is a promising alternative to valorizing slaughterhouse blood proteins. Nevertheless, it has some limitations such as low yield, high cost of enzymes, and the use of chemical reagents. The latter is aggravated by the pH increase to inactivate the enzyme, which can affect the bioactivity of the peptides. Thus, this study aimed to evaluate the effect of pulsed electric fields (PEF) on the pepsin inactivation and biological activities (antimicrobial and antioxidant) of hemoglobin hydrolysates. Bovine (Hb-B) and porcine (Hb-P) hemoglobin were hydrolyzed with pepsin for 3 h and treated with PEFs to inactivate the enzyme. The degree of hydrolysis (DH) did not show significant changes after PEF inactivation, whereas peptide population analysis showed some changes in PEF-treated hydrolysates over time, suggesting residual pepsin activity. PEF treatments showed no significant positive or negative impact on antimicrobial and antioxidant activities. Additionally, the impact of pH (3, 7, and 10) on bioactivity was studied. Higher pH fostered stronger anti-yeast activity and DPPH-scavenging capacity, whereas pH 7 fostered antifungal activity. Thus, the use of hemoglobin from the meat industry combined with PEF treatments could fit the circular economy concept since bioactive peptides can be produced more eco-efficiently and recycled to reduce the spoilage of meat products. Nevertheless, further studies on PEF conditions must be carried out to achieve complete inactivation of pepsin and the potential enhancement of peptides' bioactivity.

Physicochemical properties of oils extracted from γ-irradiated Sacha Inchi (Plukenetia volubilis L.) seeds.

This study evaluated the physicochemical properties of oils extracted from γ-irradiated Sacha Inchi (Plukenetia volubilis L.) seeds (SIS) at four different doses (0, 1, 5 and 8kGy). Fatty acid composition, tocopherol content, FTIR spectra, density, refractive index, acidity, peroxide value (PV), p-anisidine index (p-An), oxidation induction period (IP), and color were chosen as test parameters. Overall, the irradiation treatment did not significantly affect the physicochemical properties of the Sacha Inchi oils, although slight increases were found in the PV and p-An, as the irradiation dose increased. γ-Irradiation led to a decrease in the concentration of γ- and δ-tocopherol, as well as in the IP. However, according to the FTIR analyses, the functional groups of the oils were not significantly affected by the γ-irradiation. These results suggest that γ-irradiation at 1-5kGy, might be recommended as a suitable eco-friendly technology for the preservation of SIS used for oil production.