RSM Optimization for the Recovery of Technofunctional Protein Extracts from Porcine Hearts

Beef protein ingredients from fat rendering process are promising functional ingredients

The valorization of co-products may be a promising way to meet the dual challenge of increasing global food resources and sustainability of food systems. In particular, meat co-products may be nutritionally interesting protein resources, if they offer functional properties in accordance with food applications. In that aim, two bovine co-products, resulting from the fat rendering process, have been characterized, regarding the protein solubility, gelling, and emulsifying properties. The effect of protein concentration, pH variation and NaCl addition on these properties was tested. Despite an effect of the ionic strength on the protein solubility of the two ingredients, a little or no significant impact was observed on the functionalities. Similarly, the functional properties were scarcely affected by pH. In the end, the protein concentration has proven to be the only important parameter, which points to an easy utilization of these ingredients in many food conditions.

Physicochemical and Techno-Functional Properties of Dried and Defatted Porcine Liver

Porcine liver has a high nutritional value and is rich in proteins, minerals, and vitamins, making it an interesting co-product to alleviate the growing global demand for protein. The objective of this study was to analyze how the drying and defatting processes of porcine liver affect the physicochemical and techno-functional properties of its proteins. Two drying temperatures (40 and 70 °C) were studied, and dried samples were defatted using organic solvents. The drying process turned out to be an effective method for the stabilization of the protein fraction; however, when the drying temperature was high (70 °C), greater protein degradation was found compared to drying at a moderate temperature (40 °C). Regarding the defatting stage, it contributed to an improvement in certain techno-functional properties of the liver proteins, such as the foaming capacity (the average of the dried and defatted samples was 397% higher than the dried samples), with the degree of foaming stability in the liver dried at 40 °C and defatted being the highest (13.76 min). Moreover, the emulsifying capacity of the different treatments was not found to vary significantly (p > 0.05). Therefore, the conditions of the drying and defatting processes conducted prior to the extraction of liver proteins must be properly adjusted to maximize the stability, quality, and techno-functional properties of the proteins.

Somatostatin and Its Receptors in Myocardial Ischemia/Reperfusion Injury and Cardioprotection

Little is known about the role of the neuropeptide somatostatin (SST) in myocardial ischemia/reperfusion injury and cardioprotection. Here, we investigated the direct cardiocytoprotective effect of SST on ischemia/reperfusion injury in cardiomyocyte cultures, as well as the expression of SST and its receptors in pig and human heart tissues. SST induced a bell-shaped, concentration-dependent cardiocytoprotection in both adult rat primary cardiomyocytes and H9C2 cells subjected to simulated ischemia/reperfusion injury. Furthermore, in a translational porcine closed-chest acute myocardial infarction model, ischemic preconditioning increased plasma SST-like immunoreactivity. Interestingly, SST expression was detectable at the protein, but not at the mRNA level in the pig left ventricles. SSTR1 and SSTR2, but not the other SST receptors, were detectable at the mRNA level by PCR and sequencing in the pig left ventricle. Moreover, remote ischemic conditioning upregulated SSTR1 mRNA. Similarly, SST expression was also detectable in healthy human interventricular septum samples at the protein level. Furthermore, SST-like immunoreactivity decreased in interventricular septum samples of patients with ischemic cardiomyopathy. SSTR1, SSTR2, and SSTR5 but not SST and the other SST receptors were detectable at the mRNA level by sequencing in healthy human left ventricles. In addition, in healthy human left ventricle samples, SSTR1 and SSTR2 mRNAs were expressed especially in vascular endothelial and some other cell types as detected by RNA Scope® in situ hybridization. This is the first demonstration that SST exerts a direct cardiocytoprotective effect against simulated ischemia/reperfusion injury. Moreover, SST is expressed in the heart tissue at the peptide level; however, it is likely to be of sensory neural origin since its mRNA is not detectable. SSTR1 and SSTR2 might be involved in the cardioprotective action of SST, but other mechanisms cannot be excluded.