In-depth characterization of the sarcoplasmic muscle proteome changes in lambs fed with hazelnut skin by-products: Relationships with meat color

This study investigated the effect of agro-industrial hazelnut skin by-products supplementation on lamb meat color variation and the changes in the sarcoplasmic muscle proteome during post-mortem storage (0, 4 and 7 days). Gel-based proteomics and bioinformatics approaches were applied to better understand the potential role of feeding strategies in modulating the mechanisms underpinning meat discoloration and post-mortem changes during storage. Therefore, twenty-two Valle del Belice male lambs were randomly assigned to two dietary treatments: control (C), lambs fed with maize-barley diet, and hazelnut skin (H), lambs fed hazelnut skin by-product as maize partial replacer in the concentrate diet. Hazelnut dietary treatment led to better lamb meat color stability as evidenced by the lowest decrease in redness and saturation index values. Proteomics and bioinformatics results revealed changes in the abundance of 41 proteoforms, which were mainly involved in glycolytic processes, responses to oxidative stress, and immune and endocrine system. The proteins allowed revealing interconnected pathways to be behind meat color variation as a consequence of using hazelnut skin by-products to sustainable feed lamb. The proteins can be used as potential predictors of lamb meat color variation. Accordingly, the regression equations developed in this paper revealed triosephosphate isomerase (TPI1) as a reliable candidate biomarker of color stability in lamb meat. SIGNIFICANCE: The use of agro-industrial by-products in animal feeding can be a potential sustainable strategy to reduce the environmental impacts of the food production chain and consequently improve animal welfare and product quality. The inclusion of hazelnut skin by-products in the animal's diet, due to the high concentration of polyphenols, represents an effective strategy to improve the oxidative stability of meat, with significant implications on color. The use of proteomics combined with bioinformatics on the sarcoplasmic proteome is a powerful approach to decipher the underlying mechanism. Accordingly, this approach allowed in this trial a deeper understanding of the molecular mechanisms involved in the post-mortem processes through the discovery of several biological pathways linked with lamb meat color variation. Glycolysis, followed by responses to oxidative stress, and other proteins involved in the immune and endocrine system were found as the major interconnected pathways that could act as potential predictors of lamb meat color stability. Candidate proteins biomarkers were further revealed in this study to be related with multiple meat color traits.

Identification of meat species in processed meat products by using protein based laser induced breakdown spectroscopy assay

The detection of meat fraud and mislabeling in processed meat products is a raising concern for consumers. The aim of this study was to develop and demonstrate the potential of protein-based laser induced breakdown spectroscopy (LIBS) method to be used for the identification of beef, chicken, and pork in fermented sausage and salami products. In this respect, bulk protein and protein fractions rich in sarcoplasmic and myofibrillar protein of sausage and salami products were obtained and subjected to LIBS analysis. LIBS spectrum was evaluated with chemometric methods to classify meat species and determine adulteration ratio by using principal component analysis and partial least square analysis, respectively. Limit of detection values for chicken and pork adulteration in beef sausage were found as 3.68 and 3.83% for myofibrillar fraction, while those values in beef salami were found as 3.80 and 3.47% for sarcoplasmic fraction, respectively.

Proteomic analysis to understand the relationship between the sarcoplasmic protein patterns and meat organoleptic characteristics in different horse muscles during aging

The study investigates the changes in meat organoleptic characteristics and sarcoplasmic proteins of 3 horse muscles during aging. Longissimus lumborum (LL), semimembranosus (SM) and semitendinosus (ST) muscles, were removed from 12 Italian Heavy Draft Horse carcasses and aged for 1, 3, 6, 9 and 14 days. The lowest values of hardness and chewiness were found in LL muscle. During aging, a decrease of hardness was observed in ST muscle reaching the lowest value at 14 days. 2DE revealed a decrease of 15 sarcoplasmic protein spots in all muscles. Muscle-differences were found at 14 days. An increase of tropomyosin spots was found in LL muscle while, ST was characterized by a rise of superoxide dismutase, phosphoglucomutase-1 and two isoforms of myoglobin. Principal component analysis applied to color, texture parameters and spots volume differentiated the muscles into three different clusters. Data revealed that myofibrillar, glycolytic and mitochondrial proteins are potential muscle-biomarkers to monitor post-mortem processes and meat quality characteristics in horse meat.

Estimating the structure of sarcoplasmic proteins extracted from pork tenderloin thawed by a high-voltage electrostatic field

The application of high-voltage electrostatic field (HVEF) is a novel method of thawing. To determine if HVEF thawing could lead to sarcoplasmic proteins denaturation, and to provide a theoretical estimation of the structure of the sarcoplasmic proteins, pork tenderloin was thawed by traditional and HVEF methods. The results from protein solubility analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimeter showed that HVEF thawing did not result in more protein denaturation than those thawed under air or running water. From the principal component analysis of FTIR raw spectra (1700-1600 cm^-1, Amide I region), we observed some separations of samples with different thawing treatments. It was found that the proportions of α-helix (1650-1640 cm^-1 spectral bands in the original data) could lead to the differences on the PC2 axis of score plots.

Fish sarcoplasmic proteins as a high value marine material for wound dressing applications

Fish sarcoplasmic proteins (FSP) constitute around 25-30% of the total fish muscle protein. As the FSP are water soluble, FSP were isolated from fresh cod (Gadus morhua) by centrifugation. By SDS-PAGE, it was possible to determine the composition of FSP extracts (FSP-E). The FSP-E undergo denaturation at 44.12 ± 2.34° C, as characterized by differential scanning calorimetry thermograms (DSC). The secondary structure of FSP-E is mainly composed by α-helix structure, as determined by circular dichroism. The cytocompatibility of FSP-E, at concentrations ranging from 5 to 20 mg/mL, was investigated. Concentrations lower than 10 mg/mL have no cytotoxicity cultures of fibroblasts over 72 h. Further on, FSP membranes (FSP-M) were produced by spin coating to evaluate its properties. FSP-M shown having uniform surface as analyzed by Scanning Electron Microscopy (SEM). The relative amount of α-helix structures is higher when compared with the FSP-E. The FSP-M have higher temperature stability than the FSP-E, since they presented a denaturation temperature of 58.88 ± 3.36° C, according to the DSC analysis. FSP-M shown distinctive mechanical properties, with a stiffness of 16.57 ± 3.95 MPa and a yield strength of 23.85 ± 5.97 MPa. Human lung fibroblasts cell lines (MRC-5) were cultured in direct contact with FSP-M, demonstrating its cytocompatibility for 48 h. Based on these results, FSP can be considered a potential biomaterial recovered from nature, for wound dressing applications.