Proteome profile of glycrol-mediated salt-reduction cured meat reveals the formation mechanism of eating quality

Dietary protein restriction regulates skeletal muscle fiber metabolic characteristics associated with the FGF21-ERK1/2 pathway

Under conditions of dietary amino acid balance, decreasing the dietary crude protein (CP) level in pigs has a beneficial effect on meat quality. To further elucidate the mechanism, we explored the alteration of muscle fiber characteristics and key regulators related to myogenesis in the skeletal muscle of pigs fed a protein restricted diet. Compared to pigs fed a normal protein diet, dietary protein restriction significantly increased the slow-twitch muscle fiber proportion in skeletal muscle, succinic dehydrogenase (SDH) activity, the concentrations of ascorbate, biotin, palmitoleic acid, and the ratio of s-adenosylhomocysteine (SAM) to s-adenosylhomocysteine (SAH), but the fast-twitch muscle fiber proportion, lactate dehydrogenase (LDH) activity, the concentrations of ATP, glucose-6-phosphate, SAM, and SAH in skeletal muscle, and the ratio of serum triiodothyronine (T3) to tetraiodothyronine (T4) were decreased. In conclusion, we demonstrated that dietary protein restriction induced skeletal muscle fiber remodeling association the regulation of FGF21-ERK1/2-mTORC1 signaling in weaned piglets.

Characterization of the Effects of Low-Sodium Salt Substitution on Sensory Quality, Protein Oxidation, and Hydrolysis of Air-Dried Chicken Meat and Its Molecular Mechanisms Based on Tandem Mass Tagging-Labeled Quantitative Proteomics

The effects of low-sodium salt mixture substitution on the sensory quality, protein oxidation, and hydrolysis of air-dried chicken and its molecular mechanisms were investigated based on tandem mass tagging (TMT) quantitative proteomics. The composite salt formulated with 1.6% KCl, 0.8% MgCl2, and 5.6% NaCl was found to improve the freshness and texture quality scores. Low-sodium salt mixture substitution significantly decreased the carbonyl content (1.52 nmol/mg), surface hydrophobicity (102.58 μg), and dimeric tyrosine content (2.69 A.U.), and significantly increased the sulfhydryl content (74.46 nmol/mg) and tryptophan fluorescence intensity, suggesting that protein oxidation was inhibited. Furthermore, low-sodium salt mixture substitution significantly increased the protein hydrolysis index (0.067), and cathepsin B and L activities (102.13 U/g and 349.25 U/g), suggesting that protein hydrolysis was facilitated. The correlation results showed that changes in the degree of protein hydrolysis and protein oxidation were closely related to sensory quality. TMT quantitative proteomics indicated that the degradation of myosin and titin as well as changes in the activities of the enzymes, CNDP2, DPP7, ABHD12B, FADH2A, and AASS, were responsible for the changes in the taste quality. In addition, CNDP2, ALDH1A1, and NMNAT1 are key enzymes that reduce protein oxidation. Overall, KCl and MgCl2 composite salt substitution is an effective method for producing low-sodium air-dried chicken.

Characterizations and molecular docking mechanism of the interactions between peptide FDGDF (Phe-Asp-Gly-Asp-Phe) and SOD enzyme

In this study, we investigated the antioxidant properties of dry-cured beef crude peptide (BPH) at different storage periods. The combination characteristics of different concentrations of Phe-Asp-Gly-Asp-Phe (FDGDF) and superoxide dismutase (SOD) at different temperatures were analyzed by ultraviolet-visible spectroscopy, fluorescence spectroscopy, and FT-IR spectroscopy, combined with the detection of a SOD activity detection box. It was found that FDGDF could improve the activity of SOD by changing its secondary structure. Bonds were formed at O32/O40/O52 using quantum chemical simulation calculations, and the Fukui index was higher than that of most atoms, indicating that these atoms were more likely to participate in the reaction. SPR biological force analysis showed that FDGDF and SOD were in a fast binding and dissociation mode. This study revealed the theoretical basis for studying the antioxidant mechanism of dry-cured beef and provided ideas for developing new dry-cured beef products.

Structural and functional changes on polyhydroxy alcohol-mediated curing pork myofibrillar protein: Experimental and molecular simulation investigations

This study aimed to investigate the structural and functional changes in polyhydroxy alcohol-mediated curing on pork myofibrillar proteins (MP). The results obtained from total sulfhydryl groups, surface hydrophobicity, fluorescence and Raman spectroscopies, and solubility demonstrated that the polyhydroxy alcohols (especially xylitol) significantly modified the MP tertiary structure, making this structure more hydrophobic and tighter. However, no significant differences were detected in the secondary structure. Furthermore, the thermodynamic analysis revealed that polyhydroxy alcohols could develop an amphiphilic interfacial layer on the MP surface, significantly increasing the denaturation temperature and enthalpy of denaturation (P < 0.05). On the other hand, the molecular docking and dynamics simulations showed that polyhydroxy alcohols interact with actin mainly through hydrogen bonds and van der Waals forces. Therefore, this could help reduce the effect of high-content salt ions on MP denaturation and improve the cured meat quality.

Perspective of sodium reduction based on endogenous proteases via the strategy of sodium replacement in conjunction with mediated-curing

NaCl is the main curing agent in dry-cured meat products, and a large amount of NaCl addition leads to high salt content of final products. Salt content and composition are important factors affecting the activity of endogenous proteases, which in turn could affect proteolysis as well as the quality of dry-cured meat products. With the increasing emphasis on the relationship between diet and health, reducing sodium content without sacrificing quality and safety of products is a great challenge for dry-cured meat industry. In this review, the change of endogenous proteases activity during processing, the potential relationship between sodium reduction strategy, endogenous proteases activity, and quality were summarized and discussed. The results showed that sodium replacement strategy and mediated-curing had a complementary advantage in influencing endogenous proteases activity. In addition, mediated-curing had the potential to salvage the negative effects of sodium substitution by affecting endogenous proteases. Based on the results, a sodium reduction strategy that sodium replacement in conjunction with mediated-curing based on endogenous proteases was proposed for the future perspective.

Effects of Microwave Pasteurization on the Quality and Shelf-Life of Low-Sodium and Intermediate-Moisture Pacific Saury (Cololabis saira)

The objective of this study was to investigate the effects of microwave pasteurization on the quality and shelf-life of low-sodium and intermediate-moisture Pacific saury. Microwave pasteurization was used to process low-sodium (1.07% ± 0.06%) and intermediate-moisture saury (moisture content 30% ± 2%, water activity 0.810 ± 0.010) to produce high-quality ready-to-eat food stored at room temperature. Retort pasteurization with the same thermal processing level of F₉₀ = 10 min was used for comparison. Results showed that microwave pasteurization had significantly (p < 0.001) shorter processing times (9.23 ± 0.19 min) compared with traditional retort pasteurization (17.43 ± 0.32 min). The cook value (C) and thiobarbituric acid (TBARS) content of microwave-pasteurized saury were significantly lower than that of retort-pasteurized saury (p < 0.05). With more microbial inactivation, microwave pasteurization brought better overall texture than retort processing. After 7 days of storage at 37 °C, the total plate count (TPC) and TBARS of microwave pasteurized saury still met the edible standard, while the TPC of retort pasteurized saury no longer did. These results showed that the combined processing of microwave pasteurization and mild drying (Aw < 0.85) could produce high-quality ready-to-eat saury products. These results indicate a new methodology for producing high-quality products stored at room temperature.

Effect of Ultrasound Combined with Glycerol-Mediated Low-Sodium Curing on the Quality and Protein Structure of Pork Tenderloin

Considering the hazards of high salt intake and the current status of research on low-sodium meat products, this study was to analyze the effect of ultrasound combined with glycerol-mediated low-sodium salt curing on the quality of pork tenderloin by analyzing the salt content, water activity (aw), cooking loss, and texture. The results of scanning electron microscope (SEM) analysis, Raman spectroscopy, ultraviolet fluorescence, and surface hydrophobicity were proposed to reveal the mechanism of the effect of combined ultrasound and glycerol-mediated low sodium salt curing on the quality characteristics of pork tenderloin. The results showed that the co-mediated curing could reduce salt content, aw, and cooking loss (p < 0.05), improve texture and enhance product quality. Compared with the control group, the co-mediated curing increased the solubility of the myofibrillar protein, improved the surface hydrophobicity of the protein, increased the content of reactive sulfhydryl groups (p < 0.05), and changed the protein structure. The SEM results showed that the products treated using a co-mediated curing process had a more detailed and uniform pore distribution. These findings provide new insights into the quality of ultrasonic-treated and glycerol-mediated low-salt cured meat products.

Mechanism of polyhydroxy alcohol-mediated curing on moisture migration of minced pork tenderloin: On the basis of molecular docking

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Polyhydroxy alcohols affect salt diffusion and moisture migration.

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Polyhydroxy alcohols cause the water to migrate out to reduce aw in meat.

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Polyhydroxy alcohols retard salt diffusion into the meat by forming a viscose barrier.

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Polyhydroxy alcohols can prevent meat structural damage by binding to myosin.

This study investigated the mechanism of glycerol, xylitol, and sorbitol-mediated curing of cured minced pork tenderloin. The use of polyhydroxy alcohol during mediated curing significantly reduced the salt content (p < 0.01) and water activity (aw) of the cured pork tenderloin. Low-field nuclear magnetic resonance (LFNMR) revealed that 1 % glycerol, 1 % xylitol, 1 % sorbitol, and 10 % glycerol-mediated curing decreased water mobility, and improved water holding capacity (WHC), and produced uniform dense microstructures. Raman spectroscopy and molecular docking indicated that polyhydroxy alcohols formed hydrogen bonds with myosin, as well as hydrogen bonds with free water molecules to convert free water into bound water to reduce aw, and altered the hydrophobic environment of myosin surface to reduce structural damage caused by high salt content. In conclusion, using polyhydroxy alcohol to mediate curing can effectively reduce the salt content of cured meat and provide a theoretical basis for its application in the cured meat industry.