Sarcoplasmic Proteins Research Articles

The sarcoplasmic protein profile of breast muscle in Turkeys in response to different dietary ratios of limiting amino acids and Clostridium perfringens-induced inflammation

In this study, the effects of the Arginine/Lysine (Arg/Lys) ratio in low- and high-methionine (Met) diets on the sarcoplasmic protein profile of breast muscles from turkeys reared under optimal or challenge (Clostridium perfringens infection) conditions were determined. One-day-old Hybrid Converter female turkey poults (216 in total) obtained from a commercial hatchery on hatching day, and on the basis of their average initial body weight were randomly allocated to 12 pens (4 m2 each; 2.0 m × 2.0 m) containing litter bedding and were reared over a 42-day experimental period. Diets with high levels of Lys contained approximately 1.80% and 1.65% Lys and were offered in two successive feeding periods (days 1–28 and days 29–42). The supplemental levels of Lys were consistent with the nutritional specifications for birds at their respective ages as established in the Management Guidelines for Raising Commercial Turkeys. The experiment was based on a completely randomized 3 × 2 × 2 factorial design with three levels of Arg (90%, 100% and 110%) relative to the content of dietary Met (30 or 45%) and without (−) or with (+) C. perfringens challenge at 34, 36, or 37 d of age. Meat samples were investigated in terms of pH, color, and sarcoplasmic protein profile. The experimental factors did not influence meat quality but the dietary Arg content affected meat color. The sarcoplasmic protein profile was influenced by all studied factors, and glycolytic enzymes were the most abundant. This study evidenced strong association between the challenge conditions and the involvement of glycolytic enzymes in cell metabolism, particularly in inflammatory processes, and DNA replication and maintenance in turkeys. The results showed an effect of C. perfringens infection and feeding with different doses of Arg and Met may lead to significant consequences in cell metabolism.

Protein phosphorylation profile of Atlantic cod (Gadus morhua) in response to pre-slaughter pumping stress and postmortem time

This study aimed to evaluate the effect of pumping stress (pumping and pumping-resting) and postmortem time (before and after rigor mortis) on phosphorylation profiles of myofibrillar protein (MP) and sarcoplasmic protein (SP) of Atlantic cod (Gadus morhua) fillets. The result showed that MP had higher global phosphorylation levels than SP regardless of stress condition and postmortem time. The pumping process resulted in significant changes in phosphorylation of structural proteins including myosin heavy and light chains. Pumping also affected the phosphorylation status of heat shock proteins and metabolic enzymes involved in the glycolytic pathways, indicating the possible role of phosphorylation in regulating energy hemostasis of fish under stressful conditions. The pumping-induced phosphorylation changes mainly occurred before rigor mortis, and postmortem time affected the phosphorylation status to a less extent. This work contributes to a deeper understanding on protein phosphorylation affected by pre-slaughter stress and postmortem time of fish.

Shrimp pmo-miR-750 regulates the expression of sarcoplasmic calcium-binding protein facilitating virus infection in Penaeus monodon

MicroRNAs (miRNAs) regulate gene expression post-transcriptionally and play crucial roles in antiviral responses. Penaeus monodon miR-750 (pmo-miR-750) was found to be strongly up-regulated in the late phase of white spot syndrome virus (WSSV) infection, but its function remains uncharacterized. Herein, the targets that were translationally down-regulated in the shrimp stomach following a pmo-miR-750 mimic injection were identified using two-dimensional gel electrophoresis. Sarcoplasmic calcium-binding protein (Scp) and actin1 (Act1) were revealed to be down-regulated protein spots. The genuine binding of pmo-miR-750 mimic to Scp but not Act1 mRNA was validated in vitro. In addition, a negative correlation between the Scp transcript and pmo-miR-750 expression level in WSSV-infected P. monodon stomach implies that pmo-miR-750 regulates Scp expression in vivo. When injected into WSSV-infected shrimp, the pmo-miR-750 mimic suppressed Scp expression but significantly increased the WSSV copy number. Consistent with the miRNA mimic-mediated Scp suppression, the loss of function assay of Scp in WSSV-challenged shrimp by RNA interference revealed a decreased survival rate with a dramatic increase in viral copy number. Besides that, apoptosis was activated in the hemocytes of the Scp knockdown shrimp upon WSSV infection. Collectively, our findings reveal that up-regulated pmo-miR-750 suppresses Scp expression at both the transcript and protein levels in the late stage of WSSV infection, which contributes to modulating apoptosis and eventually enabling viral propagation.

In-Vitro Study on the Antibacterial and Antioxidant Activity of Four Commercial Essential Oils and In-Situ Evaluation of Their Effect on Quality Deterioration of Pacific White Shrimp (Litopenaeus vannamei) during Cold Storage.

The antioxidant and antibacterial properties of four essential oils (oregano essential oil (OEO), tea tree essential oil (TTEO), wild orange essential oil (WOEO), and clove leaf essential oil (CLEO)) were determined. The in-vitro experiment indicated that CLEO had the highest total phenolic content and DPPH scavenging activity, and OEO displayed the highest antibacterial effect, so they were applied to maintain the quality of shrimp for further study. In-situ study, the total viable counts of shrimp were inhibited from 9.05 log CFU/g to 8.18 and 8.34 log CFU/g by 2% of OEO and CLEO treated alone on 10 d. The melanosis ratio was also retarded from 38.16% to 28.98% and 26.35% by the two essential oils. The inhibitory effects of OEO and CLEO on the increase of PPO activity, weight loss, and TCA-soluble peptides, and the decreasing tendency of whiteness, the contents of myofibrillar and sarcoplasmic proteins were also founded. The samples treated with 1% OEO + 1% CLEO had better quality than those treated alone. Therefore, the combination of OEO and CLEO had a synergistic effect, which displayed the highest efficiency to prevent the melanosis, bacterial growth, and protein hydrolysis of shrimp.

Muscle Protein Oxidation and Functionality: A Global View of a Once-Neglected Phenomenon

Muscle is a highly organized apparatus with a hierarchic microstructure that offers the protection of cellular components against reactive oxygen species (ROS). However, fresh meat immediately postmortem and meat undergoing processing become susceptible to oxidation due to physical disruption and the influx of molecular oxygen. Upon the activation by endogenous prooxidants, oxygen species are rapidly produced, and both myofibrillar and sarcoplasmic proteins become their primary targets. Direct ROS attack of amino acid sidechains and peptide backbone leads to protein conformational changes, conversion to carbonyl and thiol derivatives, and subsequent aggregation and polymerization. Interestingly, mild radical and nonradical oxidation enables orderly protein physicochemical changes, which explains why gels formed by ROS-modified myofibrillar protein have improved rheological properties and binding potential in comminuted meat and meat emulsions. The incorporation of phenolic and other multifunctional compounds promotes gel network formation, fat emulsification, and water immobilization; however, extensive protein modification induced by high levels of ROS impairs protein functionality. Once neglected but now recognized to be a natural occurrence, protein oxidation has drawn much interest and is being intensively studied within the international community of meat science. This review describes the history and evolution of muscle protein oxidation, the mechanism and functionality impact hereof, and innovative oxidant/antioxidant strategies to control and manipulate oxidation in the context of meat processing, storage, and quality. It is hoped that the review will stimulate in-depth discussion of scientific as well as industrial relevance and importance of protein oxidation and inspire robust international collaboration in addressing this underappreciated challenge.

Effects of High-Voltage Atmospheric Cold Plasma Treatment on Microbiological and Quality Characters of Tilapia Fillets.

Cold plasma (CP) has become an alternative to conventional thermal processing of food products. In this study, the effect of cold plasma treatment time on the inactivation and quality of tilapia fillets was investigated. The surfaces of tilapia fillets were inoculated with Salmonella enteritis (S. enteritis), Listeria monocytogenes (L. monocytogenes), and a mixture of both before being treated with cold plasma at 70 kV for 0, 60, 120, 180, 240, and 300 s. With the extension of treatment time, the number of colonies on the surface of the fillets decreased gradually; after 300 s of cold plasma treatment, S. enteritis and L. monocytogenes populations were reduced by 2.34 log CFU/g and 1.69 log CFU/g, respectively, and the a* value and immobile water content decreased significantly (p < 0.05), while the free water content increased significantly (p < 0.05). TBARS value increased significantly (p < 0.05) to 1.83 mg MDA/kg for 300 s treatment. The carbonyl value and sulfhydryl value of sarcoplasmic protein significantly (p < 0.05) increased and decreased, respectively, as treatment time extension, while no significant changes were found in myofibrillar protein. No significant differences were observed in pH, b* value, elasticity, chewiness, thiol value, and TVB-N value. The results showed that cold plasma had an inactivation effect on tilapia fillets and could preserve their original safety indicators. It was concluded that CP treatment could be used as an effective non-thermal method to maintain the quality of tilapia fillets and extend their shelf-life.

Update on dermatomyositis.

This review summarizes and comments on current knowledge in dermatomyositis. The 2018 European Neuromuscular Centre classification of dermatomyositis has been challenging by the discovery of clinicopathological features associated with dermatomyositis-specific antibody (DMSA) that were not incorporated in the original criteria. These features include but may not be limited to the presence of perifascicular necrosis in anti-Mi-2 dermatomyositis; presence of diffuse nonperifascicular sarcoplasmic myxovirus resistance protein A expression in anti-MDA5 dermatomyositis; and dermatomyositis sine dermatitis in anti-NXP-2 dermatomyositis. Variations and subclassifications within the same DMSA subtypes are observed: anti-MDA5 dermatomyositis is clinically subcategorized into good, intermediate, and poor prognostic subgroups; concurrent anti-CCAR1 and anti-TIF1-γ positivity identify anti-TIF1-γ-positive patient with a lower risk for cancer-associated myositis. Owing to distinct IFN1-signaling pathway activation in dermatomyositis, JAK-STAT inhibitor - the pathway-targeted therapy, have been studied with promising results in refractory dermatomyositis and some new-onset dermatomyositis. In addition, the potential serum biomarkers for IFN1 pathway activation are being investigated for their performance in monitoring the disease activity and the efficacy of the treatment. DMSA, evidence of prominent IFN1 pathway activation, and risk/severity-associated biomarkers would likely play major roles in future dermatomyositis classification, disease monitoring, and treatment decision.

Poor maternal diet during gestation alters offspring muscle proteome in sheep.

Poor maternal nutrition during gestation can result in reduced offspring muscle growth and altered muscle metabolism. We hypothesized that over- or restricted-nutrition during gestation would alter the longissimus dorsi muscle (LM) proteome of offspring. Pregnant ewes were fed 60% (restricted), 100% (control), or 140% (over) of National Research Council requirements for total digestible nutrients from day 30 of gestation until parturition. Fetal (RES, CON, OVER) LM were collected at days 90 and 135 of gestation, or from offspring within 24 h of birth. Sarcoplasmic proteins were isolated, trypsin digested, and subjected to multiplexed, label-based quantitative mass spectrometry analysis integrating tandem mass tag technology. Differential expression of proteins was identified by ANOVA followed by Tukey's HSD post hoc tests, and regularized regression via the elastic net. Significance was set at P < 0.05. Over-represented pathways containing differentially expressed proteins were identified by Reactome and included metabolism of proteins, immune system, cellular response to stress/external stimuli, developmental biology, and infectious disease. As a result of maternal diet, a total of 312 proteins were differentially expressed (day 90 = 89 proteins; day 135 = 115 proteins; birth = 131 proteins). Expression of eukaryotic initiation factor (EIF) 2S3, EIF3L, and EIF4G2 was lower in OVER fetuses at day 90 of gestation (P < 0.05). Calcineurin A and mitogen-activated protein kinase 1 were greater in RES fetuses at day 90 (P < 0.04). At day 135 of gestation, pyruvate kinase and lactate dehydrogenase A expression were greater in OVER fetuses than CON (P < 0.04). Thioredoxin expression was greater in RES fetuses relative to CON at day 135 (P = 0.05). At birth, proteins of the COP9 signalosome complex were greater in RES offspring relative to OVER (P < 0.05). Together, these data indicate that protein degradation and synthesis, metabolism, and oxidative stress are altered in a time and diet-specific manner, which may contribute to the phenotypic and metabolic changes observed during fetal development and postnatal growth.

Evaluation of protein degradation and flavor compounds during the processing of Xuan'en ham.

Protein degradation occurs during the processing of dry-cured ham, which has important influences on the flavor and quality of products. The aim of this work was to study the degradation kinetics of myofibrillar proteins (MPs) and sarcoplasmic proteins (SPs) extracted from the biceps femoris muscle during the processing of Xuan'en ham. A relationship between protein degradation and the flavor formation was found. During the processing of Xuan'en ham, MPs and SPs were mainly degraded in the salting stage and incipient fermentation. Accompanied by protein degradation, the content of carbonyl group in SPs increased gradually, but in MPs, it first increased and then decreased. Interconversion between sulfhydryl and disulfide bonds was investigated during this processing. Oxidation, degradation, and thermal effects significantly affected the surface hydrophobicity of proteins. More than one hundred volatile compounds have been identified at each stage of ham preparation. Among them, organic acids were the predominant group, followed by hydrocarbons, aldehydes, alcohols, ketones, and esters.

Dietary guanidinoacetic acid supplementation improves water holding capacity and lowers free amino acid concentration of fresh meat in finishing pigs fed with various dietary protein levels.

The current study was carried out to detect the effect of dietary guanidinoacetic acid (GAA) supplementation on carcass characteristics and meat quality in finishing pigs fed different dietary crude protein (CP) levels. Sixty-four barrows with an initial body weight of 73.05 ± 2.34 kg were randomly allocated into 1 of 4 dietary treatments in a 2 (100% vs. 125% NRC CP level) × 2 (0 vs. 300 mg/kg GAA) factorial arrangement (n = 7). The feeding trial lasted for 49 d. GAA supplementation significantly reduced drip loss (P = 0.01), free water distribution (T23 peak area ratio) (P = 0.05) and the concentrations of free alanine, threonine, methionine and isoleucine (P < 0.05); but increased total glycine content (P = 0.03) in the longissimus dorsi muscle of finishing pigs regardless of the dietary CP levels. Furthermore, primary myogenic cell differentiation system was employed to investigate the influence of inclusion of GAA on free amino acid concentrations in myotubes (n = 4) and validate the finding in the animal feeding trial. We found that GAA inclusion in culture medium also decreased intracellular concentrations of free alanine, threonine, methionine, isoleucine, valine and proline in differentiated primary myogenic cells in vitro (P < 0.05). Meanwhile, relative to diets with 100% NRC CP level, the intake of diets with 125% NRC CP level improved sarcoplasmic protein solubility, increased the contents of carnosine and total free amino acids as well as flavor amino acids in the longissimus dorsi muscle and decreased backfat thickness at the 6–7th ribs in pigs (P < 0.05). In addition, we observed that the impact of dietary GAA supplementation on the last rib fat thickness, shear force, and free lysine content in the longissimus dorsi muscle was dependent on dietary CP levels (P < 0.05). Collectively, dietary GAA supplementation can reduce drip loss, decrease the concentrations of free amino acids and flavor amino acids of fresh meat independent of dietary CP levels.

Thermophysical Properties of Beef Steaks Varying in USDA Quality Grade and Internal Temperature

The objectives of this study were to determine the influence of quality grade and internal temperature on the thermophysical properties of beef strip steaks. Beef strip loins (n=24) were collected from USDA Prime (PR), Low Choice(LC), and Standard (ST) carcasses. Strip loins were fabricated into 2.54 cm steaks at 21 d postmortem and randomly assigned to an internal temperature (4°C, 25°C, 55°C, 60°C, 71°C, 77°C). Steaks were subjected to various thermal and physical property measurements. No quality grade × internal temperature interaction was observed for diffusivity and conductivity (P &amp;gt; 0.05). Steaks tempered to 25°C had the greatest conductivity compared with all other internal temperature treatments (P = 0.021). A quality grade×internal temperature interaction was observed for center myosin and sarcoplasmic protein enthalpy values (P &amp;lt; 0.001). Raw (4°C and 25°C) ST steaks had lower enthalpy values compared with raw PR and LC steaks (P &amp;lt; 0.05). Raw steaks had greater surface myosin and both center and surface actin enthalpy values (P &amp;lt; 0.05). A quality grade × internal temperature was observed for surface and center viscoelasticity (P &amp;lt; 0.05). Raw steaks possessed less elastic behavior compared with cooked steaks, regardless of quality grade (P&amp;lt;0.05). Quality grade and internal temperature impacted expressible moisture and water holding capacity (P ≤ 0.001). ST steaks possessed increased expressible moisture and water holding capacity compared with LC and PR steaks (P&amp;lt;0.05). A quality grade×internal temperature was observed for Warner-Bratzler shear force and springiness (P ≤ 0.008). Internal temperature impacted all texture profile analysis attributes (P &amp;lt; 0.05). PR steaks were more cohesive than ST steaks (P = 0.011). These data show that final internal temperature and USDA quality grade impact thermophysical properties of beef steaks.

The potential of goat meat as a nutrition source for schoolchildren

The issue of rational nutrition of children is still extremely relevant and an effective factor in ensuring the preservation of the life and health of children. Pathological conditions associated with intolerance to certain components of food are increasingly common. Biologically complete products play an important role in the organization of rational nutrition of children, which can be created only in industrial production conditions. When assessing the chemical composition of experimental goat meat samples (Zaanenskaya, Alpine, Nubian), no abnormal deviations were detected, and all indicators were in the generally accepted contents of this type of animal muscle tissue. The mineral composition showed that goat meat is rich in such elements as potassium – 1693.22 – 4125.83 mg/kg; sodium – 852.27 – 1518 mg/kg, magnesium – 125.33 – 295.8 mg/kg; calcium – 79.27 – 160.79 mg/kg, iron 11.42-87.52 mg/kg. The vitamin composition of goat meat showed that the content of pantothenic acid (B5) was 0.53 – 0.62 mg / 100g, pyridoxine (B6) 0.52 – 0.64 mg/100g tocopherol 0.27 – 0.33 mg/100g. The mass fraction of goat meat proteins was 2.1 ±0.3 – 2.4 ±0.4%. The study of the dynamics of changes in the composition of protein fractions based on the results of comparative studies of the ratio of sarcoplasmic proteins showed the content of water-soluble (1.75 – 4.06%), salt-soluble (1.75 – 2.44%), alkali-soluble (11.15 – 15.10%) proteins. The salt-soluble fraction reflects the total changes in the state of protein fractions, the solubility of which was not the same for the rocks under consideration (the highest concentration was determined in the Nubian rock).

Microchip coupled with MALDI-TOF MS for the investigation of bacterial contamination of fish muscle products

Bacterial contamination is a significant concern in food safety. Traditional methods, though being a gold standard for bacterial detection, are time-consuming. In this work, we managed to establish a simple and versatile magnetic-assisted microfluidic method for rapid bacterial detection of fish muscle products, by manipulating anti-human IgG functionalized magnetic beads in a zig-zag shaped microfluidic channel, increasing the probability for bacteria capture. The captured bacteria were characterized by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). This method is capable of isolating Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae from 5 μL of sablefish sarcoplasmic protein sample, and detecting Escherichia coli in the range of 6.0 to 6.0×104 CFU/mL with a detection limit of 6 CFU/mL. Bacterial growth on salmon sashimi during its period of storage was successfully monitored. The current protocol holds great potential for pathogen detection and microbial control in the food industry.

Preliminary investigations on antimicrobial, antioxidant and nutritional properties of freshwater snail Brotia costula (Rafinesque, 1833)

The present study aimed to evaluate the bioactive properties of freshwater snail Brotia costula (Rafinesque, 1833) meat along with its nutritional and functional properties. The soft tissue of B. costula had excellent nutritional properties as reflected in the high protein (13.83%), carbohydrate (10.70%) and polyunsaturated fattyacid (PUFA) content (37.7% of total fatty acid) of the meat. Among protein fractions, the major fraction was myofibrillar (51.40%) followed by sarcoplasmic (23.86%), stroma (17.89%) and alkali-soluble protein fractions (11.67%), whilst high non-protein nitrogen (27.23%) was also observed. To assess the bioactive properties, snail meat was extracted in three different solvents viz. 100% ethanol (l00EE), 50% ethanol (50EE) and 100% water (10WE). Among the three solvent extracts, 100% ethanol extract (100EE) showed excellent antioxidative properties as confirmed by four different antioxidant assays. The FTIR spectral analysis revealed strong absorbance for functional groups (phenol and carbonyl) in 100 EE tissue extract. The 100 EE showed maximum inhibition against spoilage bacteria (Pseudomonas putida, 21.3 mm) than pathogenic bacteria (Escherichia coli, 11.6 mm). Overall, it can be concluded that B. costula may be used as a good nutritional source and a potent natural antioxidant and antimicrobial agent in food and feed preparations. Keyword: Antioxidant activity, Antibacterial activity, Cholesterol, Freshwater snail, FTIR

Heat stress induced changes in the major carcass traits and quantitative expression patterns of selective meat quality determining genes in Kanni Aadu Goats

A study was carried out to evaluate the effect of heat stress on carcass traits and expression of Myostatin,Heat Shock Protein (HSP) 70and HSP110expression in skeletal muscle of Kanni Aadu goat. Twelve female (one year old) Kanni Aadu goats were randomly allocated into two groups of six animals each, control (KC) goats were placed in the thermo neutral zone (TNZ), i.e., control chamber, while the heat stress (KHS) goats were exposed to heat stress in hot chamber (40°C) for 45 days. Major carcass traits remained intact between the groups. Physico-chemical characteristics revealed a significantly (p<0.01) higher pH values, higher drip loss, cooking loss, lower water holding capacity and lower sarcoplasmic protein in Longissimus thoracis et lumborum (LTL)and muscle in KHS group as compared to the KC group. Heat stress significantly (p<0.05) increased Lightness (L*), decreased tenderness (higher shear and low tenderness score), whereas no significant effect could be observed in myoglobin, met-myoglobin and other organoleptic characteristics. The HSP110 and myostatinmRNA expression was significantly (p<0.01) higher in KHS as compared to KC group. Results of our study indicated that Kanni Aadu breed may be considered an extremely adapted breed with high climate resilience capacity as reflected by the intact meat production characteristics.

Effect of Penicillium candidum and Penicillium nalgiovense and their combination on the physicochemical and sensory quality of dry-aged beef

This study was designed to investigate the effect of starter culture on the improvement of physicochemical and sensory properties of dry-aged beef. Penicillium nalgiovense and Penicillium candidum were used as single starter cultures and mixed suspensions (1:1) to determine the effect of mixed starter culture. Starter cultures were spray-inoculated on the surface of beef samples, and samples were dry-aged for 0, 7, 10, 14, and 21 days. Dry-aged samples were then analyzed for microbial population, physicochemical properties (pH, water content, and color), proteolytic activity on sarcoplasmic and myofibrillar proteins, and flavor compounds (free amino acids, nucleotides, and volatile compounds). The microbial activities of starter cultures affected the physicochemical traits and enhanced sensory quality. Penicillium candidum particularly influenced proteolytic activity and volatile compounds, whereas P. nalgiovense affected free amino acid and nucleotide content, with the most significant effect on day 7. Combination of the two strains resulted in different patterns when compared to the single strains. Therefore, the inoculation of mold starter cultures significantly affected the physicochemical properties and improved the sensory qualities of dry-aged beef, and the effect differed between single and mixed strains.

Study on the changes of goat meat quality and the expression of 17 quality-related genes within 48 h of postmortem aging

This research revealed the changes of color, cooking loss, texture, protein, amino acids, and the expression of 17 meat quality-related genes in longissimus thoracis from goats during postmortem aging of 0, 12, 24 and 48 h at 4 °C, and preliminarily studied the expression of 11 genes in cultured muscle cells under similar aging conditions. Along with the development of rigor mortis, shear force, texture indicators and cooking loss reached maximum at 12 h. The color and contents of aspartic acid, serine, tyrosine, phenylalanine changed significantly within 48 h. Both myofibrillar and sarcoplasmic proteins were degraded from 12 h onwards with myosin heavy chain, troponin T, desmin and actin as the main degraded proteins. The expression levels of the 17 genes in muscle tissues mostly peaked at 12 or 24 h, which was consistent with the changes of some physicochemical indexes. Gene expression in cultured muscle cells demonstrated similarity to those in muscle tissues, whereas the corresponding variations in same genes occurred later.

Hydrolysis of pork sarcoplasmic protein extracts by unique staphylococci isolated from low-salt dry-cured ham

Dry-cured hams were produced using two curing agents with low-salt group and full-salt group. The salt content and the free amino acid (FAA) content were measured during the production process. The low-salt group was found to have a lower salt content (P < 0.05) and a higher FAA content (P < 0.05) in the final product than the other group. Three protease-producing strains (Staphylococcus cohni, Staphylococcus saprophyticus and Staphylococcus equorum) were further isolated from the low-salt hams, and their ability to hydrolyze proteins were assessed in porcine sarcoplasmic protein extracts. Gel electrophoresis showed that all strains were similar in their ability to degrade sarcoplasmic proteins. Samples inoculated with Staphylococcus saprophyticus had higher FAA content than those inoculated with the other two strains (P < 0.05). Glycine and alanine were the most increased FAAs compared to the control group. The results suggest that the novel Staphylococcus saprophyticus isolated from dry-cured ham has potential as a starter for fermented meat products.

Characteristic and effect analysis of protein and peptide in Cantonese cured meat processing

The aim of this work was to explore the physicochemical and structural properties, lipid oxidation and antioxidant capacity of the peptides extracted from Cantonese cured meat and as well as to investigate the effect of drying time on the sarcoplasmic and myofibrillar proteins of Cantonese cured meat. The results suggested that salting out, protein oxidation and heat treatment were closely related to surface hydrophobicity and the secondary structure of peptides was changed by processing. And the peroxide value and the value of tributyltin compounds were different in evaluating the degree of lipid oxidation. Glu and His were the major amino acid. The approximate molecular weights of the sarcoplasmic proteins and myofibrillar proteins ranged from 31 kDa to 50 kDa and 66 kDa, respectively. The results indicated that reducing the levels of protein oxidation and improvement of the antioxidant properties should be of great interest to preserve the nutritional quality of meat products and prolong preservation period.

Angiotensin‐converting enzyme (ACE) inhibitory peptides from fermented sausages inoculated with Lactobacillus plantarum CD101 and Staphylococcus simulans NJ201

AbstractNatural ACE inhibitory peptides derived from food are considered to be an effective supplement for lowering blood pressure. This study investigated the effects of Lactobacillus plantarum CD101 and Staphylococcus simulans NJ201 on proteolysis and the sequence composition of ACE inhibitory peptides in fermented sausages. The ACE inhibitory activity of the inoculated group reached the maximum values on day 35 during the production of fermented sausages. A more positive effect in the hydrolysis of the sarcoplasmic and myofibrillar protein was observed in the inoculated group through sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS‐PAGE). The free amino acid content of the inoculated group was 865.21 ± 12.55 mg/100 g, which was significantly higher (P &lt; 0.05) than that of the control group. The molecular weight distribution showed a significant increase (P &lt; 0.05) in peptides with a molecular weight less than 1 kDa in the inoculated group. A total of thirty‐four peptides with high hydrophobicity were identified by liquid chromatograph‐mass spectrometer/mass spectrometer (LC–MS/MS). Furthermore, the peptides were isolated and purified using gel filtration chromatography (GFC) and reversed‐phased high‐performance liquid chromatography (RP‐HPLC). Eleven novel peptides were identified by Nano‐LC‐ESI‐MS/MS, in which VALSLSRP with X‐Pro structure exhibited the highest ACE inhibition rate (75.36 ± 2.45%). These results indicated that mixed starters are conducive to protein degradation and the formation of peptides with high ACE inhibitory activity, especially peptides less than 1 kDa, and could be used as a functional material for antihypertensive drugs.