Sarcoplasmic Protein Fractions Research Articles

Changes of Raw Texture, Intramuscular Connective Tissue Properties and Collagen Profiles in Broiler Wooden Breast during Early Storage.

A recently identified broiler myopathy known as wooden breast (WB) is predominantly found in the pectoralis major muscle of fast-growing broiler hybrids and is causing significant losses to the poultry industry. The aim of this study was to investigate the effects of WB syndrome on raw meat texture, purge loss and thermal properties of intramuscular connective tissue of pectoralis major muscle in the early postmortem period (1-3 days). Results showed that the presence of the WB muscles condition at 1 day postmortem was associated with significantly increased stiffness (27.0 N vs. 23.1 N) and significantly increased purge loss (1.8% vs. 1.0%) compared to normal breast (NB). However, on 3 days postmortem, these parameters did not differ between WB and NB groups. Insoluble and total collagen content was significantly higher in WB muscles compared to NB muscles, and the extractability of intramuscular connective tissue (IMCT) of WB was also higher (0.42% vs. 0.37%) compared to NB and remained stable in the early postmortem period. There was significantly lower protein content in the sarcoplasmic protein fraction and myofibrillar protein fraction of WB muscles compared to NB muscles (p < 0.05). The IMCT of these two groups showed different thermal properties, as the enthalpy of denaturation (ΔH) was significantly lower in WB muscles compared to NB muscles. The WB syndrome had a great effect on the texture and connective tissue properties of the meat compared to normal muscle, with a tendency for having a lower purge loss and higher raw meat hardness.

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

Cytokine Pattern of Peripheral Blood Mononuclear Cells Isolated from Children Affected by Generalized Epilepsy Treated with Different Protein Fractions of Meat Sources.

The objective of the present study was the evaluation of cytokine patterns in terms of TNF-α, IL-10, IL-6, and IL-1β secretion in peripheral blood mononuclear cell (PBMC) supernatants isolated from blood of children affected by generalized epilepsy and treated in vitro with myofibrillar, sarcoplasmic, and total protein fractions of meat and fish sources. Children with generalized epilepsy (EC group, n = 16) and children without any clinical signs of disease, representing a control group (CC group n = 16), were recruited at the Complex Structure of Neuropsychiatry Childhood-Adolescence of Policlinico Riuniti (Foggia, Italy). Myofibrillar (MYO), sarcoplasmic (SA), and total (TOT) protein fractions were obtained from longissimus thoracis muscle of beef (BF) and lamb (LA); from pectoralis muscle of chicken (CH); and from dorsal white muscle of sole (Solea solea, SO), European hake (Merluccius merluccius, EH), and sea bass fish (Dicentrarchus labrax, SB), respectively. PBMCs were isolated from peripheral blood of EC and CC groups, and an in vitro stimulation in the presence of 100 μg/mL for each protein fraction from different meat sources was performed. Data were classified according to three different levels of cytokines produced from the EC group relative to the CC group. TNF-α, IL-10, and IL-6 levels were not affected by different meat fractions and meat sources; on the contrary, IL-1β levels were found to be significantly affected by the tested proteins fractions, as well as different meat sources, in high-level cytokine group. On average, the protein fractions obtained from LB, BF, and CH meat sources showed a higher level of IL-1β than the protein fractions obtained from EH and SB fish samples. When all cytokine classes were analyzed, on average, a significant effect was observed for IL-10, IL-1β, and TNF-α. Data obtained in the present study evidence that the nutritional strategy based on protein from fish and meat sources may modulate the immunological cytokine pattern of infants with generalized epilepsy.

Proteomics of Fish White Muscle and Western Blotting to Detect Putative Allergens.

A detailed workflow is provided for preparation from teleost fish white muscle of extracts for proteomics analysis. The protocol generates samples that can be analyzed by SWATH (Sequential Window data independent Acquisition of the Total High-resolution-Mass Spectra), a modern MS-based quantitative label free technology. The main steps for the extraction of three independent protein fractions, (1) soluble sarcoplasmic, (2) soluble myofibrillar, and (3) insoluble material, from fish white muscle are detailed. Coupled to the protein extraction protocol a Western blotting approach is outlined for detection of common fish allergens, in this case β-parvalbumin, in the white muscle sarcoplasmic protein fraction.

Analysis of Se and Hg biomolecules distribution and Se speciation in poorly studied protein fractions of muscle tissues of highly consumed fishes by SEC-UV-ICP-MS and HPLC-ESI-MS/MS

Distribution of Se and Hg in sarcoplasmic, myofibrillar and alkali-soluble protein fractions extracted from muscle tissue of tuna, swordfish and salmon (wild vs. farmed) is investigated for the first time. SEC-UV-ICP-MS analyses revealed that Se and Hg are mostly bound to proteins of 2–12 kDa and up to 574 kDa, respectively. Moreover, Se and Hg appeared associated to proteins of same molecular weight, evidencing that Se–Hg interaction may occur at the level of the fish tissue evaluated. Important differences were found between farmed and wild salmon, suggesting the effect of the type of feed and growing conditions on Se and Hg content and their distribution through protein fractions. Finally, Se speciation studies performed by HPLC-ICP-MS and confirmed by HPLC-ESI-MS/MS showed SeMeSeCys as the only Se specie found in soluble, sarcoplasmic, myofibrillar and alkali-soluble proteins of all fishes analysed, except in soluble proteins extracted from tuna, where SeMet was also identified.

Effects of Farm Management Practices and Transport Time on Post-Mortem Changes of Longissimus lumborum Muscle Proteins in Suckling Goat Kids.

The combined effect of farm management practices, transport time, and ageing time on the electrophoretic changes of sarcoplasmic (SPP) and myofibrillar (MFP) protein fractions of goat kids was studied. A total of 64 suckling goat kids were withdrawn from two farms with “high” (GW) and “low” (DW) welfare-friendly management practices, and they were transported for 2 or 6 h immediately before slaughtering. Longissimus lumborum samples were obtained at 3, 8, and 21 days post-mortem, and muscle proteins were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis SDS-PAGE. Both protein extracts displayed significant changes attributable to meat maturation. Managing conditions of kids in DW farms increased the post-mortem susceptibility of muscle proteins. Some MFP of Longissimus lumborum muscle, such as troponin T, as well as 26–30 and 35–37 kDa fractions were influenced significantly by deficient on-farm management, and therefore, these protein fragments might be considered as indicators of low-welfare on-farm management in goat kids.

Effect of Feeding a Low Vitamin a Diet to Beef Steers on Calpain 1 Activation during Meat Aging

ObjectivesThe objective of the study was to determine if a vitamin A deficient diet during beef finishing influences calpain 1 activation during meat aging.Materials and MethodsSixty-four steers of approximately 7 mo of age were subjected to a 14-d acclimation period followed by a 95-d growing period on a low vitamin A diet (1017 IU vitamin A/kg DM) designed to deplete liver vitamin A stores. Steers were assigned to a randomized complete blocked design with a 2 × 2 arrangement of treatments (breed: commercial Angus, n = 32, and purebred Simmental, n = 32; and a Low Vitamin A diet or a control diet). The low Vitamin A (LVA) treatment was a finishing diet with no supplemental vitamin A (723 IU vitamin A/kg DM). The control (CON) treatment was the LVA diet plus supplementation with 2200 IU vitamin A/kg DM for a total of 2923 IU vitamin A/kg DM. Serum retinol concentrations were monitored at the beginning and end of treatment. Upon completion of finishing, steers were slaughtered in two groups at a commercial plant. After fabrication, boneless strip loins (IMPS 180) were collected and transported to NDSU. Samples (approximately 40 g) were collected from the anterior portion of the strip loin on d-2 and d-7 of aging and immediately frozen. Protein was extracted from meat samples in fractionation buffers to yield sarcoplasmic and myofibrillar portions, separated by SDS-PAGE, and transferred to PVDF membranes. Immunoblot analysis was done using anti-desmin (d-2 and d-7) and anti-calpain 1 (d-2) antibodies, and results were visualized and documented. A pooled control was run on all membranes and set to a value of one for normalizing results. All experimental data were analyzed using the Proc Mixed procedure of SAS with breed of steers, dietary treatments, their interaction and slaughter date used as a fixed effect.ResultsCalpain 1 autolysis in the sarcoplasmic protein fraction of the d-2 aged loin samples were not affected by treatment or breed. The myofibrillar protein fraction from Angus loins had greater (P = 0.02) accumulation of the 76 kDa calpain 1 autolysis product than that from the Simmental loins; the myofibrillar fraction of the loins from the LVA treatment tended (P = 0.07) to have more 76 kDa calpain 1 autolysis product than that from the CON. There were not any differences (P &gt; 0.19) in the 80 kDa calpain 1 band or the 78 kDa calpain 1 intermediate autolysis product in the myofibrillar fraction. There was a treatment by breed interaction (P = 0.01) for desmin in the d-7 aged loins where Angus loins from the CON treatment had less accumulation of the 46 kDa band than Angus loins on the LVA treatment and Simmental loins from either treatment.ConclusionVitamin A restriction increased protein proteolysis in Angus but not in Simmental steers. The increased calpain 1 autolysis in Angus vs. Simmental, regardless of Vitamin A treatment, indicates a genetic difference that may be the driver for the increased protein degradation in steers a restricted vitamin A diet.

Effect of Feeding a Low Vitamin a Diet to Beef Steers on Calpain 1 Activation during Meat Aging

ObjectivesThe objective of the study was to determine if a vitamin A deficient diet during beef finishing influences calpain 1 activation during meat aging.Materials and MethodsSixty-four steers of approximately 7 mo of age were subjected to a 14-d acclimation period followed by a 95-d growing period on a low vitamin A diet (1017 IU vitamin A/kg DM) designed to deplete liver vitamin A stores. Steers were assigned to a randomized complete blocked design with a 2 × 2 arrangement of treatments (breed: commercial Angus, n = 32, and purebred Simmental, n = 32; and a Low Vitamin A diet or a control diet). The low Vitamin A (LVA) treatment was a finishing diet with no supplemental vitamin A (723 IU vitamin A/kg DM). The control (CON) treatment was the LVA diet plus supplementation with 2200 IU vitamin A/kg DM for a total of 2923 IU vitamin A/kg DM. Serum retinol concentrations were monitored at the beginning and end of treatment. Upon completion of finishing, steers were slaughtered in two groups at a commercial plant. After fabrication, boneless strip loins (IMPS 180) were collected and transported to NDSU. Samples (approximately 40 g) were collected from the anterior portion of the strip loin on d-2 and d-7 of aging and immediately frozen. Protein was extracted from meat samples in fractionation buffers to yield sarcoplasmic and myofibrillar portions, separated by SDS-PAGE, and transferred to PVDF membranes. Immunoblot analysis was done using anti-desmin (d-2 and d-7) and anti-calpain 1 (d-2) antibodies, and results were visualized and documented. A pooled control was run on all membranes and set to a value of one for normalizing results. All experimental data were analyzed using the Proc Mixed procedure of SAS with breed of steers, dietary treatments, their interaction and slaughter date used as a fixed effect.ResultsCalpain 1 autolysis in the sarcoplasmic protein fraction of the d-2 aged loin samples were not affected by treatment or breed. The myofibrillar protein fraction from Angus loins had greater (P = 0.02) accumulation of the 76 kDa calpain 1 autolysis product than that from the Simmental loins; the myofibrillar fraction of the loins from the LVA treatment tended (P = 0.07) to have more 76 kDa calpain 1 autolysis product than that from the CON. There were not any differences (P > 0.19) in the 80 kDa calpain 1 band or the 78 kDa calpain 1 intermediate autolysis product in the myofibrillar fraction. There was a treatment by breed interaction (P = 0.01) for desmin in the d-7 aged loins where Angus loins from the CON treatment had less accumulation of the 46 kDa band than Angus loins on the LVA treatment and Simmental loins from either treatment.ConclusionVitamin A restriction increased protein proteolysis in Angus but not in Simmental steers. The increased calpain 1 autolysis in Angus vs. Simmental, regardless of Vitamin A treatment, indicates a genetic difference that may be the driver for the increased protein degradation in steers a restricted vitamin A diet.

Implications of step-chilling on meat color investigated using proteome analysis of the sarcoplasmic protein fraction of beef longissimus lumborum muscle

In order to improve beef color and color stability, step-chilling (SC) was applied on excised bovine longissimus lumborum muscle, with chilling starting at 0–4°C for 5 h, then holding the temperature at 12–18°C for 6 h, followed by 0–4°C again until 24 h post-mortem. pH and temperature were measured during rigor on SC loins as well as those subjected to routine chilling (RC, 0–4°C, till 24 h post-mortem). Color L*, a*, b* values, metmyoglobin (MetMb) content, MetMb reducing ability (MRA) and NADH content were determined on samples aged for 1, 7, and 14 d. Sarcoplasmic proteome analysis was only conducted on d 1 samples. The results showed muscles subjected to SC maintained a temperature at around 15°C for 5 to 10 h post-mortem, and exhibited a slow temperature decline, but rapid pH decline. Beef steaks treated with SC had higher L*, a*, b* and chroma values than those of RC samples at 1 and 7 d chilled storage (0–4°C), while showing no significant difference for a*, b* and chroma values at d 14. The SC samples also exhibited a lower relative content of surface MetMb, higher MRA and NADH content, compared with RC beef steaks during storage, indicating the SC-treated beef showed an improved color stability. Eleven differential protein spots/nine proteins were identified by two-dimensional gel electrophoresis and mass spectrometry, and those proteins were mainly involved in redox, chaperone binding, metabolic and peroxidase activity. Oxidoreductases play a role in decreasing the oxidation-induced myoglobin oxidation and benefiting the production of NADH, and finally improving the colour of beef. Of these, pyruvate dehydrogenase E1 component subunit beta showed a positive correlation with color L*, a*, b* values and accounted for more than 60% of the variation in color values; this protein can be considered as a potential beef color biomarker. The present study provided valuable information for studies on the molecular mechanism of color improvement from step-chilling, as well as for identifying markers associated with beef color.

Sarcoplasmic Proteome Changes in Response to Aging and Diet

We seek to establish the change in the sarcoplasmic proteome the rat medial gastrocnemius (MG), as a function of age and dietary fish oil enriched diet. Physiological and behavioral measures were acquired in conjunction with quantitative two‐dimensional gel electrophoresis (2D PAGE) and immunoblotting (IB) of muscle sarcoplasm extracts. Significant proteomic changes were observed across experimental groups: young adult (8–9 months) and aged (22–23 months) S‐D rats assigned to control (Ctl) or Fish oil‐supplemented (FO) diets for 8 weeks (7 adult; 6 aged rats/group).Forelimb grip strength was assessed before &amp; after the 8‐week diet. In situ twitch and tetanic (100 Hz) forces were assessed at completion. MG samples were extracted and the sarcoplasmic protein fraction analyzed by 2D PAGE and the integrated spot intensity analyzed. Spots showing significant changes (± ≥ 2.00, p &lt; 0.05) were identified by HPLC/MS. For IB, PVDF blots were probed with primary antibody, then stripped and reprobed for GAPDH (loading control). Animal use and all procedures were approved by the Ohio Univ IACUC, and the “Principles of Laboratory Animal Care” (NIH Pub No. 86‐23, rev 1985), were followed throughout the study. Data were analyzed by 2 × 2 ANOVA (age × dietary group), except for grip strength, which was assessed using a repeated measures ANOVA, with time as the repeated factor.Body mass was reduced with age, but food intake did not differ across groups. Based on food disappearance, rats in the FO group ingested ~1.12 g/kg FO, with no age‐difference. There was an overall trend (P = 0.089) for FO maintaining greater grip strength vs. Ctl over time. Aged animals exhibited comparable significant reduction in MG mass and twitch &amp; tetanic (15–20%). FO diet significantly increased tetanic (P = 0.046) but not twitch force (P = 0.262), despite having no effect on muscle mass. Twitch and tetanic force, when normalized to MG anatomical cross‐sectional area, exhibited a significant diet × age interaction (P = 0.027) and a strong trend (P = 0.051) for an effect of diet, respectively. Protein changes were classified into meta‐KOG groupings: Metabolic: 54%, Oxidative Stress: 20%, Cytoskeletal: 13% and Misc: 13%. Overall, Age × Diet interactions influenced energy metabolism proteins: CKM ‐ muscle creatine kinase; TPI 1 ‐ isoform 1 ‐ triose phosphate isomerase; DJ1 ‐ a protein deglycase; PKM ‐ muscle pyruvate kinase; BE ‐ beta enolase; NADHD ‐ NADH dehydrogenase. In Ctl conditions, CKM, NADHD and PKM were elevated in the old vs. young; BE was reduced and DJ1 and TPI1 were not different; In response to dietary FO, CKM and NADHD increased for the young and decreased for the old; BE decreased in the young only; TPI increased in the young only; DJ1 decreased in the young and increased in the old and PKM decreased in the old only.An 8‐week FO diet produced some mass‐independent improvements in muscle function and performance in young and aged rats. FO affected the expression of several proteins in young and aged MG muscle, predominantly ones related to energy metabolism.Support or Funding InformationSmith Coll Blakeslee Fund and SURF, and Ohio Univ Coll Health Sci and Professions Res Dean's Innovation ChallengeThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Proteolysis during fermentation of Suanyu as a traditional fermented fish product of China

ABSTRACTProteolytic changes in Suanyu, a traditional fermented fish product of China, were determined during 6 weeks of fermentation. The gradual decrease of pH value and aw was detected, accompanied with an increasing trend detected in trichloroacetic acid–soluble C-1: peptides concentration. Protein composition changed throughout the fermentation. A decrease in sarcoplasmic and myofibrillar protein fractions was accompanied by an increase in the insoluble fraction. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed most bands of sarcoplasmic, myofibrillar, and insoluble proteins lightened or disappeared due to proteolysis or denaturation. New bands emerged especially in insoluble proteins. Fluctuation of molecular weight distribution of the water-soluble nitrogen in Suanyu was found during fermentation. The highest percentage in Suanyu end-products was observed in the fraction of <0.18 kDa, followed by 0.18–0.5 kDa, 66.02 ± 0.38% and 10.79 ± 0.27%, respectively. Free amino acids analysis showed that nearly all amino acids increased, especially for Asp, Glu, Met, Phe, Leu, Val, and Ile. Overall, intense proteolysis in Suanyu brought numerous of small peptides and free amino acids, which contribute to the taste and flavor of Suanyu.

European Carp (Cyprinus carpio L.) Protein-Derived Ex Vivo Digests and In Vitro Hydrolysates Differ in the ACE I Inhibitory Activity and Composition of Released ACE Inhibitory Peptides.

Carp muscle tissue is a valuable source of biologically active constituents known to positively influence human health. In this study, carp protein digests/hydrolysates generated by human/ porcine digestive enzymes were analysed for their angiotensin I-converting enzyme inhibitory (ACEi) activity. The ex vivo digests and in vitro hydrolysates were used in a screening for ACEi peptides as well. Carp proteins were hydrolysed more rapidly by human gastrointestinal juices than by porcine enzymes. Sarcoplasmic protein fractions were digested/hydrolysed more easily than the myofibrillar ones. The inhibitory concentrations at 50% (IC50) for ex vivo digested sarcoplasmic and myofibrillar protein fractions were established at 1.50 and 1.04 mg/mL, respectively. While, for in vitro hydrolysed sarcoplasmic and myofibrillar protein fractions, the IC50 values were calculated as 2.57 and 1.12 mg/mL, respectively. The digested/hydrolysed samples of carp sarcoplasmic and myofibrillar protein fractions were separated by RP-HPLC-MS. Amino acid sequences were identified with the use of the LC-MS/MS method coupled with in silico systematic screening for ACEi peptides. ACEi peptides with IVY, IY, VY, ALPHA and VKAGF sequences were found in the carp digests/hydrolysates. In the ex vivo carp digest, an ACEi peptide TVY was also detected, while the ACEi peptide IW was identified in in vitro hydrolysate. Our study showed that different ACEi effects of carp digests and hydrolysates were generated with the use of human gastrointestinal and porcine enzymes.

Lipid and Protein Changes Related to Quality Loss in Frozen Sardine (Sardina pilchardus) Previously Processed Under High-Pressure Conditions

This research focuses on biochemical changes related to quality loss in frozen (−18 °C for 9 months) sardine (Sardina pilchardus) previously subjected to high-pressure (HP) processing (125–200 MPa). The inhibition (p < 0.05) of lipid hydrolysis development (lower free fatty acid formation and lipase activity), observed in frozen sardine as a result of the previous HP treatment, increased with the pressure level applied. Several parameters including peroxide value, thiobarbituric acid index, fluorescent compounds, and polyenes showed that the applied HP conditions prior to sardine freezing did not increase lipid oxidation. Also, HP did not induce a substantial modification of acid phosphatase and cathepsins B and D activities, and the electrophoretic patterns of sarcoplasmic and myofibrillar protein fractions did not change. However, HP processing led to a decrease in myofibrillar protein content in frozen pressure-treated fish, an effect that was higher in 175- and 200-MPa treated samples. In conclusion, this research showed that pressure treatments in the 125–200-MPa range with holding time of 0 min cause only minor modifications in biochemical indicators of deterioration throughout the subsequent frozen storage of samples for up to 9 months. This study shows the need to optimize HP conditions, particularly in the case of applications combining HP treatments, frozen storage, and thawing to obtain products with high quality and commercial viability.

Impact of white striping on functionality attributes of broiler breast meat

The influence of white striping (WS) on the water-holding capacity (WHC) and protein functionality attributes of broiler breast meat was investigated. Boneless breast fillets (Pectoralis major) were collected from the deboning line of a commercial processing plant and categorized by WS score (normal, moderate, severe). The physical (weight, pH, CIE-color values), water-holding capacity (salt-induced water uptake, cook loss, final yield), protein functionality (solubility, emulsifying activity), and protein composition (SDS-PAGE) characteristics of the fillets were measured in three experiments. Breast meat with WS exhibited greater fillet weights, higher pH, and similar color values (L*a*b*) to normal fillets. In experiment 1, fillets were frozen-thawed prior to analysis. The WS condition reduced thaw loss, sarcoplasmic protein solubility, and the emulsifying activity of the myofibrillar proteins, but did not significantly affect salt-induced water uptake, cook loss, final yield, or myofibrillar protein solubility. In experiment 2, breast meat was analyzed fresh and after a freeze-thaw cycle. Freezing samples prior to analysis negatively influenced WHC and reduced sarcoplasmic protein solubility in both WS and normal fillets. In fresh and frozen-thawed meat, the WS condition decreased sarcoplasmic protein solubility but did not significantly alter WHC or myofibrillar protein solubility. For experiment 3, fillets were portioned into 3 sections (Location A, cranial end-ventral surface; Location B, cranial end-dorsal surface; Location C, caudal end). The effects of WS on WHC and protein solubility were dependent upon breast fillet sampling location. Fillets with WS exhibited lower salt-induced water uptake, greater cook loss, and lower sarcoplasmic protein solubility than normal fillets when sampled from location A. SDS-PAGE analysis indicated that differences in the composition of sarcoplasmic and myofibrillar protein fractions between WS and normal fillets were influenced by sampling location. These results suggest that WS diminishes the WHC and protein functionality of broiler breast meat, but demonstrate that the WS effects on these traits are not uniform throughout the breast muscle.

Interfacial properties of highly soluble crayfish protein derivatives

Abstract An analysis of the interfacial behaviour of two alternative protein derivatives with high solubility has been carried out at two different pH values (2 and 8). The protein derivatives (protein content higher than 50 wt.%) have a globular protein fraction mainly consisting of sarcoplasmic proteins (CFS); and a protein hydrolysate, (CFH), both obtained from crayfish surpluses. The physicochemical characterisation included protein solubility (higher than 80%) and surface charge as well as chemical analysis (elementary, sulfhydryl and disulphide groups). This was complemented with an interfacial characterization included measuring the surface pressure and surface dilatational measurements with a drop tensiometer, and interfacial shear rheology measurements performed using a double-wall-ring geometry. Whereas both types of protein derivative have significant interfacial activity (surface pressure between 20 and 40 mN/m), the difference in their behaviour is small In contrast, a strong influence of pH on the interfacial behaviour has been found for both soluble protein fractions. At pH 2, globular sarcoplasmic protein fraction yields lower surface pressures but highly viscoelastic interfaces, with 2D gel-like behaviour. At pH 8, on the other hand, CF proteins form quite rigid and more brittle interfaces, being resistant to dilatational deformations and showing high sensitivity to shear.

Changes in Myofibrillar and Sarcoplasmic Proteins in Salami Processing Added withLactobacillus Sakei/Staphylococcus CarnosusAccording to Modulated Differential Scanning Calorimetry and the Color Profile

Changes in the thermal and color profiles of the sarcoplasmic and myofibrillar protein fractions were analyzed during the fermentation and ripening processes of salami added with Lactobacillus sakei and Staphylococcus carnosus using modulated differential scanning calorimetry, CIELAB and reflectance. The results of the pre and postfermentation stages for the myofibrillar and sarcoplasmic fractions showed a decrease in transition temperatures (Tm) without variation in the degradation enthalpy (ΔHd). Thus, the sarcoplasmic protein fraction in these stages showed Cp values between 0.18 and 1.0 J/gC while for myofibrillar was 0.22 and 0.07 J/gC. However, in the postripening stage, the ΔHd increased to 364.1 J/g for myofibrillar fraction and 1292 J/g for sarcoplasmic fractions. Seventh day corresponds to the turning point in L*, a decreasing trend was observed in L* and the reflectance percentage in postripening stage, which can reflect structural changes in proteins. Practical Applications This study facilitates a comparison of the changes in sarcoplasmic and myofibrillar protein fractions during three stages of salami processing, correlating these changes with the bacterial population dynamics focused on the behavior of a starter culture, pH and aw. Likewise, the possibility of using a methodology such as modulated differential scanning calorimetry and color to analyze protein changes in a complex matrix such as salami is intriguing.

Antioxidant properties of salmon (Salmo salar L.) protein fraction hydrolysates revealed following their ex vivo digestion and in vitro hydrolysis.

Salmon (Salmo salar L.) myofibryllar protein (MP) and sarcoplasmic protein (SP) were digested with human gastric and duodenal juices and hydrolysed in vitro with commercial pepsin and Corolase PP. The digestion after duodenal juice/Corolase PP caused almost complete breakdown of peptide bonds in MP and SP. The DPPH(•) scavenging activity of proteins decreased during both ex vivo digestion and in vitro hydrolysis. The highest value of DPPH(•) scavenging activity was shown for the gastric digest of SP (8.88 ± 0.87%). The ABTS(+•) scavenging activity of MP and SP increased during digestion/hydrolysis. The duodenal digest of SP was characterised by the highest value of ABTS(+•) scavenging activity (72.7 ± 1.2%). In turn, the highest value of ferric-reducing power was determined for the gastric digest of SP (84.8 ± 0.2%). Salmon antioxidant peptides Phe-Ile-Lys-Lys, His-Leu, Ile-Tyr, Pro-His-Leu, Pro-Trp, Val-Pro-Trp were identified in both ex vivo digested and in vitro hydrolysed MP and SP. An antioxidant peptide, Val-Tyr, was additionally detected in the in vitro hydrolysate of SP. The results indicate the salmon myofibrillar and sarcoplasmic protein fractions as potential sources of antioxidant peptides that could be released in the gastrointestinal tract but their amino acid sequence and quantification vary. © 2015 Society of Chemical Industry.

Effect of High-Pressure Processing of Atlantic Mackerel (Scomber scombrus) on Biochemical Changes During Commercial Frozen Storage

This research focuses on biochemical changes related to quality losses observed in Atlantic mackerel (Scomber scombrus) muscle stored under commercial frozen storage conditions (9 months, −18 °C) when subjected to high-hydrostatic pressure (HHP) treatments (125, 150, 175, and 200 MPa for 0 min) before freezing. After freezing, free fatty acid (FFA) formation (lipid hydrolysis assessment) showed a marked inhibition in HHP-treated fish and during frozen storage of samples treated at 175 MPa. Fluorescence ratio (FR) assessment of tertiary lipid oxidation showed a partial inhibitory effect during the 0–9-month period for samples treated at 175 and 200 MPa. After a 3-month storage of samples treated at these pressure levels, one-dimensional SDS-PAGE analysis of the sarcoplasmic protein fraction revealed the disappearance of a band; additionally, samples treated at 150 MPa showed the same effect at month 9. After gel excision, trypsin digestion, tandem mass spectrometry (MS/MS), and sequence database analysis, the band was identified as phosphoglycerate mutase 2 (28.7 kDa). On the other hand, HHP processing did not show a significant effect on trimethylamine (TMA) values, primary and secondary lipid oxidation, PUFA levels, 1-D myofibril protein pattern, and the activity of acid phosphatase and cathepsins B and D. Biochemical quality indices such as FFA, TMA, and FR and the activity of acid phosphatase and cathepsin B showed a progressive increase throughout the frozen storage of all samples.

Labeling and label free shotgun proteomics approaches to characterize muscle tissue from farmed and wild gilthead sea bream (Sparus aurata)

The proteome characterization of fish muscle tissues, together with the relative expression of each individual protein, provides knowledge on the biochemical response of the organisms and allows to assess the effect of different types of feeding, growth site and nutritional quality of the investigated species. This type of study is usually performed by gel-based proteomics approaches, however shotgun proteomics can serve as well, reducing analysis time and improving sample high-throughput. In this work, a shotgun proteomics method was thus developed and then applied to the characterization of gilthead sea bream edible muscle. The sarcoplasmic protein fraction was extracted, in-solution digested by trypsin and finally analyzed by nanoHPLC high resolution tandem mass spectrometry. Two different quantification strategies were also tested. One was based on chemical dimethyl labeling and the other one on label free quantification. A comparison between these two analytical workflows was performed, to evaluate their individual performance in the analysis of fish samples and assess the differences induced by farming practice on the final commercial product with respect to wild gilthead sea bream. Quantitative differences were detected, and the most relevant one regarded the common fish allergen parvalbumin, found overexpressed in farmed fish samples.

Extraction of Crab (Scylla Serrata) Myofibrillar and Sarcoplasmic Proteins to Create a Skin Prick Test Reagent for Crab Allergy Diagnosis

The major and minor allergens in fish and shellfish that have been identified are broadly spread in the myofibrillar and sarcoplasmic proteins. This study aimed to create a skin prick test reagent of crab myofibrillar and sarcoplasmic proteins to improve sensitivity and specificity diagnosis of allergy. Myofibrillar protein fraction was composed of 19 protein bands with the molecular weights of 9.6-111.6 kDa and sarcoplasmic protein fraction was composed of 19 protein bands with the molecular weights of 9.5-104.6 kDa. The allergenic myofibrillar protein has the molecular weights of 13.9-155.4 kDa while the allergenic sarcoplasmic protein has the molecular weights of 8.4-129.4 kDa. Crab myofibrillar and sarcoplasmic reagents met the requirements of the European Pharmacopoeia Monograph on Allergen Products 7 (2010:1063) for the parameters of moisture content, protein content, sterility and microbiology. A skin prick test to the respondents indicated that the sensitivity value of crab myofibrillar reagent was 85% and crab sarcoplasmic reagent was 69% with a negative error rate for each myofibrillar and sarcoplasmic reagents was 15% and 31%, respectively. The result diagnosis of crab myofibrillar and sarcoplasmic sensitivities would generate sensitivity value at 100%. The separation of crab proteins into myofibrils and sarcoplasm for skin prick test could improve its sensitivity value and lowered the negative misdiagnosis. The specificity of each myofibrillar and sarcoplasmic proteins was 100% with an error rate of positive diagnosis occurrence at 0%.