High post-mortem temperature combined with rapid glycolysis induces phosphorylase denaturation and produces pale and exudative characteristics in broiler Pectoralis major muscles

Growth performance, carcass composition, and qualitative meat features of broiler chickens after galactooligosaccharides and sodium butyrate in ovo administration

The study aimed to analyze the growth performance, feed indicators, and quantitative and qualitative physicochemical features of carcass and meat from broiler chickens after rearing, stimulated in ovo on d 12 of incubation with various substances. In the experiment, 1,200 hatching eggs from meat-type hen Ross 308 parental flock were incubated. On d 12, the injection was performed. Group CON-0 was noninjected. Group CON-S was injected with saline. In the GOS group, the procedure was performed in ovo with galactooligosaccharides (dissolved 3.5 mg of GOS in 0.2 mL of NaCl). In the SB group, butyric acid sodium salt was administered in a 0.3% SB dissolved in 0.2 mL NaCl. After hatching, 336, 1-day-old chicks per group were transferred to the broiler house and kept in 7 pens with 12 chickens per group for 42 d. The body weight and feed intake indicators were calculated. Next, 40 birds were selected (n = 10 per group) and taken to analyze carcass composition and meat quality (pH, color, WHC, drip loss, chemical composition). Compared to the experimental groups, the highest body weight indicators were found in groups CON-0 and CON-S. The feed conversion ratio was the lowest in the SB group on d 36 to 42 (P < 0.05). The European Efficiency Production Factor in groups GOS and SB was lower than in group CON-S (P = 0.005). The GOS group showed higher pH24hours in the pectoral muscles than the CON-S group (P = 0.011). The leg muscles showed better WHC in the CON-S, GOS, and SB groups than in the CON-0 group (P < 0.001). A lower intramuscular fat of the pectoral and leg muscle content was demonstrated, especially in the SB group. Injection of galactooligosaccharides and sodium butyrate in ovo adversely affected broiler production but did not alter carcass composition. It varied pectoral muscles' pH and chemical composition and improved water holding capacity and chemical composition in leg muscles.

Oxidized myoglobin: Revealing new perspectives and insights on factors affecting the water retention of myofibrillar proteins

The impact of oxidized myoglobin (Mb) on myofibrillar protein (MP) oxidation and water retention was investigated. Results showed that the oxidation of Mb increased with increasing concentration of oxidized linoleic acid (OLA). In the presence of 100 mmol/L OLA, hemin iron decreased by 62.07 % compared to the control group. Further investigation showed that mild oxidation of Mb (≤10 mmol/L OLA) increased the water retention and the absolute value of the zeta potential of MP, whereas excessive oxidation (>10 mmol/L OLA) decreased these properties. With the increase of Mb oxidation, the carbonyl content in MP increased, and α-helices changed to random helix. And the tertiary structure changed. Pearson correlation analysis suggested that oxidized Mb affected the water retention of MP, which was closely related to hemin iron and non-hemin iron. In conclusion, OLA induced Mb oxidation, further promoted MP oxidation and affected its water retention.

Integration of transcriptome and machine learning to identify the potential key genes and regulatory networks affecting drip loss in pork

Low level of drip loss (DL) is an important quality characteristic of meat with high economic value. However, the key genes and regulatory networks contributing to DL in pork remain largely unknown. To accurately identify the key genes affecting DL in muscles postmortem, 12 Duroc × (Landrace × Yorkshire) pigs with extremely high (n = 6, H group) and low (n = 6, L group) DL at both 24 and 48 h postmortem were selected for transcriptome sequencing. The analysis of differentially expressed genes and weighted gene co-expression network analysis (WGCNA) were performed to find the overlapping genes using the transcriptome data, and functional enrichment and protein-protein interaction (PPI) network analysis were conducted using the overlapping genes. Moreover, we used machine learning to identify the key genes and regulatory networks related to DL based on the interactive genes of the PPI network. Finally, nine potential key genes (IRS1, ESR1, HSPA6, INSR, SPOP, MSTN, LGALS4, MYLK2, and FRMD4B) mainly associated with the MAPK signaling pathway, the insulin signaling pathway, and the calcium signaling pathway were identified, and a single-gene set enrichment analysis (GSEA) was performed to further annotate the functions of these potential key genes. The GSEA results showed that these genes are mainly related to ubiquitin-mediated proteolysis and oxidative reactions. Taken together, our results indicate that the potential key genes influencing DL are mainly related to insulin signaling mediated differences in glycolysis and ubiquitin-mediated changes in muscle structure and improve the understanding of gene expression and regulation related to DL and contribute to future molecular breeding for improving pork quality.

Effects of 2,2'-Azobis(2-methylpropionamidine) Dihydrochloride Stress on the Gel Properties of Duck Myofibrillar Protein Isolate

The aim of this study was to investigate the biochemical properties and gel-forming capacity of duck myofibrillar proteins under the effects of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH)-mediated oxidation. Duck myofibrillar proteins were extracted and treated with different concentrations of AAPH solutions (0, 1, 3, 5, 10 mmol/L) and then analysed for carbonyl content, dynamic rheology, protein profiles and gel-forming properties (colour, water holding capacity, gel strength and microstructure). The results showed that with increasing AAPH concentration, the carbonyl content of the proteins exhibited an increasing trend (p < 0.05); SDS-PAGE pattern changes indicated that moderate oxidation (3 mmol/L AAPH) induced myosin aggregation via covalent bonds including disulfide, enhanced protein-protein interactions, and thus affected the gel strength of the DMPs' heat-induced gels. However, high oxidation (5 and 10 mmol/L AAPH) led to the partial degradation of the myosin heavy chain (MHC) isoforms, as evidenced by lower storage modulus and irregular microstructures, which significantly reduced gelation ability. These results suggest that the internal relationship between alkylperoxyl radical-induced oxidation should be taken into account in the processing of duck meat, as mild protein oxidation is conducive to improving gel quality.

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.

Relationship between pre-rigor temperature of pork longissimus muscle, myofibril-bound calpain activity and protein degradation

The effect of pre-rigor temperature incubation on the activity and distribution in sarcoplasmic and myofibrillar fractions of calpains, and meat quality attributes was investigated. Porcine longissimus thoracis muscles were incubated pre-rigor at 14, 22, 30 and 38 °C to 6 h postmortem, followed by another 2 h incubation at 14 °C. Thereafter, muscles were stored at 2 °C for 1 or 4 days. With higher pre-rigor temperature, sarcoplasmic Ca²⁺ concentration, purge loss and myofibril-bound calpain-1 content increased, while shear force declined. Water-holding capacity of isolated myofibrils was lower after pre-rigor incubation at 38 °C. Desmin and troponin T degradation, and myofibril fragmentation was greater upon incubation of isolated myofibrils with added Ca²⁺ in the order 800 μM Ca²⁺ > 40 μM Ca²⁺ > no Ca²⁺, suggesting that calpain-1 and calpain-2 were associated to myofibrils and proteolytically active with sufficient Ca²⁺. Activity of myofibril-bound calpain-1 in muscle incubated pre-rigor at 22 and 30 °C were higher than when incubated at 14 and 38 °C. These results indicate that calpains translocate from the sarcoplasm onto myofibrils with higher pre-rigor temperature to 30 °C and the proteolytic potential of myofibril-associated calpains is thereby increased.

Reactive oxygen species-mediated oxidative stress accelerates glycolysis via activation of the CaMKKβ/AMPK pathway in the yak longissimus dorsi postmortem

BACKGROUND

Adenosine monophosphate-activated protein kinase (AMPK) is instrumental in the initiation of early postmortem glycolysis and the advent of pale, soft, and exudative (PSE) meat when cellular energy is altered. However, conflicting studies show that AMPK activation without corresponding energy level changes in PSE meat challenges this long-held notion. Here, we examined the effects of reactive oxygen species (ROS)-mediated oxidative stress on AMPK activation in the context of glycolysis, protein solubility, and water-holding capacity (WHC) in the postmortem yak longissimus dorsi (LD) muscle. Further, we explored the mechanisms underlying these effects.

RESULTS

Hydrogen peroxide (H₂ O₂ ) significantly augmented the degree of oxidative stress, increasing the production of ROS and malondialdehyde excessive production and reducing the activity of the anti-oxidants superoxide dismutase and glutathione peroxidase. In turn, oxidative stress dramatically promoted AMPK activation and glycolysis by increasing glycogen depletion and promoting hexokinase and phosphofructokinase activity. Subsequently, lactic acid accumulation increased, leading to a rapid decline in pH, which aggravated protein solubility degree and centrifugal loss in the early postmortem yak LD muscle. Importantly, these changes caused by oxidative stress were eliminated by the AMPK inhibitor. Mechanistically, oxidative stress elevated calcium ion (Ca²⁺ ) levels, which mobilized calcium/calmodulin-dependent protein kinase β (CaMKKβ) and AMPK. Rescue experiments confirmed that the increases were attenuated using Ca²⁺ and CaMKKβ chelators, respectively.

CONCLUSION

These results indicated that oxidative stress caused by ROS hastened early-stage postmortem glycolysis and reduced the WHC of yak meat. These effects were likely mediated by the alternative and energy-independent CaMKKβ/AMPK signaling pathway. © 2022 Society of Chemical Industry.

Assessment of the Effect of Cold Atmospheric Plasma (CAP) on the Hairtail (Trichiurus lepturus) Quality under Cold Storage Conditions

Cold Atmospheric Plasma (CAP) is a novel non-thermal preservation method that extends the shelf-life of food. Therefore, this study investigated the effect of CAP on the quality parameters of hairtail (Trichiurus lepturus) during cold storage conditions (at 4 °C and RH range 45−55%). For that reason, different quality parameters including the total bacteria count (TBC), total volatile basic nitrogen (TVB-N), pH, thiobarbituric acid reacting substances value (TBARS), color, texture, and sensory evaluation have been measured. The hairtail was exposed to CAP at 50 kV voltage for 2, 3, 4, and 5 min. The results showed that the samples treated with CAP at 50 kV for 5 min had significantly lower (p < 0.05) TBC (7.04 ± 0.26 log CFU/g) compared with the control sample (8.69 ± 0.06 log CFU/g). Similar results were found concerning TVB-N, which strongly decreased in the treated samples (16.63 ± 0.03 mg N/100 g) in comparison with the control sample (22.79 ± 0.03 mg N/100 g). In addition, the CAP-treated samples had lower (p < 0.05) changes in color than those of the control group. With reference to the sensory evaluation, the shelf-life of CAP-treated samples (at 50 kV for 5 min) was longer than the untreated samples by about 6 days. These results led us to the conclusion that CAP can effectively delay spoilage and deterioration, slow the rise in pH, and maintain the sensory attributes of hairtail during cold storage conditions.

Improving the poor texture and technological properties of chicken wooden breast by enzymatic hydrolysis and low-frequency ultrasound

Abstract

Wooden breast (WB) is a recurrent myopathy in fast‐growing birds, which alters the appearance, functionality, and the texture of the breast muscle. The objectives of this study were (i) to evaluate the effect of a combined use of papain enzyme and ultrasound on the texture of WB chicken using response surface methodology and (ii) to assess the effect of marinating on the quality of WB chicken meat. Full factorial experimental design method was used to obtain the ideal conditions to soften the WB meat. The independent variables were the concentration of papain (0.1%–0.3%) and the time in ultrasonic bath (10–30 min); shear force (SF) was the dependent variable. The optimum results were obtained at a concentration of 0.2% papain and 20 min on ultrasound. Papain enzyme had a great influence on the texture of WB meat, reducing its hardness. However, the effect of the ultrasound time on the SF response was not observed. The marinated WB meat showed similar SF values and texture profile than those from normal (N) meat, with reduction in the parameters of protein and lipid oxidation. The use of papain without ultrasound bath proved to be an efficient means for improving the tenderness of WB breasts.

Practical Application

This study shows the efficiency of the application of two technological procedures (enzymatic treatment and ultrasound) to improve the texture profile and technological properties of chicken breasts affected by the wooden breast myopathy. The economic loss caused by the world‐wide occurrence of wooden breast is enormous, and the application of papain has been found to counteract the impaired properties of this abnormal chicken breasts. Since papain is already widely used in the food industry to tenderize meat, its application in improving the quality of WB meat is straightforward.

Are muscle fiber types different between normal and dark-cutting beef?

Muscle fiber (MF) characteristics of Longissimus thoracis (LT) muscles from heifer (n = 11) and steer (n = 12) carcasses graded Canada AA (AA, normal, n = 4/sex) or dark-cutting (Canada B4) were examined and related to beef quality. Atypical (AB4, pH < 5.9, n = 4/sex) and typical (TB4, pH > 5.9, n = 3 and 4 for heifers and steers, respectively) dark-cutting carcasses were represented. Muscle fiber type proportions did not differ between AA, AB4 and TB4 muscles, although type I and IIB muscle fiber diameters were greater in TB4 than in AA LT. That AB4 muscle fiber proportions were not different from AA and TB4 muscles suggests that the increased MF diameter of TB4 muscle was due to water retained by muscle proteins at high ultimate pH, as evidenced by decreased cooking loss. Dark-cutting was therefore unrelated to muscle fiber proportions, and increased Type I and IIB diameters in dark cutting LT were likely driven by elevated intramuscular ultimate pH.

Denaturation manner of sarcoplasmic proteins in Pale, Soft and Exudative meat determines their positive impacts on myofibrillar water-holding capacity

The aim of the study was to investigate the denaturation manner of sarcoplasmic proteins (SP) under PSE condition to explain their positive impacts on water-holding compacity. We found that the SP precipitation under PSE-like condition (pH 5.5, 40 °C) and heating conditions (pH 5.5, 7.0, 8.0, 55 °C) were similar, but the myofibrillar water-holding capacity was improved only under PSE-like condition (pH 5.5, 40 °C). To understand the denaturation mechanism of SP, their physicochemical properties were examined. Results demonstrated that PSE-denaturation and heat-denaturation of SP were two different processes. At pH 7.0 and 8.0, the unfolding of SP due to temperature elevation did not alter the overall net surface negative charges but only increased hydrophobicity, whereas at pH 5.5, the net surface positive charges and hydrophobicity increased dramatically. We hypothesized that in PSE meat, denatured SP became highly positively charged and hydrophobic and easier to bind to the negatively charged MF, which is related to the improvement on water-holding capacity.

Pinpointing oxidative stress behind the white striping myopathy: depletion of antioxidant defenses, accretion of oxidized proteins and impaired proteostasis

BACKGROUND

This study aimed to investigate the molecular mechanisms involved in the onset of the white striping (WS) myopathy with particular attention to the role of oxidative stress and protein oxidation in the loss of meat quality.

RESULTS

It was found that WS-M (moderate degree; white stripes <1 mm thickness) and WS-S (severe degree; white stripes >1 mm thickness) breast presented higher pH, hardness, redness, lipid, and collagen content, and lower lightness than normal breast. Compared with the latter, WS-S had a more severe loss of protein thiols (70.7% less thiols than in N), reduced activity of antioxidant enzymes such as catalase (23 versus 40 U g^-1 ), glutathione peroxidase (0.21 versus 0.54 U g^-1 ), and superoxide dismutase (56 versus 73 U g^-1 ), and consequently, had greater accretion of thiobarbituric acid reactive substances (0.64 versus 0.22 mg MDAkg^-1 muscle), allysine (3.1 versus 1.9 nmol mg^-1 protein) and Schiff base structures (645 versus 258 fluorescent units). The analysis of sarcoplasmic proteins revealed that muscles severely affected by the myopathy suffered a chronic impairment of physiological (upregulation of sarcoplasmic reticulum Ca2+ ATPase, sarcalumenin and calsequestrin-2) and metabolic processes (downregulation of pyruvate kinase, creatine kinase, and l-lactate dehydrogenase).

CONCLUSION

The overexpression of ribonuclease / angiogenin inhibitor 1 and Kelch-like proteins in WS chicken breasts indicates altered protein turnover plausibly mediated by oxidative stress and accumulation of oxidized proteins. © 2020 Society of Chemical Industry.

Mimicking myofibrillar protein denaturation in frozen-thawed meat: Effect of pH at high ionic strength

This study aims at providing new insight on protein denaturation in freezing-thawing. Freezing-thawing minced pork reduced water-holding of myofibrils and increased surface hydrophobicity. One additional freezing-thawing cycle at slow freezing rate caused appearance of a 160 kDa myosin-4 fragment in SDS-PAGE, further decreased water-holding of myofibrils and increased surface hydrophobicity. Fresh minced pork was exposed to either high salt (2 M KCl) only or high salt with lower pH to mimic conditions in freezing. Exposure to high salt only increased water-holding of myofibrils and hence did not reproduce myofibrillar protein changes in freezing. Exposure to combinations of lower pHs and high salt decreased water-holding and increased surface hydrophobicity, suggesting myofibrillar protein denaturation occurred by a comparable mechanism as in freezing-thawing. We propose that exposure to decreased pH combined with high solute concentrations in the unfrozen water of frozen meat is the primary cause of myofibrillar protein denaturation in frozen-thawed meat.

Effects of Cyclic High Ambient Temperature and Dietary Supplementation of Orotic Acid, a Pyrimidine Precursor, on Plasma and Muscle Metabolites in Broiler Chickens

The aim of this study was to evaluate the effects of high ambient temperature (HT) and orotic acid supplementation on the plasma and muscle metabolomic profiles in broiler chickens. Thirty-two 14-day-old broiler chickens were divided into four treatment groups that were fed diets with or without 0.7% orotic acid under thermoneutral (25 ± 1 °C) or cyclic HT (35 ± 1 °C for 8 h/day) conditions for 2 weeks. The chickens exposed to HT had higher plasma malondialdehyde concentrations, suggesting an increase in lipid peroxidation, which is alleviated by orotic acid supplementation. The HT environment also affected the serine, glutamine, and tyrosine plasma concentrations, while orotic acid supplementation affected the aspartic acid, glutamic acid, and tyrosine plasma concentrations. Untargeted gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS)-based metabolomics analysis identified that the HT affected the plasma levels of metabolites involved in purine metabolism, ammonia recycling, pyrimidine metabolism, homocysteine degradation, glutamate metabolism, urea cycle, β-alanine metabolism, glycine and serine metabolism, and aspartate metabolism, while orotic acid supplementation affected metabolites involved in pyrimidine metabolism, β-alanine metabolism, the malate-aspartate shuttle, and aspartate metabolism. Our results suggest that cyclic HT affects various metabolic processes in broiler chickens, and that orotic acid supplementation ameliorates HT-induced increases in lipid peroxidation.

Meat quality traits of European quails reared under different conditions of temperature and air velocity

This study’s objective was to evaluate the influence of thermal environment and air velocity during the rearing phase on European quail meat quality traits. A total of 1,152 one-day-old European quail chicks were placed inside floor pens within environmental chambers. Each experimental period was approximately 5 wks, with birds slaughtered at 37 d of age. The experimental design consisted of a 2 × 4 factorial arrangement of treatments in completely randomized design with 2 air velocities (0 and 2 m/s) × 4 air temperatures (severe cold [SC], moderate cold, thermal comfort, and moderate heat [MH]). ANOVA, with air velocity and thermal environment as fixed effects, was performed to evaluate the effect of main factors and their interaction on meat quality traits, using the GLM procedure (SAS 9.4). Least square means of treatments effects were compared using Tukey’s test (α = 0.05). Lightness (L∗), redness (a∗), and yellowness (b∗), of quail meat were affected by thermal environment and air velocity (P < 0.05). Initial and final L∗ values were greater for MH (P < 0.05). Meat from birds subjected to 2 m/s air velocity had lower final L∗, but no velocity effect was noted for initial L∗. Quail meat from SC presented higher initial and final a∗ values compared with the other thermal environment groups (P ≤ 0.001). Final a∗ was affected by air velocity (P < 0.05). Initial and final b∗ values for meat from MH were greater, 13.8 and 15.2, respectively, differing from the other treatment environments (P < 0.05). However, air velocity did not influence b∗ values (P > 0.05). Interactions were not significant for pHu (P = 0.993). Thawing loss and shear force were affected by treatments (P < 0.05) but not ultimate pH, drip loss, or sarcomere length. This study demonstrates that thermal environments and air velocity affect quail meat quality traits. Further investigation is recommended to explore effects of air velocity and thermal environment on muscle proteolysis of quail meat quality.

Effects of temperature on protein phosphorylation in postmortem muscle

BACKGROUND

Phosphorylation is one of the most important post-translational modifications. Currently, many postmortem protein phosphorylation studies in muscle have been related to meat quality such as tenderness and color stability. However, the effects of various storage temperatures (25, 15, 4 and -1.5 °C) on the phosphorylation level of protein are poorly understood. Changes in the protein phosphorylation levels in postmortem ovine muscle at various storage temperatures were determined in this study.

RESULTS

The obtained data showed that pH decline rate was significantly inhibited at -1.5 °C from 12 h to 7 days postmortem (P < 0.05). The ATP consumption rate was higher at 25 °C than that at other three temperatures (P < 0.05). Analysis of the temperature, pH and ATP content revealed that the ATP content was related to the phosphorylation levels of individual protein bands. Phosphorylated myofibrillar and sarcoplasmic proteins, such as myosin binding protein C, troponin T3, myosin light chain 1, glucose-6-phosphate isomerase and pyruvate kinase, were mainly involved in glycolysis and muscle contraction.

CONCLUSION

The global and specific protein phosphorylation levels can be influenced by the postmortem storage temperature of muscle. Phosphorylation of proteins was correlated with glycolysis and muscle contraction. Certain phosphorylated proteins, such as heat shock proteins, require further study to clarify their effects on meat traits. © 2019 Society of Chemical Industry.

Water-spraying forced ventilation during holding improves the water holding capacity, impedance, and microstructure of breast meat from summer-transported broiler chickens

Heat stress is a broiler welfare issue and economic deficit to the broiler industry. Water atomizing with three-dimensional forced ventilation, a holding treatment after summer transport for broiler, has been proved to significantly improve water holding capacity of fresh meat. However, effectiveness of this treatment on water retention after freeze-thaw needs to be conducted. Therefore, the objective of this study was to assess whether water atomizing with forced ventilation could increase freeze-thaw meat quality after birds slaughtering. Arbor Acres broiler (n = 105), undergoing 32°C ambient temperature transport, was randomly categorized into 3 treatments: 1) T group, which underwent 45-min transport without rest; 2) TR group, which underwent 45-min transport with 1-h rest; and the 3) TWFR group, which underwent 45-min transport followed by 15-min water atomizing with three-dimensional forced ventilation and 45-min rest. All birds were hot-deboned within 30-min postmortem. A total of 105 breast fillets were collected and split into halves, which left part fillets were kept in 4°C and for meat analysis, the other part fillets, marked with T-F, TR-F, and TWFR-F, were frozen (−18°C) for 1 mo and then thawed overnight for meat quality analysis. Regardless of fresh or frozen treatment among 3 groups, TWFR has the highest pH which was more than 6.01 (P < 0.05). The L* value, drip loss, and cooking loss of TWFR were significantly lower compared to T and TR groups in both fresh and frozen breast fillets (P < 0.05). Compared with the T group, the TWFR meat shows closely microscopic structure which means less water loss channel. The impedance amplitude of the fresh meat was significantly higher than that of the frozen-thawing meat (P < 0.05). TWFR-treated meat has significantly higher impedance module than T and TR meat at 50 Hz frequency region, for both fresh or thawed meat. Among 6 treatments, TWFR fresh meat has significantly highest Q (modulus change ratio) value (P < 0.05). These results indicate that TWFR treatment for 15 min after transport can improve meat quality, which may be due to the improved welfare of broilers transported in hot summer months.

Effects of method and duration of restraint on stress hormones and meat quality in broiler chickens with different body weights

Objective

The study was designed to investigate the effects of restraint method, restraint duration, and body weight on stress-linked hormones (corticosterone, adrenaline, and noradrenaline), blood biochemical (namely glucose and lactate), and the meat quality in broiler chickens.

Methods

A total of 120 male broiler chickens (Cobb 500) were assigned to a 2×3×2 factorial arrangement in a completely randomized design using two restraint methods (shackle and cone), three durations of restraint (10, 30, and 60 s), and two categories of live body weight (1.8±0.1 kg as lightweight and 2.8±0.1 kg as heavyweight).

Results

Irrespective of the duration of restraint and body weight, the coned chickens were found to have lower plasma corticosterone (p<0.01), lactate (p<0.001), lower meat drip loss (p<0.01), cooking loss (p<0.05), and higher blood loss (p<0.05) compared with their shackled counterparts. The duration of restraint had significant effects on the meat initial pH (p<0.05), ultimate pH (p<0.05), and yellowness (p<0.01). The lightweight broilers exhibited higher (p< 0.001) blood loss and lower (p<0.05) cooking loss compared to the heavyweight broilers, regardless of the restraint method used and the duration of restraint. However, the interaction between the restraint method, duration of restraint, and body weight contributed to differences in pre-slaughter stress and meat quality. Therefore, the interaction between the restraint method and the duration of restraint affected the meat shear force, lightness (L*) and redness (a*).

Conclusion

The duration of restraint and body weight undoubtedly affect stress responses and meat quality of broiler chickens. Regardless of the duration of restraint and body weight, the cone restraint resulted in notably lower stress, lower meat water loss, and higher blood loss compared to shackling. Overall, the findings of this study showed that restraint method, duration of restraint, and body weight may affect the stress response and meat quality parameters in broilers and should be considered independently or interactively in future studies.

The effects of egg albumin incorporation on quality attributes of pale, soft, exudative (PSE-like) turkey rolls

Pale, soft, exudative (PSE-like) poultry phenomenon has been a growing problem in meat industry in terms of quality and economic losses, thus data is required to evaluate PSE raw material in product formulations. The aim of our study was to investigate the effects of egg albumin (EA) utilization on quality characteristics of PSE-like turkey rolls. Turkey Pectoralis major muscles were exposed to either 40 °C to stimulate typical processing causing PSE or 0 °C to reduce PSE and keep the muscles "normal". Turkey rolls were prepared in nine different formulations; using 100% normal (N), 50% normal + 50% PSE (NP) or 100% PSE meat (P). Treatments also included 0, 1 or 2% EA. Addition of EA increased protein content of all samples. L*, a* and b* values were affected by PSE level. Increased levels of PSE caused decreased processing yields, while EA incorporation increased processing yield of the samples. Addition of 1% EA increased water-holding capacity (WHC) of the samples, while higher level of EA (2%) caused decrement in the same. Addition of either 1% or 2% EA was effective in reducing purge loss in P samples. Texture profile analysis showed that EA addition rather had considerable effects on N samples. Sensory scores showed that 1% EA utilization has the potential to increase mostly the mouthfeel of PSE-like products. Results showed that EA could be used as a promising ingredient that improved overall quality of PSE-like turkey rolls.

Comparison of Meat Quality and Fatty Acid Composition of Longissimus Muscles from Purebred Pigs and Three-way Crossbred LYD Pigs

This study was conducted to find pork quality to meet the needs of consumers. Thus, the meat quality and fatty acid composition of longissimus muscles from purebred pigs (Landrace, Yorkshire, and Duroc) and three-way crossbred LYD pigs were compared and evaluated. Chemical compositions of longissimus muscles were significant (p<0.05) different among pigs. Duroc contained significant (p<0.05) higher fat contents than other pigs, whereas significant (p<0.05) higher moisture contents were observed in Landrace, Yorkshire, and LYD pigs compared to those of Duroc pigs. The values of pH_{24 h} and pH_{14 d} were the highest in Landrace pigs. Myoglobin contents of LYD pigs were higher (p<0.05) than those of purebred pigs. Regarding meat color, Duroc and Yorkshire pigs had higher redness values than Landrace and LYD pigs, while Landrace pigs had the lowest (p<0.05) color values among all pigs. There was no significant difference in shear force or water holding capacity (WHC). Duroc pigs maintained the lowest drip loss during 14 d of cold storage. In sensory evaluation, the marbling scores of Duroc pigs were higher (p<0.05) than other pigs. Regarding fatty acid compositions, total USFA, poly-, n-3, and n-6 contents were the highest (p<0.05) in LYD pigs, while total SFA contents were the highest (p<0.05) in Duroc pigs. Based on these results, purebred pigs had superior overall meat quality to crossbred pigs.

Quality Characteristics of PSE-Like Turkey Pectoralis major Muscles Generated by High Post-Mortem Temperature in a Local Turkish Slaughterhouse

The objective of this study was to investigate the effects of high post-mortem temperature application on development of pale, soft, exudative (PSE) turkey meat characteristics in terms of local slaughter conditions. Within this scope, it was targeted to obtain PSE-like muscles benefiting from different post-mortem temperature applications. Immediately after slaughter, turkey Pectoralis major (n=15) muscles were kept at various post-mortem temperatures (0, 10, 20, 30, and 40℃) for 5 h. pH values of 40℃ treatment were lower than four other treatments (p<0.05). L* values, drip loss, cook loss, and thawing loss of 40℃ group were higher than the other groups (p< 0.05). Napole yield of 40℃ treatment indicated that high post-mortem temperature decreases brine uptake. Protein solubility of 40℃ group was lower than 0℃ group (p<0.05). Expressible moisture did not differ between 0 and 40℃ treatments. Hardness, gumminess and chewiness of 40℃ treatment were higher than 0℃ treatment. The results of this research showed that high post-mortem temperature treatment induced development of PSE-like turkey meat, with lower pH, paler color, higher technological and storage losses, and reduced protein solubility and texture.

Relationship between water-holding capacity and protein denaturation in broiler breast meat

The objective of this study was to determine the relationship between water-holding capacity (WHC) attributes and protein denaturation in broiler breast meat. Boneless skinless breast fillets (n = 72) were collected from a commercial processing plant at 2 h postmortem and segregated into low-WHC and high-WHC groups based on muscle pH and color (L*a*b*). At 6 and 24 h postmortem, brine uptake (%), cooking loss (%), and protein solubility (sarcoplasmic and myofibrillar) were measured and protein fractions were analyzed using SDS-PAGE. Drip loss accumulation (%) was measured after storage for 2 and 7 days postmortem. High-WHC fillets exhibited lower L*-lightness values and greater pH values at 2 and 24 h postmortem than low-WHC fillets. High-WHC fillets had greater brine uptake and less cooking loss at both 6 and 24 h postmortem compared to low-WHC fillets. Aging from 6 to 24 h postmortem increased brine uptake in high-WHC fillets, but did not affect cooking loss in either low-WHC or high-WHC fillets. Drip loss accumulation was greater in low-WHC fillets at both 2 and 7 days postmortem. Myofibrillar protein solubility decreased with postmortem time but was not different between low-WHC and high-WHC fillets. Sarcoplasmic protein solubility increased with postmortem time and was greater in high-WHC fillets. SDS-PAGE analysis indicated that low-WHC fillets exhibited more glycogen phosphorylase denaturation than high-WHC fillets as evidenced by a more extensive shift of the protein from the sarcoplasmic to the myofibrillar protein fraction. Correlation analysis revealed that overall protein solubility measurements were not related to WHC attributes but that the degree of glycogen phosphorylase denaturation was significantly correlated (|r| = 0.52 to 0.80) to measures of WHC. Data indicated that WHC differences in broiler breast fillets were not due to differences in myofibrillar protein denaturation and suggested that the denaturation of sarcoplasmic proteins onto myofibrils may influence WHC in breast meat.

Effect of pH and postmortem aging on protein extraction from broiler breast muscle

This study determined the effects of extraction buffer pH and postmortem aging on the extraction of salt-soluble and water-soluble proteins from broiler pectoralis muscle. Deboned broiler breast fillets were collected at 4 h postmortem, packaged, and then stored at 4°C until 1, 5, or 8 d postmortem. After the designated aging period, salt-soluble and water-soluble protein extractions were performed using buffers at 7 different pH levels (pH 5.4, 6.4, 6.9, 7.2, 7.5, 8.0, 9.0). Protein concentrations of the extracts were measured and SDS-PAGE analysis was performed. Salt-soluble protein concentration increased (P < 0.0001) as buffer pH increased from pH 5.4 to 6.9 and then remained unchanged from pH 6.9 to 9.0. Water-soluble protein concentration increased (P < 0.0001) as buffer pH increased from pH 5.4 to 7.2 and then remained unchanged from pH 7.2 to 9.0. There was not a significant extraction buffer pH by aging treatment interaction for the total protein concentration of either the salt-soluble or water-soluble protein extracts. The protein concentrations of salt-soluble extracts were similar at both 1 and 8 d postmortem but lower (P < 0.0001) at 5 d postmortem. The protein concentrations of water-soluble extracts were similar at both 1 and 5 d postmortem, but higher (P < 0.0001) at 8 d. Both extraction buffer pH and postmortem aging influenced the SDS-PAGE protein profiles of salt-soluble and water-soluble protein extracts from breast muscles. Data demonstrate that postmortem aging and extraction buffer pH influence both the total amount and the composition of the myofibrillar and sarcoplasmic proteins that can be extracted from broiler breast fillets.

Influence of high pre-rigor temperature and fast pH fall on muscle proteins and meat quality: a review

The impacts of accelerated pH decline combined with high muscle temperature on post-mortem muscle metabolism and subsequent meat quality attributes have been extensively studied. Traditionally, this phenomenon has been observed in pork muscles, primarily due to the relatively fast post-mortem glycolysis rate and its relationships to stress susceptibility of pigs before slaughter. However, the protein-denaturing condition of high temperature/rapid pH fall and subsequent PSE (pale, soft and exudative)-like abnormal meat quality characteristics have been observed in muscles from other species such as beef, lamb, venison and even poultry. Various pre-rigor conditions including the application of electrical stimulation, hot-boning, and/or pre-rigor carcass chilling temperatures in various muscles, in conjunction with carcass stretching/hanging methods, can also contribute to muscle-protein denaturation pre-rigor. This review considers the influence of a faster than normal pH fall at a higher than normal pre-rigor temperature on glycolysis, post-mortem muscle proteins and subsequently meat quality attributes. Gaps in current knowledge are identified and recommendations made for additional research.

Relationship between changes in core body temperature in lambs and post-slaughter muscle glycogen content and dark-cutting

Pre-slaughter stress may decrease muscle glycogen content, a key element for a suitable low ultimate pH and prevention of dark-cutting meat. Body temperature monitoring is a tool used in research on animal stress, as an indicator of stress events. Possible relationships between body temperature of sheep and post-mortem muscle glycogen were investigated in this study. Body temperature was measured with intravaginal loggers inserted into each animal at 3 days pre-slaughter, to record body temperature every 3 min over a period of 3 days. Blood samples were collected from each animal at exsanguination for measurement of glucose and lactic acid concentrations. The muscle content of glycogen and lactic acid were determined in samples of M. longissimus collected at the level of the 13th rib, at 1 h post-slaughter. A plot of body temperature versus time showed a rise in body temperature from all animals during events such as mustering, loading onto the truck, unloading at the abattoir, during pre-slaughter handling and at slaughter. Pearson’s correlation coefficients were determined between (1) the main temperature increments occurring between farm and slaughter; and (2) post-slaughter muscle glycogen and lactate levels. A significant negative correlation was detected between elevation in core body temperature due to physical stress of sheep and muscle glycogen levels at slaughter. A low correlation was detected between body temperature and blood glucose or lactate concentrations. Further research should examine the relationship between core body temperature and meat quality in order to better understand the complex relationship between animal stress and meat quality.

Changes in body temperature during growth and in response to fasting in growing modern meat type chickens

1. Rectal or core body temperature was determined in a study to examine the effects of fasting in modern meat type broilers at three stages of growth, namely d 19, 33 and 47. 2. There were two treatment groups: fed with feed available ad libitum and fasted. Rectal temperatures were determined at noon (1200 h). At that time, feed was removed from the fasted group. The body temperatures were then determined again after 6, 12, 18 and 24 h. 3. Core body temperatures decreased with fasting. The decrease was evident after as little as 6 h of fasting with a further decline evident by 12 h. 4. Accompanying the decrease in body temperature with fasting there were decreases in the venous concentrations of carbon dioxide in the blood and sodium in the plasma. 5. The decrease in both body temperature and carbon dioxide presumably reflects depressed metabolic rate. 6. Unexpectedly, the core body temperature increased progressively with age in the control fed group (d 19 = 41·04 ± 0·02°C, d 33 = 41·65 ± 0·05°C, d 47 = 42·21 ± 0·12°C). 7. In the fed control group, core body temperatures were reduced at night, when feeding activity would be anticipated to be greatly reduced.