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It is generally held that the content of several free amino acids and dipeptides is closely related to the energy-supplying metabolism of skeletal muscles. Metabolic characteristics of muscles are involved in the variability of meat quality due to their ability to influence the patterns of energy metabolism not only in living animal but also during postmortem time. Within this context, this study aimed at establishing whether the concentration of histidine dipeptides can affect muscle postmortem metabolism, examining the glycolytic pathway of 3 chicken muscles (pectoralis major, extensor iliotibialis lateralis, and gastrocnemius internus as glycolytic, intermediate, and oxidative-type, respectively) selected based on their histidine dipeptides content and ultimate pH. Thus, a total of 8 carcasses were obtained from the same flock of broiler chickens (Ross 308 strain, females, 49 d of age, 2.8 kg body weight at slaughter) and selected immediately after evisceration from the line of a commercial processing plant. Meat samples of about 1 cm3 were excised from bone-in muscles at 15, 60, 120, and 1,440 min postmortem, instantly frozen in liquid nitrogen and used for the determination of pH, glycolytic metabolites, buffering capacity as well as histidine dipeptides content through 1H-NMR. Overall results suggest that glycolysis in leg muscles ceased already after 2 h postmortem, whereas in breast muscle continued until 24 h, when it exhibited significantly lower pH values (P < 0.05). However, considering its remarkable glycolytic potential, pectoralis major muscle should have exhibited a greater and faster acidification, suggesting that its higher (P < 0.05) histidine dipeptides' content might have prevented a potentially stronger acidification process. Accordingly, breast muscle also showed greater (P < 0.05) buffering ability in the pH range 6.0–7.0. Therefore, anserine and carnosine, being highly positively correlated with muscle's buffering capacity (P < 0.001), might play a role in regulating postmortem pH decline, thus exerting an effect on muscle metabolism during prerigor phase and the quality of the forthcoming meat. Overall results also suggest that total histidine dipeptides content along with muscular ultimate pH represent good indicators for the energy-supplying metabolism of chicken muscles.

C ommercial interest in the production of cultured myoproducts (cultured "meat") has grown in a broad range of companies. As has been shown with plant-based meat alternatives, consumer acceptance of such products will depend on their eating quality, as well as cost, ethical and sustainability issues. Principal factors in the sensory quality of conventionally-produced meat (texture, colour, flavour, juiciness) are very much affected by post-mortem metabolism in muscle tissue. However, there is a lack of information on how cell death and subsequent metabolism may affect the eating quality of cultured myoproducts. The main mechanisms of cell death in cell culture are apoptosis, necrosis and autophagy. Knowledge of the conditions and pathways inducing these and other mechanisms of cell death provides a conceptual framework of how cell harvesting conditions could be used to manipulate post-mortem metabolism in cultured myoproducts. Because the structure, composition and protein isoforms present will differ in conventional meat versus cultured products, a key question will be whether the well-understood post-mortem metabolic processes in the conversion of muscle to meat are desirable, or should be altered, to achieve acceptable sensory qualities of cultured myoproducts. Published information on post-mortem metabolism in cultured muscle cells is entirely lacking. Although post-mortem metabolism will differ with specific cell line and bioreactor conditions, general studies in the area should provide important tools in manipulating the end-product quality of cultured myofoods. [Display omitted] • Commercial interest in developing cultured myofoods has grown. • Post-mortem metabolism is used to control eating quality in conventional meat. • Harvesting and post-harvest metabolism in cultured myoproducts is currently unreported. • Information of the impact of cell death mechanisms and postmortem metabolism on product quality is needed. [ABSTRACT FROM AUTHOR]

1. Turkey production has increased dramatically as genetic selection has succeeded in increasing body weight and muscle yield to fulfil increasing consumer demand. However, producing fast-growing, heavily muscled birds is linked to increased heat stress susceptibility and can result in pale, soft, exudative (PSE) meat. Previous studies indicated that pyruvate dehydrogenase kinase 4 (PDK4) is significantly reduced in PSE samples, suggesting this as a candidate gene associated with the development of this problem. 2. The objective of this study was to determine whether pre-market thermal challenge results in PSE meat as a result of differential expression of PDK4. Two genetic lines of turkeys were used in this study; the Randombred Control Line 2 (RBC2) and a commercial line. Turkeys were exposed to a pre-market thermal challenge of 12 h at 35°C followed by 12 h at 27°C for 5 d. Birds were slaughtered and processed according to industry standards. Pectoralis major samples were categorised as PSE or normal based on marinade uptake and cook loss indicators. In the first experiment, the relative expression of pyruvate dehydrogenase (PDH) and the phosphorylation state of PDH in normal and PSE turkey meat were analysed by western blotting. In the second experiment, the same samples were used to measure metabolite levels at 5 min post-mortem, comparing the normal to the PSE samples. 3. The results of the first experiment showed that PSE samples had significantly lower total PDH (P = 0.029) compared to normal meat. However, there was no significant difference in the degree of phosphorylation of sites 1, 2 or 3. In the second experiment, there were no significant differences in glycogen, lactate, glycolytic potential or ATP when comparing PSE to control samples. 4. These results suggested that a reduction in PDK4 expression alone does not explain the development of PSE meat. [ABSTRACT FROM AUTHOR]

In this study, the effect of high pressure (HP) pretreatment on the stability of pork loins during supercooling (SC) preservation was investigated, and the freshness and postmortem metabolism of pork loins preserved by SC was evaluated. Based on the differential scanning calorimetry (DSC), the peak enthalpies of 200 MPa treatment were lower than those of 50 MPa treatment (P < 0.05). For the nuclear magnetic resonance (NMR) relaxometry, extramyofibrillar water in pork loins was decreased with increasing intermyofibrillar water at >100 MPa (P < 0.05). Compared to unpressurized control all HP treatment had less α-helix structure while random coil was dominated from the Fourier transform infrared (FTIR) spectroscopy (P < 0.05). A 200 MPa was selected to estimate the relationship between HP pretreatment and stability of SC preservation of pork loins. The HP-treated pork loins showed high stability during SC preservation under the relatively low temperature algorithm. Compared to fresh control, HP pretreatment caused physicochemical changes of pork loins which did not recover even after 2 weeks of preservation. Nevertheless, HP followed by SC preservation was able to reduce property changes better than pork loins preserved by normal refrigeration. According to the analyses of transmission electron microscopy (TEM), the HP pretreatment influenced the postmortem biochemical metabolism of pork loins, however, it did not affect the freshness and quality parameters of pork loins due to the subsequently applied low preservation temperature of SC. Therefore, this study demonstrated that moderate HP pretreatment was a potential pretreatment for SC preservation of pork loins. • Moderate pressurization enhanced protein-water interactions of pork loins. • High pressure inhibited ice nucleation of pork loins during supercooled preservation. • Modified qualities of pressurized pork were not recovered during supercooled preservation. • High pressure affected post-mortem biochemical changes of pork during supercooled preservation. [ABSTRACT FROM AUTHOR]

Abstract Background Pre-slaughter stress (PSS) impairs animal welfare and meat quality. Dark, firm and dry (DFD) are terms used to designate poor quality meats induced by PSS. Protein phosphorylation can be a potentially significant mechanism to explain rapid and multiple physiological and biochemical changes linked to PSS-dependent muscle-to-meat conversion. However, the role of reversible phosphorylation in the response to PSS is still little known. In this study, we report a comparative phosphoproteomic analysis of DFD and normal meats at 24 h post-mortem from the longissimus thoracis (LT) bovine muscle of male calves of the Rubia Gallega breed. For this purpose, two-dimensional gel electrophoresis (2-DE), in-gel multiplex identification of phosphoproteins with PRO-Q Diamond phosphoprotein-specific stain, tandem (MALDI-TOF/TOF) mass spectrometry (MS), novel quantitative phosphoproteomic statistics and bioinformatic tools were used. Results Noticeable and statistically significant differences in the extent of protein phosphorylation were detected between sample groups at the qualitative and quantitative levels. Overall phosphorylation rates across significantly changed phosphoproteins were about three times higher in DFD than in normal meat. Significantly changed phosphoproteins involved a variable number of isoforms of 13 myofibrillar and sarcoplasmic nonredundant proteins. However, fast skeletal myosin light chain 2 followed by troponin T, F-actin-capping and small heat shock proteins showed the greatest phosphorylation change, and therefore they were the most important phosphoproteins underlying LT muscle conversion to DFD meat in the Rubia Gallega breed. Conclusions This is the first study reporting global meat phosphoproteome changes in response to PSS. The results show that reversible phosphorylation is a relevant mechanism underlying PSS response and downstream effects on meat quality. This research opens up novel horizons to unravel the complex molecular puzzle underlying muscle-to-meat conversion in response to PSS.

Abstract Over the past few decades, a considerable scientific progress has been achieved in the area of fish welfare at all stages—farming, transportation, various pre-slaughter manipulations, stunning/killing procedures, etc. The increasing scientific interest is mainly due to the serious need of developing and implementing specific fish welfare requirements across the whole chain for both ethical (welfare) and commercial (meat quality) reasons. Since there has been substantial evidence that fish are able to experience pain and suffering, the provoked stress response could be a major cause of altered post-mortem metabolism and impaired meat quality. The present review was aimed to present the relationship between ante-mortem stress, course of post-mortem metabolic processes and the potential alterations in some quality traits of fish for human consumption.

The elevated ultimate pH (pHu) found in wooden breast (WB) meat suggests an altered muscular energetic status in WB but also could be related to a prematurely terminated post-mortem pH decline. The aims of this study were to explore the factors contributing to the elevated pHu and establish whether the occurrence of WB defect alters muscle post-mortem carbohydrate metabolism and determine if the contractile apparatus reflects such changes. A total of 24 carcasses from Ross 308 male chickens were obtained from a commercial producer and harvested using commercial processing procedures. Carcasses were categorized into unaffected (NORM) and WB groups (n = 12 each), and samples were collected from cranial bone-in pectoralis major (PM) muscles at 15 min and 24 h post-mortem for the determination of pH, glycolytic metabolites, adenonucleotides, buffering capacity, phosphofructokinase (PFK) activity, and in vitro pH decline. Twenty-four additional deboned PM samples (12 NORM and 12 WB) were collected from the same processing plant to assess muscle histology and sarcomere length at four different locations throughout the PM muscle. Data show that the reduced glycolytic potential of WB muscles only partially explains the higher (P < 0.001) pHu of WB meat, as residual glycogen along with unaltered PFK activity suggests that neither glycogen nor a deficiency of PFK is responsible for arresting glycolysis prematurely. The dramatic reduction in ATP concentrations in the early post-mortem period suggests a defective ATP-generating pathway that might be responsible for the reduced pH decline in WB samples. Further, the addition of excess of ATPase extended post-mortem glycolysis of WB meat in an in vitro glycolytic system. WB-affected samples have longer (P < 0.001) sarcomeres compared to NORM, indicating the existence of compromised energy-generating pathways in myopathic muscles that may have had consequences on the muscle contraction and tension development, as in vivo, also during the post-mortem period. Considering the overall reduced glycolytic potential and the myodegenerative processes associated with WB condition, we speculate that the higher pHu of WB meat might be the outcome of a drastically impaired energy-generating pathway combined with a deficiency and/or a dysfunction of muscle ATPases, having consequences also on muscle fiber contraction degree.

Cultured meat aspires to be biologically equivalent to traditional meat. If cultured meat is to be consumed, sensorial (texture, color, flavor) and nutritional characteristics are of utmost importance. This paper compares cultured meat to traditional meat from a tissue engineering and meat technological point of view, focusing on several molecular, technological and sensorial attributes. We outline the challenges and future steps to be taken for cultured meat to mimic traditional meat as closely as possible.

The elevated ultimate pH (pH u ) found in wooden breast (WB) meat suggests an altered muscular energetic status in WB but also could be related to a prematurely terminated post-mortem pH decline. The aims of this study were to explore the factors contributing to the elevated pH u and establish whether the occurrence of WB defect alters muscle post-mortem carbohydrate metabolism and determine if the contractile apparatus reflects such changes. A total of 24 carcasses from Ross 308 male chickens were obtained from a commercial producer and harvested using commercial processing procedures. Carcasses were categorized into unaffected (NORM) and WB groups (n = 12 each), and samples were collected from cranial bone-in pectoralis major (PM) muscles at 15 min and 24 h post-mortem for the determination of pH, glycolytic metabolites, adenonucleotides, buffering capacity, phosphofructokinase (PFK) activity, and in vitro pH decline. Twenty-four additional deboned PM samples (12 NORM and 12 WB) were collected from the same processing plant to assess muscle histology and sarcomere length at four different locations throughout the PM muscle. Data show that the reduced glycolytic potential of WB muscles only partially explains the higher (P < 0.001) pH u of WB meat, as residual glycogen along with unaltered PFK activity suggests that neither glycogen nor a deficiency of PFK is responsible for arresting glycolysis prematurely. The dramatic reduction in ATP concentrations in the early post-mortem period suggests a defective ATP-generating pathway that might be responsible for the reduced pH decline in WB samples. Further, the addition of excess of ATPase extended post-mortem glycolysis of WB meat in an in vitro glycolytic system. WB-affected samples have longer (P < 0.001) sarcomeres compared to NORM, indicating the existence of compromised energy-generating pathways in myopathic muscles that may have had consequences on the muscle contraction and tension development, as in vivo , also during the post-mortem period. Considering the overall reduced glycolytic potential and the myodegenerative processes associated with WB condition, we speculate that the higher pH u of WB meat might be the outcome of a drastically impaired energy-generating pathway combined with a deficiency and/or a dysfunction of muscle ATPases, having consequences also on muscle fiber contraction degree. [ABSTRACT FROM AUTHOR]

Over the past few decades, a considerable scientific progress has been achieved in the area of fish welfare at all stages—farming, transportation, various pre-slaughter manipulations, stunning/killing procedures, etc. The increasing scientific interest is mainly due to the serious need of developing and implementing specific fish welfare requirements across the whole chain for both ethical (welfare) and commercial (meat quality) reasons. Since there has been substantial evidence that fish are able to experience pain and suffering, the provoked stress response could be a major cause of altered post-mortem metabolism and impaired meat quality. The present review was aimed to present the relationship between ante-mortem stress, course of post-mortem metabolic processes and the potential alterations in some quality traits of fish for human consumption. [ABSTRACT FROM AUTHOR]

As nitric oxide (NO) is postulated to be a mediator of the effects of pre-slaughter stress on meat quality the aims of this experiment were to investigate the effects of modulating NO pharmacologically on meat quality of sedentary lambs. As pharmacological NO donors are prohibitively expensive to use in the lamb model l -Arginine, the substrate for NO synthase (NOS) was infused into lambs and increased NO production by ~ 30%. In a 2 × 2 factorial design we infused either l -Arginine (500 mg/kg) or the NOS inhibitor L-N G nitroarginine methyl ester hydrochloride (L-NAME, 30 mg/kg) 190 min pre-slaughter and investigated meat quality in the Longissimus thoracis lumborum (LTL) or Semimembranosus (SM). The principal outcome of the experiment was that L-NAME inhibited proteolysis and reduced tenderness in the SM. These data indicate that events pre-slaughter that affect NO synthesis can influence meat tenderness, potentially via altered muscle metabolism or modulation of proteolytic enzymes. [ABSTRACT FROM AUTHOR]

It is generally held that the content of several free amino acids and dipeptides is closely related to the energy-supplying metabolism of skeletal muscles. Metabolic characteristics of muscles are involved in the variability of meat quality due to their ability to influence the patterns of energy metabolism not only in living animal but also during postmortem time. Within this context, this study aimed at establishing whether the concentration of histidine dipeptides can affect muscle postmortem metabolism, examining the glycolytic pathway of 3 chicken muscles (pectoralis major, extensor iliotibialis lateralis, and gastrocnemius internus as glycolytic, intermediate, and oxidative-type, respectively) selected based on their histidine dipeptides content and ultimate pH. Thus, a total of 8 carcasses were obtained from the same flock of broiler chickens (Ross 308 strain, females, 49 d of age, 2.8 kg body weight at slaughter) and selected immediately after evisceration from the line of a commercial processing plant. Meat samples of about 1 cm 3 were excised from bone-in muscles at 15, 60, 120, and 1,440 min postmortem, instantly frozen in liquid nitrogen and used for the determination of pH, glycolytic metabolites, buffering capacity as well as histidine dipeptides content through 1 H-NMR. Overall results suggest that glycolysis in leg muscles ceased already after 2 h postmortem, whereas in breast muscle continued until 24 h, when it exhibited significantly lower pH values (P < 0.05). However, considering its remarkable glycolytic potential, pectoralis major muscle should have exhibited a greater and faster acidification, suggesting that its higher (P < 0.05) histidine dipeptides' content might have prevented a potentially stronger acidification process. Accordingly, breast muscle also showed greater (P < 0.05) buffering ability in the pH range 6.0-7.0. Therefore, anserine and carnosine, being highly positively correlated with muscle's buffering capacity (P < 0.001), might play a role in regulating postmortem pH decline, thus exerting an effect on muscle metabolism during prerigor phase and the quality of the forthcoming meat. Overall results also suggest that total histidine dipeptides content along with muscular ultimate pH represent good indicators for the energy-supplying metabolism of chicken muscles., (Copyright © 2020. Published by Elsevier Inc.)

Cultured meat aspires to be biologically equivalent to traditional meat. If cultured meat is to be consumed, sensorial (texture, color, flavor) and nutritional characteristics are of utmost importance. This paper compares cultured meat to traditional meat from a tissue engineering and meat technological point of view, focusing on several molecular, technological and sensorial attributes. We outline the challenges and future steps to be taken for cultured meat to mimic traditional meat as closely as possible., (Copyright © 2020 Fraeye, Kratka, Vandenburgh and Thorrez.)