Effect of muscle and post-mortem rate of pH and temperature fall on antioxidant enzyme activities in beef

New findings on post-mortem chicken quality changes: The ROS-influenced MAPK-JNK signaling pathway affects chicken quality by regulating muscle cell apoptosis

Research conducted previously has demonstrated that apoptosis significantly influences the chicken quality. While ROS are acknowledged as significant activators of apoptosis, the precise mechanism by which they influence muscle cell apoptosis in the post-mortem remains unclear. In this study, chicken samples were treated with rosemarinic acid and H2O2 to induce varying ROS levels, and the ROS-triggered apoptosis mechanism in chicken muscle cells in post-mortem was analyzed. The TUNEL results revealed that elevated ROS levels in chicken were associated with a greater degree of muscle cell apoptosis. Western-blot results suggested that sarcoplasmic ROS could initiate apoptosis through the mitochondrial pathway by activating the MAPK-JNK signaling pathway. Moreover, TEM and shear force results demonstrated that muscle cell apoptosis initiates myofiber fragmentation and structural damage to sarcomeres, ultimately reducing chicken tenderness. This study enhances our understanding of post-mortem muscle cell apoptosis, providing valuable insights for regulating chicken quality.

Life after death? Exploring biochemical and molecular changes following organismal death in green turtles, Chelonia mydas (Linnaeus, 1758)

Green turtles, Chelonia mydas, have been included in biomonitoring efforts given its status as an endangered species. Many studies, however, rely on samples from stranded animals, raising the question of how death affects important biochemical and molecular biomarkers. The goal of this study was to investigate post mortem fluctuations in the antioxidant response and metabolism of carbohydrates in the liver of C. mydas. Liver samples were obtained from six green turtles which were submitted to rehabilitation and euthanized due to the impossibility of recovery. Samples were collected immediately after death (t = 0) and at various time intervals (1, 2, 3, 4, 5, 6, 12, 18 and 24 h post mortem), frozen in liquid nitrogen and stored at -80 °C. The activities of catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glucose-6-phosphate dehydrogenase (G6PDH) were analyzed, as were the levels of lipid peroxidation, glycogen concentration, RNA integrity (RNA IQ) and transcript levels of carbonic anhydrase and pyruvate carboxylase genes. Comparison between post mortem intervals showed a temporal stability for all the biomarkers evaluated, suggesting that changes in biochemical and molecular parameters following green turtle death are not immediate, and metabolism may remain somewhat unaltered up to 24 h after death. Such stability may be associated with the overall lower metabolism of turtles, especially under an oxygen deprivation scenario such as organismal death. Overall, this study supports the use of biomarkers in sea turtles sampled within a period of 24 h post mortem for biomonitoring purposes, though it is recommended that post mortem fluctuations of particular biomarkers be evaluated prior to their application, given that proteins may show varying degrees of susceptibility to proteolysis.

The effect of postmortem pH decline rate on caspase-3 activation and tenderness of bovine skeletal muscle during aging

This study aimed to investigate the effect of postmortem pH decline rate on caspase-3 activity and bovine muscle tenderness during aging. Protein denaturation, reactive oxygen species (ROS) levels, mitochondrial apoptosis factors, and shear force were assessed in bovine muscles with different pH decline rates. The results showed that, compared with the slow group, the fast pH decline group had a 1.79% and 1.39% higher sarcoplasmic protein denaturation at 6 and 12 h, respectively (p < .05), and a significantly or extremely significantly higher ROS levels at 6-24 (p < .05, p < .01). Moreover, the fast group had a 14.05%, 22.39%,18.34%, and 25.28% of higher mitochondrial dysfunction at 6, 12, 24, and 72 h, respectively (p < .05); a 16.71%, 23.39%, 17.05%, and 26.61% of lower cytochrome c reduction levels at 6, 12, 24, and 120 h, respectively (p < .05); a significantly increased caspase-3 activity and proportion of apoptotic nuclei at 12-168 and 24-168 h, respectively (p < .05); and a 5.70%, 7.24%, 12.16%, 10.10% and 10.49% decreased shear force at 12, 24, 72,120, and 168 h, respectively (p < .05). These results demonstrated that the fast postmortem pH decline enhanced caspase-3 activation and bovine muscle tenderization by mitochondrial dysfunction-induced apoptosis during aging. PRACTICAL APPLICATIONS: Beef tenderness has long been one of the most important concerns for consumers and the meat industry. To date, the postmortem aging process has been an effective way to improve the tenderness of chilled beef. However, changes in many of the elements in a cattle's muscle after slaughter might actually determine the final tenderness of the meat. The present study suggested that the fast postmortem pH decline could promote the activation of caspase-3 and improve the tenderness of beef during aging. This finding can provide a basis for the meat processing industry to produce beef with high tenderness. In the future, beef tenderness could even be improved by adjusting the glycolytic rate and pH of muscle for a short time after slaughter.

The Activity of Chosen Antioxidant Enzymes in Ostrich Meat in Relation to the Type of Packaging and Storage Time in Refrigeration

The aim of the study was to investigate the changes in the activity of antioxidant enzymes, i.e., superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity in ostrich meat, as influenced by various packaging systems and storage time under refrigeration. Three packaging methods were used: vacuum packaging (VP) and modified atmosphere packaging (MAP) in two combinations of gases, MAP1 (40% O₂/40% CO₂/20% N₂) and MAP2 (60% O₂/30% CO₂/10% N₂). Meat samples were taken from the M. ilifibularis (IF) muscles of eight ostriches in each treatment group. The meat samples were stored in a refrigerator in 2 °C and analyzed at days 0, 4, 8, 12 and 16. The lowest level of SOD activity during storage was observed in ostrich muscles packed in vacuum, as compared to MAP1 and MAP2. In turn, the highest increase in GPx activity was recorded in VP, especially up to day 8 of storage, when this parameter reached maximum value (54.37). GR increased up to the eighth day of storage in MAP1 and VP. Between the 12th and 16th days of storage, stabilization of the GR activity level was observed only in VP, while under MAP1, it further decreased. DPPH remained relatively stable until the eighth day of storage and after this period, a decrease in this parameter was recorded, reaching the lowest value on day 12 for all types of packaging systems.

Influence of Crescentia cujete and Launaea taraxacifolia leaves on growth, immune indices, gut microbiota, blood chemistry, carcass, and meat quality in broiler chickens

The rising concerns pertaining to the safety of synthetic supplements in livestock production have encouraged the exploration of potential alternatives. This study investigated the growth, gut microbiota, blood chemistry, immune indices, meat quality, and antioxidant status in broiler chickens supplemented with Crescentia cujete leaf (CCL), Launaea taraxacifolia leaf (LTL), and a combination of antibiotic (70% oxytetracycline + 30% neomycin) and tert-Butylhydroxyanisole. One-day-old Ross 308 chicks (n = 420) were randomly assigned to either T-1, basal diet (BD) only; T-2, BD + 0.4 g/kg antibiotic + 0.13 g/kg tert-butylhydroxyanisole; T-3, BD + 2.5 g/kg LTL; T-4, BD + 5 g/kg LTL; T-5, BD + 2.5 g/kg CCL; or T-6, BD + 5 g/kg CCL for 42 days. Each dietary group had seven replicates with ten chicks per replicate. Body weight gain and carcass weight were higher (P < 0.05) in the T-2, T-4, T-5, and T-6 birds compared with those of other birds. At 1-21 days, the T-2 and T-4 birds consumed more feed than the T-1 and T-3 birds. At 22-42 days, the T-4 birds consumed more (P < 0.05) feed than the T-1 and T-3 birds. During 1-42 days, the T-1 and T-3 birds consumed less (P < 0.05) feed than other birds. At 22-42 days and 1-42 days, the T-1 had lower feed efficiency (P < 0.05) than other birds except for the T-3 birds. The CCL and LTL birds had lower (P < 0.05) serum LDL cholesterol and higher HDL cholesterol compared with other birds. Hematology, splenic interleukin-1β, immunoglobulin M, ileal and caecal total aerobic bacteria counts, caecal Lactobacillus spp., and meat physicochemical properties were unaffected by diets. The T-1 birds had higher (P < 0.05) ileal and caecal Clostridium spp., E. coli, and Salmonella spp. compared with birds fed other diets. The CCL and LTL birds had higher ileal Lactobacillus counts. Splenic IL-10 was higher (P < 0.05) in the T-2, T-4, and T-6 birds compared with that in other birds. Dietary supplementation with CCL, LTL, and a combination of antibiotic and tert-butylhydroxyanisole repressed (P < 0.05) splenic tumor necrosis-α and immunoglobulin G. The T-1 breast meat had lower glutathione peroxidase and catalase. The T-4 meat had higher (P < 0.05) superoxide dismutase, glutathione peroxidase, catalase, and total antioxidant capacity compared with other meats. On day 3 postmortem, meats obtained from birds supplemented with CCL, LTL, and a combination of antibiotic and tert-butylhydroxyanisole had lower (P < 0.05) carbonyl and malondialdehyde contents than the meat from the non-supplemented birds. The 5 g/kg CCL and 5 g/kg LTL could be used as antimicrobial and antioxidant in broiler diets.

Evaluation of RNA quality and functional transcriptome of beef longissimus thoracis over time post-mortem

Evaluating RNA quality and transcriptomic profile of beef muscle over time post-mortem may provide insight into RNA degradation and underlying biological and functional mechanisms that accompany biochemical changes occurring post-mortem during transformation of muscle to meat. RNA was extracted from longissimus thoracis (LT) sampled from British Continental crossbred heifer carcasses (n = 7) stored at 4°C in an abattoir drip cooler at 5 time points post-mortem, i.e., 45 min (0 h), 6 h, 24 h, 48 h, and 72 h. Following RNA-Sequencing, processed reads were aligned to the ARS-UCD1.2 bovine genome assembly. Subsequent differential expression (DE) analysis identified from 51 to 1434 upregulated and 27 to 2256 downregulated DE genes at individual time points compared to time 0 h, showing a trend for increasing counts of both upregulated and downregulated genes over time. Gene ontology and biological pathway term enrichment analyses on sets of DE genes revealed several processes and their timelines of activation/deactivation that accompanied or were involved with muscle transformation to meat. Although the quality of RNA in refrigerated LT remained high for several days post-mortem, the expression levels of several known biomarker genes for meat quality began to change from 24 h onwards. Therefore, to ensure accuracy of predictions on meat quality traits based on the expression levels of those biomarker genes in refrigerated beef muscle tissue, it is crucial that those expression measurements be made on RNA sampled within 24 h post-mortem. The present study also highlighted the need for more research on the roles of mitochondrial genes and non-coding genes in orchestrating muscle tissue processes after death, and how pre-mortem immune status might influence post-mortem meat quality.

Wild antelope skeletal muscle antioxidant enzyme activities do not correlate with muscle fibre type or oxidative metabolism

Wild antelope are some of the fastest land animals in the world, presenting with high oxidative and glycolytic skeletal muscle metabolism. However, no study has investigated their muscle antioxidant capacity, and may assist in understanding their physical ability and certain pathophysiological manifestations, such as capture myopathy. Therefore, the primary aim of this study was to determine the antioxidant activities superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR), as well as five key regulatory enzymes that serve as markers of glycolysis (phosphofructokinase (PFK) and lactate dehydrogenase (LDH)), the tricarboxylic acid cycle (citrate synthase (CS)), β-oxidation (3-hydroxyacetyl CoA dehydrogenase (3HAD)) and the phosphagen pathway (creatine kinase (CK)), in the Vastus lateralis muscle of six southern African wild antelope species (mountain reedbuck, springbok, blesbok, fallow deer, black wildebeest and kudu). Four different muscle groups from laboratory rats served as reference values for the enzyme activities. SOD, CS and LDH activities were the highest in the wild antelope, whereas CK appeared highest in rat fast twitch muscles. Between the wild antelope species, differences exist for SOD, CAT, PFK, CK and LDH, but not for CS, 3HAD and GR. CAT and GR correlated positively only with type I fibres. No correlations could be found between muscle fibre type and the oxidative enzymes, CS and 3HAD, from the wild animals, concurring with previous studies on porcine and rats. However, wild antelope and rat muscle CK and SOD strongly correlated, hinting towards an antioxidant role for CK.

Computational prediction of nsSNPs effects on protein function and structure, a prioritization approach for further in vitro studies applied to bovine GSTP1

The development of high-throughput technologies in the last decade produced an exponential increase in the amount of biological data available. The case of redox biology and apoptosis is not an exception, and nowadays there is a need to integrate information from multiple "omics" studies. Therefore, validation of proposed discoveries is essential. However, the study in biological systems of the effect of the massive amounts of sequence variation data generated with next-generation sequencing (NGS) technologies can be a very difficult and expensive process. In this context, the present study aimed to demonstrate the advantages of a computational methodology to systematically analyze the structural and functional effects of protein variants, in order to prioritize further studies. This approach stands out for its easy implementation, low costs and low time consumed. First, the possible impact of mutations on protein structure and function was tested by a combination of tools based on evolutionary and structural information. Next, homology modeling was performed to predict and compare the 3D protein structures of unresolved amino acid sequences obtained from genomic resequencing. This analysis applied to the bovine GSTP1 allowed to determine that some of amino acid substitutions may generate important changes in protein structure and function. Moreover, the haplotype analysis highlighted three structure variants worthwhile studying through in vitro or in vivo experiments.

Changes in the colour and sensory properties of beef frozen after seven days of ageing in a modified atmosphere

The aim of the study was to evaluate the colour, sensory properties and shear force values of meat from ten young bulls produced by crossing Polish Black-and-White Holstein-Friesian cows with Belgian White Blue bulls. The quality of the longissimus lumborum (LL) muscle was determined after seven-day ageing under various modified atmosphere (MA) conditions (vacuum – group B; 40% CO2 + 60% N2 – group C; 30% CO2 + 70% Ar – group D) followed by freezing and frozen storage. The process of seven- day ageing in MA composed of 40% CO2 + 60% N2 significantly increased the colour lightness of the beef samples. Eight-month frozen storage increased colour lightness in the meat samples aged in MA composed of 30% CO2 + 70% Ar. Meat samples aged under various MA conditions had a higher contribution of redness (a*) and yellowness (b*) than non-aged beef. Meat samples frozen after ageing in MA containing Ar had less redness than the samples from other groups. After frozen storage, meat samples from all groups had less redness and yellowness. Ageing and frozen storage had no significant effect on the juiciness of the beef. The beef aged in vacuum conditions was the most tender, both before and after frozen storage. Ageing had no significant influence on the shear force of meat samples evaluated before freezing. Meat samples aged in MA composed of 30% CO2 + 70% Ar evaluated after frozen storage had lower average shear force values than beef that had not been aged prior to freezing.

Fatty acid compositions, free radical scavenging activities, and antioxidative enzyme activities of high-preference and low-preference beef cuts of Hanwoo (Bos taurus coreanae) cows

Objective

This study compared fatty acid compositions and antioxidant activities of high-preference cuts (loin, tenderloin, and rib) and low-preference cuts (brisket, topside, and shank) of Hanwoo (Bos taurus coreanae) cows to obtain potentially useful information for promoting the consumption of various low-preference cuts.

Methods

Individual 500 g samples of fresh beef were collected from each of the six cuts from 10 Hanwoo cows (quality grade 1) and immediately freeze-dried. The dried samples were evaluated for fatty acid composition, free radical scavenging activities (hydroxyl, alkyl, and 2, 2′-diphenyl-1-picrylhydrazyl [DPPH] radical), and antioxidative enzyme activities (glutathione peroxidase [GPx], glutathione-S-transferase [GST], and superoxide dismutase [SOD]).

Results

The percentages of total polyunsaturated fatty acids were significantly higher in low-preference cuts than in high-preference cuts (p<0.05). Hydroxyl, alkyl, and DPPH radical scavenging activities were significantly higher in low-preference cuts than in high-preference cuts (p<0.05). In addition, the activities of antioxidant enzymes, such as GPx, GST, and SOD, were significantly higher in low-preference cuts compared with high-preference cuts (p<0.05).

Conclusion

These results may influence consumers to include more low-preference cuts in their selections based on the nutritional facts, which could help to balance the beef market in South Korea.

Modelling postmortem evolution of pH in beef M. biceps femoris under two different cooling regimes

A model based on enzyme kinetics was developed to predict differences in postmortem pH change in beef muscles as affected by cooling rate. For the calibration and validation of the model, pH and temperature measurements were conducted at different positions in M. biceps femoris following conventional carcass cooling or faster cooling of the muscle after hot boning. The glycogen conversion, and, hence, the pH fall, was observed to significantly vary with position and cooling regime but only during the initial hours of cooling. Comparison of the cooling regimes indicated that fast cooling following hot boning avoids heat shortening induced by the combined effect of high temperature and low pH.

Proteome basis for intramuscular variation in color stability of beef semimembranosus

The objective of the present study was to characterize the proteome basis for intramuscular color stability variations in beef semimembranosus. Semimembranosus muscles from eight carcasses (n=8) were fabricated into 2.54-cm thick color-labile inside (ISM) and color-stable outside (OSM) steaks. One steak for sarcoplasmic proteome analysis was immediately frozen, whereas other steaks were allotted to retail display under aerobic packaging. Color attributes were evaluated instrumentally and biochemically on 0, 2, and 4days. Sarcoplasmic proteome was analyzed using two-dimensional electrophoresis and tandem mass spectrometry. ISM steaks demonstrated greater (P<0.01) abundance of glycolytic enzymes (fructose-bisphosphate aldolase A, phosphoglycerate mutase 2, and beta-enolase) and phosphatidylethanolamine-binding protein 1 than their OSM counterparts. Possible rapid post-mortem glycolysis in ISM, insinuated by over-abundance of glycolytic enzymes, could lead to rapid pH decline during early post-mortem, which in turn could potentially compromise its color stability. These results indicated that differential abundance of sarcoplasmic proteome contributes to intramuscular variations in beef color stability.