Dietary ractopamine causes a muscle fiber shift in cattle, and the biochemistry of mitochondria in postmortem muscles is influenced by fiber type. Nonetheless, the influence of ractopamine on beef skeletal muscle mitochondrial proteome has not been evaluated. Therefore, the objective of this study was to examine the effects of dietary ractopamine on mitochondrial proteome of postmortem longissimus lumborum (LL) from feedlot crossbred steers. Pen-housed crossbred steers were fed either a corn-based basal diet (CON) or a diet top-dressed with Optaflexx 45 (Elanco Animal Health) to provide 400 mg of ractopamine hydrochloride/steer per day (RAC). Ractopamine was fed the last 28 days prior to the harvest. The LL muscle samples were obtained from nine (n = 9) RAC and nine (n = 9) CON carcasses. The mitochondrial proteome was analyzed using two-dimensional gel electrophoresis and mass spectrometry. Seven differentially abundant proteins (P < 0.05) were identified. Three proteins over-abundant in RAC were complement component 1 Q subcomponent-binding protein (C1QBP), very long-chain specific acyl-CoA dehydrogenase (ACADVL), and aconitate hydratase (ACO2). On the other hand, four proteins, ATP synthase subunit beta (ATP5B), prohibitin (PHB), cytochrome b-c1 complex subunit (UQCRC1), and thioredoxin-dependent peroxide reductase (PRDX3), were over-abundant in CON. The differentially abundant proteins belong to four functional groups - energy metabolism (ATP5B, UQCRC1, and ACO2); chaperone activity (C1QBP and PHB); redox metabolism (PRDX3); and fatty acid degradation (ACADVL). The increased protein synthesis and leanness reported in ractopamine-fed cattle may be attributed to the increased expression of enzyme involved in fatty acid degradation and the decreased expression of enzymes involved in oxidative phosphorylation. Additionally, the decreased tenderness previously reported in beef from ractopamine-fed cattle may be attributed to the increased expression of antiapoptotic protein (C1QBP) and decreased expression of proapoptotic protein (PHB) resulted from ractopamine supplement.

Mitochondrial functionality affects muscle-specific beef color stability. Nonetheless, the relationship between mitochondrial proteome and muscle-specific beef color stability is yet to be examined. Therefore, the objective of the present study was to differentiate the proteomes of mitochondria from beef longissimus lumborum (LL; color-stable muscle) and psoas major (PM; color-labile muscle) steaks during retail display. LL and PM muscles from 7 beef carcasses (USDA Choice; 48 h postmortem) were fabricated into 1.92-cm-thick steaks and were aerobically packaged and retail displayed for 6 d. Mitochondria were isolated on day 3 and 6, whereas instrumental color and biochemical attributes were evaluated on day 0, 3, and 6. Mitochondrial proteome was analyzed employing two-dimensional electrophoresis. The protein spots exhibiting 1.5-fold or more intensity differences (P < 0.05) between the muscles and display days were subjected to tryptic digestion and identified by tandem mass spectrometry. Whereas color stability decreased in both muscles during retail display, LL steaks demonstrated greater (P < 0.05) color stability during display than their PM counterparts. Mitochondria could not be isolated from PM steaks on day 6 because of extensive degradation. Seven proteins were differentially abundant ( P < 0.05) in LL and PM on day 3 of display. In LL steaks, 7 proteins were more abundant (P < 0.05) on day 3 than on day 6 of retail display. The differentially abundant proteins were enzymes, binding proteins, and proteins involved in biosynthesis. These results indicated that differential abundance of mitochondrial proteome could also contribute to the variations in color stability of beef LL and PM muscles during retail display.

Supplementation of vitamin E improves beef colour stability by minimizing lipid oxidation-induced myoglobin oxidation. Mitochondria affect myoglobin redox stability, and dietary vitamin E influences mitochondrial functionality in skeletal muscles. Nonetheless, the influence of vitamin E on the mitochondrial proteome of beef skeletal muscles has yet to be investigated. Therefore, the objective of this study was to examine the effect of dietary vitamin E on mitochondrial proteome of post-mortem beef longissimus lumborum (LL) muscle. Beef LL muscle samples (24 hours post-mortem) were obtained from the carcasses of nine (n = 9) vitamin E-fed (VITE) (1000 IU vitamin E for 89 days) and nine (n = 9) control (CONT) (diet without supplemental vitamin E) heifers. The mitochondrial proteome was analysed using two-dimensional gel electrophoresis and mass spectrometry, and nine differentially abundant spots were identified. All the differentially abundant spots were over-abundant in CONT, and the proteins were electron transport chain enzymes (NADH dehydrogenase iron-sulphur protein 8, NADH dehydrogenase flavoprotein 2, and cytochrome c oxidase subunit 5B), metabolic enzymes (succinate-CoA ligase (ADP-forming) subunit beta; dihydrolipoyllysine-residue succinyltransferase component of 2-oxoglutarate dehydrogenase complex; pyruvate dehydrogenase protein X component), and enzymes involved in ATP regeneration (creatine kinase S-type). The low abundance of these proteins in VITE may decrease mitochondrial activity, resulting in low oxidative activity. These findings suggest that the strong antioxidant activity of vitamin E leads to less expression of mitochondrial oxidative enzymes in beef skeletal muscles.

ObjectivesVitamin E is a lipid-soluble antioxidant that can inhibit lipid oxidation and improve beef color stability. The effect of vitamin E on fresh beef color, from the standpoint of lipid oxidation-induced myoglobin oxidation, have been extensively studied. However, the influence of vitamin E on sarcoplasmic proteome profile of beef skeletal muscles is yet to be investigated. Therefore, the objective of this study was to examine the effect of dietary vitamin E on sarcoplasmic proteome of postmortem beef longissimus lumborum (LL) muscle.Materials and MethodsCrossbred heifers, managed with a GrowSafe feeding system, were fed ad libitum corn-based diet containing either no supplemental (CONT) or 1000 IU vitamin E/heifer per day (VITE) for 89 d. The animals were harvested, and carcasses were chilled. The LL muscle samples were obtained from the carcasses of nine (n = 9) VITE and nine (n = 9) CONT heifers 24 h postmortem. The muscle samples were individually vacuum-packaged and frozen at –80°C for proteome analysis. Sarcoplasmic proteome was analyzed using two-dimensional electrophoresis, employing immobilized pH gradient strips (pH 3–10; 17 cm) in the first dimension and 12% sodium dodecyl sulfate polyacrylamide gel electrophoresis in the second dimension. The gels were scanned, and the digital gel images were analyzed. The protein spots exhibiting more than 1.5-fold intensity differences (P < 0.10) between VITE and CONT were subjected to in-gel tryptic digestion and were identified by tandem mass spectrometry.ResultsFive differentially abundant spots were identified using mass spectrometry, and all the spots were over-abundant in CONT. The proteins in the differentially abundant spots were antioxidant proteins (thioredoxin-dependent peroxide reductase, peroxiredoxin-6, and serum albumin) and glycolytic enzymes (β-enolase and triosephosphate isomerase). The antioxidant proteins minimize oxidation of lipids and proteins in muscle matrix, whereas the glycolytic enzymes generate NADPH, which helps maintain the antioxidant proteins in their reduced forms.ConclusionThe strong antioxidant protection offered by vitamin E could have possibly led to less expression of antioxidant proteins as well as glycolytic enzymes that generate antioxidant metabolites in the VITE group, whereas the lack of such protection in CONT group may have led to increased expression of these proteins in the skeletal muscles.

ObjectivesRactopamine is a β-adrenergic agonist approved as growth promotant in beef cattle, and it increases muscle deposition while limiting fat deposition. Dietary ractopamine causes a muscle fiber shift in cattle, and the biochemistry of mitochondria in postmortem beef skeletal muscles is influenced by fiber type. Therefore, dietary ractopamine may potentially affect mitochondrial functionality. Nonetheless, the influence of ractopamine on beef skeletal muscle mitochondrial proteome has not been evaluated. Therefore, the objective of this study was to examine the effects of ractopamine on mitochondrial proteome of postmortem longissimus lumborum (LL) from beef cattle.Materials and MethodsPen-housed crossbred steers were fed either a corn-based basal diet (CON) or a diet top-dressed with Optaflexx 45 (Elanco Animal Health) to provide 400 mg of ractopamine hydrochloride/steer per day (RAC). Ractopamine was fed the last 28 d prior to the harvest. The animals were harvested, and carcasses were chilled for 24 h. The LL muscle samples were obtained from nine (n = 9) RAC and nine (n = 9) CON carcasses. Mitochondrial proteome was analyzed using two-dimensional electrophoresis, and the digital gel images were analyzed. The protein spots exhibiting more than 1.5-fold intensity differences (P < 0.10) between RAC and CON were subjected to in-gel tryptic digestion and were identified by tandem mass spectrometry.ResultsSeven differentially abundant proteins were identified in the mitochondrial proteome. Three proteins were over-abundant (P < 0.10) in RAC, whereas four spots were over-abundant in CON. The proteins over-abundant in RAC mitochondrial proteome was complement component 1 Q subcomponent-binding protein, very long-chain specific acyl-CoA dehydrogenase, and aconitate hydratase. On the other hand, ATP synthase subunit β, prohibitin, Cytochrome b-c1 complex subunit, and thioredoxin-dependent peroxide reductase were over-abundant in CON samples. The differentially abundant proteins belong to four functional groups; i.e., energy metabolism (ATP synthase subunit β, Cytochrome b-c1 complex subunit 1, and aconitate hydratase), chaperone activity (complement component 1 Q subcomponent-binding protein and prohibitin), antioxidant activity (thioredoxin-dependent peroxide reductase), and lipid metabolism (very long-chain specific acyl-CoA dehydrogenase).ConclusionDietary ractopamine impacts mitochondrial proteome in postmortem beef LL muscle and influences the abundance of proteins involved in cellular metabolism and protective mechanisms. The increased protein synthesis and leanness previously reported in ractopamine-fed cattle may be attributed to the decreased expression of enzymes involved in respiratory electron transport pathways and the increased expression of enzymes involved in lipolysis.

Ractopamine is a beta-adrenergic agonist that is approved for use in beef cattle, pigs and turkeys as a repartitioning agent to increase lean muscle deposition and decrease lipogenesis. Although the effects of dietary ractopamine on the proteome profile of post-mortem pork muscles have been examined, its influence on beef muscle proteome has not been studied. Therefore, the objective of this study was to examine the effect of ractopamine on the proteome profile of post-mortem beef longissimus lumborum (LL) muscle. LL muscle samples were obtained from the carcasses of six (n = 6) steers fed ractopamine (RAC; 400 mg ractopamine hydrochloride for 28 days) and six (n = 6) steers fed no ractopamine (CON). The muscle proteome was analysed using two-dimensional gel electrophoresis and tandem mass spectrometry. Five differentially abundant spots were identified, and all the spots were over-abundant in RAC. The identified proteins were involved in muscle structure development (F-actin-capping protein subunit beta-2; PDZ and LIM domain protein-3), chaperone activity (heat shock protein beta-1), oxygen transport (myoglobin), and glycolysis (L-lactate dehydrogenase A chain). These results suggested that dietary ractopamine could influence the abundance of enzymes associated with muscle development and muscle fibre type shift in beef LL muscle.

Beef color is a muscle-specific trait, and sarcoplasmic proteome influences muscle-specific variations in beef color stability. Postmortem aging influences the color and sarcoplasmic proteome of beef muscles. Nonetheless, muscle-specific changes in sarcoplasmic proteome of beef muscles with differential color stability during aging have not been characterized yet. Therefore, our objective was to examine the changes in the sarcoplasmic proteome of 3 differentially color stable muscles from beef hindquarters during postmortem aging. Longissimus lumborum (LL), psoas major (PM), and semitendinosus (ST) separated from 8 (n = 8) beef carcasses (24 h postmortem) were subjected to aging in vacuum packaging (2°C) for 0, 7, 14, and 21 d. On each aging day, steaks were fabricated, and allotted to refrigerated storage (2°C) under aerobic packaging. Samples for proteome analysis obtained during fabrication were frozen at –80°C. Instrumental color and metmyoglobin reducing activity were evaluated on d 0, 3, and 6 of storage. Sarcoplasmic proteome was analyzed, and differentially abundant proteins were identified using mass spectrometry. Color attributes and biochemical parameters were influenced by muscle source and aging (P < 0.05); LL and ST had greater (P < 0.05) surface redness than PM. Aging also influenced surface redness, with 7-d aged steaks demonstrating greatest values (P < 0.05). Proteome analysis identified 135 protein spots differentially abundant (P < 0.05) between the muscles and aging time points indicating muscle-specific changes during aging. The identified proteins included glycolytic enzymes, proteins associated with energy metabolism, antioxidant proteins, chaperones, and transport proteins. Overall, the glycolytic enzymes were more abundant (P < 0.05) in color-stable muscles and at aging times with greater color stability, indicating that these proteins could be used as potential biomarkers for beef color.

ObjectivesModified atmosphere packaging (MAP) containing carbon monoxide (CO) is employed to stabilize and improve color of fresh red meats. CO binds with myoglobin to form carboxymyoglobin (COMb), which provides consumer-desirable bright cherry-red color to fresh meats. Although lipid oxidation-induced discoloration in COMb has been documented, the molecular basis for interactions between lipid oxidation products (i.e., reactive aldehydes) and red meat COMb has not been investigated. Therefore, our objective was to characterize the adduction of 4-hydroxy-2-nonenal (HNE), a model aldehyde, in beef COMb and pork COMb at typical meat storage condition.Materials and MethodsMyoglobin was purified from beef and pork cardiac muscle tissue. Deoxymyoglobin was prepared by sodium hydrosulfite-meditated reduction of myoglobin in 50 mM sodium citrate buffer (pH 5.6). COMb was prepared by bubbling deoxymyoglobin with a gas mixture containing 0.4% CO, 30% CO2, and 69.6% N2 for 40 min. Beef COMb (0.15 mM) and pork COMb (0.075 mM) were incubated with 1.0 mM HNE at pH 5.6 and 4°C (typical meat storage condition) for 8 d. Controls consisted of COMb plus an equivalent volume of ethanol used to deliver HNE. At the end of the storage, the samples were digested with trypsin, and the peptides were analyzed using liquid chromatography tandem-mass spectrometry (LC-MS/MS) for HNE adductsResultsLC-MS/MS spectra revealed that HNE adducted seven histidines (at positions 24, 48, 64, 88, 93, 119, and 152) in beef COMb, whereas only five histidines (at positions 24, 36, 48, 64, and 119) were adducted in pork COMb.ConclusionThese findings suggested that the molecular interactions between reactive lipid oxidation products and COMb are species-specific, and beef COMb is more susceptible to nucleophilic adduction by aldehydes than pork COMb. Additionally, the results indicated that lipid oxidation is more critical to color in fresh beef than in pork when retailing red meats in CO MAP.

Ractopamine is a beta-adrenergic agonist that increases leanness and carcass weight in finishing pigs. Our previous study observed that dietary ractopamine increased the abundance of several glycolytic enzymes in the sarcoplasmic proteome of post-rigor pork longissimus thoracis muscle. Pork semimembranosus is an economically important muscle and demonstrates differences in biochemistry compared with longissimus thoracis. Nonetheless, the effects of ractopamine on sarcoplasmic proteome of semimembranosus have not been evaluated yet. Therefore, this study examined the influence of ractopamine on sarcoplasmic proteome of post-rigor pork semimembranosus. Analyses of sarcoplasmic proteome of semimembranosus muscles from control (CON; diet without ractopamine) and ractopamine-fed (RAC; 7.4 mg/kg for 14 days followed by 10.0 mg/kg for 14 days) barrows revealed that haemoglobin subunit beta, alpha-crystallin B, and titin fragments were over-abundant in CON. In contrast, myosin light chain 1/3 and tripartite motif-containing protein 72 were over-abundant in RAC. The low abundance of haemoglobin subunit beta and alpha crystallin B in RAC could be attributed to fibre type shift (from oxidative to glycolytic) in response to ractopamine. The over-abundance of MLC 1/3 and tripartite motif-containing protein 72 in RAC could be due to the increased myofibrillar protein synthesis and muscle mass in ractopamine-fed pigs. Dietary ractopamine decreased the abundance of sarcoplasmic proteins involved in oxygen transport and chaperone activity, but increased the abundance of proteins involved in muscle contraction and plasma membrane repair in pork semimembranosus muscle.

ObjectivesMeat color is highly critical to fresh beef marketability as it influences consumer purchase decisions at the point-of-sale. Longissimus lumborum (LL) is an economically important and color-stable muscle in beef hindquarter which has been extensively studied with respect to color biochemistry. Previous research indicated that sarcoplasmic proteome influences fresh beef color. Post-mortem aging employed to improve beef tenderness and palatability can influence color as well as the sarcoplasmic proteome. Our objective was to examine color attributes and sarcoplasmic proteome profile of beef LL during wet-aging, and to identify potential biomarkers for beef color attributes.Materials and MethodsLL muscles were obtained from both sides of eight (n = 8) beef carcasses (USDA Choice, 24 h post-mortem). LL from each side was further divided into two equal-length sections and vacuum-packaged. The vacuum-packaged muscle sections were randomly assigned to aging at 2°C for either 0 (LL0), 7 (LL7), 14 (LL14), or 21 (LL21) days. On each aging period, muscle sections were fabricated into 2.5-cm thick steaks. Samples for proteome analysis obtained during fabrication were frozen at –80°C. After respective aging, the steaks were allowed to bloom for 2 h, and lightness (L*), redness (a*), yellowness (b*), hue (trueness of red), chroma (saturation index), pH, and metmyoglobin reducing activity (MRA) were evaluated. The color data, pH, and MRA were analyzed using MIXED procedure in SAS (SAS Inst. Inc., Cary, NC). Sarcoplasmic proteome was analyzed using two-dimensional electrophoresis (pH 5 to 8; 13.5% acrylamide gels). The images of Coomassie Blue-stained gels were obtained using VersaDoc and were analyzed by PDQuest software. The influence of aging on proteome profile was examined by comparing LL0 against rest of the aging days. Protein spots exhibiting 1.5–fold intensity difference and associated with P 0.05) on all aging days. Proteome analyses revealed that adenylate kinase isoenzyme 1 was more abundant in LL7, whereas creatine kinase M-type, β-enolase, phosphoglucomutase-1, heat shock cognate 71 kDa protein, and alanine aminotransferase 1 were more abundant in LL14. Comparison of LL0 and LL21 proteomes revealed greater abundance of ɑ-enolase in LL21, whereas malate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase were more abundant in LL0.ConclusionOur results indicated that beef LL demonstrates lower surface redness, lightness, yellowness, hue, and chroma on d 0 of aging compared to the other aging periods. Majority of the differentially abundant proteins observed in LL during aging are chaperones and enzymes associated with energy metabolism. Chaperones have been reported to prevent protein denaturation and aggregation in biological systems, whereas metabolic enzymes are well-known to play a critical role on beef color biochemistry. Therefore, these findings indicated that differentially abundant sarcoplasmic proteins could be utilized as potential biomarkers for color attributes in fresh beef LL.

ObjectivesRactopamine is a β-adrenergic agonist approved for use in cattle and pigs as a repartitioning agent to increase muscle deposition and potentially limit fat deposition. While the effects of ractopamine on proteome profile of postmortem pork muscles have been examined recently, its influence on beef muscle proteome has not been evaluated. Therefore, the objective of this study was to examine the effects of ractopamine on muscle proteome of postmortem longissimus lumborum (LL) from beef cattle.Materials and MethodsCrossbred steers housed in pens were fed either a corn-based basal diet (CON) or a diet top-dressed with Optaflexx 45 (Elanco Animal Health) to provide 400 mg of ractopamine hydrochloride/steer per day (RAC). Ractopamine was fed the last 28 d before slaughter. Steers were harvested, and carcasses were chilled. The LL muscle samples were obtained from the carcasses of 9 (n = 9) RAC and CON steers 24 h postmortem. The muscle samples were individually vacuum-packaged and frozen at –80°C for proteome analysis. Whole-muscle proteome was analyzed using 2-dimensional electrophoresis, and the digital gel images were analyzed. The protein spots exhibiting more than 1.5-fold intensity differences (P < 0.10) between RAC and CON were subjected to in-gel tryptic digestion and were identified by tandem mass spectrometry.ResultsFive differentially abundant protein spots identified were of greater (P < 0.10) abundance in LL samples from RAC compared to those from CON. The proteins identified were F-actin-capping protein subunit β2, PDZ and Lim domain protein-3, heat shock protein β-1, myoglobin, and L-lactate dehydrogenase A chain. The differentially abundant proteins belong to 4 functional groups; i.e., skeletal muscle organization (F-actin-capping protein subunit β2, and PDZ and LIM domain protein-3), chaperone activity (heat shock protein β-1), oxygen transportation (myoglobin), and energy metabolism (L-lactate dehydrogenase A chain).The over-abundance of F-actin-capping protein subunit β2 as well as PDZ and LIM domain protein-3 in RAC may be attributed to the increase in myofibrillar protein synthesis and increase in muscle mass as a result of ractopamine feeding. Heat shock protein β-1 is a chaperone that protects muscle proteins, and its increased abundance in RAC compared to CON may be due to the increased muscle protein synthesis. The over-abundance of myoglobin could possibly result from the increased oxygen consumption due to additional muscle mass accretion in RAC compared to CON, whereas the increased levels of L-lactate dehydrogenase A chain in RAC could potentially be due to the shift of muscle fiber type.ConclusionThe findings indicated that feeding ractopamine to steers influences the abundance of proteins involved in skeletal muscle organization, chaperone activity, oxygen transportation, and energy metabolism in postmortem beef LL muscle.

ObjectivesFresh beef color is critical to consumers’ purchase decisions. Beef color stability is muscle-specific, and the muscle-specific variations in sarcoplasmic proteome influence beef color. Post-mortem aging is a common practice employed by beef industry for improving beef tenderness and palatability. However, the color attributes and sarcoplasmic proteome of beef muscles undergo changes during aging. The objective of this study was to examine the changes in the sarcoplasmic proteome profile of 3 differentially color-stable muscles from beef hindquarters during postmortem aging.Materials and MethodsLongissimus lumborum (LL), psoas major (PM), and semitendinosus (ST) muscles were obtained from both sides of 8 (n = 8) beef carcasses (USDA Choice, 24 h post-mortem). Muscles were further divided into 2 equal-length sections and vacuum-packaged. The vacuum-packaged muscle sections were randomly assigned to aging at 2°C for either 0, 7, 14, or 21 d. On each aging period, muscle sections were fabricated into 2.5-cm thick steaks, individually over-wrapped, and allocated to refrigerated storage for 0, 3, or 6 d. Samples for proteome analysis obtained during fabrication were frozen at –80°C. On each storage day, lightness (L*), redness (a*), yellowness (b*), hue (trueness of red), chroma (saturation index), pH, and metmyoglobin reducing activity (MRA) were evaluated. The instrumental color, pH, and MRA data were analyzed using MIXED procedure in SAS (SAS Inst. Inc., Cary, NC). Sarcoplasmic proteome was analyzed using 2-dimensional electrophoresis (pH 5 to 8; 13.5% acrylamide gels). The images of Coomassie Blue-stained gels were obtained and analyzed. Protein spots exhibiting 1.5–fold intensity difference (P < 0.05) were considered differentially abundant and were subjected to tryptic digestion and tandem mass spectrometry for identificationResultsThe results indicated that instrumental color attributes and biochemical parameters during storage were influenced by muscle source and aging (P < 0.05). LL and ST had greater (P < 0.05) surface redness (a* value) than PM, whereas the color stability (R630/580) followed the order: LL > ST > PM. Aging also influenced surface redness with 7-d aged steaks demonstrating greatest values (P < 0.05). Proteome analysis identified differentially abundant glycolytic enzymes between the treatments (muscle source and aging days; P < 0.05) indicating muscle-specific changes in sarcoplasmic proteins during aging. The glycolytic enzymes identified (triosephosphate isomerase, glyceraldehyde-3-phosphate dehydrogenase, enolase, and phosphoglucomutase-1) were more abundant (P < 0.05) in color-stable LL and ST compared to color-labile PM.ConclusionOur results indicated that the color attributes and sarcoplasmic proteome profile of beef LL, PM, and ST were influenced by aging for 21 d. Furthermore, the aging-induced changes in the sarcoplasmic proteome profile and color traits were muscle-specific. The differentially abundant glycolytic enzymes could be used as biomarkers for beef color, and for developing muscle-specific processing strategies to improve beef color stability.

Intramuscular color stability variations in beef semimembranosus have been reported previously. Mitochondria remain biochemically active in postmortem muscle and can influence fresh beef color stability. However, the role of mitochondrial functionality in intramuscular color variations in beef semimembranosus is yet to be examined. We examined the functionality of mitochondria isolated from outside (OSM) and inside (ISM) regions of beef semimembranosus . Semimembranosus muscles (n = 5) were collected from inside rounds of beef carcasses 48 h post-mortem and were separated to OSM and ISM steaks. Color attributes were evaluated instrumentally and biochemically on days 0 and 4 of retail display, whereas mitochondrial oxygen consumption rate (OCR) was measured on day 0 using succinate as substrate using steaks frozen during fabrication. Mitochondrial OCR was significantly greater in OSM than in ISM on day 0. The ISM steaks exhibited significantly greater redness (a* value) than OSM steaks on day 0, but OSM steaks had significantly greater redness than the ISM counterparts on day 4. During retail display, ISM steaks exhibited greater lightness (L* value) than OSM steaks. However, OSM demonstrated significantly greater color stability and metmyoglobin reducing activity than ISM throughout the display. The observed differences in mitochondrial OCR between ISM and OSM steaks indicated that mitochondrial biochemistry possibly contributes to the intramuscular color variations in beef semimembranosus. Keywords : Beef color, color stability, mitochondria, semimembranosus

Woody breast meat has recently become prevalent in the broiler industry in both the United States and European Union. Recent publications have described the meat quality characteristics of woody breast meat as having hardened areas and pale ridge-like bulges at both the caudal and cranial regions of the breast. The present study investigated the meat quality (pH, color, cooking loss, and shear force) and protein quality characteristics (protein and salt-soluble protein content) in woody breast meat as compared to normal breast meat. In addition, the differences in the muscle proteome profiles of woody and normal breast meat were characterized. Results indicated that woody breast meat had a greater average pH (P < 0.0001) and cooking loss (P = 0.001) than normal breast meat, but woody breast meat did not differ in shear force (P > 0.05) in comparison to normal breast meat samples. The L*, a*, and b* values of woody breast fillets were greater than normal breast fillets (P < 0.0001 to L*; P = 0.002 to a*; P = 0.016 to b*). The woody breast meat had more fat (P < 0.0001) and moisture (P < 0.021) and less protein (P < 0.0001) and salt-soluble protein (P < 0.0001) when compared with normal breast fillets. Whole muscle proteome analysis indicated 8 proteins that were differentially expressed (P < 0.05) between normal and woody breast meat samples. The differences in muscle proteome between normal and woody breast meat indicated an increased oxidative stress in woody breast meat when compared to normal meat. In addition, the abundance of some glycolytic enzymes, which are critical to the regeneration of adenosine triphosphate (ATP) in postmortem muscles, was lower in woody breast meat than in normal breast meat. Proteomic differences provide additional information on the biochemical pathways and genetic variations that lead to woody breast meat. Further research should be conducted to elucidate the genetic and nutritional contributions to the proliferation of woody breast meat in the United States.

Pig semimembranosus muscles, sampled from normal hams or from PSE-zones of defective hams, were analysed by histochemistry and electrophoretic techniques. PSE zones were characterised by a disorganisation of fibre alignment and a significant increase of inter fibre spacing (26.2% vs. 16.9%, p < 0.05). Protein solubility was significantly lower in defective muscle (55.4 vs. 91.5 mg/g, p < 0.001). SDS–PAGE evidenced in such samples a lower abundance of the 97, 40 and 26 kDa bands in the sarcoplasmic fraction and a higher abundance of the 97, 58, 34, 31, 15 and 11 kDa bands in the myofibrillar fraction. Intensity of the MHC band (200 kDa) was lower in PSE zone samples. By 2-D electrophoresis, it was shown that troponin T, MLC 1 and alpha-crystallin were less proteolysed in defective muscles, while creatine kinase fragments were more represented. One form of HSP 27 was absent from PSE zone samples. Overall, meat from PSE-zones and fast pH fall-PSE meat show numerous histological and biochemical similarities, particularly in their protein characteristics.

Pale, Soft, and Exudative (PSE) broiler breast meat has poor protein functionality, which leads to quality problems and economic loss in the poultry industry. Proteomics has been applied to characterize the biochemical mechanisms governing tenderness, color, and water-holding capacity in meat. However, the proteome basis of PSE has not yet been characterized for broiler breast meat. Therefore, this study was conducted to determine the differences in meat quality (cooking loss and shear force), descriptive sensory characteristics, consumer acceptance, and whole muscle proteome between normal and PSE-like broiler breast meat. Male Hubbard × Cobb 500 birds (n = 1,050) were raised in commercial houses. Prior to harvest, a sample of the broilers (n = 900) were subjected to short-term stress (38°C for 2 h), and the remaining broilers (n = 150) were maintained at control conditions (21°C for 2 h). Broiler breast (Pectoralis major) meat was collected and characterized by pH24 and L*24 as normal (pH24 5.8 to 6.2, L*24 45 to 55) or PSE-like (pH24 5.4 to 5.7, L*24 55 to 65) samples. Normal broiler breast meat had lower shear force values than PSE-like meat (P < 0.05). Based on sensory descriptive analysis, normal cooked chicken breast meat was more tender and juicier than PSE-like breast meat (P < 0.05). Consumer sensory analysis results indicated that 81% of consumer panelists liked normal breast meat whereas 62% of the panelists liked PSE-like breast meat. Whole muscle proteome profiling identified fifteen differentially abundant proteins in normal and PSE-like broiler breast samples. Actin alpha, myosin heavy chain, phosphoglycerate kinase, creatine kinase M type, beta-enolase, carbonic anhydrase 2, proteasome subunit alpha, pyruvate kinase, and malate dehydrogenase were over-abundant (P < 0.05) in PSE-like broiler breast whereas phosphoglycerate mutase-1, alpha-enolase, ATP-dependent 6-phosphofructokinase, and fructose 1,6-bisphosphatase were over-abundant (P < 0.05) in normal meat. Thus, results indicated that differences in proteome abundance could be related to the meat quality differences between normal and PSE-like broiler breast meat.

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.

Wash water streams coming from rinsing of equipment in a detergent production site is in many cases considered as waste. On site treatment in waste water plants is possible but typically requires advanced oxidation process (AOP) technology which uses chemicals and creates a waste sludge. A new treatment approach, based on nanofiltration, has been demonstrated at industrial scale in a detergent production site in China. Wash water could be split into a concentrate stream and water fraction. The concentrate stream contains most of the valuable surfactants and has a value to recycle. The water fraction can easily be polished by MBR to feed cooling towers. As such, this production site does not discharge any process wash water and recovers all resources out of the rinsing water: both chemicals (as surfactants) as the water.

The sarcoplasmic proteome of beef Longissimus lumborum demonstrating animal-to-animal variation in color stability was examined to correlate proteome profile with color. Longissimus lumborum (36h post-mortem) muscles were obtained from 73 beef carcasses, aged for 13days, and fabricated to 2.5-cm steaks. One steak was allotted to retail display, and another was immediately vacuum packaged and frozen at −80°C. Aerobically packaged steaks were stored under display, and color was evaluated on days 0 and 11. The steaks were ranked based on redness and color stability on day 11, and ten color-stable and ten color-labile carcasses were identified. Sarcoplasmic proteome of frozen steaks from the selected carcasses was analyzed. Nine proteins were differentially abundant in color-stable and color-labile steaks. Three glycolytic enzymes (phosphoglucomutase-1, glyceraldehyde-3-phosphate dehydrogenase, and pyruvate kinase M2) were over-abundant in color-stable steaks and positively correlated (P<0.05) to redness and color stability. These results indicated that animal variations in proteome contribute to differences in beef color.