Temperature, but not excess of glycogen, regulate post-mortem AMPK activity in muscle of steer carcasses (original) (raw)
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Meat Science, 2015
Muscle glycogen concentration (MGC) and lactate (LA), activity of glycogen debranching enzyme (GDE), glycogen phosphorylase (GP) and adenosine monophosphate kinase (AMPK) were determined at 0.5 h (T0) and 24 h (T24) post-mortem in Longissimus dorsi samples from 38 steers that produced high pH (N 5.9) and normal pH (b 5.8) carcasses at 24 h postmortem. MGC, LA and glycolytic potential were higher (P b 0.05) in normal pH carcasses. GDE activity was similar (P N 0.05) in both pH categories. GP activity increased between T0 and T24 only in normal pH carcasses. AMPK activity was four times higher in normal pH v/s high pH carcasses, without changing its activity over time. Results reinforce the idea that differences in postmortem glycogenolytic/glycolytic flow in L. dorsi of steers showing normal v/s high muscle pH at 24 h, could be explained not only by the higher initial MGC in normal pH carcasses, but also by a high and sustained activity of AMPK and an increased GP activity at 24 h postmortem.
Dehydrogenase Enzymes Associated to Glycolysis in Beef Carcasses Stored at 0 °C
Food and Bioprocess Technology, 2012
After the death of an animal, cell metabolism is controlled locally. The post-mortem oxygen depletion increases the glycolytic activity and lactate production. However, many mechanisms of post-mortem metabolic regulation have not been fully investigated in beef carcasses. In this work, we studied the post-mortem glycolytic behavior (including lactate dehydrogenase) and three dehydrogenase associated to glycolysis (glycerophosphate dehydrogenase, glucose 6-phosphate dehydrogenase, and glycerol dehydrogenase) by using cytochemistry techniques in three fasttwitch muscles (M. longissimus dorsi, M. semimembranosus, and M. cutaneus trunci) of carcasses stored at 0°C. Our results indicate that glycolysis depends on the type of muscle. The post-mortem glycolytic flux and lactate dehydrogenase activity of M. cutaneus trunci was the lowest of the three muscles studied. Of the other dehydrogenases analyzed, only glycerophosphate and glycerol dehydrogenase showed clear cytochemical reaction. Glucose 6-phosphate dehydrogenase was not used by muscles very much. The glycerophosphate dehydrogenase was the strongest enzymatic activity correlated to the post-mortem glycolytic flux. In addition, a relationship between glycerophosphate dehydrogenase and glycerol dehydrogenase was detected by using a multiple regression model. This phenomenon was studied by using bioinformatics tools, suggesting that glycerophosphate dehydrogenase could oxidize the glycerol in bovine fast-twitch muscles.
Glycogen determination in post-mortem beef muscles
Food Chemistry, 1984
lactate in post-mortem muscle. Results suggest that this could be due to dijficulties in assessing glycogen content. In the present study it was found that glycogen was particularly difficult to analyse in beef of a high ultimate pH, but no apparent explanation for this can be given. Four different methods involving enzymatic hydrolysis and acid hydrolysis were compared for measurement of glycogen. It was found that enzymatic hydrolysis was preferable and that the glycogen method should include boiling, particularly if the samples had been jrozen jor several months. Prolonged freezer storage decreased the glycogen values obtained by about 15-25 %. Stoichiometry in the conversion of glycogen into intermediates of the Embden-Meyerhof pathway and lactate was Jbund if glycerol-3-phosphate was taken into consideration and the results were adjusted for the effect of freezer storage. * Present address: AB Ferrosan, PO Box 839, S-201 80, Malmoe, Sweden. 269 Food Chemistry 0308-8146/84/$03'00
Meat Science, 2006
The objective of this study was to determine the effects of the halothane (HAL) and Rendement Napole (RN) genes on the rate-limiting reactions of glycolysis and their relationship to pork quality development. Samples were collected from the longissimus muscle at 0, 30, 60, and 120 min and 24 h postmortem from homozygous HAL and RN pigs (NN/rn + rn + , NN/RN À RN À , nn/rn + rn + , nn/RN À RN À). Muscle pH was recorded at 0, 15, and 45 min, and 24 h postmortem. HAL mutants, compared with HAL normal, had lower (P < 0.05) ATP concentrations at 0 and 30 min, lower (P < 0.05) pH at 45 min, and hastened glycogen degradation and lactate accumulation in the first 120 min postmortem (HAL • time, P < 0.0001). RN mutants had greater (P < 0.0001) glycolytic potentials than RN normal, and lower (P < 0.05) 24 h pH compared with the normal genotype, but not the HAL mutant genotype. The HAL mutation negatively affected (P < 0.05) L * , b * and color scores whereas both HAL and RN mutations independently decreased (P < 0.05) firmness, marbling and water holding capacity. RN mutant genotypes had higher (P < 0.0001) phosphocreatine concentrations than other genotypes at 0 min. Compared with HAL normal, HAL mutants had elevated (P < 0.05) muscle glucose concentrations at 30, 60, and 120 min, and 24 h. RN mutants had higher (P < 0.05) glucose levels than RN normal after 60 min. Glucose-6-phosphate (G6P) concentrations decreased (P < 0.05) during the first hour postmortem except in HAL/RN mutants, which had higher (P < 0.01) G6P concentrations than all other genotypes at 30 min. From 60 min to 24 h postmortem, G6P increased (P < 0.05) in HAL normal genotypes. Altogether, these data show that elevated muscle glycogen content does not further aggravate rapid early postmortem metabolism.
Meat Science, 2007
The aim of this study was to investigate how manipulation of glycolytic rate by post-mortem processing conditions influences quality of aged beef of two bovine muscles of different physiological character, longissimus dorsi (LD) and adductor (AD). Post-mortem glycolysis was manipulated by low-voltage electrical stimulation (LV-ES) of half carcasses and by chilling rate of the muscles. Multivariate statistical analysis was used to visualise the data, while ANOVA was used to identify significant effects and interactions. As expected there was a significant effect of LV-ES on the pH decline in the first hours post-mortem in both muscles. Moreover, significant effects of LV-ES on WB shear force measured 2 and 8 days after slaughter were observed for LD at both chilling temperatures, while for AD no effect on WB shear force was observed. Furthermore, the results revealed a large individual variation in the response of LV-ES on both pH decline and WB shear force, and this variation did not always correlate for the two responses. Some animals showed no response of LV-ES on pH decline, but still had an improved WB shear force, and vice versa. The results from this study indicate that there probably are other mechanisms than accelerated pH decline and prevention of coldshortening, by which LV-ES can affect meat tenderness.
Annals of Animal Science, 2014
The objective of this study was to investigate the effect of the range of pH decline from 45 min to 48 h after the slaughter on the quality of meat in (Landrace × Yorkshire) × Hampshire fattening pigs. The mean value and standard deviation for the range of pH fall from 45 min to 48 h postmortem served to create the following experimental groups: group I with pH decline less or equal to 0.88 units pH; group II with pH decline higher than 0.88 but lower than 1.26 pH units; and group III where pH decline was equal to 1.26 units or higher. This investigation showed that glycolytic resources in meat (glycogen and lactate) were connected with the range of pH decline from 45 min to 48 h postmortem. The different ultimate pH in meat with the same lactate concentration was noted (group I vs. II). Although the range and the rate of pH decline from 3 h postmortem was higher and significantly faster (P≤0.05 and 0.01) in both groups with a higher pH fall (groups II and III), there was no statist...
2020
Preslaughter exposure to high ambient temperature could accelerate postmortem glycolysis and impair chicken breast (pectoralis major muscle) quality. However, previous studies indicated that it might be different when the temperature of short-term heat exposure (SHE) raises to extreme range (above 38°C). Therefore, the objectives of this study were to evaluate the effect of SHE in the range of extreme temperatures (36°C, 38°C, and 40°C) on the activity of glycolytic enzymes and AMP-activated protein kinase (AMPK) in postmortem muscles. The activity of key glycolytic enzymes and phosphorylation of Threonine 172 in AMPK α subunit (p-AMPK-α[Thr172]) during early postmortem (0.1, 1, 2, and 4 h) and the muscle pH decline (0.1, 1, 2, 4, and 24 h) were evaluated. SHE did not affect (P > 0.05) glycogen phosphorylase a (GPa) and pyruvate kinase (PK) activity within 4 h postmortem. However, the phosphofructokinase-1 (PFK-1) activity and phosphorylation of AMPK-α[Thr172] decreased (P < 0...
Australian Journal of Agricultural Research, 2006
The objective of this study was to establish the effect of sire (n = 9) estimated breeding values (EBVs) and pasture-based nutritional systems (low and high quality and availability) from birth to slaughter on the metabolic characteristics and post-mortem pH changes in muscle of ∼8-month-old lambs (n = 56). Nutritional restriction resulted in a general decrease in glycolytic capacity as indicated by the enzymes phosphofructokinase and lactate dehydrogenase (LDH), suggesting greater metabolic efficiency. Alternatively, it also depressed oxidative capacity as indicated by myoglobin and isocitrate dehydrogenase, which aligns with the histological results suggesting a fast glycolytic fibre type characteristic of less mature animals. Increasing PEMD EBV resulted in a marked shift towards a metabolically more glycolytic muscle type as demonstrated by LDH, although this did not correspond strongly with an increase in the proportion of type 2B fibres based on histological assessment of myofibre type using immunostaining of myosin heavy chain isoforms. Myoglobin concentration aligned with this trend, decreasing in all muscles as PEMD EBV increased, suggesting that selection for muscling will lead to a whiter muscle appearance. Rate of pH decline was increased in the low nutrition lambs, and through selection for PEMD EBV, this response aligning with the metabolically more glycolytic muscle type.