Low-Voltage Electrical Stimulation of Beef Carcasses Slows Carcass Chilling Rate and Improves Steak Color

Electrical stimulation (ES) is used in beef slaughter plants to improve tenderness; however, varying levels of low-voltage ES have not been well characterized. The objective was to evaluate the influence of two levels of low-voltage ES on temperature decline, pH, glycolytic potential, and meat quality. Forty-two beef carcasses were chosen from a commercial packing facility. One side of each carcass received either 40 or 80 volts of ES for 60 s at 45 min postmortem. The paired side of each carcass did not receive ES (Control). Temperature loggers were placed in the sirloin of 12 carcasses to record temperature decline. Longissimus muscle pH was measured at 1, 12, and 24 h, and 3 d postmortem. Strip steaks were fabricated for determination of meat quality. A treatment by time interaction was observed for carcass temperature decline (p < 0.001) where ES sides stayed warmer longer than Control sides. A treatment by time interaction was observed for pH decline with Control sides exhibiting an increased pH at 1 h postmortem (p < 0.001). Instrumental color values were increased for ES compared to Control sides (p < 0.001). These results indicate ES slows carcass temperature decline, hastens initial pH decline, and improves instrumental color. Similar results were observed between the ES treatments indicating either ES level may be used to achieve similar quality characteristics.

Guanidino-Acetic Acid: A Scarce Substance in Biomass That Can Regulate Postmortem Meat Glycolysis of Broilers Subjected to Pre-slaughter Transportation

The different substances in biomass can regulate the metabolism and reproduction of broilers. Guanidino-acetic acid (GAA) is a natural feed additive that showed a potential application in dietary for broilers, while its amount is scarce in biomass. The objective of the present study was to investigate the effects of dietary supplemented with GAA on muscle glycolysis of broilers subjected to pre-slaughter transportation. A total of 160 Qiandongnan Xiaoxiang chickens were randomly assigned into three treatments, including a basal control diet without GAA supplementation (80 birds) or supplemented with 600 mg/kg (40 birds) or 1,200 mg/kg (40 birds) GAA for 14 days. At the end of the experiment, the control group was equally divided into two groups, thus resulting in four groups. All birds in the four groups aforementioned were separately treated according to the following protocols: (1) no transport of birds of the control group fed with the basal diet; (2) a 3-h transport of birds of the control group fed with the basal diet; (3) a 3-h transport of birds fed with diets supplemented with 600 mg/kg GAA; and (4) a 3-h transport of birds fed with diets supplemented with 1,200 mg/kg GAA. The results demonstrated that 3-h pre-slaughter transport stress increased corticosterone contents and lowered glucose contents in plasma (P &lt; 0.05), decreased pH24h (P &lt; 0.05), and resulted in inferior meat quality evidenced by elevating the drip loss, cooking loss, and L∗ value (P &lt; 0.05). Meanwhile, 3-h pre-slaughter transport stress decreased the contents of Cr and ATP in muscle (P &lt; 0.05) and elevated the ratio of AMP:ATP and the glycolytic potential of muscle (P &lt; 0.05). Moreover, 3-h pre-slaughter transport resulted in a significant elevation of mRNA expressions of LKB1 and AMPKα2 (P &lt; 0.05), as well as the increase in protein abundances of LKB1 phosphorylation and AMPKα phosphorylation (P &lt; 0.05). However, 1,200 mg/kg GAA supplementation alleviated negative parameters in plasma, improved meat quality, and ameliorated postmortem glycolysis and energy metabolism through regulating the creatine–phosphocreatine cycle and key factors of AMPK signaling. In conclusion, dietary supplementation with 1,200 mg/kg GAA contributed to improving meat quality via ameliorating muscle energy expenditure and delaying anaerobic glycolysis of broilers subjected to the 3-h pre-slaughter transport.

LncRNA XIST/miR-137 axis strengthens chemo-resistance and glycolysis of colorectal cancer cells by hindering transformation from PKM2 to PKM1

BACKGROUND: Glycolysis was an essential driver of chemo-resistance in colorectal cancer (CRC), albeit with limited molecular explanations. OBJECTIVE: We strived to elucidate the involvement of lncRNA XIST/miR-137/PKM axis in chemo-tolerance and glycolysis of CRC. METHODS: Altogether 212 pairs of tumor tissues and adjacent normal tissues were collected from CRC patients. Moreover, human CRC epithelial cell lines, including HT29, SW480, SW620 and LoVo, were purchased in advance, and their activity was estimated after transfection of si-XIST or miR-137 mimic. Furthermore, 5-FU/cisplatin-resistance of CRC cells was determined through MTT assay, and glycolytic potential of CRC cells was appraised based on oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). RESULTS: Highly-expressed XIST were predictive of severe symptoms and unfavorable 3-year survival of CRC patients (P< 0.05). Besides, silencing of XIST not only diminished proliferative, migratory and invasive power of CRC cells (P< 0.05), but also enhanced sensitivity of CRC cells responding to 5-FU/cisplatin (P< 0.05). Glycolytic potency of CRC cells was also undermined by si-XIST, with decreased maximal respiration and maximal glycolytic capacity in the si-XIST group as relative to NC group (P< 0.05). Nevertheless, miR-137 mimic attenuated the facilitating effect of pcDNA3.1-XIST on proliferation, migration, invasion, 5-FU/cisplatin-resistance and glycolysis of CRC cells (P< 0.05). Ultimately, ratio of PKM2 mRNA and PKM1 mRNA, despite being up-regulated by pcDNA3.1-XIST, was markedly lowered when miR-137 mimic was co-transfected (P< 0.05). CONCLUSIONS: LncRNA XIST/miR-137 axis reinforced glycolysis and chemo-tolerance of CRC by elevating PKM2/PKM1 ratio, providing an alternative to boost chemo-therapeutic efficacy of CRC patients.

β-alanine or L-carnosine prevents the development of pale, soft and exudative pork by inhibiting the glycolysis of porcine longissimus dorsi muscle

Carnosine plays an important role in regulating muscle buffering capacity and glycolysis. In order to investigate the effects of dietary β-alanine, L-histidine, and L-carnosine supplementation on the pH value, glycolytic potential, the activities of AMP-activated protein kinase (AMPK) and pyruvate kinase (PK) activities in the porcine longissimus dorsi muscle, a total of 60 barrows with an average body weight (BW) of 50.5 ± 1.7 kg were assigned into five groups which received diets containing basal diet (control, CON), 0.04% β-alanine (β-ALA), 0.06% L-histidine (L-HIS), 0.04% β-alanine+0.06% L-histidine (β-ALA+L-HIS), or 0.1% L-carnosine (L-CAR). The results showed that dietary supplementation of the combination of β-ALA and L-HIS or L-CAR significantly increased (P < 0.05) the average daily gain (ADG) of pigs with 50-75 kg BW, compared with other three groups. Compared with L-CAR group, L-HIS supplementation significantly decreased (P < 0.05) the average daily feed intake (ADFI) of pigs. There were no significant difference (P > 0.05) in back fat thickness and loin eye area among treatments. At 0, 1 and 24 h postmortem (PM) the pH values in the longissimus dorsi muscle (LM) of pigs receiving L-CAR were higher (P < 0.05) than that of pigs receiving CON diet. The redness (a*) values of LM of pigs in the β-ALA+L-HIS or L-CAR group were higher (P < 0.05) than those in other three groups. The glycolytic potential of LM was not significantly different (P > 0.05) among treatments. At 1, 24 h PM the AMPK activities in LM of pigs receiving β-ALA, β-ALA+L-HIS and L-CAR were much lower (P < 0.05) than those of pigs receiving CON diet or L-HIS. 0.1% L-carnosine or 0.04% β-alanine supplemented to pigs’ diet was effective in regulating AMPK and PK activities in the porcine longissimus dorsi muscle and preventing the development of pale, soft and exudative (PSE) pork.

Impact of Two Levels of Low Voltage Electrical Stimulation on Beef Quality

ObjectivesElectrical stimulation (ES) prior to rigor mortis accelerates postmortem glycolysis, resulting in rapid postmortem depletion of glycogen and can partially simulate the physiological conditions created by stress. The objective of this study was to evaluate the influence of two levels of high voltage electrical stimulation on incidence of dark cutters, temperature decline, muscle pH, glycolytic potential, and meat quality.Materials and MethodsFifty beef carcasses were chosen at 3 collection times over 7 h; 14 at collection 1, 18 at collection 2, and 18 at collection 3. One side of each carcass received either 40 (E40) or 80 (E80) volts of ES. The paired side of each carcass served as a control and did not receive ES (C40 or C80). Temperature data loggers were placed into the sirloin of both sides of the first 4 carcasses from each collection period to monitor temperature decline. Muscle pH was measured on the longissimus muscle at 1, 12, 24, and 72 h postmortem. Steaks were fabricated from the longissimus lumborum for determination of WBSF, cook loss, glycolytic potential (GP), and objective color. Data were analyzed using PROC Mixed of SAS with fixed effect of treatment and random effect of carcass. Analysis of carcass temperature decline was conducted with control carcasses pooled to one treatment to better evaluate the effect of ES on temperature decline. Temperature data, WBSF, and pH were considered repeated measures. Significance was determined at P < 0.05.ResultsNo dark cutting carcasses were observed in this study. A time by treatment interaction was observed for carcass temperature decline (P < 0.001) where ES sides stayed warmer for longer than control sides. A treatment by time interaction was observed for pH decline (P < 0.001) with C40 sides having an increased pH at 1 h postmortem compared to E80 sides. Carcass characteristics did not differ among treatments (P > 0.05). A treatment effect was observed for WBSF values (P = 0.006) with ES sides being more tender than C40 sides. A day effect was observed (P = 0.009) with steaks aged for 7 d being less tender than steaks aged for 14 d (P = 0.007). Cook loss did not differ among treatments (P > 0.05). A difference in cook loss by aging period (P = 0.014) was observed. Steaks aged for 3 d had less cook loss than steaks aged for 7 d (17.3% vs. 18.8% respectively; (P = 0.017) and tended to have less cook loss than steaks aged for 14 d (18.3%; P = 0.065). Glucose, lactate, and overall GP measurements did not differ among treatments (P > 0.05). Objective L* values for E80 sides were greater than C40 (P = 0.0009) and C80 (P < 0.0001), and E40 values were greater than C40 (P < 0.0001). Objective a* values for E80 sides were greater than C40 (P = 0.002) and C80 (P = 0.035), and E40 values were greater than C40 (P < 0.0001). Objective b* values were greater for E80 than C80 (P = 0.005) and C40 (P = 0.001), and E40 was greater than C40 (P < 0.0001).ConclusionThese data suggest ES does not influence the incidence of dark cutters. However, utilization of an ES system can improve tenderness of steaks in addition to producing brighter, more red beef products. The results of this study indicate that similar quality characteristics can be obtained using 40 or 80 V of ES. Therefore, beef packing plants applying ES to carcasses may be able to reduce voltage without sacrificing quality.