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Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstracts: In this study, the changes in autophagy and its relationship with beef quality during 14 days of postmortem aging were investigated. In terms of meat color, the L* value increased with aging time, and the a* and b* values increased first and then decreased; the tenderness increased, while the shear force and the expression of desmin decreased (P < 0.05). The water-holding capacity decreased during postmortem aging, while the purge loss and cooking loss increased (P < 0.05). Further studies on autophagy-related proteins showed that the expression of Beclin-1 and microtubule associated protein 1 light chain 3 (LC3), as the markers of autophagy, increased first and then decreased, reaching the maximum at 12 h. AMP-activated protein kinase (AMPK)-mammalian target of rapamycin (mTOR)-yeast Atg1 homolog unc-51 like kinase 1 (ULK1), as an important energy metabolic pathway, activated autophagy in an ischemia and hypoxia environment. During postmortem aging, the protein expressions of AMPK, p-AMPKThr172, and ULK1 all initially increased and subsequently decreased, reaching the maximum at 12 h. The expression of mTOR continuously decreased (P < 0.05), suggesting that autophagy was up-regulated from 0 to 12 h postmortem aging. Pearson correlation analysis showed that the expression levels of autophagy-related proteins were negatively correlated with meat color, but positively correlated with water-holding capacity and shear force during postmortem aging process (P < 0.05). In summary, autophagy could be activated through the AMPK-mTOR-ULK1 signaling pathway during the 336 h postmortem aging process, thereby regulating beef quality.

This study investigated the effects of treatment with different concentrations of sodium chloride (NaCl) on the characteristics of intramuscular collagen and related endogenous enzyme activities in beef during 72 h postmortem in order to provide theoretical evidence that NaCl contributes to improving postmortem beef tenderness. Enzyme-linked immunosorbent assay (ELISA) was used to determine the changes in the level of mature collagen cross-linking and endogenous enzyme activities in bovine longissimus dorsi muscle after being treated with 1% or 3% (m/m) NaCl solution. At the same time, differential scanning calorimetry (DSC), endogenous and exogenous fluorescence spectroscopy and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) were used to determine physicochemical properties such as thermal solubility, thermal stability, surface hydrophobicity to characterize the structural changes and degradation status of collagen. The results showed that treatment of NaCl at both concentrations could regulate the activity of lysine oxidase, β-glucuronidase and β-galactosidase in beef during 72 h postmortem, thereby enhancing the thermal solubility of intramuscular collagen, reducing the thermal stability, promoting conformational changes and degradation of collagen and ultimately contributing to improving the tenderness of postmortem beef.

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper aimed to investigate the effects of ultrasound‐assisted L‐lysine treatment on meat quality and myofibrillar proteins (MPs) properties of pork longissimus dorsi during postmortem aging. The results revealed that the L‐lysine (Lys) and/or ultrasound treatment significantly increased (p < 0.05) the water‐holding capacity and tenderness of the pork during postmortem aging, while the ultrasound‐assisted Lys treatment had the lowest cooking loss, pressurization loss, Warner–Bratzler shear force, and hardness. In addition, L‐lysine and/or ultrasound treatment increased (p < 0.05) pH value, T21, and myofibrillar fragmentation index, while the ultrasound‐assisted Lys treatment had the highest value. Meanwhile, the protein solubility was increased with Lys and/or ultrasound treatment during postmortem aging, and ultrasound‐assisted Lys treatment had the highest solubility, reaching 88.19%, 92.98%, and 91.73% at 0, 1, and 3 days, respectively. The result of protein conformational characteristics showed that Lys and/or ultrasound treatment caused the unfolding of the α‐helix structure, resulting in the exposure of more hydrophobic amino acids and buried sulfhydryl groups, ultimately enhancing MPs solubility. In summary, ultrasound‐assisted Lys treatment altered the structure of MPs, resulting in the enhancement of the water‐holding capacity and tenderness of the pork. Practical Application: This study showed that ultrasound‐assisted L‐lysine (Lys) treatment could enhance the water‐holding capacity and tenderness of pork during postmortem aging. The results might provide a reference for the application of ultrasound‐assisted Lys treatment on the improvement of pork meat quality. To facilitate practical applications in production, the development of medium and large‐sized ultrasound equipment for conducting small‐scale and pilot experiments is crucial for future research. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to clarify the relationship between the degree of glycolysis and water-holding capacity during the maturation of Tan sheep meat, the M. longissimus dorsi of six-month-old Tan sheep was aged at 4 ℃ postmortem and evaluated for drip loss, purge loss, calpain-1 activity, myofibril fragmentation index (MFI), ATP content, glucose content, glycogen content, lactic acid content, lactate dehydrogenase (LDH) activity, pyruvate kinase (PK) activity and pH after 0, 1, 2, 3, 4 and 8 days. The results showed that as maturation time increased, drip loss, purge loss and centrifugal loss increased first and then decreased (P < 0.05), reaching their maximum values on day 4. ATP and glycogen contents continued to decrease (P < 0.05). The contents of glucose and lactic acid increased first and then decreased (P < 0.05), and so did LDH activity (P < 0.05), reaching its maximum level on day 4. PK activity showed a constant decreasing trend (P < 0.05). The correlation analysis showed that glycogen content was negatively correlated with drip loss (P < 0.05) as well as purge loss and centrifugal loss (P < 0.01), and positively correlated with nuclear magnetic resonance (NMR) transverse relaxation times (T21, T22 and T23) (P < 0.05 or P < 0.01). LA content was significantly positively correlated with drip loss (P < 0.001) as well as purge loss and centrifugal loss (P < 0.01), but had no correlation with T21, T22 or T23. Therefore, the glycolysis process of Tan sheep meat was activated rapidly after slaughter, which caused change in the activity of glycolysis-related enzymes and the contents of metabolites, thereby resulting in changes in the water adsorption capacity of muscle proteins, and ultimately affecting the water-holding capacity of Tan sheep meat after slaughter.

Oula Tibetan sheep meat has rich nutritional value but relatively poor tenderness. Recently, apoptosis of muscle cells has gradually become a research hotspot for improving meat tenderness during postmortem aging. Smac can promote the decrease of IAPs expression in tumor cells, thereby inducing mitochondrial apoptosis. However, the relationship between Smac, IAPs and mitochondrial apoptosis, muscle tenderness during postmortem meat aging is still unclear. Thus, the aim of this work was to explore the relationship between Smac, IAPs and mitochondrial apoptosis as well as muscle tenderness during postmortem meat aging. Smac concentration, IAPs concentration, pH value, ATP content, SDH activity, MPTP opening degree, MMP, caspase-3/9 activity, apoptotic rate, MFI and shear force value of Oula Tibetan sheep meat were measured at different aging times and correlation analysis was performed. Correlation analysis revealed that Smac, IAPs were markedly related to mitochondrial apoptosis and muscle tenderness during postmortem aging of Tibetan sheep meat. The results suggest that Smac may regulate IAPs to promote mitochondrial apoptosis and muscle tenderization in Oula Tibetan sheep meat during postmortem aging.

Background: Metabolic changes in donkey meat during the early postmortem period have not been previously reported. Methods: The LC–MS-based metabolomics technique was conducted to understand the metabolic profiles and identify the key metabolites of donkey meat in the first 48 h postmortem. Results: The pH values showed a decreasing trend followed by an increasing trend. Shear force was the lowest at 4 h and the highest at 24 h (p < 0.05). For the metabolome, some candidate biomarker metabolites were identified, such as adenine, inosine, n-acetylhistidine, citric acid, isocitrate, and malic acid. Predominant metabolic pathways, such as citrate cycle (TCA cycle), alanine, aspartate and glutamate metabolism, and purine metabolism, were affected by aging time. Overabundant n-acetylhistidine was identified in LT, declined at 12 h postmortem aging, and then increased. This may explain the significantly lower pH at 12 h postmortem. Adenine was higher at 4 h postmortem, then declined. Decreased ADP may indicate a fast consumption of ATP and subsequent purine metabolism in donkey meat. Conclusions: The results of this study provided new insights into early postmortem aging of donkey meat quality. [ABSTRACT FROM AUTHOR]

Japanese Brown (JBR) cattle have moderately marbled beef compared to the highly marbled beef of Japanese Black (JBL) cattle; however, their skeletal muscle properties remain poorly characterized. To unveil interbreed metabolic differences over the previous results, we explored the metabolome network changes before and after postmortem 7-day aging in the trapezius muscle of the two cattle breeds by employing a deep and high-coverage metabolomics approach. Using both capillary electrophoresis (CE) and ultra-high-performance liquid chromatography (UHPLC)–Fourier transform mass spectrometry (FT/MS), we detected 522 and 384 annotated peaks, respectively, across all muscle samples. The CE-based results showed that the cattle were clearly separated by breed and postmortem age in multivariate analyses. The metabolism related to glutathione, glycolysis, vitamin K, taurine, and arachidonic acid was enriched with differentially abundant metabolites in aged muscles, in addition to amino acid (AA) metabolisms. The LC-based results showed that the levels of bile-acid-related metabolites, such as tauroursodeoxycholic acid (TUDCA), were high in fresh JBR muscle and that acylcarnitines were enriched in aged JBR muscle, compared to JBL muscle. Postmortem aging resulted in an increase in fatty acids and a decrease in acylcarnitine in the muscles of both cattle breeds. In addition, metabolite set enrichment analysis revealed that JBR muscle was distinctive in metabolisms related to pyruvate, glycerolipid, cardiolipin, and mitochondrial energy production, whereas the metabolisms related to phosphatidylethanolamine, nucleotide triphosphate, and AAs were characteristic of JBL. This suggests that the interbreed differences in postmortem trapezius muscle are associated with carnitine/acylcarnitine transport, β-oxidation, tricarboxylic acid cycle, and mitochondrial membrane stability, in addition to energy substrate and AA metabolisms. These interbreed differences may characterize beef quality traits such as the flavor intensity and oxidative stability. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Our purpose was to clarify the effect of CaCl2 treatment on the energy level and quality of Tan sheep meat during postmortem aging. Tan sheep hind leg meat was injected with 200 mmol/L CaCl2 solution, and aged at 4 ℃ for 0, 2, 4, 6, and 8 days. The protein expression of phosphofructokinase (PFKM) was detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot to verify whether the glycolysis pathway could be activated by CaCl2. At the same time, the energy level and meat quality indexes were measured during postmortem aging to analyze the mechanism by which the glycolysis pathway affects the metabolic level and quality of Tan sheep meat. The results showed that the protein expression of PFKM decreased during postmortem aging, indicating activation of the glycolytic pathway. CaCl2 treatment accelerated the glycolysis process after slaughter, thereby promoting the decomposition of glycogen, increasing the production of lactic acid, and resulting in a rapid decrease in pH. Water-holding capacity (WHC), myofibril fragmentation index (MFI) and b* value were higher and shear force and a* were lower in the treatment group than in the control and blank groups. Therefore, CaCl2 could affect the color, WHC and tenderness of Tan sheep meat at different aging stages. By accelerating the decrease of pH and the accumulation of energy metabolites, the glycolytic pathway increased the level of energy metabolism during postmortem aging, while inhibiting the production of oxymyoglobin, activating the activity of calpain, changing the structure of myofibrils and shortening the space between muscle protein molecules, which accelerated the process of myofibril fragmentation and the hydrolysis of myofibrillar protein, and led to a deterioration in meat color and an increase in water loss and meat tenderness.

Meat and meat products have a critical role in the human diet as important high-nutrient foods that are widely consumed worldwide. This study evaluated the effects of postmortem aging on Hu sheep's meat quality in the longissimus dorsi (LD) muscle during postmortem aging. The samples were stored at 4 ± 1 °C; the meat quality was measured at 6 h, 12 h, 24 h, 36 h, 48 h, 72 h, 96 h, 120 h, 144 h, and 168 h of postmortem aging. The results showed that, during the postmortem aging process, the pH of the muscles first decreased and then increased, and the shear force first increased and then decreased. The muscle fiber skeleton began to degrade, and the overall meat quality was improved to some extent. In addition, through ACQUITY UPLC I-Class Plus IMS Qtof identification of the muscle samples at different time points during the postmortem maturation process of the meat of Hu sheep, a total of 2168 metabolites were identified, and 470 metabolites were screened based on the VIP, P, and FC values, of which 79 were involved in KEGG pathways. In addition, pathways such as sphingolipid metabolism, glycerophospholipid metabolism, phenylalanine metabolism, and fatty acid elongation and degradation play an important role in the metabolic product changes in the meat of Hu sheep throughout the entire maturation process. These findings provide some insights into the changes in meat quality during the post-slaughter maturation process of lake lamb. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to explore the effect of dietary supplementation of Clostridium butyricum on the volatile flavor substances in the meat of small-tailed Han sheep during postmortem aging and its possible mechanism, the Longissimus dorsi muscle of small-tailed Han sheep slaughtered at the age of six months was taken for postmortem maturation at 4 ℃, and then the volatile flavor substances, the contents of lipid metabolism-related enzymes including adenosine monophosphate activated protein kinase (AMPK), acetyl CoA carboxylase (ACC) and carnitine lipoyltransferase 1 (CPT1) were measured on days 0, 1, 2, 3, 4 and 5. The results of electronic nose test showed that the contents of alkanes, hydroperoxide and nitrogen oxides in the C. butyricum supplementation group were higher than in the control group without C. butyricum supplementation. According to the results of gas chromatography-mass spectrometry (GC-MS), the types of aldehydes, alcohols and ketones in the C. butyricum group were more than in the control group, while the contents of fatty oxidation products such as octanal, nonanal, decanal and heptaldehyde were obviously reduced. The key flavor substances common to both groups, as determined by relative odor activity value (ROAV), included octanal, nonanal, trans-2-decenal and 1-octen-3-ol, nonanal being the greatest contributor to the flavor of lamb meat. Compared with the control group, the contents of AMPK and CPT1 in the C. butyricum group decreased significantly during postmortem aging (P < 0.05), while the contents of ACC in the C. butyricum group were significantly higher than those in the control group at 0, 1, 3 and 5 days postmortem (P < 0.05). The correlation analysis showed that AMPK and CPT1 were significantly positively correlated with nonanal (P < 0.001), while ACC was significantly negatively correlated with nonanal and decanal (P < 0.001). In conclusion, the addition of C. butyricum to the diet can affect the volatile flavor substances in the meat of small-tailed Han sheep during postmortem aging by regulating the AMPK-ACC-CPT1 signaling pathway.

The water distribution have a profound influence on meat quality, and proteins play a critical role in water distribution. The water distribution detected with proton NMR and its relationship with protein related properties were investigated. Three populations of water were detected: bound water (T21, P21), immobilized water (T22, P22), and free water (T23, P23). The decreased T22 and T23 indicated an increase in water-holding capacity in both muscles from 3 days of aging. The P22 in cattle was higher than that in yak and the P23 in cattle was lower than that in yak, suggesting that cattle exhibited a greater water-holding capacity compared to yak. Moreover, postmortem aging affected muscle protein oxidation, denaturation, and degradation. Correlation analysis suggested that protein oxidation and denaturation caused muscle water loss and protein degradation could allow the muscle to retain water. It provides a basis for the optimization of quality of meat and products.

Post-mortem aging could enhance the unique flavors of beef via several biochemical pathways. The microbiota is one of the important factors in the flavor development of aging beef, but their potential relationship has rarely been studied. This study characterized the apparent meat quality, flavor profiles, and microbial communities of beef during the different post-mortem processes, followed by the investigation of the correlations between the dominant microbiota and key volatile compounds. The results showed that wet-aged beef has a higher product yield and more stable color than dry-aged beef, as evidenced by the significantly lower value of aging loss and discoloration (ΔE). According to the odor activity value, 11 out of 65 compounds were categorized as aroma-active components, and 9 of them, including 1-pentanol, 1-octen-3-ol, hexanal, nonanal, heptanal, octanal, 2-nonenal, (E)-, 2-octenal, (E)- and 2-decenal, (E)-, were enriched in beef wet-aged for 7 d. Significant variances were found in the microbial communities of different aging beef. Of these, 20 microbiota (with 10 bacterial and 10 fungal genera) were recognized as the dominant genus. Partial least squares regression combined with a correlation network model revealed that five microbial genera, including Trichosporon, Prauserella, Rhodotorula, Malassezia, and Corynebacterium, constituted the functional microbiota responsible for flavor formation in aging beef and were positively associated with ≥7 key volatile compounds (p < 0.05, |ρ| > 0.7). This study suggests that the application of wet aging within 7 d on beef is better for meat quality and provides novel insights into the mechanisms of flavor formation in post-mortem aging beef via functional microbiota. [ABSTRACT FROM AUTHOR]

Objective Japanese Brown (JBR) cattle, especially the Kochi (Tosa) pedigree (JBRT), is a local breed of moderately marbled beef. Despite the increasing demand, the interbreed differences in muscle metabolites from the highly marbled Japanese Black (JBL) beef remain poorly understood. We aimed to determine flavor-related metabolites and postmortem metabolisms characteristic to JBRT beef in comparison with JBL beef. Methods Lean portions of the longissimus thoracis (loin) muscle from four JBRT cattle were collected at 0, 1, and 14 d postmortem. The muscle metabolomic profiles were analyzed using capillary electrophoresis time-of-flight mass spectrometry. The difference in postmortem metabolisms and aged muscle metabolites were analyzed by statistical and bioinformatic analyses between JBRT (n = 12) and JBL cattle (n = 6). Results A total of 240 metabolite annotations were obtained from the detected signals of the JBRT muscle samples. Principal component analysis separated the beef samples into three different aging point groups. According to metabolite set enrichment analysis, postmortem metabolic changes were associated with the metabolism of pyrimidine, nicotinate and nicotinamide, purine, pyruvate, thiamine, amino sugar, and fatty acid; citric acid cycle; and pentose phosphate pathway as well as various amino acids and mitochondrial fatty acid metabolism. The aged JBRT beef showed higher ultimate pH and lower lactate content than aged JBL beef, suggesting the lower glycolytic activity in postmortem JBRT muscle. JBRT beef was distinguished from JBL beef by significantly different compounds, including choline, amino acids, uridine monophosphate, inosine 5′-monophosphate, fructose 1,6-diphosphate, and betaine, suggesting interbreed differences in the accumulation of nucleotide monophosphate, glutathione metabolism, and phospholipid metabolism. Conclusion Glycolysis, purine metabolism, fatty acid catabolism, and protein degradation were the most common pathways in beef during postmortem aging. The differentially expressed metabolites and the relevant metabolisms in JBRT beef may contribute to the development of a characteristic flavor.

Background: Metabolic changes in donkey meat during the early postmortem period have not been previously reported. Methods: The LC–MS-based metabolomics technique was conducted to understand the metabolic profiles and identify the key metabolites of donkey meat in the first 48 h postmortem. Results: The pH values showed a decreasing trend followed by an increasing trend. Shear force was the lowest at 4 h and the highest at 24 h (p < 0.05). For the metabolome, some candidate biomarker metabolites were identified, such as adenine, inosine, n-acetylhistidine, citric acid, isocitrate, and malic acid. Predominant metabolic pathways, such as citrate cycle (TCA cycle), alanine, aspartate and glutamate metabolism, and purine metabolism, were affected by aging time. Overabundant n-acetylhistidine was identified in LT, declined at 12 h postmortem aging, and then increased. This may explain the significantly lower pH at 12 h postmortem. Adenine was higher at 4 h postmortem, then declined. Decreased ADP may indicate a fast consumption of ATP and subsequent purine metabolism in donkey meat. Conclusions: The results of this study provided new insights into early postmortem aging of donkey meat quality.

Japanese Brown (JBR) cattle have moderately marbled beef compared to the highly marbled beef of Japanese Black (JBL) cattle; however, their skeletal muscle properties remain poorly characterized. To unveil interbreed metabolic differences over the previous results, we explored the metabolome network changes before and after postmortem 7-day aging in the trapezius muscle of the two cattle breeds by employing a deep and high-coverage metabolomics approach. Using both capillary electrophoresis (CE) and ultra-high-performance liquid chromatography (UHPLC)–Fourier transform mass spectrometry (FT/MS), we detected 522 and 384 annotated peaks, respectively, across all muscle samples. The CE-based results showed that the cattle were clearly separated by breed and postmortem age in multivariate analyses. The metabolism related to glutathione, glycolysis, vitamin K, taurine, and arachidonic acid was enriched with differentially abundant metabolites in aged muscles, in addition to amino acid (AA) metabolisms. The LC-based results showed that the levels of bile-acid-related metabolites, such as tauroursodeoxycholic acid (TUDCA), were high in fresh JBR muscle and that acylcarnitines were enriched in aged JBR muscle, compared to JBL muscle. Postmortem aging resulted in an increase in fatty acids and a decrease in acylcarnitine in the muscles of both cattle breeds. In addition, metabolite set enrichment analysis revealed that JBR muscle was distinctive in metabolisms related to pyruvate, glycerolipid, cardiolipin, and mitochondrial energy production, whereas the metabolisms related to phosphatidylethanolamine, nucleotide triphosphate, and AAs were characteristic of JBL. This suggests that the interbreed differences in postmortem trapezius muscle are associated with carnitine/acylcarnitine transport, β-oxidation, tricarboxylic acid cycle, and mitochondrial membrane stability, in addition to energy substrate and AA metabolisms. These interbreed differences may characterize beef quality traits such as the flavor intensity and oxidative stability.

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study aimed to investigate the effect of reactive oxygen species (ROS) on early postmortem energy metabolism in bovine muscle via regulating the expression of hypoxia-inducible factor-1α (HIF-1α). The muscle samples were treated with hydrogen peroxide (H2O2), N-acetyl-L-cysteine (NAC), and normal saline (control), separately. The ROS content, proline hydroxylase (PHD) activity, phosphoinositide-3 kinase/protein kinase B (PI3K/AKT) and HIF-1α expression levels, energy metabolism, and pH were determined at 0.5, 6, 12, 24 and 48 h postmortem. The results revealed that the H2O2-treated group showed a significantly higher ROS content than the other two groups at 0.5 h postmortem (P < 0.05) and remained at a high level within 48 h, while NAC inhibited the accumulation of ROS for a short period of time (during 0.5–12 h) postmortem. The PHD activity in the H2O2-treated group was significantly lower than that in the other two groups during 0.5–48 h (P < 0.05). Meanwhile, the expression levels of PI3K from 0.5 to 12 h and phosphorylated AKT (p-AKT) from 0.5 to 6 h were significantly higher than those in the other groups (P < 0.05). Consequently, the expression level of HIF-1α in the H2O2-treated group was significantly higher than that of the other two groups during 6–48 h (P < 0.05), the rate of glycogenolysis and the rate of increase in R value were significantly faster in the H2O2-treated group during 6–24 h (P < 0.05), and the pH of the H2O2-treated group reached the limit value earlier (at 12 h). In conclusion, ROS can activate the stable expression of HIF-1α by reducing the activity of PHD and up-regulating the PI3K/AKT signaling pathway and consequently accelerate energy metabolism dominated by glycolysis and the decrease in pH in bovine muscle at the initial stage of postmortem aging, which may have a crucial impact on meat quality.

Skeletal muscle metabolism regulates homeostatic balance in animals. The metabolic impact persists even after farm animal skeletal muscle is converted to edible meat through postmortem rigor mortis and aging. Muscle metabolites resulting from animal growth and postmortem storage have a significant impact on meat quality, including flavor and color. Metabolomics studies of postmortem muscle aging have identified metabolisms that contain signatures inherent to muscle properties and the altered metabolites by physiological adaptation, with glycolysis as the pivotal metabolism in postmortem aging. Metabolomics has also played a role in mining relevant postmortem metabolisms and pathways, such as the citrate cycle and mitochondrial metabolism. This leads to a deeper understanding of the mechanisms underlying the generation of key compounds that are associated with meat quality. Genetic background, feeding strategy, and muscle type primarily determine skeletal muscle properties in live animals and affect post-mortem muscle metabolism. With comprehensive metabolite detection, metabolomics is also beneficial for exploring biomarker candidates that could be useful to monitor meat production and predict the quality traits. The present review focuses on advances in farm animal muscle metabolomics, especially postmortem muscle metabolism associated with genetic factors and muscle type.

Postmortem aging is a critical approach to improving the eating quality of meat, such as tenderness, juiciness, and flavor. There are three common aging methods, namely wet aging, dry aging, and their combination, each of which has its own characteristics. The final goal of these aging methods is to improve the edibility and palatability of meat. However, too long aging will lead to adverse effects such as severe mass loss and lipid and protein oxidation. Therefore, elucidating the postmortem aging mechanism of meat, monitoring and optimizing the aging process, and improving the eating quality of meat and simultaneously minimizing the quality defects caused by excessive aging are of great significance to the development of the meat industry. Although few studies have so far been reported on the monitoring and optimization of the meat aging process and meat quality prediction, precise control of the postmortem aging process will be an important development direction for the meat industry in the future. In this paper, the effects and mechanisms of different postmortem aging strategies on meat tenderness, flavor, color and oxidation stability are reviewed. Monitoring of the dry aging process based on mold coverage and electrical resistance on meat surfaces, and monitoring of the wet aging process based on meat exudate are discussed and future prospects are proposed in order to lay a theoretical foundation for the establishment of muscle-specific aging strategies.

Meat and meat products have a critical role in the human diet as important high-nutrient foods that are widely consumed worldwide. This study evaluated the effects of postmortem aging on Hu sheep’s meat quality in the longissimus dorsi (LD) muscle during postmortem aging. The samples were stored at 4 ± 1 °C; the meat quality was measured at 6 h, 12 h, 24 h, 36 h, 48 h, 72 h, 96 h, 120 h, 144 h, and 168 h of postmortem aging. The results showed that, during the postmortem aging process, the pH of the muscles first decreased and then increased, and the shear force first increased and then decreased. The muscle fiber skeleton began to degrade, and the overall meat quality was improved to some extent. In addition, through ACQUITY UPLC I-Class Plus IMS Qtof identification of the muscle samples at different time points during the postmortem maturation process of the meat of Hu sheep, a total of 2168 metabolites were identified, and 470 metabolites were screened based on the VIP, P, and FC values, of which 79 were involved in KEGG pathways. In addition, pathways such as sphingolipid metabolism, glycerophospholipid metabolism, phenylalanine metabolism, and fatty acid elongation and degradation play an important role in the metabolic product changes in the meat of Hu sheep throughout the entire maturation process. These findings provide some insights into the changes in meat quality during the post-slaughter maturation process of lake lamb.

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of this research was to determine the effect of the extended dry aging period (0, 20, 40, and 60 days) on lipid oxidation, fatty acid profile, and tenderness in selected dry-aged Hanwoo cow beef cut loins. Dry aging regimes were 40C and 85% relative humidity. Lipid oxidation was determined by using 2- thiobarbituric acid reactive substances. Shear force values of the highly marbled beef decreased first 20d aging and did not significantly change after that, until 60d. The hardness of texture profile analysis gradually decreased, but the chewiness value did not differ. A total of 16 fatty acids were identified in dryaged beef. The most predominant FAs in the aged beef were C18:1, C16:0, and C18:0. The C18:2 was the predominant polyunsaturated fatty acid in the samples. Total PUFA gradually and C18:2n-6 decreased (p<0.05) during aging. C20:1, C18:3n-3, C20:4, and C22:1 acid significantly decreased (p<0.05) until 20d aging, and no changes were observed after 20d to 60d. 2-thiobarbituric acid reactive values of beef increased (p<0.001) during dry-aging days, dry aging for 40d and 60d resulted in excessive oxidation of lipids. Dry-aged meat is so popular because of its unique taste. Improvements in tenderness are associated with the 20d aging of beef subprimal, however, some lipid oxidation may be associated with the development of specific dry-aged beef flavor. [ABSTRACT FROM AUTHOR]

Simple Summary: This manuscript investigated the effects of different feeding regimes on antioxidant activity, meat quality, fatty acid composition, lipid oxidation, and volatile matter production in the longissimus thoracis muscle of Sunit sheep during postmortem aging. It was found that pasture-fed sheep had better oxidative stability, meat quality, and fatty acid composition. At the same time, aging affected the oxidative stability, meat quality, and fatty acid composition of sheep meat, which in turn had an impact on the flavor composition of sheep meat. Aging also eliminates the differences caused by different feeding regimes to a certain extent. The purpose of this study was to investigate the effects of feeding regimes and aging time on the meat quality of sheep and to provide meat professionals with a theoretical basis that can be applied in practical production. It also accelerated the transition from traditional grazing to indoor rearing to maintain ecological balance. The effects of different feeding regimes on antioxidant activity, meat quality, fatty acid composition, lipid oxidation, and volatile matter production in the longissimus thoracis (LT) of Sunit sheep at 0, 24, 48, 72, and 96 h postmortem were investigated. The results showed that the activity of antioxidant enzymes, tenderness, water retention, and percentage of unsaturated fatty acids were significantly higher in the pasture-fed sheep (PF) than in the concentrate-fed sheep (CF) (p < 0.05). During postmortem aging, antioxidant activity, water retention, and the proportion of unsaturated fatty acids decreased in the PF and CF (p < 0.05), while malondialdehyde (MDA) content, the proportion of saturated fatty acids, and the content of flavor substances resulting from fat oxidation increased. After 24 h of LT muscle aging, the pH and shear force of the meat started to increase and the color stabilized. The differences between shear force values and lipid volatile flavor substance content of sheep meat under different feeding regimes disappeared with increasing aging time. PF had better oxidative stability and fatty acid composition. Postmortem aging changed the oxidative stability of sheep meat, thus affecting meat quality and fatty acid composition and consequently meat flavor composition, while aging also eliminated to some extent the differences caused by feeding regimes. [ABSTRACT FROM AUTHOR]

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This research aimed to explore the effects of the nitric oxide synthase (NOS) inhibitor (L‐NAME) on mitochondria apoptosis in postmortem Gannan yak (Bos grunniens) longissimus dorsi (LD) muscle and to explore its effect on meat quality further. The Gannan yak meat samples were treated with the control group (0.9% NaCl) and L‐NAME (20, 60, and 100 mM) for 24 h and then stored for 0, 1, 3, 5, and 7 days at 4°C. NOS activity and NO content were investigated, and the parameters of mitochondrial apoptosis of the postmortem Gannan yak meat were determined. Meanwhile, the meat quality such as the centrifugation loss, meat color, and myofibril fragmentation index (MFI) was evaluated. The results indicated that after treatment with L‐NAME, NOS activity and NO content decreased, causing mitochondrial membrane damage, Bax protein, and Cyt‐c levels increased, and resulted in increased activities of caspase‐9 and ‐3, promoting the occurrence of mitochondrial apoptosis. Furthermore, it increased the tenderness and water retention of Gannan yak meat. The results indicated that NOS inhibitor played a regulatory role in postmortem Gannan yak meat quality by regulating mitochondria apoptosis during postmortem aging. Practical applications: The meat's tenderness is often considered the most important factor affecting consumers' willingness to repurchase. The relationship of caspases and MFI suggested that L‐NAME played a regulatory role in postmortem Gannan yak meat quality by regulating mitochondria apoptosis during postmortem aging. This study provides valuable information for the development of the Gannan yak economy in Tibetan areas. [ABSTRACT FROM AUTHOR]

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Oula Tibetan sheep meat has rich nutritional value but relatively poor tenderness. Recently, apoptosis of muscle cells has gradually become a research hotspot for improving meat tenderness during postmortem aging. Smac can promote the decrease of IAPs expression in tumor cells, thereby inducing mitochondrial apoptosis. However, the relationship between Smac, IAPs and mitochondrial apoptosis, muscle tenderness during postmortem meat aging is still unclear. Thus, the aim of this work was to explore the relationship between Smac, IAPs and mitochondrial apoptosis as well as muscle tenderness during postmortem meat aging. Smac concentration, IAPs concentration, pH value, ATP content, SDH activity, MPTP opening degree, MMP, caspase-3/9 activity, apoptotic rate, MFI and shear force value of Oula Tibetan sheep meat were measured at different aging times and correlation analysis was performed. Correlation analysis revealed that Smac, IAPs were markedly related to mitochondrial apoptosis and muscle tenderness during postmortem aging of Tibetan sheep meat. The results suggest that Smac may regulate IAPs to promote mitochondrial apoptosis and muscle tenderization in Oula Tibetan sheep meat during postmortem aging., Competing Interests: We confirm that no conflict interest conflict., (© 2024 The Authors.)

Post-mortem aging could enhance the unique flavors of beef via several biochemical pathways. The microbiota is one of the important factors in the flavor development of aging beef, but their potential relationship has rarely been studied. This study characterized the apparent meat quality, flavor profiles, and microbial communities of beef during the different post-mortem processes, followed by the investigation of the correlations between the dominant microbiota and key volatile compounds. The results showed that wet-aged beef has a higher product yield and more stable color than dry-aged beef, as evidenced by the significantly lower value of aging loss and discoloration (ΔE). According to the odor activity value, 11 out of 65 compounds were categorized as aroma-active components, and 9 of them, including 1-pentanol, 1-octen-3-ol, hexanal, nonanal, heptanal, octanal, 2-nonenal, (E)-, 2-octenal, (E)- and 2-decenal, (E)-, were enriched in beef wet-aged for 7 d. Significant variances were found in the microbial communities of different aging beef. Of these, 20 microbiota (with 10 bacterial and 10 fungal genera) were recognized as the dominant genus. Partial least squares regression combined with a correlation network model revealed that five microbial genera, including Trichosporon, Prauserella, Rhodotorula, Malassezia, and Corynebacterium, constituted the functional microbiota responsible for flavor formation in aging beef and were positively associated with ≥7 key volatile compounds (p < 0.05, |ρ| > 0.7). This study suggests that the application of wet aging within 7 d on beef is better for meat quality and provides novel insights into the mechanisms of flavor formation in post-mortem aging beef via functional microbiota.

This study evaluated the effects of oxidative stability variation on meat quality and flavor in biceps femoris (BF) and longissimus dorsi (LD) muscles of lambs during postmortem aging. The samples were stored at 4±1℃; the meat quality, flavor and muscle oxidative stability were measured on day 0, 1, 2, 3, and 4 of postmortem aging. The results showed that malondialdehyde (MDA) content increased in both muscle types; superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH‐Px) activities decreased, as did total antioxidative capacity (T‐AOC). LD muscle showed lower MDA content and antioxidative activity than BF muscle. Meat quality analyses indicated that aging increased the lightness (L*), redness (a*), and yellowness (b*) values of meat while improving its tenderness. Gas chromatography–mass spectrometry results showed that volatile flavor compounds were more abundant in LD muscle than in BF muscle. As the aging time extended, relative contents of aldehyde and alcohol increased in both muscles. The key flavor compounds during postmortem aging including heptanal, octanal, nonanal, and decanal were screened by relative odor activity value (ROAV), and the content of key flavor compounds showed the trend of increasing, which were usually associated with fresh green grass, nutty, and fat descriptors. In conclusion, the oxidative muscles displayed better antioxidative capacity, and postmortem aging altered the oxidative stability of lamb muscle, which affected the meat quality and flavor. Practical Application: Meat aging is an important strategy to improve the quality of various meat traits (including flavor). The results of this work could be of interest to meat professionals who will be able to apply in actual production by choosing the best aging time based on flavor and meat quality for different muscle parts. [ABSTRACT FROM AUTHOR]

This investigation was aimed to evaluate the proteins related to beef tenderness at different aging times (1, 3, 7 d) and to explain the changes in the longissimus lumborum at the molecular level with ultrasound treatment. The pH value decreased significantly (p <0.05) with increasing aging time, and was lower in the ultrasonic group compared to the non-ultrasonic group. It indicated that ultrasound had a positive effect on tenderness by maintaining lower cooking loss, higher water-holding capacity (WHC), and higher myofibril fragmentation index (MFI), as demonstrated by the immunoblotting analysis of desmin and caspase-3. Twenty-eight proteins were identified as potential markers of tenderness. A PCA analysis confirmed the differential expression of tenderness-related proteins. Bioinformatics analysis suggested that these proteins, which were distributed in the cytoplasm, membrane, and mitochondria, were more likely to be impacted by ultrasound. Overall, the identified proteomics database of beef serves as a valuable reference for using ultrasound to enhance meat quality and reduce aging duration. [Display omitted] • Ultrasound can effectively improve the tenderness and shorten the aging time of beef. • 28 proteins (FC＞1.5, VIP＞1) might be potential markers for tenderness. • Ultrasound is more likely to affect proteins in cytoplasm, membrane, and mitochondria. [ABSTRACT FROM AUTHOR]

Tan lamb is highly recommended breed in China. It is of great significance to understand the underlying mechanism of how water‐soluble flavor precursors metabolize in Tan lamb muscles during the postmortem aging period. In this study, we investigated the muscle pH, lactate dehydrogenase (LDH) activity, and the variations in water‐soluble flavor‐related metabolites. The proteome changes were profiled to provide insights into the biochemical changes affecting accumulation of water‐soluble flavor precursors in different aging stages (days 0, 4, and 8). The results indicated that pH value considerably decreased from day 0 to day 4, and increased from day 4 to day 8 (p <.05). The activity of LDH significantly increased from day 0 to day 4, and decreased from day 4 to day 8 (p <.05). Postmortem glycolysis was activated in 4 days, which directly affected the variations in metabolic enzymes and triggered the accumulation of flavor‐related carbohydrates. The free amino acids accumulated due to hydrolysis of structural proteins, with 3‐hydroxy‐L‐proline, aspartic acid, and methionine increasing from day 0 to day 4, and aspartic acid, serine, threonine, tyrosine, phenylalanine, and D‐phenylalanine from day 4 to day 8. The inosine and hypoxanthine accumulated due to the degradation of ATP. The results of the present study provide insightful information, revealing the differences in biochemical attributes in Tan lamb muscles caused by postmortem aging. [ABSTRACT FROM AUTHOR]

Previous studies on Japanese Black beef showed that single nucleotide polymorphisms in the ecto‐5′‐nucleotidase (NT5E) gene affected the degradation rate of inosine 5′‐monophosphate (IMP), which has contributed to the umami taste, especially between Postmortem Days 4 and 7. Therefore, this study estimated the genetic parameters of IMP and its degradation products on Postmortem Days 4 and 7 using the model with or without the NT5E genotype. The heritability estimates of IMP on Postmortem Days 4 and 7 were moderate by the model without the NT5E genotype (0.44 and 0.32, respectively). When the NT5E genotype was included in the model, the heritability of IMP on Postmortem Day 4 did not change, whereas that on Day 7 decreased from 0.32 to 0.08. The genetic correlation of IMP between Postmortem Days 4 and 7 was highly positive using the model with the NT5E genotype. Regarding the estimated breeding values (EBVs) of IMP, the ranking of EBVs among NT5E genotypes was not changed between Postmortem Days 4 and 7, when the model with the NT5E genotype was used. The study suggested that the model including NT5E genotype would allow for appropriate genetic parameter estimation and breeding value evaluation in adenosine triphosphate‐related compounds (ATPRCs) under different aging periods. [ABSTRACT FROM AUTHOR]

This study aimed to verify the role of AMP‐activated protein kinase (AMPK) in mitochondrial dysfunction‐induced apoptosis and postmortem bovine muscle tenderization. AMPK phosphorylation levels, mitochondrial dysfunction, mitochondrial apoptotic factors, and myofibrillar protein hydrolysis were assessed in the control group and Compound C (AMPK inhibitor) group over a 168 hr aging period. Compared with the Compound C group, the control group had an extremely significantly increased AMPK activity at 6–120 hr (p <.01) and a 62.3% and 42.1% higher mitochondrial Bax/Bcl‐2 ratio at 6 and 12 hr, respectively (p <.05). Moreover, the control group had a significantly or extremely significantly higher mitochondrial dysfunction and cytoplasmic cytochrome c content at 6–72 and 12–72 hr, respectively (p <.05, p <.01); a 23.2%, 26.5%, and 26.1% increased caspase‐3 expression levels at 12, 24, and 72 hr, respectively (p <.05); a significantly higher proportion of apoptotic nuclei at 24–168 hr (p <.05); and a 30.8%, 35.8%, 43.9%, and 39.5% increased production of 45‐, 38‐, 36‐, 30‐, and 28‐kDa proteins at 168 hr, respectively (p <.05). Taken together, these results suggested that activated AMPK promoted mitochondrial apoptosis and bovine muscle tenderization during postmortem aging by increasing the Bax/Bcl‐2 ratio on the mitochondrial membrane. Practical applications: Based on consumer preference, chilled fresh meat is gradually becoming the future trend of the meat industry. Poorly tenderized beef often affects consumers' desire to make secondary purchases and leads to large losses to the meat industry. Therefore, AMP‐activated protein kinase, which regulates postmortem mitochondrial apoptosis and bovine muscle tenderization, is a valid research target. [ABSTRACT FROM AUTHOR]

HSP27 and αβ‐crystallin are molecular chaperones participating in multiple cellular processes. Their roles in the development of postmortem meat quality remain unclear. The current study was designed to investigate the relationship between the concentrations of HSP27 and αβ‐crystallin with meat quality during postmortem aging. Specifically, cooking loss, color, pH, and the myofibril fragmentation index (MFI) of Oula Tibetan sheep meat were determined, and changes in the concentrations of HSP27 and αβ‐crystallin were evaluated. The results indicated that HSP27 concentration significantly decreased in 0–3 days (p < 0.05), presenting a positive correlation with pH (p < 0.05) and a negative correlation with L*, b*, cooking loss, and MFI (p < 0.05, p < 0.05, p < 0.01, p < 0.01). Besides, αβ‐crystallin concentration significantly decreased in 0–2 days (p < 0.05), exhibiting a significant positive correlation with pH (p < 0.05) and a negative correlation with L*, b*, cooking loss, and MFI (p < 0.01, p < 0.01, p < 0.01, p < 0.01). The results suggested that the HSP27 and αβ‐crystallin may participate in the development of meat quality in Oula Tibetan sheep during postmortem early aging. Practical Application: Tenderness, color, and water holding capacity (WHC) are crucial quality attributes of meat. The relationship between the concentrations of HSP27 and αβ‐crystallin and meat quality reveals that HSP27 and αβ‐crystallin may contribute to the development of meat quality in Oula Tibetan sheep during postmortem aging. Therefore, HSP27 and αβ‐crystallin are effective research objects for regulating meat quality during postmortem aging. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The effects of different feeding regimes on antioxidant activity, meat quality, fatty acid composition, lipid oxidation, and volatile matter production in the longissimus thoracis (LT) of Sunit sheep at 0, 24, 48, 72, and 96 h postmortem were investigated. The results showed that the activity of antioxidant enzymes, tenderness, water retention, and percentage of unsaturated fatty acids were significantly higher in the pasture-fed sheep (PF) than in the concentrate-fed sheep (CF) (p < 0.05). During postmortem aging, antioxidant activity, water retention, and the proportion of unsaturated fatty acids decreased in the PF and CF (p < 0.05), while malondialdehyde (MDA) content, the proportion of saturated fatty acids, and the content of flavor substances resulting from fat oxidation increased. After 24 h of LT muscle aging, the pH and shear force of the meat started to increase and the color stabilized. The differences between shear force values and lipid volatile flavor substance content of sheep meat under different feeding regimes disappeared with increasing aging time. PF had better oxidative stability and fatty acid composition. Postmortem aging changed the oxidative stability of sheep meat, thus affecting meat quality and fatty acid composition and consequently meat flavor composition, while aging also eliminated to some extent the differences caused by feeding regimes.

Myosin heavy chain (MHC) isoforms and meat quality characteristics of different muscles were investigated to explore their potential relationships in yaks. Results showed that semitendinosus (ST), longissimus thoracis (LT), and infraspinatus (IS) have a greater ratio of MHC IIb (47.84%), MHC IIa (73.27%), and MHC I (24.26%), respectively, than the other two muscles. Compared with LT or ST, IS exhibited more intense color, greater water-holding capacity, and initial tenderness with higher intermuscular fat (IMF) and collagen (of lower cross-linking level), presenting overall better quality. Variations in MHC isoforms accounted for the muscle-specific meat quality. Specifically, MHC I was positively associated with redness, myoglobin, IMF, collagen, pH, and thermal stability and negatively associated with myofibril fragmentation index, fiber thickness, collagen cross-linking, and drip loss. These results provide insights into the relationships between MHC isoforms and meat quality in yaks and the MHC I isoform has an extensive influence on meat quality. • ST, LT, and IS muscles showed different compositions of MHC isoforms. • IS muscle was darker and redder in appearance, with higher WHC and initial tenderness. • Variations in MHC isoforms account for muscle-specific effect on meat quality. • MHC I isoform comprehensively define meat quality attributes. [ABSTRACT FROM AUTHOR]

Yak is a rare breed of resources in Tibetan Plateau, with high protein and low-fat content, and has other important application value. Yaks are managed by herders and slaughtered in various ages, changing from three years to twelve years of age, and there has a significant difference on meat tenderness in different ages. This study was conducted to investigate the effects of age at harvest, ageing time and the correlation analysis to meat tenderness calpains activity. The work may be used to establish a classification system and grading standards for yak meat. Four groups were established as fewer than 3 years-old, 3-5 years-old, 5-7 years-old and more than 7-years old. The results demonstrated that the content of tenderness has significantly different (P

Objective Meat quality attributes in postmortem muscle tissues depend on skeletal muscle metabolites. The objective of this study was to determine the key metabolic compounds and pathways that are associated with postmortem aging and beef quality in Japanese Black cattle (JB; a Japanese Wagyu breed with highly marbled beef). Methods Lean portions of Longissimus thoracis (LT: loin) muscle in 3 JB steers were collected at 0, 1, and 14 days after slaughter. The metabolomic profiles of the samples were analyzed by capillary electrophoresis time-of-flight mass spectrometry, followed by statistical and multivariate analyses with bioinformatics resources. Results Among the total 171 annotated compounds, the contents of gluconic acid, gluconolactone, spermidine, and the nutritionally vital substances (choline, thiamine, and nicotinamide) were elevated through the course of postmortem aging. The contents of glycolytic compounds increased along with the generation of lactic acid as the beef aging progressed. Moreover, the contents of several dipeptides and 16 amino acids, including glutamate and aromatic and branched-chain amino acids, were elevated over time, suggesting postmortem protein degradation in the muscle. Adenosine triphosphate degradation also progressed, resulting in the generation of inosine, xanthine, and hypoxanthine via the temporal increase in inosine 5′-monophosphate. Cysteine-glutathione disulfide, thiamine, and choline increased over time during the postmortem muscle aging. In the Kyoto encyclopedia of genes and genomes database, a bioinformatics resource, the postmortem metabolomic changes in LT muscle were characterized as pathways mainly related to protein digestion, glycolysis, citric acid cycle, pyruvate metabolism, pentose phosphate metabolism, nicotinamide metabolism, glycerophospholipid metabolism, purine metabolism, and glutathione metabolism. Conclusion The compounds accumulating in aged beef were shown to be nutritionally vital substances and flavor components, as well as potential useful biomarkers of aging. The present metabolomic data during postmortem aging contribute to further understanding of the beef quality of JB and other breeds.

The objective of this study was to investigate the effect of cooking and in vitro digestion on antioxidant activity of peptides in duck meat after 7 days postmortem aging. The 1, 1-diphenyl-2- picrylhydrazyl (DPPH) free radical scavenging activity and reducing power of the obtained peptides were evaluated. Results showed that the cooked sample possessed higher antioxidant activity than the raw sample and upon cooking at different temperatures, sample aged for 7 days had significantly higher antioxidant activity than that of unaged (day 0). The samples which showed higher antioxidant activity after cooking (65°C–30 min, 100°C–20 min, 121°C–10 min) were selected for in vitro digestion, and it is found that their DPPH radical scavenging activity decreased significantly but the reducing power increased significantly after gastrointestinal digestion. These results show the potential of aged duck meat as a good source of antioxidant peptides with high bioactivity after cooking and gastrointestinal digestion.

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Our objective was to investigate the effects of extended aging on the flavor characteristics of Australian grass- and grain-fed beef longissimus thoracis. Ribeye rolls from Australian grass- and grain-fed beef carcasses were collected, randomly assigned to one of 4 postmortem aging days (35, 45, 55, and 65), vacuum packaged, and shipped under refrigeration (0°C–2°C) to Texas Tech University (Lubbock, TX). Aged longissimus thoracis were fabricated on their respective aging day into 2.54-cm steaks, vacuum packaged individually, and frozen (−24°C) until further analyses. According to trained flavor panelists, beef flavor identity, fat-like, metallic, umami, bitter, and sweet flavors were not influenced by diet or postmortem aging (P > 0.05). Diet influenced (P < 0.05) liver-like, rancid, grassy, and sour flavors, as well as juiciness. For all flavors except liver-like, grass-fed samples had stronger flavors than grain-fed samples. Postmortem aging influenced (P < 0.05) bloody/serumy, liver-like, rancid, and grassy flavors, along with tenderness and juiciness. Flavor detection typically became stronger for those flavors as postmortem aging increased; however, bloody/serumy, juiciness, and tenderness generally did not follow a linear trend as postmortem aging increased. Content of acetic acid and hexanal were each greater (P < 0.05) in grain-fed beef. The majority of lipid oxidation compounds were most prominent (P < 0.05) in samples aged 45 and 55 d, while content in 35 and 65 d were lower and did not differ (P > 0.05). Aging also influenced content of acetic acid and ethanol (P ≤ 0.04), which increased with aging duration. For 1-octen-3-ol, grain-fed samples aged 65 d had the greatest (P < 0.05) content compared with all other diet and aging combinations. Results indicate that aging up to 65 d had no impact on beef flavor identity and umami, but it led to stronger generation of certain off-flavors such as rancid, grassy, and liver-like.

Yak is a rare breed of resources in Tibetan Plateau, with high protein and low-fat content, and has other important application value. Yaks are managed by herders and slaughtered in various ages, changing from three years to twelve years of age, and there has a significant difference on meat tenderness in different ages. This study was conducted to investigate the effects of age at harvest, ageing time and the correlation analysis to meat tenderness calpains activity. The work may be used to establish a classification system and grading standards for yak meat. Four groups were established as fewer than 3 years-old, 3-5 years-old, 5-7 years-old and more than 7-years old. The results demonstrated that the content of tenderness has significantly different (P<0.05) in various ages and it increased and then decreased during postmortem aging. The muscle fiber diameter has decreased with the increase of slaughter age, while the MFI showed the contrary. The MFI increased with aging. The myofibrils' ultrastructure was completely disrupted. Calpains activity was significantly decreased (P<0.05) in the first 3 d and then decreased with aging. The calpains activity of yak meat in different ages has increased and then decreased with the different ages. The nitration of μ-calpain promoted its ability in degrading a part of myofibrillar proteins and the degrading of myofibrillar proteins related to the tenderness of meat. [ABSTRACT FROM AUTHOR]

This study evaluates the effect of a low-voltage electrical stimulation (ES) on the tenderness of yak longissimus muscle (LM). Samples from 16 yak bulls were divided into four treatment groups: normal chilling (NC), ES and chilling (ES & C) for 72 s (ES &C 72 s), ES & C for 90 s (ES & C 90 s), and ES & C for 108 s (ES & C 108 s). The temperature, the pH, the glycogen content, the Warner-Bratzler shear force (WBSF), the myofibril fragmentation index (MFI), and the muscle ultrastructure were determined during the course of postmortem aging. ES caused a rapid decrease in the pH to form a high-temperature and low-pH environment. The glycogen content gradually decreased with aging. The WBSF value of the ES & C groups was significantly lower than for the NC group (p < .05). The MFI values of ES & C groups after 24 hr postmortem aging were significantly higher than for the NC group. We concluded that ES improved yak meat tenderness during postmortem aging and that the different duration time by ES indicated different effects, and its affect was remarkable in the ES & C 90 s. [ABSTRACT FROM AUTHOR]