Proteome changes on water-holding capacity of yak longissimus lumborum during postmortem aging

Identifying Meat from Grazing or Feedlot Yaks Using Visible and Near-infrared Spectroscopy with Chemometrics

The quality of meat can differ between grazing and feedlot yaks. The present study examined whether spectral fingerprints by visible and near-infrared (Vis-NIR) spectroscopy and chemo-metrics could be employed to identify the meat of grazing and feedlot yaks. Thirty-six 3.5-year-old castrated male yaks (164 ± 8.38 kg) were divided into grazing and feedlot yaks. After 5 months on treatment, liveweight, carcass weight, and dressing percentage were greater in the feedlot than in grazing yaks. The grazing yaks had greater protein content but lesser fat content than feedlot yaks. Principal component analysis (PCA) was able to identify the meat of the two groups to a great extent. Using either partial least squares discriminant analysis (PLS-DA) or the soft independent modeling of class analogies (SIMCA) classification, the meat could be differentiated between the groups. Both the original and processed spectral data had a high discrimination percentage, especially the PLS-DA classification algorithm, with 100% discrimination in the 400-2500 nm band. The spectral preprocessing methods can improve the discrimination percentage, especially for the SIMCA classification. It was concluded that the method can be employed to identify meat from grazing or feedlot yaks. The unerring consistency across different wavelengths and data treatments highlights the model's robustness and the potential use of NIR spectroscopy combined with chemometric techniques for meat classification. PLS-DA's accurate classification model is crucial for the unique evaluation of yak meat in the meat industry, ensuring product traceability and meeting consumer expectations for the authenticity and quality of yak meat raised in different ways.

Effect of glycolysis on water holding capacity during postmortem aging of Jersey cattle-yak meat

BACKGROUND

Postmortem muscle moisture loss leads to a decrease in carcass weight and can adversely impact overall meat quality. Therefore, it is critical to investigate water holding capacity (WHC) to enhance meat quality. Current research has primarily focused on examining the correlation between signaling molecules and meat quality in relation to the glycolysis effect on muscle WHC. But there exists a significant knowledge gap regarding the mechanism of WHC in Jersey cattle-yak meat.

RESULTS

Jersey cattle-yak meat pH decreased and then increased during postmortem aging. Lactate content, cooking loss, pressing loss, drip loss and centrifuging loss of Jersey cattle-yak meat increased and then decreased during postmortem aging. The glycogen content of Jersey cattle-yak meat was significantly higher than that of yak meat at 6-120 h, being 8.40% higher than that of yak meat at 120 h. The activity of key glycolytic enzymes hexokinase (HK), pyruvate kinase (PK), phosphofructokinase (PFK) and lactate dehydrogenase (LDH) in Jersey cattle-yak meat was lower than that in yak meat. Correlation analysis showed that Jersey cattle-yak meat WHC was positively correlated with the activity of HK, PK, PFK and LDH.

CONCLUSIONS

The WHC of Jersey cattle-yak meat was higher than that of Gannan yak meat, and it was significantly positively correlated with the activity of key enzymes of the glycolytic signaling pathway. Therefore, the glycolysis rate can be reduced by inhibiting enzyme activity to improve Jersey cattle-yak meat WHC and meat quality. © 2023 Society of Chemical Industry.

LF-NMR determination of water distribution and its relationship with protein- related properties of yak and cattle during postmortem aging

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.

Phosphorylated Trehalose Suppresses the Denaturation of Myofibrillar Proteins in Peeled Shrimp (Litopenaeus vannamei) during Long-Term Frozen Storage

The protective effects of phosphorylated trehalose on the quality and characteristics of peeled shrimp (Litopenaeus vannamei) were determined. Quality changes in treated samples were evaluated by assessing the physicochemical properties of myofibrillar proteins (MP) and compared to fresh water-, sodium tripolyphosphate-, and trehalose-treated samples during 12 weeks of frozen storage. The sensitivity of MP to oxidation and denaturation was increased during frozen storage. Phosphorylated trehalose significantly improved the quality of shrimp by increasing water-holding capacity. Further analysis showed that the addition of phosphorylated trehalose reduced the decrease in soluble MP content, Ca²⁺-ATPase activity, and total sulfhydryl contents and also effectively inhibited the increase in the surface hydrophobicity of MP. In addition, atomic force microscopy and hematoxylin and eosin staining revealed that phosphorylated trehalose preserved the integrity of the myofibril microstructure. Thermal stability results further confirmed that the denaturation temperature and denaturation enthalpy of MP were improved by phosphorylated trehalose. Overall, phosphorylated trehalose suppresses the denaturation of MP in peeled shrimp during long-term frozen storage.

Metabolic, proteomic and microbial changes postmortem and during beef aging

The purpose of this review is to provide an overview of the current knowledge about proteomic and metabolic changes in beef, the microbiological alteration postmortem and during aging, and observe the influence on beef quality parameters, such as tenderness, taste and flavor. This review will also focus on the different aging types (wet- and dry-aging), the aging or postmortem time of beef and their effect on the proteome and metabolome of beef. The Ca2+ homeostasis and adenosine 5'-triphosphate breakdown are the main reactions in the pre-rigor phase. After rigor mortis, the enzymatic degradation of connective tissues and breakdown of energy metabolism dominate molecular changes in beef. Important metabolic processes leading to the formation of saccharides, nucleotides, organic acids (e.g. lactic acid), creatine and fatty acids are considered in this context as possible flavor precursors or formers of beef flavor and taste. Flavor precursors are substrates for lipid oxidation, Strecker degradation and Maillard reaction during cooking or roasting. The findings presented should serve as a basis for a better understanding of beef aging and its molecular effects and are intended to contribute to meeting the challenges of improving beef quality.

Proteomic changes involved in water holding capacity of frozen bovine longissimus dorsi muscles based on DIA strategy

As freeze/thaw procedure leads to inevitable drip loss, elucidation of mechanism on dynamic changes in water holding capacity (WHC) of muscle is urgently needed. In this study, the proteomic profile by DIA-based strategy, muscle microstructure, water mobility, and WHC indices of bovine longissimus dorsi muscles were investigated under different freezing conditions as well as the correlations among them. Results indicated that slow freezing (SF) sample exhibited significantly higher water mobility, thaw loss, total loss, and shear force value than the samples subjected to fast freezing (FF) and non-frozen control (CON). According to the protein profile, we have identified 272 differential abundance proteins (DAPs), in which more significant proteome changes were found in SF/CON samples as compared with FF/CON. Among the 132 DAPs in FF/SF comparison, correlation analysis revealed that MYL3, DES, SYNE2, EXR, RPL35A, RPS6, and Hsp40 were closely correlated with T₂₃ , thaw loss, and total loss. Accordingly, we considered those seven proteins as potential biomarkers related to WHC of frozen muscle. Our study should give a further understanding on mechanisms behind the various WHC of muscle when subjected to different freezing conditions. PRACTICAL APPLICATIONS: Freezing plays a key role in the preservation method for meat and meat products. However, the drip loss during freezing and subsequent thawing procedure causes considerable economic and nutritional losses. To minimize the losses, elucidation of mechanism on the mechanism of thaw loss formation is urgently needed. DIA-based proteomics is a novel, robust method that provides further understanding on the mechanisms behind the dynamic changes in water holding capacity of muscle. The screened protein biomarkers in frozen muscle would play key roles in the development of WHC, especially for the thaw loss formation. Through this perspective, we can explain the origin of thaw loss and the variation under different freezing conditions, which should provide the meat industries with theoretical basis for reducing losses.

Proteomics and metabolomics combined study on endopathic changes of water-soluble precursors in Tan lamb during postmortem aging

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.

Estimation of the proteome affecting changes in tenderness of yak meat during storage by label-free mass spectrometry

Background

Tenderness is the main quality of meat products. However, the meat tenderness formation is a complex biological process, and pathways and proteins that affect the tenderness of yak meat are unknown.

Methods

Label‐free proteomics method was used to explore the effects of differentially expressed proteins on the tenderness of yak skeletal muscle (tenderloin) during post‐mortem storage (0, 3, and 7 days) at 3 ± 1°C.

Results

The tenderness of yak skeletal muscle improved significantly during storage. A total of 91 differentially expressed proteins of yak skeletal muscle during post‐mortem storage were identified by the following comparisons: day 3 versus 0, day 7 versus 0, and day 7 versus 3. NDUFS6, CYCS, COX6A2, LDB3, HSPB7, TPM4, TAGLN, COL1A1, LUM, MYH11, ACTC1, and MYOZ1 proteins showed a significant difference during yak skeletal muscle post‐mortem storage. Furthermore, bioinformatics analyses revealed that the identified proteins were related to carbon metabolism, citrate cycle, glycolysis, oxidative phosphorylation, and RNA degradation.

Conclusion

The results of the present study could provide proteomic insights into changes in yak skeletal muscle tenderness during storage and may be a valuable resource for future investigations.

Metabolites Analysis on Water-Holding Capacity in Beef Longissimus lumborum Muscle during Postmortem Aging

Currently, the metabolomic research on water-holding capacity (WHC) of beef during postmortem aging is still insufficient. In this paper, the kit method was adopted for energy metabolites testing, the ultra-high-performance liquid chromatography (UHPLC) system was used for sample separation, and the mass spectrometer was applied to collect the primary and secondary spectra of the samples. The results showed that lactic acid reached saturation at day 2 postmortem, while energy metabolites changed significantly within day 2 postmortem (p < 0.05). Based on these findings, it was suggested that the energy metabolism qualities of the beef had already achieved a largely stable state at around day 2 postmortem. Then, through metabolomic analysis, 25 compounds were differentially abundant at days 0, 0.5, 1, and 2 during postmortem aging. Within the period of day 0−2 postmortem, the purine metabolism in beef was relatively active until 0.5 d postmortem, while glycolysis metabolism remained active until day 2 postmortem. The functions of the identified metabolites contribute to a more detailed molecular view of the processes behind WHC and are a valuable resource for future investigations into the flavor of postmortem beef.

Housekeeping Proteins in Meat Quality Research: Are They Reliable Markers for Internal Controls in Western Blot? A Mini Review

Advancements in technology and analytical methods enable researchers to explore the biochemical events that cause variation in meat quality. Among those, western blot techniques have been successfully used in identifying and quantifying the key proteins that have critical functions in the development of meat quality. Housekeeping proteins, like β-actin, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), and tubulins are often used as internal controls in western blots to normalize the abundance of the protein of interest. However, there are increasing concerns about using housekeeping proteins for western blot normalization, as these proteins do not demonstrate any loading differences above the relatively small total protein loading amounts of 10μg. In addition, the interaction between these housekeeping proteins and programmed cell death processes highlights the concerns about using the housekeeping protein as the internal control in meat quality research. Moreover, recent proteomic research has indicated that the abundance of some housekeeping proteins, like β-actin, GAPDH, and tubulin, can be altered by preslaughter stress, dietary supplementation, sex, slaughter method, genotype, breed, aging period, muscle type, and muscle portion. Furthermore, these housekeeping proteins could have differential expression in meat with differing color stability, tenderness, and water holding capacity. Therefore, this review aims to examine the realities of using housekeeping proteins as the loading control in meat quality research and introduce some alternative methods that can be used for western blot normalization.

The Quality Changes and Proteomic Analysis of Cattle Muscle Postmortem during Rigor Mortis

Rigor mortis occurs in a relatively early postmortem period and is a complex biochemical process in the conversion of muscle to meat. Understanding the quality changes and biomarkers during rigor mortis can provide a theoretical basis for maintaining and improving meat quality. Herein, a tandem mass tag proteomic method is used to investigate the effects of differentially expressed proteins on the meat quality of cattle Longissimus lumborum muscle postmortem (0, 6, and 24 h). The pH, total sulfhydryl content and sarcomere length decrease significantly during storage. In contrast, meat color values (L*, a*, and b*) and the myofibril fragmentation index increase significantly. Altogether, 147 differentially expressed proteins are identified, most being categorized as metabolic enzymes, mitochondrial proteins, necroptosis and ferroptosis proteins and structural proteins. The results also reveal additional proteins that are potentially involved in rigor mortis, such as cardiac phospholamban, acetyl-coenzyme A acyltransferase, and ankyrin repeat domain 2. The current results provide proteomic insights into the changes in meat quality during rigor mortis.

Integrated proteomic, phosphoproteomic, and N-glycoproteomic analyses of the longissimus thoracis of yaks

Yaks (Bos mutus) live in the Qinghai–Tibet plateau. The quality of yak meat is unique due to its genetic and physiological characteristics. Identification of the proteome of yak muscle could help to reveal its meat-quality properties. The common proteome, phosphoproteome, and N-glycoproteome of yak longissimus thoracis (YLT) were analyzed by liquid chromatography-tandem mass spectrometry-based shotgun analysis. A total of 1812 common proteins, 1303 phosphoproteins (3918 phosphorylation sites), and 204 N-glycoproteins (285 N-glycosylation sites) were identified in YLT. The common proteins in YLT were involved mainly in myofibril structure and energy metabolism; phosphoproteins were associated primarily with myofibril organization, regulation of energy metabolism, and signaling; N-glycoproteins were engaged mainly in extracellular-matrix organization, cellular immunity, and organismal homeostasis. We reported, for the first time, the “panorama” of the YLT proteome, specifically the N-glycoproteome of YLT. Our results provide essential information for understanding post mortem physiology (rigor mortis and aging) and the quality of yak meat.

•

A total of 2650 proteins were identified in yak longissimus thoracis.

•

Common proteins were involved mainly in myofibril structure and energy metabolism.

•

Phosphoproteins were associated with myofibrils, energy metabolism, and signaling.

•

N-glycoproteins were engaged mainly in ECM organization, immunity, and homeostasis.

Proteomics discovery of protein biomarkers linked to yak meat tenderness as determined by label-free mass spectrometry

Tenderness is one of the most important qualities in meat. A proteomic approach is a suitable way to ensure meat tenderness. Thirty-six tenderloin samples from yak were classified as exhibiting high (n = 12) or low (n = 12) tenderness and were evaluated using label-free proteomics for the identification of the proteins and pathways most influential in tenderness variability. Between the two groups, proteomic changes were mainly caused by 33 differentially expressed proteins as displayed in reference patterns in heat maps. The expression of ENO2, SUCLG2, ETFDH, PGM1, TNNT3, TNNT1, HSDL2, GPI, ALAD, and COL1A1 proteins was very different between yak meats with high and low tenderness, and therefore, they are candidate biomarkers of yak meat tenderness. Furthermore, bioinformatics analyses revealed that the identified proteins are related to pentose phosphate, glycolysis, the citrate cycle, fatty acid metabolism, and the calcium signaling pathway.

Effect of refrigeration on the collagen and texture characteristics of yak meat

To investigate the effect of refrigeration on the collagen and texture characteristics of yak meat, the changes in collagen content, solubility, shear force, hardness, cohesiveness, springiness, gumminess, and chewiness of yak meat at 4 ± 1 °C were measured. The results showed that the contents and solubility of collagen in yak meat significantly decreased (P < 0.05). The myofibrillar fragmentation index of yak meat significantly increased (P < 0.05). The shear force, hardness, cohesiveness, springiness, gumminess, and chewiness of yak meat significantly decreased (P < 0.05). Correlation analysis and histological structure analysis confirmed that myofibrillar fragmentation and collagen characteristics significantly affected the formation of yak meat texture during refrigeration. After 5 d of refrigerated storage, yak meat has a higher quality. The results provide a theoretical basis and data to support the deep processing and quality control of yak meat.

Concentrations of HSP27 and αβ-crystallin in Oula Tibetan sheep meat and their relationship with meat quality during postmortem aging

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.

Transcriptome profiling analysis of muscle tissue reveals potential candidate genes affecting water holding capacity in Chinese Simmental beef cattle

Water holding capacity (WHC) is an important sensory attribute that greatly influences meat quality. However, the molecular mechanism that regulates the beef WHC remains to be elucidated. In this study, the longissimus dorsi (LD) muscles of 49 Chinese Simmental beef cattle were measured for meat quality traits and subjected to RNA sequencing. WHC had significant correlation with 35 kg water loss (r = − 0.99, p < 0.01) and IMF content (r = 0.31, p < 0.05), but not with SF (r = − 0.20, p = 0.18) and pH (r = 0.11, p = 0.44). Eight individuals with the highest WHC (H-WHC) and the lowest WHC (L-WHC) were selected for transcriptome analysis. A total of 865 genes were identified as differentially expressed genes (DEGs) between two groups, of which 633 genes were up-regulated and 232 genes were down-regulated. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment revealed that DEGs were significantly enriched in 15 GO terms and 96 pathways. Additionally, based on protein–protein interaction (PPI) network, animal QTL database (QTLdb), and relevant literature, the study not only confirmed seven genes (HSPA12A, HSPA13, PPARγ, MYL2, MYPN, TPI, and ATP2A1) influenced WHC in accordance with previous studies, but also identified ATP2B4, ACTN1, ITGAV, TGFBR1, THBS1, and TEK as the most promising novel candidate genes affecting the WHC. These findings could offer important insight for exploring the molecular mechanism underlying the WHC trait and facilitate the improvement of beef quality.

Proteomics analysis as an approach to understand the formation of pale, soft, and exudative (PSE) pork

We investigated ten pale, soft, and exudative (PSE), and ten normal meat samples from pig carcasses. The meat quality at 0, 5, 12, and 24 h post-mortem and the key enzyme activities at 0 and 24 h post-mortem were determined. We selected three PSE and three normal samples for proteomics analysis at 0 h and 24 h post-mortem. No remarkable differences in pyruvate kinase (PK) and lactate dehydrogenase (LDH) activity were observed between samples at 0 h post-mortem; however, creatine kinase (CK) activity was significantly higher in PSE meat. Hexokinase (HK) activity in PSE samples was higher than that in normal samples at 24 h post-mortem. Bioinformatics analysis of the proteome showed that PSE was related to glycolysis, TCA cycle, oxidative phosphorylation, muscle tissue structure, signal transduction, and molecular chaperones. This research found that proteins such as troponin T slow skeletal muscle isoform X, GADPH, L-lactate dehydrogenase A chain, and gamma-enolase isoform X1 might be responsible for PSE.

Insights into the similarities and differences of whiteleg shrimp pre-soaked with sodium tripolyphosphate and sodium trimetaphosphate during frozen storage

In this study, similarities and differences of sodium tripolyphosphate (STPP) and sodium trimetaphosphate (STMP) pre-soaking on the stability of muscle proteins in shrimp were investigated during 12 weeks of frozen storage (-30 °C). The physicochemical analysis indicated significant improvements in the WHC, springiness, chewiness, and thermal stability of STPP and STMP pre-soaked samples when compared to the control. Interestingly, STMP pre-soaking showed better cryoprotective effects than the STPP treatment when the storage period reached the end of the 12 weeks. Furthermore, the label-free based proteomics results indicated that 62 upregulated differentially abundant proteins (DAPs) were detected in STMP when compared to STPP. These identified DAPs specifically included 40S ribosomal proteins, actin-related proteins, heat shock proteins, myosin heavy chain, and tubulin beta chain. Additionally, the gene ontology (GO) and eukaryotic clusters of orthologous group (KOG) analyses verified that the incorporation of STMP molecules enhanced the resistance of cytoskeleton proteins to cold-temperature stress.

Quantitative changes in peptides derived from proteins in beef tenderloin (psoas major muscle) and striploin (longissimus lumborum muscle) during cold storage

Peptides derived from whole proteins in beef tenderloin (M. psoas major, PM) and striploin (M. longissimus lumborum, LL) associated with meat quality and muscle fiber composition were identified and quantified during 21 days of aging. Peptide quantification revealed 40-43 proteins to be significantly degraded during all aging time, and these were mostly sarcoplasmic proteins. Cooking loss of both muscles was not changed by aging (P > 0.05), whereas Warner-Bratzler shear force and meat color were affected by aging. Sensory tenderness increased in PM after 14 days of aging (P < 0.05). PM had a higher type I fiber content, whereas LL had a higher type IIX fiber content (P < 0.05), resulting in differences in proteolysis during all aging periods tested. These findings improve our understanding of different biochemical and physicochemical changes in aged meat according to the muscle type.

Influence of collagen changes on the tenderness of yak rumen smooth muscle during storage

The aim of the present study was to investigate the influence of collagen changes on the tenderness of yak rumen smooth muscle during storage. Yak rumen smooth muscle was stored at 3 ± 1 °C for 7 d and the Warner–Bratzler shear force (WBSF); total, soluble, and insoluble collagen content (TCC, SCC); collagen solubility (CS); and histological structure were monitored. Label-free mass spectrometry was used to validate the changes in collagen. Collagen changes significantly influenced yak rumen smooth muscle tenderness. A significant positive relationship was found between WBSF and TCC, SCC, as well as CS. The label-free mass spectrometry results validated that the collagen of smooth muscle was degraded during storage. Histological analysis revealed that yak rumen smooth muscle structure was destroyed during storage. Smooth muscle underwent a similar change in tenderness as skeletal muscle, and the weakening of connective tissue was the main reason for smooth muscle tenderness development.

Influence of temperature fluctuations on growth and recrystallization of ice crystals in frozen peeled shrimp (Litopenaeus vannamei) pre-soaked with carrageenan oligosaccharide and xylooligosaccharide

Temperature fluctuation is a common problem in the frozen storage of shrimp products. This study investigated the influence of carrageenan oligosaccharide (CO) and xylooligosaccharide (XO) on the growth and recrystallization of ice crystals in frozen peeled shrimp exposed to temperature fluctuations. Shrimp soaked with water and 3.0% (w/v) Na₄P₂O₇ solution were designated as the negative and positive controls, respectively. Our data revealed that both CO- and XO-soaked shrimp had significant improvements in thawing and cooking loss, myofibrillar protein content, Ca²⁺-ATPase activity, and textural variables when exposed to temperature fluctuations compared to control samples. Microstructural imaging indicated that soaking the shrimp in CO and XO slowed the progression of damage caused to tissue myofibrils by large ice crystals, as well as inhibited the growth and recrystallization of ice crystals in muscle tissues. SDS-PAGE analysis confirmed that treatment with the oligosaccharides exhibited marked effects on the stability of muscle proteins and inhibited the degradation of muscle proteins affected by the temperature fluctuations. Based on these data, we hypothesize that the incorporated CO and XO may bind to muscle proteins and capture water molecules in the myofibrillar network through hydrogen bonding, thereby suppressing the myofibrillar denaturation and tissue structure destruction induced by the growth and recrystallization of ice crystals.

Study on the effect of CaMKKβ-mediated AMPK activation on the glycolysis and the quality of different altitude postmortem bovines longissimus muscle

This study investigated the activity of adenosine monophosphate-activated protein kinase (AMPK), glycolysis, and meat quality index in three altitude bovines during postmortem aging process. Local cattle (altitude:1,500 m), Gannan yak (3,000 m), and Yushu yak (4,500 m) postmortem Longissimus Dorsi (LD) muscle were used. Results indicated that CaCl₂ significantly increased the AMPK activity by increasing the calcium-regulated protein kinase kinase (CaMKKβ) activity. Besides, AMPK activation enhanced the activity of lactate dehydrogenase (LDH) and Ca²⁺ -ATPase and accelerated the rate of muscle maturation during postmortem aging. Moreover, the expression of HIF-1, PRKAA2, and GLUT4 genes in high-altitude Yushu yak was higher than that of low-altitude bovines. CaCl₂ activates AMPK by activating CaMKKβ cascade and accelerates postmortem glycolysis affecting the intramuscular environment, color, and muscle protein degradation to accelerate postmortem muscle maturation, suggesting that AMPK has essential effects on postmortem muscle glycolysis and quality, and can regulate muscle quality by regulating postmortem muscle AMPK activity. PRACTICAL APPLICATIONS: Insufficient postmortem glycolysis usually leads to DFD (dark, firm, and dry) meat. Beef have relatively high incidences of DFD meat, which has an unattractive dark color and causes significant loss to the meat industry. Therefore, AMPK, which can regulate postmortem glycolysis to affect meat quality, is a valid research target.

Growth Performance and Meat Quality Evaluations in Three-Way Cross Cattle Developed for the Tibetan Plateau and their Molecular Understanding by Integrative Omics Analysis

Despite of favorable characteristics of high protein, low fat, and free-pollution, yak meat has intrinsically poor performance in tenderness and color, which is ever challenging yak sector. To this end, a three-way cross system was first developed for high quality beef of the Tibetan Plateau using Angus cattle ( Bos taurus) as terminal sire to mate with 1/2 yak (F1) generated from♂Qaidam cattle ( Bos taurus) × ♀yak ( Bos grunniens). The withers height, chest girth, and body weight of 1/4 yak (F2) were all great higher than that of yak and 1/2 yak ( P < 0.01), especially at later period, suggesting the faster growth rate of 1/4 yak. Also the dressing percentage was much better in 1/4 yak ( P < 0.01). Tenderness and meat color were both significantly improved in 1/4 yak with some unpleasant sacrifice of PUFAs, such as EPA and DHA, and meat protein, given the significantly lower shear force and higher L* ( P < 0.01). A total of 769 genes, including SREBF1, GHR, and FASN, the widely recognized causal genes of meat quality, were identified from 11947 differently expressed genes by the data integration of transcriptome, GWAS and QTL. These genes were significantly enriched for important pathway and GO terms, such as insulin signaling pathway, fatty acid biosynthesis, calcium signaling pathway, metabolic pathway, and cellular response to stress ( P < 0.01). And 12 promising candidates were exemplified with annotation of H3K4me3 data from divergent meat quality, such as OSTF1, NRAS1, and KCNJ11. Interestingly, 75 high-altitude adaptive candidate genes were also detected in the list. This study is a first step toward high quality beef of the Tibetan Plateau and provides useful information for their molecular understanding.