Changes In Meat Quality Research Articles

Changes in meat quality of Esox Lucius during postmortem storage: Based on the lysosomal-mitochondrial apoptotic pathway

In this study, we explored the correlation between the lysosome–mitochondrial apoptosis pathway and fish softening, as well as the correlation between ferritin degradation and lysosomal iron changes. The results indicated that ferritin levels gradually decreased, lysosomal iron first increased and then decreased and tended to stabilize, and lysosomal membrane stability significantly decreased (p < 0.05). Spearman's analysis suggested that an increase in lysosomal iron was associated with ferritin degradation. Lysosomal instability promoted the release of cathepsin D, thereby increasing the release of Bid and Bax, and inhibiting the expression of Bcl-2. Subsequently, caspase-9/−3 was activated. In addition, transmission electron microscopy revealed ultrastructural damage to mitochondria and cell nuclei, which are morphological features of apoptosis during post-mortem storage. Moreover, TUNEL staining confirmed the occurrence of apoptosis. We concluded that the lysosome– mitochondrial apoptosis pathway was active during the storage of Esox Lucius, in which ferritin degradation and increased lysosomal iron were key factors inducing lysosomal damage, and cathepsin D released by lysosomes was a key factor connecting lysosomes and mitochondria.

Microwave cavity antenna for automatic detection of chicken breast muscles affected by wooden breast defect

Over the past years, artificial selection for meat-type (broiler) chickens has resulted in improved production efficiency, but also in an increased incidence of skeletal muscle abnormalities. In particular, wooden breast (WB) abnormality causes abrupt changes in meat quality and enormous economic losses. Thus, the poultry processing industry requires a reliable method to detect the abnormality in production lines in a non-destructive and contactless way. The present research aimed to evaluate the effect of WB on dielectric properties to develop a potential online technique to distinguish unaffected from affected breasts. Sixty-five pectoralis major muscles were picked 3 h post-mortem from the same flock (42-day-old broilers, 2.8 kg average live weight) and classified by visual inspection according to their phenotype as normal (N, not showing not any signs of the WB condition; n = 33) or WB (exhibiting extensive hardened areas and stiffness perceived by manual palpation throughout the entire fillet; n = 32). WB muscles exhibited remarkably higher values of dielectric constant and loss factor in a wide range of the explored frequencies (200 MHz–14 GHz), suggesting higher water mobility and a higher solvate capacity; this makes the electromagnetic technique for classification promising. Based on the above evidence, a rapid microwave electric technique in the range 1.5 GHz–3 GHz was developed for the online detection of WB. Indeed, combining the use of a cavity antenna (vector network analyzer instrumental chain with partial least square – discriminant analysis), this technique correctly classified 100% of the validation test set.

Bilayer pH-sensitive colorimetric indicator films based on chitosan/purple carrot extract and gellan gum/Mg-carbon dots for visual monitoring of pork freshness

A pH-sensitive colorimetric bilayer film was constructed on the basis of layer-by-layer self-assembly, with chitosan (CS)-loaded purple carrot anthocyanin (PCA) as the inner indicator layer and gellan gum (GG)-loaded Mg-doped carbon dots (Mg-CDs) as the protective outer layer. X-ray diffraction and scanning electron microscopy analyses confirmed the successful preparation of the bilayer film and the incorporation of Mg-CDs. Fourier transform infrared spectroscopy indicated that the Mg-CDs formed hydrogen bonds with the film matrix. Thermogravimetric analysis revealed that the Mg-CDs improved the thermal stability of the double-layer films. Moreover, the addition of 7 wt% Mg-CDs increased the water vapor permeability, oxygen permeability, and tensile strength of the films by 0.94-, 0.79-, and 3.18-fold, respectively. The antioxidant and antimicrobial activities of the films were significantly enhanced by including Mg-CDs as the active agents. Illumination experiments revealed that the relative color change (S values) increased by only 2.76 % and 4.69 % after the addition of 7 wt% Mg-CDs to the GG -Mg-CDs layer after 21 days of visible light and 72 h of UV light exposure, respectively. These bilayer films containing PCA and Mg-CDs exhibit good pH color responsiveness and biosafety. The C-P/G-7 %CD film had the best overall performance and can effectively reflect pork freshness during storage. Therefore, this research has great potential for developing a double-layer film for monitoring meat quality changes in intelligent food packaging.

Lipidome and metabolome profiling of longissimus lumborum beef with different ultimate pH and postmortem aging

The objective of this exploratory study was to assess the changes on lipidome and metabolome profiling of Longissimus lumborum bull muscle with different ultimate pH (pHu) and aging periods. The bull muscles classified as normal, intermediate, or high pHu were collected from a Brazilian commercial slaughterhouse, cut into steaks, individually vacuum-packaged, and aged for 3 days (3-d) or 21 days (21-d) at 2 °C. Muscle extracts were analyzed for the profiles of both lipids, by mass spectrometry (via direct flow-injection), and metabolites, by nuclear magnetic resonance, with downstream multivariate data analysis. As major results, pairwise comparisons identified C12:0 and C14:0 acylcarnitines as potential biomarkers of the intermediate pHu-muscle, which are related to lipid catabolism for alternative energy metabolism and indicate less protein breakage postmortem. Interestingly, the concentration of arginine at early postmortem aging (3-d) may influence the previously reported improved tenderness in normal and high pHu-muscles. Moreover, upregulation of fumarate, formate, and acetate with increased pHu muscle at 21-d aging indicate more intense tricarboxylic acid cycle, amino acid degradation, and pyruvate oxidation by reactive oxygen species, respectively. These three compounds (fumarate, formate, and acetate) discriminated statistically the muscle with high pHu at 21-d aging. The normal pHu-muscle showed higher concentrations of glycogenolysis and glycolysis metabolites, including glucose, mannose, and pyruvate. Hence, our results enhance knowledge of postmortem biochemical changes of beef within different pHu groups aged up to 21 days, which is essential to understand the mechanisms underpinning bull meat quality changes.

Designing the pH-sensitive indicator based on starch nanoparticle with bromocresol green for monitoring meat spoilage

ABSTRACT The starch nanoparticle, combined with bromocresol green (BCG), served as a pH-sensitive indicator to monitor meat quality throughout an 8-day refrigerated storage period. The meat samples were sealed in package which the pH-sensitive indicator attached to the interior part of packaging lid. The changes in meat quality were evaluated by total volatile base nitrogen (TVBN), pH, total viable count (TVC), sensory analysis, and color in interval of 0, 3, 5, 7, and 8-days storage at 4°C. Initial TVBN values were recorded at 19.6 mg/100 g, increased to 26.6 mg/100 g by the end of storage period. The pH value was significantly increased after 8 days storage at 4°C. The observed color variation in the indicator from yellow to blue was attributed to the concurrent increases in TVBN, TVC, and pH. The indicator color changes had significant correlation with analyzed chemical quality of stored meat. Therefore, the designed BCG pH-sensitive indicator could be effective in monitoring the meat spoilage during storage.

Changes in meat quality and volatile flavor compounds profile in beef loin during dry-aging

The objective of this study was to evaluate the effects of dry-aging on beef meat quality changes and flavor compound developments during dry-aging periods. The results showed increased pH and weight loss (P < 0.01), while decreased water content, drip loss, centrifugation loss, and cooking loss (P < 0.01) with dry-aging. The extension of dry-aging significantly improved shear force and myofibrillar protein fragmentation (P < 0.05) of beef loins. However, longer-term dry-aged (28 d) meat exhibited much lower a* values, and higher 2-thiobarbituric reactive substances and carbonyl content (P < 0.01) at the end of dry-aging and even subsequent display. A total of 62 volatile flavor compounds were detected with whole dry-aging periods, and aldehydes were the major potential contributors to cooked beef meat flavor. Principal component analysis indicated the difference in flavor compounds profiles between unaged and dry-aged beef. The content of Strecker aldehydes (2-methyl-butanal and 3-methyl-butanal), some acids, heterocyclic compounds, and ethyl acetate increased with the prolongation of dry-aging time. By combining partial least squares discrimination analysis, 34 compounds with variable importance projection (VIP) > 1 were screened as important aroma compounds changed during the dry-aging processing of beef.

Changes in meat quality, metabolites and microorganisms of mutton during cold chain storage

During the cold chain storage process, changes in metabolites and microorganisms are highly likely to lead to changes in meat quality. To elucidate the changes in the composition of metabolites and microbiota during cold chain storage of mutton, this study utilized untargeted metabolome and 5R 16S rRNA sequencing analyses to investigate the changes in the longissimus dorsi under different cold chain temperatures (4 °C and −20 °C). With the extension of cold chain storage time, the meat color darkened and the content of C18:2n-6, C20:3n-6, and C23:0 were significantly increased in mutton. In this study, nine metabolites, including 1,2-Dioleoyl-sn-glycero-3-phosphoethanolamine, alanylphenylala-nine, indole-3-acrylic acid and the others, were significantly altered during cold chain storage. The abundance of the dominant microorganisms, including Brachymonas, Aeromonas, Corynebacterium and Steroidobacter, was significantly altered. Furthermore, a high correlation was observed between the different metabolites and microorganisms. These findings provide an in-depth understanding of the effects of different cold chain storage temperatures and times on the quality of mutton.

Changes in meat quality and muscle fiber characteristics of beef striploin (M. longissimus lumborum) with different intramuscular fat contents following freeze-thawing

Adipose (fat) tissue has different physical properties from skeletal muscle tissue, and its moisture content is relatively low; thus, freezing or freeze-thawing of meat affects its quality. However, the effect of intramuscular fat (IMF) of meat has not been comprehensively studied. The changes in the meat quality and muscle fiber characteristics of beef striploin (M. longissimus lumborum; LL) with different IMF contents (63.5 g/kg‒260.3 g/kg; n = 52) following freeze-thawing were examined. Freeze-thawing destroyed muscle fibers, and the fiber size was decreased irrespective of muscle fiber type or IMF content. However, the size of type I and IIA muscle fibers was largely altered in LL muscles with lower IMF content. Low IMF content increased the tenderness and decreased the pH of LL muscles; the effects of low IMF content on discoloration in LL muscles were less prominent. Larger IMF particles and higher density were associated with reduced thawing loss in LL muscles. IMF content reduced the lightness of frozen-thawed meat, but it did not excessively reduce water-holding capacity and pH. Thus, deterioration in meat quality can be prevented by considering the IMF content during the freezing process.

Effect of postmortem aging and fast-freezing on meat quality of various lamb cuts under prolonged frozen storage and repeated freezing/thawing conditions

This study aimed to investigate the effects of aging and fast-freezing on meat quality attributes of various lamb cuts under conditions of prolonged frozen storage (Experiment 1) and repeated freezing/thawing cycles (Experiment 2). The paired lamb muscles including longissimus dorsi, gluteus medius, quadriceps femoris, semimembranosus, and biceps femoris from 15 lamb carcasses were collected at 1 d postmortem. In Experiment 1, the muscles were vacuum-packaged and randomly assigned to one of 3 treatments: (1) non-frozen control (aged only for 5 wk at −1.5°C); (2) aging for 4 wk, fast-frozen in a −18°C glycol immersion chamber, and frozen storage in −18°C for 1 week; or (3) aging for 4 wk, fast-frozen, and frozen storage for 24 wk. In general, regardless of muscle cuts, samples that were aged, fast-frozen, stored for 1 wk, and thawed exhibited similar water-holding capacity, shear force, and color attributes as those of the aged-only (never frozen) lamb muscles (P&amp;gt;0.05). Furthermore, extending the frozen storage duration up to 24 wk did not result in any adverse effects on color, shear force, purge loss, or microbiological attributes of the aged/fast-frozen/thawed lamb muscles (P&amp;gt;0.05). In Experiment 2, the repeated freezing and thawing of aged and fast-frozen lamb loins (n=8) had no adverse impacts on color, tenderness, or microbiological attributes (P&amp;gt;0.05), although slight increases in purge and cook losses were observed compared to non-repeated slow-frozen loins. The findings of the present study suggest that the combined treatment of aging and fast-freezing can minimize changes in meat quality during the freezing and thawing process, even with prolonged frozen storage of up to 24 wk.

New Implications of Metabolites and Free Fatty Acids in Quality Control of Crossbred Wagyu Beef during Wet Aging Cold Storage.

Efficient cold-chain delivery is essential for maintaining a sustainable global food supply. This study used metabolomic analysis to examine meat quality changes during the "wet aging" of crossbred Wagyu beef during cold storage. The longissimus thoracic (Loin) and adductor muscles (Round) of hybrid Wagyu beef, a cross between the Japanese Black and Holstein-Friesian breeds, were packaged in vacuum film and refrigerated for up to 40 days. Sensory evaluation indicated an increase in the umami and kokumi taste owing to wet aging. Comprehensive analysis using gas chromatography-mass spectrometry identified metabolite changes during wet aging. In the Loin, 94 metabolites increased, and 24 decreased; in the Round, 91 increased and 18 decreased. Metabolites contributing to the umami taste of the meat showed different profiles during wet aging. Glutamic acid increased in a cold storage-dependent manner, whereas creatinine and inosinic acid degraded rapidly even during cold storage. In terms of lipids, wet aging led to an increase in free fatty acids. In particular, linoleic acid, a polyunsaturated fatty acid, increased significantly among the free fatty acids. These results provide new insight into the effects of wet aging on Wagyu-type beef, emphasizing the role of free amino acids, organic acids, and free fatty acids generated during cold storage.

Physiological and transcriptomic analysis dissects the molecular mechanism governing meat quality during postmortem aging in Hu sheep (Ovis aries).

Hu sheep, known for its high quality and productivity, lack fundamental scientific research in China. This study focused on the effects of 24 h postmortem aging on the meat physiological and transcriptomic alteration in Hu sheep. The results showed that the 24 h aging process exerts a substantial influence on the mutton color, texture, and water content as compared to untreated group. Transcriptomic analysis identified 1,668 differentially expressed genes. Functional enrichment analysis highlighted the importance of glycolysis metabolism, protein processing in endoplasmic reticulum, and the FcγR-mediated phagocytosis pathway in mediating meat quality modification following postmortem aging. Furthermore, protein-protein interaction analysis uncovered complex regulatory networks involving glycolysis, the MAPK signaling pathway, protein metabolism, and the immune response. Collectively, these findings offer valuable insights into the molecular mechanisms underlying meat quality changes during postmortem aging in Hu sheep, emphasizing the potential for improving quality control strategies in mutton production.

Changes in Meat of Hu Sheep during Postmortem Aging Based on ACQUITY UPLC I-Class Plus/VION IMS QTof.

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.

PH-sensitive films based on carboxymethyl cellulose/date pits anthocyanins: A convenient colorimetric indicator for beef meat freshness tracking

The pH-sensitive intelligent film is a much-awaited advancement in packaging technology, which uses visually discernible color changes to warn consumers about the freshness or spoilage of perishable food products. This study aims to develop an intelligent indicating film based on carboxymethyl cellulose (CMC), formulated with date pits anthocyanins-rich extract (DPAE) at 1.5 %. The incorporation of DPAE significantly enhanced the physical (moisture content, swelling index, water solubility and biodegradability) and mechanical (thickness, elongation at break and thickness). Developed films exhibited a higher antioxidant and antibacterial activity against food-borne pathogens. Furthermore, the inclusion of DPAE had a noticeable effect on pH-sensitive characteristics of the CMC/DPAE films. Interestingly, the CMC/DPAE film displayed a color change from yellow to dark brownish in response to changes in pH levels, covering a wide range from 1 to 13. The CMC/DPAE films were also capable of detecting ammonia at concentrations ranging from 0.125 to 1 mg/mL. In order to monitor the freshness of minced beef meat stored under refrigerated conditions at 4 °C over 14 days, CMC/DPAE films exhibited noticeable color variations corresponding to the changes in meat quality, which were assessed based on total volatile basic nitrogen, microbial count, and pH during storage. The color alteration on the packaging label shifted from yellow to dark, signifying changes in meat freshness. The obtained results stipulated that the newly developed CMC/DPAE films hold promise as innovative colorimetric pH indicators for tracking the freshness and spoilage meat-products in the food industry and supermarkets.

Role of housing system and season on the carcass and meat quality traits of growing rabbits reared in Italian commercial farms

The aim of this study was to compare the carcass traits and meat quality of growing rabbits reared in four types of commercially available housing systems (i.e. bicellular cages, dual-purpose cages, enriched cages and elevated pens) across three production cycles covering different seasons (i.e. autumn, winter and summer) under field conditions. The rabbits originated from 12 commercial farms (three farms per housing system) located in the Northeast of Italy and were slaughtered in five commercial slaughterhouses at a slaughter age from 71 to 90 d. Twenty carcasses per farm and cycle were randomly selected at the slaughterhouse and carcass and meat quality traits were evaluated 24 h post-mortem. The heaviest carcass weights were found in rabbits reared in enriched cages, followed by those in parks, while the lightest carcasses were found in rabbits from bicellular cages. Carcass fat and longissimus lumborum proportions were higher and hind legs proportion lower in carcasses of rabbits kept in enriched cages compared to those from the other systems. Based on significant differences for meat quality traits (i.e. pH, L*, thawing losses and shear force) among housing systems, ante-mortem stress was likely lower in rabbits from enriched cages and parks than in those from bicellular and dual-purpose cages. Nevertheless, these differences were not translated into noticeable changes in meat quality because of the small variations among housing systems. Overall, the observed differences could not be strictly and exclusively related to the enclosure in which the animals were housed, but also to other production and ante-mortem factors. The rearing season significantly affected slaughter traits, with lower slaughter and carcass weights in summer compared to winter and autumn. Despite the limit in the sample size of investigated farms, this study highlighted that under field conditions the final product quality of rabbits is not clearly distinguishable based on the housing system per se.

Meat Quality Changes in Aged Pork Loin using Jeju Volcanic Scoria Earthenware.

This study aimed to investigate changes in the quality of meat aged using Jeju scoria earthenware. Water-holding properties, pH, color, tenderization, fatty acid composition, and free amino acid characteristics of aged pork loin were evaluated to determine the effects of wet and dry (normal and Jeju Scoria) aging methods and aging time (0, 10, 20, 30, and 40 days) on meat quality. The aging methods altered pH and CIE L* after 10 days of aging. However, the aging method did not alter the pH and CIE L* of the aged pork loin after 10 days of aging. The shear force was significantly lower in the Scoria aging method than in the wet aging method after 10 and 20 days of aging. Both the normal and Scoria aging methods increased aging loss compared to the wet aging method, which could be attributed to longer air exposure times of the two non-packaged aging methods than in the packaged aging method. The scoria aging method had significantly higher contents and ratios of saturated (SFA) to mono-unsaturated fatty acids but lower ratios of poly-unsaturated fatty acids to SFA than the wet aging method. The content of most free amino acids significantly increased with aging time, especially those related to the sweet, and umami categories. In summary, this study suggests that the Scoria aging method provides positive aspects of eating quality, such as improvement of meat tenderness and taste, including umami, with minimum changes in the overall meat quality.

Interactions of rumen microbiota, and metabolites with meat quality-related genes to regulate meat quality and flavor of Tibetan sheep under nutrient stress in the cold season.

The meat of Tibetan sheep has unique flavor, delicious taste and superior nutritional value. However, the change of grass will lead to a change in meat quality. This study aimed to explore the potential regulatory mechanism of microbial metabolites with respect to meat quality traits of Tibetan sheep under nutrient stress in the cold season. We determined and analyzed the longissimus dorsi quality, fatty acid composition, expression of genes and rumen microbial metabolites of Tibetan sheep in cold and warm seasons. The shear force was decreased (P < 0.05), the meat color a*24h value was increased (P < 0.05), and the contents of crude fat (EE) and protein (CP) were decreased in the cold season. Polyunsaturated fatty acids (PUFAs)-linoleic acid and docosahexaenoic acid (DHA) increased significantly in the cold season (P < 0.05). The expressions of meat quality genes MC4R, CAPN1, H-FABP and LPL were significantly higher in the warm season (P < 0.05), and the CAST gene was significantly expressed in the cold season (P < 0.01). The different microbial metabolites of Tibetan sheep in the cold and warm seasons were mainly involved in amino acid metabolism, lipid metabolism and digestive system pathway, and there was some correlation between microbiota and meat quality traits. There are similarities between microbial metabolites enriched in the lipid metabolism pathway and muscle metabolites. Under nutritional stress in the cold season, the muscle tenderness of Tibetan sheep was improved, and the fat deposition energy was weakened, but the levels of beneficial fatty acids were higher than those in the warm season, which was more conducive to healthy eating.

Relationship between peptides and the change in quality characteristics of beef strip loin (M. longissimus lumborum) and tenderloin (M. psoas major)

Peptides in fresh and aged beef strip loin (M. longissimus lumborum) and tenderloin (M. psoas major) were quantified to investigate the relationship between proteolysis-induced peptides and beef quality characteristics. A total of 409 and 450 peptides were quantified from strip loin and tenderloin, respectively, and found to be significantly correlated to beef quality characteristics. Changes in redness and yellowness were significantly correlated to the peptides derived from G3P, ENOB, and KCRM in both muscles during 14 days of storage. The peptides produced from MYG, ENOB, HBA, PGK1, and TPIS were strongly associated with improved tenderness, while those derived from major myofibrillar proteins, such as MYH1, MYH2, ACTS, and DESM, were associated with changes in tenderloin color. These results improve our understanding of the association between peptides and changes in meat quality during cold storage, indicating that proteolysis-induced peptides can be indicators of the quality characteristics of fresh and aged meat.

Effect of Pre-Slaughter Transport Stress on Protein S-Nitrosylation Levels of Pork during Postmortem Aging.

This study aimed to investigate the effect of pre-slaughter transport stress on the protein S-nitrosylation levels of pork during 0, 3, and 6 days of aging. Pigs (N = 16) were randomly selected and divided into two treatments: 3 h transport (transport stress, TS) and 3 h transport followed by 3 h resting (control, CON). Results showed that the TS group at 0 and 3 days presented a higher nitric oxide synthase (NOS) activity and neuronal NOS (nNOS) expression than the CON group (P < 0.05). Additionally, nNOS was not only abundantly localized in the membrane but also observed in small amounts in the cytoplasm. The immunoblot of overall S-nitrosylated protein showed that protein S-nitrosylation levels in the TS group were greater than in the CON group during postmortem aging (P < 0.05). This work can deliver novel insights into the mechanism of meat quality changes in response to pre-slaughter stress.

The potential of metabolomics in meat science: Current applications, trends, and challenges

Metabolites are the final products of metabolism and provide insights into the biochemical balance of tissue systems. A cascade of reactions involving proteins, carbohydrates, and lipids affects meat color, tenderness, and flavor, specifically, metabolites that are key biomolecules in biochemical reactions associated with attainment of acceptable meat quality. Bioinformatics platforms, such as Kyoto Encyclopedia of Genes and Genomes (KEGG) databases and MetaboAnalyst, are utilized to help understanding the role of differentially abundant metabolites and characterizing their roles in cellular function/metabolism. However, the inability to identify all metabolites using a single platform and limited metabolite libraries specifically for meat/food remains a challenge. Therefore, the advances in metabolite separation, easy-to-use data processing, increased resolution of mass-spectrometry, and data analysis will help to make inferences or develop biomarkers related to meat quality. This review discusses how metabolomics can be exploited to characterize meat quality, the challenges, and current trends. SignificanceMetabolites play an important role in attaining consumer-preferred meat quality traits and nutritive value of foods. Visual appearance of fresh foods, such as muscle foods, are utilized by consumers to assess the quality at the retail market before making purchases. Similarly, tenderness and flavor of meats influence eating satisfaction and re-purchase decisions. Inconsistencies in meat quality lead to enormous economic losses to the food industry. For instance, consumers often associate a bright-cherry red color with freshness, and the US beef industry loses $3.74 billion annually due to discoloration during storage. Both pre-and post-harvest factors influence the extent of meat quality changes. Metabolomics offer robust tools to get a snapshot of small molecules such as acids, amino acids, glycolytic- and tricarboxylic acids, fatty acids, and sugars present in post-mortem muscle tissue and their role in meat quality. Further, using bioinformatics platforms enables characterizing the role of differentially present metabolites in meat quality as well as identifying biomarkers for desirable quality traits such as tender meat or color-stable carcasses. Innovative applications of metabolomics can be exploited to elucidate the underpinnings of meat quality and to develop novel strategies to enhance marketability of retail fresh meats.

Monitoring and traceability of spoilage bacteria from three representative braised chickens based on culture-dependent and high-throughput sequencing

Culture-dependent methods and high-throughput sequencing technology were used to monitor the spoilage bacteria of braised chickens from three regions. The microorganisms in the braised chickens, which were vacuum-packed and stored at 4 °C, were isolated, identified, and traced, and the changes in meat quality were also measured. The high-throughput sequencing of braised chickens from different regions showed that the bacterial diversity decreased and the relative abundance increased during storage. At the end of storage, Lactobacillus, Brochothrix, Leuconostoc, Carnobacterium, and Enterobacteriaceae; Lactobacillus, Weissella, Aerococcus, Enterobacter, and Lactococcus; Enterobacteriaceae, Enterococcus, Serratia, Vagococcus, Lactobacillus, and Hafnia-obesumbacterium were the dominant microorganisms of braised chickens from the three regions. Twelve strains, namely Lactobacillus curvatus, Weissella viridescens, Leuconostoc citreum, Lactobacillus sakei, Brochothrix thermophacta, Serratia liquefaciens, Weissella hellenica, Lelliottia amnigena, Pantoea agglomerans, Rahnella sp., Enterococcus devriesei, and Enterobacteriaceae bacterium, were isolated and identified. The random forest method was used to predict the source of the samples according to the species of bacteria, and prediction accuracies of 91.7%, 83.3%, and 75% at the order, family, and genus levels, respectively, were achieved. The source of food spoilage bacteria could be traced with high accuracy through the sample microorganism, which provides a new direction for the study of food spoilage bacteria.