bims-metlip Biomed News
on Methods and protocols in metabolomics and lipidomics
Issue of 2023‒05‒21
eighteen papers selected by
Sofia Costa

  1. Int J Mol Sci. 2023 Apr 30. pii: 8111. [Epub ahead of print]24(9):
      In current clinical practice, a thorough understanding of vitamin D metabolism is in high demand both for patients with various diseases and for healthy individuals. Analytical techniques that provide simultaneous measurement of multiple metabolites are preferred. Herein, the development of an HPLC-DMS-MS/MS method for the quantitation of vitamin D compounds (25(OH)D3, 25(OH)D2, 1,25(OH)2D3, 3-epi-25(OH)D3, 24,25(OH)2D3, and D3) in serum is described. The selected sample preparation procedure based on the combination of liquid-liquid and solid-phase extraction, which excluded a lengthy derivatization step, was compared with other common approaches. Sensitivity was increased through the implementation of differential ion mobility separation. The proposed assay allowed us to determine the low abundant 1,25(OH)2D3 with the detection limit of 10 pg/mL. The validation study showed good linearity (r2 > 0.99), a wide analytical range (2.5-75 ng/mL for 25(OH)D3), and acceptable precision (<7%) for all metabolites. The recovery ranged from 71% to 93% and the matrix effect from 0.80 to 0.95 depending on the metabolite; accuracy determination was performed using DEQAS controls.
    Keywords:  HPLC-MS/MS; differential ion mobility; vitamin D metabolites
  2. J Forensic Sci. 2023 May 17.
      Zopiclone (ZOP) is a hypnotic drug prescribed to treat insomnia. Due to the chiral nature of ZOP, the psychologically active S-form and inactive R-form need to be determined enantiomerically in a forensic drug analysis. In the present study, a supercritical fluid chromatography (SFC) method was designed with a faster analysis ability than that of previously reported techniques. The SFC-tandem mass spectrometry (SFC-MS/MS) method was optimized using a column with a chiral polysaccharide stationary phase (Trefoil CEL2). ZOP was extracted from pooled human serum using solid-phase extraction (Oasis HLB) and analyzed. The developed SFC-MS/MS method achieved the baseline separation of S-ZOP and R-ZOP within 2 min. The fit-for-purpose method validation indicated that the optimized solid-phase extraction achieved near complete recovery and approximately 70% of the matrix effect. Both the retention time and peak area showed sufficient precision. The lower and upper limits of quantification (LOQ) were 5.7 × 10-2  ng/mL and 25 ng/mL for R-ZOP, and 5.2 × 10-2  ng/mL and 25 ng/mL for S-ZOP. The calibration line was linear in the range from lower LOQ to upper LOQ. The stability test indicated that ZOP in serum stored in a refrigerator (4°C) degraded and about 55% remained in 31 days. The quick analysis of the SFC-MS/MS method makes it a valid option for the enantiomeric analysis of ZOP.
    Keywords:  MS; SFC; chiral analysis; mass spectrometry; supercritical fluid chromatography; zopiclone
  3. Anal Chem. 2023 May 18.
      A solid-phase microextraction (SPME) pin device with a biocompatible coating on the tip was developed for direct coupling to mass spectrometry (MS) via a vertical dipping-and-spray strategy using an automated probe electrospray ionization (PESI) interface. The developed method provides superior sensitivity compared to standard PESI-MS due to the enrichment effects of SPME and the significant increase in the volume of sample and/or solvent collected during dipping due to the SPME pin's notably larger size. The tips of the SPME pins were coated with a biocompatible coating consisting of small sorbent particles embedded into a polyacrylonitrile (PAN) binder. This coating enables the extraction of small molecules, while preventing larger molecules such as tissue fragments, proteins, and cell matter from coming into the sorbent. The developed SPME pin-PESI-MS method also features much lower matrix effects compared to PESI-MS for the analysis of complex biology samples. When applied for the analysis of 8 drugs of abuse in urine samples, the SPME pin-PESI-MS method provided good linearity (R2 ≥ 0.9997), high sensitivity with limits of detection between 0.003 to 0.03 ng/mL, and good reproducibility with RSD% ≤ 6%. The vertical design of the SPME-PESI-MS direct-coupling interface allows the potential fully automation of the system using a conventional autosampler.
  4. J Cheminform. 2023 May 12. 15(1): 52
      Metabolomics experiments generate highly complex datasets, which are time and work-intensive, sometimes even error-prone if inspected manually. Therefore, new methods for automated, fast, reproducible, and accurate data processing and dereplication are required. Here, we present UmetaFlow, a computational workflow for untargeted metabolomics that combines algorithms for data pre-processing, spectral matching, molecular formula and structural predictions, and an integration to the GNPS workflows Feature-Based Molecular Networking and Ion Identity Molecular Networking for downstream analysis. UmetaFlow is implemented as a Snakemake workflow, making it easy to use, scalable, and reproducible. For more interactive computing, visualization, as well as development, the workflow is also implemented in Jupyter notebooks using the Python programming language and a set of Python bindings to the OpenMS algorithms (pyOpenMS). Finally, UmetaFlow is also offered as a web-based Graphical User Interface for parameter optimization and processing of smaller-sized datasets. UmetaFlow was validated with in-house LC-MS/MS datasets of actinomycetes producing known secondary metabolites, as well as commercial standards, and it detected all expected features and accurately annotated 76% of the molecular formulas and 65% of the structures. As a more generic validation, the publicly available MTBLS733 and MTBLS736 datasets were used for benchmarking, and UmetaFlow detected more than 90% of all ground truth features and performed exceptionally well in quantification and discriminating marker selection. We anticipate that UmetaFlow will provide a useful platform for the interpretation of large metabolomics datasets.
    Keywords:  Analysis; High-throughput workflow; Processing; Software; Untargeted metabolomics
  5. Clin Chem Lab Med. 2023 May 19.
      OBJECTIVES: The analysis of organic acids in urine is an important part of the diagnosis of inherited metabolic disorders (IMDs), for which gas chromatography coupled with mass spectrometry is still predominantly used.METHODS: Ultra-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for urinary organic acids, acylcarnitines and acylglycines was developed and validated. Sample preparation consists only of dilution and the addition of internal standards. Raw data processing is quick and easy using selective scheduled multiple reaction monitoring mode. A robust standardised value calculation as a data transformation together with advanced automatic visualisation tools are applied for easy evaluation of complex data.
    RESULTS: The developed method covers 146 biomarkers consisting of organic acids (n=99), acylglycines (n=15) and acylcarnitines (n=32) including all clinically important isomeric compounds present. Linearity with r2>0.98 for 118 analytes, inter-day accuracy between 80 and 120 % and imprecision under 15 % for 120 analytes were achieved. Over 2 years, more than 800 urine samples from children tested for IMDs were analysed. The workflow was evaluated on 93 patient samples and ERNDIM External Quality Assurance samples involving a total of 34 different IMDs.
    CONCLUSIONS: The established LC-MS/MS workflow offers a comprehensive analysis of a wide range of organic acids, acylcarnitines and acylglycines in urine to perform effective, rapid and sensitive semi-automated diagnosis of more than 80 IMDs.
    Keywords:  inherited metabolic disorders; liquid chromatography; mass spectrometry; organic acidurias
  6. J Mass Spectrom. 2023 Jun;58(6): e4925
      We developed an ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method to determine four antibacterial drugs in human plasma for clinical usage. Samples were prepared using protein precipitation with methanol. Chromatographic separation was accomplished in 4.5 min on a BEH C18 column (2.1 × 50 mm, 1.7 μm) using a gradient elution of methanol and water (containing 7.71 g/L concentrated ammonium acetate, adjusted to pH 6.5 with acetic acid) at a flow rate of 0.4 mL/min. Positive electrospray was used for ionization. The method was linear in the concentration range 1-100 μg/mL for vancomycin, norvoncomycin, and meropenem; and 0.5-50 μg/mL for R-isomer of moxalactam and S-isomer of moxalactam. For all analytes, the intra- and inter-day accuracies and precisions were -8.47%-10.13% and less than 12%, respectively. The internal standard normalized recoveries and matrix effect were 62.72%-105.78% and 96.67%-114.20%, respectively. All analytes were stable at six storage conditions, with variations of less than 15.0%. The method was applied in three patients with central nervous system infection. The validated method might be useful for routine therapeutic drug monitoring and pharmacokinetic study.
    Keywords:  UHPLC-MS/MS; meropenem; moxalactam; norvancomycin; vancomycin
  7. Anal Methods. 2023 May 15.
      Investigations of untargeted metabolomics are based on high-quality data acquisition usually from multiplatform systems that include high-resolution mass spectrometry equipment. The comprehensive set of results is used as data entry for bioinformatics and machine learning sciences to access reliable metabolic and biochemical information for clinical, forensic, environmental, and endless applications. In this context, design of experiments is a powerful tool for optimizing data acquisition procedures, using a multivariate approach, which enables the maximization of a high-quality amount of information with reduced number of tests. In this study, we applied a 33 Box-Behnken factorial design with central point triplicate for optimizing the ionization of an HPLC-ESI-QTOF method used for screening urine samples. Nozzle voltage (V), fragmentor voltage (V) and nebulizer pressure (psig) were the factors selected for variation. The response surface methodology was applied in the molecular features extracted at each level, resulting in a statistical model that helps evaluating the synergic interaction between these factors. Together with the qualitative analysis of the resulting total ion chromatograms, we came across a reproducible (6.14% RSD) and highly efficient method for untargeted metabolomics of human urine samples. The proposed method can be useful for applications in several urine-based metabolomics-driven studies, as the factorial design can be applied in the development of any analytical protocol considering different LC-MS setups.
  8. Anal Chem. 2023 May 16.
      Fatty acids (FAs) and fatty alcohols (FOHs) are essential compounds for maintaining life. Due to the inherent poor ionization efficiency, low abundance, and complex matrix effect, such metabolites are challenging to precisely quantify and explore deeply. In this study, a pair of novel isotope derivatization reagents known as d0/d5-1-(2-oxo-2-(piperazin-1-yl) ethyl) pyridine-1-ium (d0/d5-OPEPI) were designed and synthesized, and an in-depth screening strategy for FAs and FOHs was established based on d0/d5-OPEPI coupled with liquid chromatography-tandem high-resolution mass spectrometry (LC-HRMS/MS). Using this approach, a total of 332 metabolites were identified and annotated (some of the FAs and FOHs were reconfirmed by standards). Our results demonstrated that OPEPI labeling could significantly enhance the MS response of FAs and FOHs via the introduction of permanently charged tags. The detection sensitivities of FAs were increased by 200-2345-fold compared with the nonderivatization method. At the same time, for FOHs, due to the absence of ionizable functional groups, sensitive detection was achieved utilizing OPEPI derivatization. One-to-one internal standards were provided by using d5-OPEPI labeling to minimize the errors in quantitation. Moreover, the method validation results showed that the method was stable and reliable. Finally, the established method was successfully applied to the study of the FA and FOH profiles of two heterogeneous severe clinical disease tissues. This study would improve our understanding of the pathological and metabolic mechanisms of FAs and FOHs for inflammatory myopathies and pancreatic cancer and also prove the generality and accuracy of the developed analytical method for complex samples.
  9. Anal Methods. 2023 May 15.
      Evaluating total parenteral nutrition (TPN) products for quality assurance and quality control is crucial due to the chemical complexity of its components. With the advent of exploring different approaches for analysing TPN components using tandem mass spectrometry techniques, there is still a need for a robust and reproducible method for industrial routine analyses. This study allows simple, simultaneous determination of 22 fatty acids (FAs) commonly found in TPN components using gas chromatography-mass spectrometry (GC-MS). Five different transesterification techniques were applied for the FA standards and the sodium methoxide in methanol-dimethyl carbonate method was selected due to its good methylation efficiency. Fatty acid methyl esters (FAMEs) were separated in gas chromatography using an HP-5MS UI column with helium as the carrier gas. Mass spectrometry was used to fragment and quantify FAMEs using electron ionization (EI) and selected ion monitoring (SIM) mode. The analytical method was evaluated using the guidelines from the US Food and Drug Agency (FDA) and European Medicines Agency (EMA) in compliance with the International Council for Harmonization (ICH) document Q2(R2). Correlation coefficients (R2) of the calibration curves for FAMEs were 0.99, except for C24:1 n-9 and C24:0, both R2 = 0.98. The limits of detection (LOD) and quantification (LOQ) were found to be 1.69 μg mL-1 and 5.14 μg mL-1, respectively. The linear range was from 3.10-179.9 μg mL-1 for most FAMEs, except for C18:1 n-7 (3.96-224.9 μg mL-1) and C18:1 n-9 (6.30-349.57 μg mL-1). The intra-day and inter-day precision coefficients of variance (CV) of the method were less than 11.10% and 11.30%, respectively. Freeze-thaw cycles and ambient temperature measurements were performed for assessing sample stability. The validated method was applied to analyse major TPN components-fish and olive oils, and an unidentified lipid sample. The presented GC-MS method is simple and robust in the identification and quantification of 22 fatty acids simultaneously in the tested TPN components.
  10. Talanta. 2023 May 09. pii: S0039-9140(23)00404-6. [Epub ahead of print]260 124653
      Alkenones are among the most widely used paleotemperature biomarkers. Traditionally, alkenones are analyzed using gas chromatography-flame ionization detector (GC-FID), or GC-chemical ionization-mass spectrometry (GC-CI-MS). However, these methods encounter considerable challenges for samples that exhibit matrix interference or low concentrations, with GC-FID requiring tedious sample preparations and GC-CI-MS suffering from nonlinear response and a narrow linear dynamic range. Here we demonstrate that reversed-phase high pressure liquid chromatography-mass spectrometry (HPLC-MS) methods provide excellent resolution, selectivity, linearity and sensitivity for alkenones in complex matrices. We systematically compared the advantages and limitations of three mass detectors (quadrupole, Orbitrap, and quadrupole-time of flight) and two ionization modes (electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI)) for alkenone analyses. We demonstrate that ESI performs better than APCI as response factors of various unsaturated alkenones are similar. Among the three mass analyzers tested, orbitrap MS provided the lowest limit of detection (0.4, 3.8 and 8.6 pg injected masses for Orbitrap, qTOF and single quadrupole MS, respectively) and the widest linear dynamic range (600, 20 and 30 folds for Orbitrap, qTOF and single quadrupole MS, respectively). Single quadrupole MS operated in ESI mode provides accurate quantification of proxy measurements over a wide range of injection masses, and with its modest instrument cost, represents an ideal method for routine applications. Analysis of global core-top sediment samples confirmed the efficacy of HPLC-MS methods for the detection and quantification of paleotemperature proxies based on alkenones and their superiority over GC-based methods. The analytical method demonstrated in this study should also allow highly sensitive analyses of diverse aliphatic ketones in complex matrices.
    Keywords:  APCI; Alkenones; ESI; Orbitrap; Reversed-phase HPLC
  11. Methods Mol Biol. 2023 ;2660 137-148
      Mass spectrometry (MS) is an important tool for biological studies because it is capable of interrogating a diversity of biomolecules (proteins, drugs, metabolites) not captured via alternate genomic platforms. Unfortunately, downstream data analysis becomes complicated when attempting to evaluate and integrate measurements of different molecular classes and requires the aggregation of expertise from different relevant disciplines. This complexity represents a significant bottleneck that limits the routine deployment of MS-based multi-omic methods, despite the unmatched biological and functional insight the data can provide. To address this unmet need, our group introduced Omics Notebook as an open-source framework for facilitating exploratory analysis, reporting and integrating MS-based multi-omic data in a way that is automated, reproducible and customizable. By deploying this pipeline, we have devised a framework for researchers to more rapidly identify functional patterns across complex data types and focus on statistically significant and biologically interesting aspects of their multi-omic profiling experiments. This chapter aims to describe a protocol which leverages our publicly accessible tools to analyze and integrate data from high-throughput proteomics and metabolomics experiments and produce reports that will facilitate more impactful research, cross-institutional collaborations, and wider data dissemination.
    Keywords:  Automated pipeline; Biological functional modules; Graphical user interface (GUI); Mass spectrometry; Metabolomics; Multi-omics data integration; Omics Notebook R package; Omics Notebook interface; Pathway enrichment; Principal component analysis (PCA); Proteomics; Proteomics search engines; Systems biology
  12. Int J Mol Sci. 2023 Apr 27. pii: 7931. [Epub ahead of print]24(9):
      Designing studies for lipid-metabolism-related biomarker discovery is challenging because of the high prevalence of various statin and fibrate usage for lipid-lowering therapies. When the statin and fibrate use is determined based on self-reports, patient adherence to the prescribed statin dose regimen remains unknown. A potentially more accurate way to verify a patient's medication adherence is by direct analytical measurements. Current analytical methods are prohibitive because of the limited panel of drugs per test and large sample volume requirement that is not available from archived samples. A 4-min-long method was developed for the detection of seven statins and three fibrates using 10 µL of plasma analyzed via reverse-phase liquid chromatography and tandem mass spectrometry. The method was applied to the analysis of 941 archived plasma samples collected from patients before cardiac catheterization. When statin use was self-reported, statins were detected in 78.6% of the samples. In the case of self-reported atorvastatin use, the agreement with detection was 90.2%. However, when no statin use was reported, 42.4% of the samples had detectable levels of statins, with a similar range of concentrations as the samples from the self-reported statin users. The method is highly applicable in population studies designed for biomarker discovery or diet and lifestyle intervention studies, where the accuracy of statin or fibrate use may strongly affect the statistical evaluation of the biomarker data.
    Keywords:  LC-MS/MS; cardiovascular disease; fibrates; human plasma; mass spectrometry; medical records; statins
  13. J Chromatogr B Analyt Technol Biomed Life Sci. 2023 May 06. pii: S1570-0232(23)00148-4. [Epub ahead of print]1224 123738
      Metarrestin is a first-in-class small molecule inhibitor targeting the perinucleolar compartment, a subnuclear body associated with metastatic capacity. Promising preclinical results led to the clinical translation of the compound into a first-in-human phase I trial (NCT04222413). To characterize metarrestin's pharmacokinetic profile in humans, a uHPLC-MS/MS assay was developed and validated to determine the disposition of the drug in human plasma. Efficient sample preparation was accomplished through one-step protein precipitation paired with elution through a phospholipid filtration plate. Chromatographic separation was achieved with gradient elution through an Acuity UPLC® BEH C18 column (50 × 2.1 mm, 1.7 µm). Tandem mass spectrometry facilitated the detection of metarrestin and tolbutamide, the internal standard. The effective calibration range spanned 1-5000 ng/mL and was both accurate (range -5.9 % to 4.9 % deviation) and precise (≤9.0 %CV). Metarrestin proved stable (≤4.9 % degradation) under various assay-imposed conditions. Matrix effects, extraction efficiency, and process efficiency were assessed. Further, the assay was successfully able to determine the disposition of orally administered metarrestin in patients from the lowest dose cohort (1 mg) for 48 h post-administration. Thus, the validated analytical method detailed in this work is simple, sensitive, and clinically applicable.
    Keywords:  Clinical Pharmacology; Mass spectrometry; Metarrestin; Ultra-HPLC
  14. Molecules. 2023 May 07. pii: 3945. [Epub ahead of print]28(9):
      Pentacyclic triterpenoids (PCTs), which possess a number of bioactive properties, are considered one of the most important classes of secondary plant metabolites. Their chromatographic determination in plant biomass is complicated by the need to separate a large number of structurally similar compounds belonging to several classes that differ greatly in polarity (monools, diols, and triterpenic acids). This study proposes a rapid, sensitive, and low-cost method for the simultaneous quantification of ten PCTs (3β-taraxerol, lupeol, β-amyrin, α-amyrin, betulin, erythrodiol, uvaol, betulinic, oleanolic, and ursolic acids) by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) using porous graphitic carbon (Hypercarb) as a stationary phase capable of hydrophobic retention and specific interactions with analytes. Revealing the effects of the mobile phase composition, pH, ionic strength, and column temperature on retention and selection of chromatographic conditions on this basis allowed for the effective separation of all target analytes within 8 min in gradient elution mode and attaining limits of detection in the range of 4-104 µg L-1. The developed method was fully validated and successfully tested in the determination of PCTs in common haircap (Polytrichum commune) and prairie sphagnum (Sphagnum palustre) mosses, and fireweed (Chamaenerion angustifolium) stems and leaves.
    Keywords:  HPLC-MS; high performance liquid chromatography; hypercarb; pentacyclic triterpenoids; plant biomass; porous graphitic carbon
  15. Bioanalysis. 2023 May 18.
      Background: The aim of this work was to develop and validate sensitive and efficient analytical methods for estimating systemic drug exposure and residual drug following the application of topical delivery systems. Materials & methods: Lidocaine was extracted using a liquid-liquid extraction technique from commercial topical products and analyzed using ultra high-performance liquid chromatography. A separate LC-MS/MS method was developed for analyzing human serum samples. Results & conclusion: The developed methods were successfully applied for estimating lidocaine content in two commercial products demonstrating 97.4-104.0% for product A and 105.0-110.7% for product B. The LC-MS/MS method displayed successful analysis of lidocaine from human serum samples. The developed methods are recommended for quantifying systemic exposure and residual drug analysis of topical systems.
    Keywords:  LC–MS/MS; UPLC; lidocaine; residual drug; topical delivery systems
  16. J Chromatogr B Analyt Technol Biomed Life Sci. 2023 May 05. pii: S1570-0232(23)00149-6. [Epub ahead of print]1224 123739
      The objective of this study was to develop and validate a simple method using liquid chromatography hyphenated to high resolution mass spectrometry (HRMS) allowing both the performance of a non-targeted screening and the simultaneous quantification of 29 compounds of interest in clinical and forensic toxicology. Extraction was done with QuEChERS salts and acetonitrile, after addition of internal standard to 200 μL of human plasma samples. The mass spectrometer was an Orbitrap, with a heated electrospray ionization (HESI) probe. The analyses were carried out in full scan experiment with a nominal resolving power of 60,000 FWHM within the 125-650 m/z mass range, followed by four cycles of data dependent analysis (DDA) with a mass resolution of 16,000 FWHM. The untargeted screening was evaluated using 132 compounds, mean limit of identification (LOI) was 8.8 ng/mL (min = 0.05 ng/mL, max = 500 ng/mL) and mean limit of detection (LOD) was 0.25 ng/mL (min = 0.05 ng/mL, max = 5 ng/mL). The method was linear in the 5 to 500 ng/mL range (0.5 to 50 ng/mL for cannabinoids, 6-acetylmorphine and buprenorphine) with correlation coefficients > 0.99, intra- and inter-day accuracy and precision were < 15% for all compounds. The method was successfully applied to 31 routine samples.
    Keywords:  Forensic toxicology; High resolution mass spectrometry; Orbitrap; Plasma; QuEChERS; Toxicology
  17. Trends Analyt Chem. 2023 Jun;pii: 117055. [Epub ahead of print]163
      In the past two decades, the power of mass spectrometry imaging (MSI) for the label free spatial mapping of molecules in biological systems has been substantially enhanced by the development of approaches for imaging with high spatial resolution. With the increase in the spatial resolution, the experimental throughput has become a limiting factor for imaging of large samples with high spatial resolution and 3D imaging of tissues. Several experimental and computational approaches have been recently developed to enhance the throughput of MSI. In this critical review, we provide a succinct summary of the current approaches used to improve the throughput of MSI experiments. These approaches are focused on speeding up sampling, reducing the mass spectrometer acquisition time, and reducing the number of sampling locations. We discuss the rate-determining steps for different MSI methods and future directions in the development of high-throughput MSI techniques.
    Keywords:  Continuous scanning; MSI; Multimodal; Sparse sampling; Throughput
  18. J Proteomics. 2023 May 17. pii: S1874-3919(23)00115-X. [Epub ahead of print] 104926
      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. SIGNIFICANCE: Metabolites are the final products of metabolism and provide insights into the biochemical balance of tissue systems. They play an important role in quality traits (i.e., color, texture, and flavor) 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 huge economic losses to 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.
    Keywords:  Bioinformatics; Meat; Meat color; MetaboAnalyst; Metabolomics; Mitochondria; Myoglobin