Spoilage Mechanisms Research Articles

Microbiome Evolution of Brewer’s Spent Grain and Spent Coffee Ground Solid Sidestreams Under Industrial Storage Conditions

Brewer’s spent grain (BSG) and spent coffee ground (SCG) are solid sidestreams from beverage production increasingly being upcycled into food, feed and other value-added products. These solid sidestreams are prone to microbial spoilage, negatively impacting their upcycling potential. Three samples each of BSG and SCG were obtained from generators and recycling facilities in Singapore, and their chemical, elemental, and microbial composition was characterized. The spoilage mechanisms were investigated during storage under anaerobic and aerobic conditions. Bacterial loads of sidestreams were low from craft brewery and café sources (<1 and 3.53 ± 0.03 log10 CFU/g) and high from recycling facilities (>6 log10 CFU/g). The microbiome of BSG from recycling facilities was dominated by Bacilli, and B. coagulans was identified as the most prevalent species. SCG from recycling facilities was dominated by lactic acid bacteria, with L. panis being the most prevalent species. Storage up to 14 days under anaerobic conditions led to further bacterial proliferation mainly by Bacilli, lactic acid bacteria, and acetic acid bacteria, while aerobic storage led to extensive fungal contamination, including potential aflatoxin-producing Aspergillus flavus. The results shed light on the spoilage mechanisms, while highlighting the short shelf-life and food safety risks of BSG and SCG to inform valorization strategies.

Pseudomonas fragi and Pseudomonas lundensis drove the co-spoilage in chilled pork: Insights from the metabolome

Pseudomonas fragi and Pseudomonas lundensis are key spoilage microorganisms in aerobically stored chilled meat, which had co-spoilage effect on chilled pork. However, the mechanism of co-spoilage interaction of P. fragi and P. lundensis has not been elucidated. The metabolism of nutrients in pork by mixed bacteria may differ from that by single strains. This study applied metabolomics and in vitro metabolite utilization experiment to assess the mechanism of that co-metabolize raw pork during storage. Results showed that co-spoilage group had 104 differential metabolites (histamine, N-methylhydantoin and D-gluconic acid, etc.) and 78 differential metabolites (putrescine, uracil acid and uracil, etc.) compared to P. fragi and P. lundensis group, respectively. These differential metabolites were mainly related to histidine metabolism, arginine biosynthesis, and purine. The co-spoilage effect of P. fragi and P. lundensis was related to the promotion of deamination and decarboxylation of histidine to produce histamine, the promotion of α-ketoglutarate and glutamate-mediated transamination, and the full utilization of the arginine deiminase pathway by the co-culture bacteria in the degradation of arginine to produce putrescine. In vitro experiment, co-cultures of these strains resulted in greater consumption of glucose, higher utilization activity, and promoted deamination and decarboxylation of amino acids. These findings reveal the complex and competitive interactions of co-culture of P. fragi and P. lundensis, providing insight into microbial spoilage mechanisms in chilled pork.

Specific spoilage bacteria in cold chain logistics: A study on ATP-related compounds degradation in large yellow croaker (Larimichthys crocea)

This study evaluated the contribution of three spoilage bacteria (Shewanella putrefaciens (S. putrefaciens), Pseudomonas fluorescens (P. fluorescens), and Aeromonas salmonicida (A. salmonicida)) to the degradation of adenosine triphosphate (ATP)-related compounds in fish juice and fillet systems of large yellow croaker during cold chain logistics. The contribution of spoilage bacteria was explored by determining the microbial counts, ATP-related compounds, and associated enzyme activities. The results revealed that the S. putrefaciens, P. fluorescens, and A. salmonicida have the highest activities in 5′-nucleotidase (5′-NT), acid phosphatase (ACP), and alkaline phosphatase (AKP), with 49.78, 162.24, and 142.3 U/gprot, respectively. The rapid degradation of inosine monophosphate (IMP) occurs with increasing 5′-NT activity. It indicates that S. putrefaciens, P. fluorescens, and A. salmonicida mainly secreted 5′-NT, ACP, and AKP to degrade IMP, respectively, and that 5′-NT was the key enzyme in degrading IMP. All three are notable producers of purine nucleoside phosphorylase (PNP) and xanthine oxidase (XOD). The results showed that S. putrefaciens is the primary bacterium in the pre-degradation phase of ATP-related compounds, and A. salmonicida presumably dominates in the post-degradation phase. This study offers critical insights into the research on spoilage mechanisms of marine fish throughout the cold chain logistics.

Revealing the spoilage characteristics of refrigerated prepared beef steak by advanced bioinformatics tools.

Although microorganisms are the main cause of spoilage in prepared beef steaks, very few deep spoilage mechanisms have been reported so far. Aiming to unravel the mechanisms during 12 days of storage at 4 °C affecting the quality of prepared beef steak, the present study investigated the changes in microbial dynamic community using a combined high-throughput sequencing combined and bioinformatics. In addition, gas chromatography-mass spectrometry combined with multivariate statistical analysis was utilized to identify marker candidates for prepared steaks. Furthermore, cloud platform analysis was applied to determine prepared beef steak spoilage, including the relationship between microbiological and physicochemical indicators and volatile compounds. The results showed that the dominant groups of Pseudomonas, Brochothrix thermosphacta, Lactobacillus and Lactococcus caused the spoilage of prepared beef steak, which are strongly associated with significant changes in physicochemical properties and volatile organic compounds (furan-2-pentyl-, pentanal, 1-octanol, 1-nonanol and dimethyl sulfide). Metabolic pathways were proposed, among which lipid metabolism and amino acid metabolism were most abundant. The present study is helpful with respect to further understanding the relationship between spoilage microorganisms and the quality of prepared beef steak, and provides a reference for investigating the spoilage mechanism of dominant spoilage bacteria and how to extend the shelf life of meat products. © 2024 Society of Chemical Industry.

Effects of temperature fluctuations on the quality and microbial diversity of beef meatballs during simulated cold chain distribution.

Cold chain distribution with multiple links maintains low temperatures to ensure the quality of meat products, whereas temperature fluctuations during this are often disregarded by the industry. The present study simulated two distinct temperatures cold chain distribution processes. Quality indicators and high-throughput sequencing were employed to investigate the effects of temperature fluctuations on the quality and microbial diversity of beef meatballs during cold chain distribution. Quality indicators revealed that temperature fluctuations during simulated cold chain distribution significantly (P < 0.05) exacerbated the quality deterioration of beef meatballs. High-throughput sequencing demonstrated that temperature fluctuations affected the diversity and structure of microbial community. Lower microbial species abundance and higher microbial species diversity were observed in the temperature fluctuations group. Proteobacteria and Pseudomonas were identified as the dominant phylum and genus in beef meatballs, respectively, exhibiting faster growth rates and greater relative abundance under temperature fluctuations. The present study demonstrates that temperature fluctuations during simulated cold chain distribution can worsen spoilage and shorten the shelf life of beef meatballs. It also offers certain insights into the spoilage mechanism and preservation of meat products during cold chain distribution. © 2024 Society of Chemical Industry.

LC-MS/MS-based peptidomics and metabolomics reveal different metabolic patterns of common spoilage bacteria in grass carp flesh

Grass carp are highly perishable under the action of spoilage bacteria including Aeromonas rivipollensis, Pseudomonas putida, and Shewanella putrefaciens. However, the metabolic characteristics of the three bacteria in degrading fish proteins and small molecular nutrients are unclear. In this study, we used LC-MS/MS-based peptidomics and metabolomics to detect peptides and small molecular metabolites in grass carp flesh inoculated with the three bacteria. The peptidomic results showed that A. rivipollensis and S. putrefaciens induced an overall increase in the molecular weight of peptides in grass carp flesh. S. putrefaciens tended to hydrolyze peptide bonds composed of at least one hydrophobic amino acid whereas A. rivipollensis and P. putida preferred hydrolyzing Xaa-serine bonds. The metabolomic results showed that amino acid metabolism and nucleotide metabolism are among the most enriched pathways of differential metabolites. P. putida and S. putrefaciens were active in decomposing amino acids and nucleosides, respectively. Besides, lipid metabolism also plays an important role in grass carp spoilage, representing as the degradation from phosphatidylcholine to lysophosphatidylcholine by the three bacteria. To conclude, this study revealed distinct metabolic characteristics of the three bacteria in degrading proteins and small molecular metabolites, and thus contribute to the understanding of fish spoilage mechanisms.

The Phase-Dependent Regulation of Lux-Type Genes on the Spoilage Characteristics of Hafnia alvei.

Hafnia alvei, a specific spoilage microorganism, has a strong capacity to destroy food protein and lead to spoilage. The aim of this study was to evaluate the phase-dependent regulation of lux-type genes on the spoilage characteristics of H. alvei H4. The auto-inducer synthase gene luxI and a regulatory gene luxR of the quorum sensing systems in H. alvei H4 were knocked out to construct the mutant phenotypes. On this basis, the research found that the luxI and luxR genes had a strong positive influence on not only flagella-dependent swimming ability and biofilm formation but also the production of putrescine and cadaverine. The luxR gene could downregulate putrescine production. The maximum accumulation of putrescine in wild type, ΔluxI, ΔluxR and ΔluxIR were detected at 24 h, reaching up to 695.23 mg/L, 683.02 mg/L, 776.30 mg/L and 724.12 mg/L, respectively. However, the luxI and luxR genes have a potential positive impact on the production of cadaverine. The maximum concentration of cadaverine produced by wild type, ΔluxI, ΔluxR and ΔluxIR were 252.7 mg/L, 194.5 mg/L, 175.1 mg/L and 154.2 mg/L at 72 h. Moreover, the self-organizing map analysis revealed the phase-dependent effects of two genes on spoilage properties. The luxI gene played a major role in the lag phase, while the luxR gene mainly acted in the exponential and stationary phases. Therefore, the paper provides valuable insights into the spoilage mechanisms of H. alvei H4.

Multiple genome sequences of lactic acid bacteria, Carnobacterium divergens and Carnobacterium maltaromaticum strains, isolated from vacuum-packaged lamb meat.

Here, we report the whole-genome sequences of 11 Carnobacterium divergens and 2 Carnobacterium maltaromaticum bacteria isolated from vacuum-packed chill-stored lamb meat in New Zealand. Examination of these lactic acid bacteria (LAB) genomes will improve our knowledge of their potential antimicrobial activities and spoilage mechanisms of importance to the meat industry.

Effect of Thermostable Enzymes Produced by Psychrotrophic Bacteria in Raw Milk on the Quality of Ultra-High Temperature Sterilized Milk.

Ultra-high temperature sterilized milk (UHT) is a popular dairy product known for its long shelf life and convenience. However, protein gel aging and fat quality defects like creaming and flavor deterioration may arise during storage. These problems are primarily caused by thermostable enzymes produced by psychrotrophic bacteria. In this study, four representative psychrotrophic bacteria strains which can produce thermostable enzymes were selected to contaminate UHT milk artificially. After 11, 11, 13, and 17 weeks of storage, the milk samples, which were contaminated with Pseudomonas fluorescens, Chryseobacterium carnipullorum, Lactococcus raffinolactis and Acinetobacter guillouiae, respectively, demonstrated notable whey separation. The investigation included analyzing the protein and fat content in the upper and bottom layers of the milk, as well as examining the particle size, Zeta potential, and pH in four sample groups, indicating that the stability of UHT milk decreases over time. Moreover, the spoiled milk samples exhibited a bitter taste, with the dominant odor being attributed to ketones and acids. The metabolomics analysis revealed that three key metabolic pathways, namely ABC transporters, butanoate metabolism, and alanine, aspartate, and glutamate metabolism, were found to be involved in the production of thermostable enzymes by psychrotrophic bacteria. These enzymes greatly impact the taste and nutrient content of UHT milk. This finding provides a theoretical basis for further investigation into the mechanism of spoilage.

The interaction of an effector protein Hap secreted by Aeromonas salmonicida and myofibrillar protein of meat: Possible mechanisms from structural changes to sites of molecular docking.

Microbial spoilage of meat products is a significant problem in the food industry. Aeromonas salmonicida is a significant microorganism responsible for spoilage in chilled meat. Its effector protein, hemagglutinin protease (Hap), has been identified as an effective substance for degrading meat proteins. The ability of Hap to hydrolyze myofibrillar proteins (MPs) in vitro demonstrated that Hap has obvious proteolytic activity, which could alter MPs' tertiary structure, secondary structure, and sulfhydryl groups. Moreover, Hap could significantly degrade MPs, focusing primarily on myosin heavy chain (MHC) and actin. Active site analysis and molecular docking revealed that the active center of Hap was bound to MPs via hydrophobic interaction and hydrogen bonding. It may preferentially cleave peptide bonds between Gly44-Val45 in actin, and Ala825-Phe826 in MHC. These findings suggest that Hap may be involved in the spoilage mechanism of microorganisms and provide crucial insights into the mechanisms of meat spoilage induced by bacteria.

Applications of Genomics, Metabolomics, Fourier Transform Infrared in the Evaluation of Spoilage Targets of Shewanella putrefaciens from Spoiled Bigeye Tuna.

Shewanella putrefaciens is a typical spoiler that is commonly found in seafood and has high spoilage potential. However, the spoilage mechanism against Shewanella putrefaciens at the gene and metabolism levels has not been well elucidated. This work determined the spoilage targets on Shewanella putrefaciens XY07 from spoiled bigeye tuna by genome sequencing, metabolomics, and Fourier transform infrared (FTIR) analysis. Shewanella putrefaciens XY07 contained some genes on spoilage regulating of cys genes, his genes, spe genes and rpoS gene involved in sulfur metabolism, histidine metabolism, arginine and proline degradation, and biofilm formation at the genome level, respectively. Some spoilage genes like speC, cysM, trxB genes were identified. In addition, ABC transporters, arginine and proline metabolism; beta-alanine metabolism; glycine, serine, and threonine metabolism; histidine metabolism; sulfur metabolism; and lipid metabolism were identified as important pathways related to aquatic food during spoilage, which indicated the functions of amino acid degradation in S. putrefaciens XY 07 by metabolomics analysis. The metabolites of l-ornithine, 5-aminopentanoate, and 4-aminobutyraldehyde could be further metabolized to spermidine and spermine, producing a spoilage odor, and were involved in arginine and proline metabolism serving as key spoilage regulating metabolisms. Therefore, Shewanella putrefaciens XY07 was applied to genomics, metabolomics analysis, and FTIR to provide comprehensive insight into the investigation of spoilage targets.

The mechanism of spoilage of a bottled soft drink leading to health problem of consumer.

The case of spoilage of flavoured and sweetened soft drink occurred in the Czech Republic in 2019. After drinking it, the consumer was admitted to a hospital with sickness. The spoilage was caused by mould and an odorous substance, 1,3-pentadiene. The mechanism of food spoilage, with the formation of 1,3-pentadiene arising from the decarboxylation of sorbic acid and mould growth, is described. This could be the second case history reported worldwide of an allergic reaction to penicillin explaining how penicillin might get into the beverage. We hypothesise three possible causes of the health problem experienced with allergic reaction to penicillin or other mycotoxin produced by Penicillium mould as the most probable one.

Genome collection of Shewanella spp. isolated from spoiled lamb.

The diversity of the genus Shewanella and their roles across a variety of ecological niches is largely unknown highlighting the phylogenetic diversity of these bacteria. From a food safety perspective, Shewanella species have been recognized as causative spoilage agents of vacuum-packed meat products. However, the genetic basis and metabolic pathways for the spoilage mechanism are yet to be explored due to the unavailability of relevant Shewanella strains and genomic resources. In this study, whole-genome sequencing of 32 Shewanella strains isolated from vacuum-packaged refrigerated spoiled lamb was performed to examine their roles in meat spoilage. Phylogenomic reconstruction revealed their genomic diversity with 28 Shewanella spp. strains belonging to the same putative novel species, two Shewanella glacialipiscicola strains (SM77 and SM91), Shewanella xiamenensis NZRM825, and Shewanella putrefaciens DSM 50426 (ATCC 8072) isolated from butter. Genome-wide clustering of orthologous gene families revealed functional groupings within the major Shewanella cluster but also considerable plasticity across the different species. Pan-genome analysis revealed conserved occurrence of spoilage genes associated with sulfur and putrescine metabolism, while the complete set of trimethylamine metabolism genes was observed in only Shewanella sp. SM74, S. glacialipiscicola SM77 and SM91 strains. Through comparative genomics, some variations were also identified pertaining to genes associated with adaptation to environmental cues such as temperature, osmotic, salt, oxidative, antimicrobial peptide, and drug resistance stresses. Here we provide a reference collection of draft Shewanella genomes for subsequent species descriptions and future investigations into the molecular spoilage mechanisms for further applications in the meat industry.

Amino acid degradation and related quality changes caused by common spoilage bacteria in chill-stored grass carp (Ctenopharyngodon idella)

To characterize the involvement of microorganisms in amino acid degradation and fish quality deterioration, three major grass carp spoilage bacteria were artificially inoculated in amino acid solutions (in-vitro) and grass carp flesh (in-situ). Results showed that Pseudomonas putida largely degraded free amino acids and produced 3.78 mM/100 g ammonia in grass carp flesh, relying on its high amino acid deamination11Amino acid deamination in this article refers to the collection of all bioreactions catalyzing the removal of the amino groups from amino acids. It can include bioreactions induced by amino acid oxidative deaminase, lyases, and dehydratases. activity. Aeromonas rivipollensis produced 3-Methyl-butanol and 2-Methyl-butanol through leucine and isoleucine degradation. Shewanella putrefaciens had potent ornithine-decarboxylation activity (423.91 × 10−9 µg/CFU) and released 22.98 mg/kg putrescine in situ. S. putrefaciens could produce more putrescine when cooperating with P. putida through the arginine deiminase pathway. To conclude, the biochemical activities identified through in-vitro tests correlated well with quality changes in inoculated grass carp flesh. The outcomes of this study provided fundamental information on the spoilage mechanisms of freshwater fish and important guidance for the development of quality control strategies.

Recent Developments and Applications of Nanosystems in the Preservation of Meat and Meat Products

Due to their high water, lipid, and protein content, meat and meat products are highly perishable. The principal spoilage mechanisms involved are protein and lipid oxidation and deterioration caused by microbial growth. Therefore, efforts are ongoing to ensure food safety and increase shelf life. The development of low-cost, innovative, eco-friendly approaches, such as nanotechnology, using non-toxic, inexpensive, FDA-approved ingredients is reducing the incorporation of chemical additives while enhancing effectiveness and functionality. This review focuses on advances in the incorporation of natural additives that increase the shelf life of meat and meat products through the application of nanosystems. The main solvent-free preparation methods are reviewed, including those that involve mixing organic–inorganic or organic–organic compounds with such natural substances as essential oils and plant extracts. The performance of these additives is analyzed in terms of their antioxidant effect when applied directly to meat as edible coatings or marinades, and during manufacturing processes. The review concludes that nanotechnology represents an excellent option for the efficient design of new meat products with enhanced characteristics.

Charactering the spoilage mechanism of “three sticks” of Jinhua ham

To investigate the spoilage characteristics of Jinhua ham, sensory scores, volatile compounds, biogenic amine, physicochemical parameters and microbial counts were evaluated between normal and spoiled hams. The results showed that off-odors of spoiled hams were dominated by rancid, sour, sulfide and ammonia odors derived from these compounds including butanoic acid, methanethiol and dimethyl disulfide. Total content of biogenic amine in spoiled hams was significantly higher (more than 10-fold) compared with normal hams, and putrescine, cadaverine and histamine were the key components of biogenic amine of spoiled hams. Lower salt content, and higher moisture, TVB-N and thiobarbituric acid reactive substances (TBARS) values were observed in spoiled hams compared with normal hams. The populations of Enterobacteriaceae and Enterococcus of spoiled hams were obviously higher than that of normal hams. High moisture and low salt content caused the abnormal growth of Enterobacteriaceae and Enterococcus in spoiled hams, which contributed to the spoilage of Jinhua ham.

Characterization of metabolite, genome and volatile organic compound changes provides insights into the spoilage and cold adaptive markers of Acinetobacter johnsonii XY27

Acinetobacter johnsonii is a critical threat to aquatic products. However, the complete genome sequences and metabolome knowledge of A. johnsonii are still limited with respect to spoilage-associated and cold adaptive characteristics. The aim of this study was to report the spoilage and cold adaptive markers of Acinetobacter johnsonii XY27 from spoiled bigeye tuna (Thunnus obesus) by complete genome sequencing and metabolomic and volatile organic compound analysis. Based on genome analysis, A. johnsonii XY27 contained several spoilage-associated genes involved in sulfur metabolism (TauE, SafE, FrdB, TST, iscS), protease secretion (DegP, htrA, clpX, clpP), and biofilm formation (gspE, gspL, gspM, gspD, gspF, gspJ, gspK, RpoN). In addition, several spoilage-related pathways were enriched in glycine, serine and threonine metabolism and histidine metabolism. Growth of A. johnsonii XY27 under cold temperature was characterized by the production of extensive amounts of tryptophan, aminoacetone, 3-methyl pyruvic acid, l-threonine, choline, PS(18:0/18:1(9Z)), and l-serine. Volatile organic compounds such as benzaldehyde, 1-hexanol and 2,4-di-tert-butylphenol might be used as biomarkers of the spoilage potential of A. johnsonii XY27 under cold adaptation. Therefore, the complete genome sequence, metabolomic analysis and gas chromatography–mass spectrometry information provide valuable tools for spoilage mechanism investigations on A. johnsonii XY27.

Assessment of Spoilage Microbiota of Rainbow Trout (Oncorhynchus mykiss) during Storage by 16S rDNA Sequencing

Due to the high contents of protein and fat in rainbow trout, it is highly susceptible to spoilage, which limits the storage and transportation processes. Exploring the spoilage microbial community during rainbow trout storage is essential to develop an effective preservation method. Here, the changes in the total bacterial colony and total volatile base nitrogen (TVB-N) during the storage of rainbow trout were investigated. Storage at 0 °C can effectively slow down the spoilage process with bacterial counts and TVB-N contents decreased from 8.7 log CFU/g and 18.7 mg/100 g obtained at 4 °C to 5.6 log CFU/g and 14.5 mg/100 g, respectively. 16S rDNA high-throughput sequencing results showed that the diversity of microbial genera decreased during storage. Acinetobacter, Pseudomonas, and Shewanells gradually became the dominant spoilage genera with contents of 59.9%, 18.6%, and 1.7%, respectively, in the late stage of storage. The spoilage abilities of bacteria belonging to the Pseudomonas and Shewanells genera were analyzed. Shewanella sp. S5-52 showed the highest level of TVB-N content (100.6 mg/100 g) in sterile fish juice, indicating that it had a strong spoilage ability. This study confirmed the dominant spoilage bacterial genera and evaluated the spoilage abilities of isolated strains during the storage of rainbow trout, which laid the foundation for further investigation of the spoilage mechanism of rainbow trout and other aquatic products.

Changes in physicochemical properties of silver carp (Hypophthalmichthys molitrix) surimi during chilled storage: The roles of spoilage bacteria

Chilled surimi has become increasingly popular owing to its superior texture and freshness. In this study, changes in the microbiota and gel properties during chilled surimi storage, and the contributions of dominant bacteria to the physicochemical properties of chilled surimi were investigated. The results showed that Pseudomonas gessardii, Aeromonas media, and Acinetobacter johnsonii were the dominant bacteria during chilled surimi storage. P. gessardii was the key bacteria that degraded protein in the process of surimi spoilage, which led to high total volatile base nitrogen (TVB-N), trichloroacetic acid (TCA)-soluble peptides as well as poor gel properties. Both P. gessardii and A. media were high putrescine producers, whereas only A. media produced cadaverine. In this study, spoilage microorganisms in chilled surimi were investigated for the first time, and it was found that P. gessardii had the greatest influence on surimi quality, which provides a research basis for in-depth study on the mechanism of microbial spoilage and the preservation of chilled surimi.

Metabolomics reveals spoilage characteristics and interaction of Pseudomonas lundensis and Brochothrix thermosphacta in refrigerated beef

Pseudomonas lundensis and Brochothrix thermosphacta are key spoilage microorganisms in aerobically stored chilled meat. The present study aimed to investigate the physicochemical and metabolomic profiles of refrigerated ground beef inoculated P. lundensis (PL) and B. thermosphacta (BT) as mono- or co-culture (BP). P. lundensis was the dominant spoilage strain in the co-culture of ground beef. A large amount of TCA-soluble peptide, TVB-N and TBA were formed in the PL and BP, while acetion was mainly produced in the BT, as accompanied by the different sensory and color changes. Meat metabolome indicated that 95, 396, and 409 metabolites with significant differences, were identified in ground beef inoculated BT, PL, and BP, respectively. These differential metabolites covered 58 metabolic pathways, in which histidine metabolism was identified as an important pathway related to spoilage in the three groups. Specifically, creatine, inosine, anserine, uracil, alanine, glutamine, 3-methylhistidine and 3-hydroxycapric acid were enriched as potential spoilage biomarkers. Taken together, those findings reveal the complex and competitive interactions of their co-culture of B. thermosphacta and P. lundensis, which provided a comprehensive insight into microbial spoilage mechanism in chilled beef.