Insights into the molecular mechanisms of lipid transformation in sturgeon fillets: Interplay between specific spoilage and dominant bacteria.

This study investigates spoilage bacteria's impact on lipid metabolism in sturgeon fillets using UHPLC-Q-Orbitrap-MS/MS-based untargeted lipidomic analysis. A total of 4041 lipid molecules across five classes and 42 subclasses were identified, including glycerophospholipids (GPs, 50.88%), glycerolipids (GLs, 36.08%), sphingolipids (SPs, 10.47%), fatty acyls (FAs, 2.45%), and sterol lipids (STs, 0.12%). Aeromonas sobria, a specific spoilage bacterium, reduced GPs and FAs while increasing GLs, SPs, and STs via extracellular lipases and esterases. Acinetobacter albensis, the dominant bacterium, mainly elevated SPs and FAs. Their interaction promoted lipid metabolism and oxidation while producing volatile organic compounds (VOCs). Ethyl isobutyrate, ethyl propionate, isobutyl formate, pentan-2-one, propan-2-one, 2-butanone, 3-methyl-3-buten-1-ol, and dimethyl sulfide were mainly associated with Acinetobacter albensis, while 1-hexanol, 1-pentanol, 1-penten-3-ol, 1-hydroxypropan-2-one, 3-methyl-1-butanol, 2-methylbutanal, 3-hydroxy-2-butanone, and propionaldehyde were mainly related to Aeromonas sobria. This work unveils the mechanism of lipid transformation in sturgeon fillets during refrigerated storage, offering insights for aquatic products quality control.

Sustainable gelatin-kappa carrageenan active packaging with Mekwiya date seeds to enhance goat meat quality and shelf life.

This research aimed to elaborate a gelatin-Kappa carrageenan-based packaging with 0.22 %, 0.44 %, and 0.88 % w/v of Mekwiya date palm seeds extract (DSEMK). This extract improved the mechanical, physical, and thermal properties of the films. Moisture content, water solubility, and water vapor permeability were reduced from 17.54 ± 0.02 to 12.18 ± 0.02, from 77.61 ± 0.02 to 25.35 ± 0.29 %, and from 5.28 ± 0.29 to 1.69 ± 0.03 g s-1 m-1 Pa-1 × 10-10, respectively. During thermal degradation, DSEMK4 film had a residual weight of 27.99 %, compared to 20.67 % for the control. Despite a decline in the film's tensile strength from 24.19 to 8.94 MPa with the incorporation of DSEMK, elongation at the breaking point increased from 37.66 ± 0.16 to 46.17 ± 0.25 %. The film containing DSEMK4 displayed the highest phenolic contents and illustrated the best antioxidant effects in DPPH and FRAP assays, with IC50s of 756 and 1445 µg/mL, respectively and inhibited pathogen growth on the meat surface. Over storage at 4 °C, monitoring of pH, lipid and protein oxidation parameters, microbial spoilage, optical properties, and sensory attributes disclosed that the DSEMK-films successfully enhanced the meat quality and safety. These findings were supported by principal component analysis and heat maps.

LED induced non-thermal preservation of muscle foods: A systematic review.

LED technology has emerged as a promising non-thermal preservation method for highly perishable muscle foods like meat and fish. Muscle foods are most susceptible to spoilage due to their high moisture content and nutrient density, which create an ideal environment for microbial growth, chemical oxidation, and enzymatic activity, which negatively alter their quality. LED treatment offers an effective solution by significantly reducing microbial loads and extending shelf life without adversely affecting sensory and nutritional properties. Specific wavelengths of LED light induce microbial inactivation through mechanisms like DNA damage, lipid oxidation, and protein alteration. Studies have shown that LED treatment can preserve the fresh-like quality of muscle foods by mitigating common spoilage processes. The advantages of LED technology include its non-thermal nature, ability to integrate with other preservation methods, and controllability in terms of intensity and wavelength. This enables for tailored applications based on food type and spoilage risks. As consumer demand grows for safe, chemical-free food options, LED technology addresses this need while enhancing food safety and quality. Further research is encouraged to optimize LED applications in various muscle food preservation contexts. With its exceptional ability to produce DNA damage in bacteria, inactivate enzymes, and malfunction biological activities, LED could serve as an inexpensive processing intervention to safeguard the quality of meat and seafood products. This review underscores the potential of LED technology as a promising alternative to traditional preservation methods for decontamination of muscle food.

Microbiota diversity of three Brazilian native fishes during ice and frozen storage.

This study aimed to assess the bacterial microbiota involved in the spoilage of pacu (Piaractus mesopotamics), patinga (female Piaractus mesopotamics x male Piaractus brachypomus), and tambacu (female Colossoma macropomum × male Piaractus mesopotamics) during ice and frozen storage. Changes in the microbiota of three fish species (N = 22) during storage were studied through 16S rRNA amplicon-based sequencing and correlated with volatile organic compounds (VOCs) and metabolites assessed by nuclear magnetic resonance (NMR). Storage conditions (time and temperature) affected the microbiota diversity in all fish samples. Fish microbiota comprised mainly of Pseudomonas sp., Brochothrix sp., Acinetobacter sp., Bacillus sp., Lactiplantibacillus sp., Kocuria sp., and Enterococcus sp. The relative abundance of Kocuria, P. fragi, L. plantarum, Enterococcus, and Acinetobacter was positively correlated with the metabolic pathways of ether lipid metabolism while B. thermosphacta and P. fragi were correlated with metabolic pathways involved in amino acid metabolism. P. fragi was the most prevalent spoilage bacteria in both storage conditions (ice and frozen), followed by B. thermosphacta. Moreover, the relative abundance of identified Bacillus strains in fish samples stored in ice was positively correlated with the production of VOCs (1-hexanol, nonanal, octenol, and 2-ethyl-1-hexanol) associated with off-flavors. 1H NMR analysis confirmed that amino acids, acetic acid, and ATP degradation products increase over (ice) storage, and therefore considered chemical spoilage index of fish fillets.

Microbiological safety of dry-aged meat: a critical review of data gaps and research needs to define process hygiene and safety criteria.

Dry-aged meat is gaining popularity among food business operators and private consumers. The process is carried out in aerobic conditions by hanging beef carcasses or placing subprimal or primal cuts in a dedicated cabinet for several weeks or even months while controlling the environment through the management of process parameters such as temperature, relative humidity, and airflow. In this review, we present a critical evaluation of the literature to evaluate tools to manage the process to guarantee food safety and identify critical control points, as well as good hygiene and manufacturing practices. In controlled aging conditions, only Listeria monocytogenes and Yersinia enterocolitica can multiply, while a reduction in the number of Salmonella spp. and Escherichia coli O157:H7 is generally reported. Enterobacteriaceae usually decrease on the surface of the meat during maturation; thus, for the purpose of the hygiene evaluation of the production process, a count no higher than that of unmatured meat is expected. Besides, various studies report that the total bacterial count and the spoilage microorganisms significantly increase on the surface of the meat, up to 5-6 Log10 CFU/g in the absence of visible spoilage. Bacteria of the Pseudomonas genus tend to progressively replace other microorganisms during maturation; thus, the total mesophilic or psychrophilic bacterial load is not a good indicator of process hygiene for matured meat. Critical parameters for the control of the process are temperature, relative humidity, and ventilation, which should be monitored during the process. For this reason, equipment designed and certified for dry-aging must be used, and the manufacturer must validate the process. Food business operators must apply general good manufacturing practices (GMP) and good hygiene practices (GHP) for meat processing and some GMP and GHP specific for dry-aging. Several research needs were identified, among them the evolution of the populations of L. monocytogenes and Y. enterocolitica and the microbiology of the inner parts of the dry-aged meat.

Shelf-life of cooked meat of southern king crab (Lithodes santolla) and false king crab (Paralomis granulosa) during refrigerated storage.

Lithodes santolla (SKC) and Paralomis granulosa (FSKC) are economically important resources exploited in southern South America. The effect of refrigerated storage (4 °C on flake ice) on physico-chemical (pH, thiobarbituric reactive substances (TBARs), total volatile basic nitrogen (TVB-N), water holding capacity (WHC), and water content (WC)), microbiological (total viable mesophilic bacteria (TVMC), psychrotrophic bacteria (TVPC), Staphylococcus spp, coliforms, enterobacteria, molds and yeasts) and sensory (odor, appearance, texture, juiciness, and taste) parameters was analyzed in the cooked SKC and FSKC merus. For each species, cooked merus from 36 animals were randomly distributed into 6 groups, corresponding to 0, 2, 5, 8, 11, and 14 days of storage. On each day, samples were taken for physico-chemical (n = 6), microbiological (n = 3), and sensory (n = 15) analyses. The pH values increased over time (P < 0.01 in both species), the TBARs only increased in FSKC (P = 0.008), whereas the TVB-N significantly rose only in SKC (P = 0.001). The WHC and the WC did not change over time for any of the king crab species (P > 0.05) in all cases. The presence of TVCM, TVCP, and Staphylococcus spp. in both species was observed from day 0. Furthermore, pathogenic microorganisms (S. aureus, coliforms, and enterobacteria) were not detected, and only the TVCP in SFKC reached the suggested microbial limit after 11 days. All sensory scores significantly decreased (P < 0.001) over time, but the quality of both king crab species remained acceptable until the 11th day. These findings suggest that the shelf-life of cooked merus was 11 and 8 days for SKC and SFKC, respectively, when stored at 4 °C with the presence of flake ice. These contributions consist of elucidating the shelf-life of these economically important seafood products and providing insights into their quality maintenance during storage.

Review on the extension of shelf life for fruits and vegetables using natural preservatives.

Fruits and vegetables are important for the nutrition and health of individuals. They are highly perishable in nature because of their susceptibility to microbial growth. Foodborne pathogens create a significant problem for consumers, food businesses, and food safety. Postharvest factors, including transportation, environment, and preservation techniques, cause a reduction in product quality. The present world is using synthetic preservatives, which have negative impacts on consumer health. Food safety and demand for healthy foods among consumers, the scientific community, and the food industry resulted in the exploitation of natural preservatives, which play an important role in their effectiveness, prolonged shelf life, and safety. Natural preservatives include plants, animals, and microbiological sources with polymers to extend shelf life, improve quality, and enhance food safety. This review specifically focuses on mechanism of action of natural preservatives, spoilage of fruit and vegetables, the importance of edible film and coating on fruits and vegetables.

A near-infrared turn-on fluorescent probe for the detection of hydrogen sulfide in water samples and food spoilage.

Hydrogen sulfide (H2S) is a poisonous pollutant that endangers the environment, and H2S is also produced during food spoilage. Herein, we constructed a dicyanoisophorone-based near-infrared (NIR) fluorescent probe (DCID) to detect H2S. DCID exhibited significant turn-on fluorescence at 700 nm with a low limit of detection (LOD = 74 nM), large Stokes shift (220 nm), prominent selectivity, and response time (100 s) toward H2S. Importantly, the DCID probe had powerful applications in the detection of H2S in environmental samples and food spoilage. In addition, based on DCID-loaded test strips and combined a smartphone sensing platform, which provided a portable and convenient approach for the detection of H2S.

Antimicrobial activity of eight plant essential oils having antioxidant property against spoilage microbes.

AIMS: To identify efficient, broad-spectrum, and non-toxic preservatives for natural agricultural products, eight essential oils were screened for high inhibitory and antioxidant activities against spoilage microbes. METHODS AND RESULTS: The zone of inhibition test and minimum inhibitory concentration (MIC) assay were performed to assess the antimicrobial activity of eight essential oils against B. subtilis, S. aureus, Penicillium, Saccharomyces, and E. coli. Among the eight essential oils, garlic and rose essential oils exhibited the best inhibitory effects, their MICs against the spoilage microbes were 40-640 µL/L and 10-320 µL/L, respectively. In addition, the antioxidant activities of eight essential oils were compared using the DPPH and ABTS radical-scavenging assays and the reducing power assay. eight essential oils had antioxidant capacity, among which rosemary, thyme, rose, and tea tree essential oils performed best. Moreover, the combination of thyme and rose exerted stronger antioxidant activity. Therefore, the concentrations of rose and garlic, and thyme essential oils were optimized using response surface methodology to obtain the optimal composite ratios, which were 1254 µL/L, 640 µL/L, and 1228 µL/L for rose, garlic, and thyme, respectively. The DPPH free radical-scavenging rate detected using this formulation was 50.2%, basically consistent with the prediction. Zone of inhibition diameters with the compound essential oil, against five spoilage microbes, were all greater than 45 mm. CONCLUSIONS: The essential oil combination had high antimicrobial, against agricultural product spoilage microbes, and antioxidant activities.

Preserving the Aromatic Profile of Aged Toma Piemontese PDO Cheese with Gaseous Ozone Technology: A Quality Assessment via SPME-GC-MS/E-Nose.

The efficacy of low gaseous ozone concentrations (300 ppb and 400 ppb) in controlling spoilage microflora and preserving the quality of the aged Toma Piemontese PDO cheese was explored. The research integrates consumer tests, Gas Chromatography-Mass Spectrometry (GC-MS) with Solid phase Microextraction (SPME) fiber and Electronic Nose (e-nose) analysis to conduct a detailed assessment of the cheese's aromatic composition. Results indicate that low ozone concentrations significantly affected spoilage microflora, preserving the overall quality. Through GC-FID (Flame Ionization Detection) analysis, 22 of all identified compounds by GC-MS were quantified, including ethyl acetate (sweety), diacetyl and acetoin (buttery). Compared with the untreated sample, ozone treatments maintained the distinctive characteristics of Toma Piemontese PDO cheese, reducing the formation of off-flavors-related compounds (i.e., ethanol). Moreover, ozone-treated samples correlated with positive aroma scores given by consumers. However, sensory perception involves complex interactions among aroma compounds, highlighting the importance of advanced approaches. The utilization of a 12-sensor Quartz Microbalance (QMB) e-nose played a crucial role in identifying subtle differences in aroma, contributing to a more nuanced understanding of ozone treatments on the cheese's sensory profile. In conclusion, this research demonstrates the potential of ozone technology as a viable and effective method for improving the quality of aged Toma Piemontese PDO cheese.

Cyberlindnera fabianii, an Uncommon Yeast Responsible for Gluten Bread Spoilage.

A single strain of yeast was isolated from industrial gluten bread (GB) purchased from a local supermarket. This strain is responsible for spoilage consisting of white powdery and filamentous colonies due to the fragmentation of hyphae into short lengths (dust-type spots), similar to the spoilage produced by chalk yeasts such as Hyphopichia burtonii, Wickerhamomyces anomalus and Saccharomycopsis fibuligera. The isolated strains were identified initially by traditional methods as Wickerhamomyces anomalus, but with genomic analysis, they were definitively identified as Cyberlindnera fabianii, a rare ascomycetous opportunistic yeast species with low virulence attributes, uncommonly implicated in bread spoilage. However, these results demonstrate that this strain is phenotypically similar to Wi. anomalus. Cy. fabianii grew in GB because of its physicochemical characteristics which included pH 5.34, Aw 0.97 and a moisture of about 50.36. This spoilage was also confirmed by the presence of various compounds typical of yeasts, derived from sugar fermentation and amino acid degradation. These compounds included alcohols (ethanol, 1-propanol, isobutyl alcohol, isoamyl alcohol and n-amyl alcohol), organic acids (acetic and pentanoic acids) and esters (Ethylacetate, n-propil acetate, Ethylbutirrate, Isoamylacetate and Ethylpentanoate), identified in higher concentrations in the spoiled samples than in the unspoiled samples. The concentration of acetic acid was lower only in the spoiled samples, but this effect may be due to the consumption of this compound to produce acetate esters, which predominate in the spoiled samples.

Milk Spoilage Model Predicts that Share Tables Would Not Meaningfully Increase Spoilage and Improved Storage Systems Can Reduce Spoilage.

School share tables offer opportunities for food recovery and increased access to healthy foods by allowing students to donate or consume unopened items, such as cartons of milk. However, stakeholders have concerns about temperature abuse potentially causing premature milk spoilage. While previous research showed short ambient temperature abuse of milk (under conditions representing share tables) does not meaningfully impact microbial milk quality, differences across school cafeterias (e.g., ambient temperatures, storage systems, bell schedules, refrigeration temperature) may limit the generalizability of this conclusion. To address this, the overnight refrigeration temperature and the milk's initial contamination were predicted to be the main drivers for milk spoilage. Share tables were predicted to only cause inconsequential microbial quality changes (4 spoiled milk per million served, which would be ≤2 milk cartons spoiled per school year) under short and medium bell schedules (≤125 min of total service), even without temperature control during the lunch period. Under long (221 min) and very long (266 min) bell schedules, share tables with ambient temperature storage were predicted to have higher milk spoilage (19 and 42 spoiled milk cartons per million served, respectively), and adding storage systems was predicted to reduce the decline in milk quality (12 and 24 spoiled milk cartons per million served, respectively). These results provide a resource to support science-based decision-making for the inclusion of milk in school cafeteria share tables, ultimately working to reduce food waste and address food insecurity.

Molecular insights into the anti-spoilage effect of salicylic acid in Favorita potato processing.

Salicylic acid is a commonly used anti-spoilage agent to prevent browning and quality degradation during potato processing, yet its precise mechanism remains unclear. This study elucidates the role of StuPPO2, a functional protein in Favorita potato shreds, in relation to the anti-browning and starch degradation effects of 52 SA analogues. By employing molecular docking and Gaussian computing, SA localizes within the hydrophobic cavity of StuPPO2, facilitated by hydroxyl and carboxyl groups. The inhibitory effect depends on the distribution pattern of the maximal electrostatic surface potential, requiring hydroxyl ion potentials of >56 kcal/mol and carboxyl ion potentials of >42 kcal/mol, respectively. Multiomics analysis, corroborated by validation tests, indicates that SA synthetically suppresses activities linked to defense response, root regeneration, starch degradation, glycoalkaloids metabolism, and potato shred discoloration, thereby preserving quality. Furthermore, SA enhances antimicrobial and insect-repellent aromas, thereby countering biotic threats in potato shreds. These collective mechanisms underscore SA's anti-spoilage properties, offering theoretical foundations and potential new anti-browning agents for agricultural preservatives.

Effect of antifungal proteins (AFPs) on the viability of heat-resistant fungi (HRFs) and the preservation of fruit juices.

The control of heat-resistant fungi (HRFs), which cause spoilage of heat-treated fruit products, is considered a challenge for the fruit juice and beverage industry and requires new strategies for the development of antifungal compounds. In this study, four antifungal proteins (AFPs) from Penicillium digitatum (PdAfpB) and Penicillium expansum (PeAfpA, PeAfpB and PeAfpC), were evaluated against conidia from a representative collection of HRFs. A total of 19 strains from 16 different species belonging to the genera Aspergillus, Hamigera, Paecilomyces, Rasamsonia, Sarocladium, Talaromyces and Thermoascus were included in the study. PeAfpA and PdAfpB exhibited potent antifungal activity in synthetic media, completely inhibiting the growth of most of the fungi evaluated in the range of 0.5-32 µg/mL. The efficacy of the four AFPs was also tested in fruit juices against ascospores of five HRFs relevant to the food industry, including P. fulvus, P. niveus, P. variotii, A. fischeri and T. flavus. PdAfpB was the most effective protein in fruit juices, since it completely inhibited the growth of the five species tested in at least one of the fruit juices evaluated. This is the first study to demonstrate the activity of AFPs against fungal ascospores. Finally, a challenge test study showed that PdAfpB, at a concentration of 32 µg/mL, protected apple fruit juice artificially inoculated with ascospores of P. variotii for 17 days, highlighting the potential of the protein as a preservative in the fruit juice industry.

Influence of physicochemical characteristics on the growth and guaiacol production of Alicyclobacillus acidoterrestris in fruit juices.

Alicyclobacillus acidoterrestris is a bacterium known for causing spoilage in the taste and odour of fruit juices due to its thermoacidophilic nature. Its spoilage is attributed to the formation of guaiacol, which requires the presence of suitable precursors in the juices that A. acidoterrestris can metabolize. Therefore, A. acidoterrestris could exhibit different behaviour depending on the physicochemical characteristics the juice. In this study, we aimed to evaluate the behaviour of five A. acidoterrestris strains in seven different fruit juices by monitoring total cell and spore populations and quantifying guaiacol production. Also, physicochemical and phenolic profile, focusing on antimicrobials and guaiacol precursors, were analysed to better understand differences. Results showed growth in orange, apple, and plum juices for all the tested strains, with total cell populations reaching approximately 7 log cfu/mL, except for plum juice. In persimmon juice, growth was only observed in 3 out of 5 strains, for both total cells and spores. In contrast, all strains were inhibited in peach, black grape, and strawberry juices, maintaining a consistent population around 4 log cfu/mL. A strong negative correlation was observed between bacterial population and compounds such as kaempferol (for strains R3, R111, and P1), cyanidin chloride (for strains R111 and P1), and p-coumaric acid (for strain 7094 T). Regarding guaiacol production, orange and persimmon juices exhibited the highest guaiacol levels, with strain P1 (362.3 ± 12.6 ng/mL) and strain EC1 (325.1 ± 1.4 ng/mL) as the top producers, respectively. Plum, black grape, and strawberry juices showed similar guaiacol concentrations (16.9 ± 2.8 to 105.0 ± 33.7 ng/mL). Vanillin was showed positive correlations with guaiacol production in almost all strains (7094 T, R3, R111, and P1), with correlation coefficients of 0.97, 0.99, 0.82, and 0.87, respectively. We have reported different behaviour of A. acidoterrestris strains depending on juice type. Despite growth inhibition observed in some juices, enough guaiacol quantities to spoil the juice can be produced. This highlights the necessity of exploring strategies to prevent guaiacol production, even under growth restriction.

Acetic and citric acids effect the type II secretion system and decrease the metabolic activities of salmon spoilage-related Rahnella aquatilis KM05.

Rahnella aquatilis causes seafoods to spoil by metabolizing sulfur-containing amino acids and/or proteins, producing H2S in products. The type II secretion system (T2SS) regulates the transport of proteases from the cytoplasm to the surrounding environment and promotes bacterial growth at low temperatures. To prevent premature fish spoilage, new solutions for inhibiting the T2SS of bacteria should be researched. In this study, global transcriptome sequencing was used to analyze the spoilage properties of R. aquatilis KM05. Two of the mapped genes/coding sequences (CDSs) were matched to the T2SS, namely, qspF and gspE, and four of the genes/CDSs, namely, ftsH, rseP, ptrA and pepN, were matched to metalloproteases or peptidases in R. aquatilis KM05. Subinhibitory concentrations of citric (18 µM) and acetic (41 µM) acids caused downregulation of T2SS-related genes (range from - 1.0 to -4.5) and genes involved in the proteolytic activities of bacteria (range from - 0.5 to -4.0). The proteolytic activities of R. aquatilis KM05 in vitro were reduced by an average of 40%. The in situ experiments showed the antimicrobial properties of citric and acetic acids against R. aquatilis KM05; the addition of an acidulant to salmon fillets limited microbial growth. Citric and acetic acids extend the shelf life of fish-based products and prevent food waste.

Indole Schiff Base Complex: Synthesis and Optical Binding Investigation with Biogenic Amines.

Biogenic amines, produced by bacterial enzymatic reactions in food storage or processing, serve as indicators in food processing industries to assess food quality and freshness. Biogenic amines also often associated with various health problems, including abnormal immune responses and gastrointestinal disease. Previously, salphen base complexes have been reported but still exhibited low fluorescence enhancement upon biogenic amines. This research focused on synthesizing and characterizing new Zn(II) Schiff base complex with indole sidechain to enhance the fluorescence property and exploring their binding behaviour with the biogenic amines, which were phenylethylamine and cadaverine. The Zn(II) indole Schiff base complex's structure was verified by diverse spectroscopic techniques. Then, the binding behaviours between the Zn(II) indole Schiff base complex with the biogenic amines were analyzed using UV-Vis, fluorescence spectroscopy, and Job's plot analysis. UV-Vis binding study results indicated that the synthesized complexes could bind stronger with phenylethylamine than cadaverine, with binding constant, Kb= (8.21 ± 0.58) × 104 M- 1 and (2.506 ± 0.004) × 104 M- 1 respectively. Moreover, Zn(II) indole Schiff base complex-phenylethylamine binding also generated higher fluorescence enhancement than cadaverine, which were 54% and 51% respectively. Based on Job's plot analysis, the complex and biogenic amines were bound in the ratio of 1:1. To conclude, the synthesized complex has promising potential as a sensing material for biogenic amines detection in food. The complex is recommended to be deployed in the development of solid-state fluorescence sensor for biogenic amines detection for monitoring the food spoilage in the food industry in the future.

Metabolic and protein expression responses of Shewanella baltica in golden pomfret broths to slightly acidic electrolysed water.

Shewanella baltica is a specific spoilage organism of golden pomfret. This study aims to explore the antibacterial mechanism of slightly acidic electrolysed water (SAEW) against S. baltica (strains ABa4, ABe2 and BBe1) in golden pomfret broths by metabolomics, proteomics and bioinformatics analyses. S. baltica was decreased by at least 3.94 log CFU/mL after SAEW treatment, and strain ABa4 had the highest resistance. Under SAEW stress, amino acids and organic acids in S. baltica decreased, and nucleotide related compounds degraded. Furthermore, 100 differentially expressed proteins (DEPs) were identified. Most DEPs of strains ABe2 and BBe1 were down-regulated, while some DEPs of strain ABa4 were up-regulated, especially those oxidative stress related proteins. These results suggest that the modes of SAEW against S. baltica can be traced to the inhibition of amino acid, carbon, nucleotide and sulphur metabolisms, and the loss of functional proteins for temperature regulation, translation, motility and protein folding.

Applications of the Third-Generation DNA Sequencing Technology to the Identification of Spoilage Microorganisms in the Brewing Industry.

A new nanopore sequencing-based method has been developed for the detection and identification of a wider range of microorganisms. This method uses universal primers to identify virtually all the bacterial or yeast/fungal species via the amplification and nucleotide sequencing of common ribosomal DNA regions. The simplicity of its protocol makes the method suitable for both small and large breweries.

Unraveling the spoilage characteristics of refrigerated pork using high-throughput sequencing coupled with UHPLC-MS/MS-based non-targeted metabolomics.

The spoilage of refrigerated pork involves nutrient depletion and the production of spoilage metabolites by spoilage bacteria, yet the microbe-metabolite interactions during this process remain unclear. This study employed 16S rRNA high-throughput sequencing and non-targeted metabolomics based on ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) to reveal the core microbiota and metabolite profiles of pork during refrigeration. A total of 45 potential biomarkers were screened through random forest model analysis. Metabolic pathway analysis indicated that eleven pathways, including biogenic amine metabolism, pentose metabolism, purine metabolism, pyrimidine metabolism, phospholipid metabolism, and fatty acid degradation, were potential mechanisms of pork spoilage. Correlation analysis revealed nine metabolites-histamine, tyramine, tryptamine, D-gluconic acid, UDP-d-glucose, xanthine, glutamine, phosphatidylcholine, and hexadecanoic acid-as spoilage biomarkers, with Pseudomonas, Serratia, and Photobacterium playing significant roles. This study provides new insights into the changes in microbial and metabolic characteristics during the spoilage of refrigerated pork.