Search Results (396)

Silage is a core roughage resource for ruminant production, but aerobic deterioration caused by microorganisms severely reduces its nutritional value and increases microbial risk. This study aimed to isolate and identify specific spoilage organisms (SSOs) from Napier grass silages during aerobic deterioration and evaluate their spoilage capability. Based on morphological observation, physiological and biochemical tests, and ITS rDNA sequence analysis, four SSOs were obtained as Trichosporon asahii (TA32), Nakaseomyces glabratus (NG38), Candida tropicalis (CT39), and Pichia kudriavzevii (PK41) with high lactate-assimilating and spoilage capacity. All four strains were facultative anaerobic yeast and exhibited robust growth within the range of 25–40 °C and pH 3.5–6.5. To verify their spoilage capability, these purified strains were inoculated into Napier grass silage and exposed to air. Fermentation and chemical parameters were monitored at 0, 2, 5, and 9 days. Results showed that silages inoculated with PK41 or TA32 exhibited the lowest aerobic stability with most rapid increase in pH (p < 0.05), while the control (CON) remained the highest aerobic stability (p < 0.05). These results provide a theoretical basis for developing targeted preservation technologies to extend the shelf-life of silage. Full article

The spoilage phenotype of microorganisms is a key mechanism leading to food spoilage, but how their metabolic environment affects the spoilage phenotype remains unclear. This study utilized metabolomics and spoilage phenotype analysis to reveal metabolic differences between different quorum sensing (QS) genotypes of Hafnia. alvei H4 and their impact on spoilage phenotypes. Ultra-high performance liquid chromatography–fluorescence detection revealed that the QS system participated in the differential metabolic regulation of eight amino acids, with serine exerting the most significant influence on the spoilage phenotype. Subsequent studies demonstrated that QS-promoted serine inhibited bacterial motility by affecting the biosynthesis of rhamnolipid (rather than c-di-GMP) and inhibiting flagellar/chemotactic genes expression. Moreover, QS-promoted serine induced the difference of bacterial inner membrane, further inhibiting bacterial motility. These findings provided fundamental information for the control of biofilms conformation within complex food nutritional background. Full article

Microbial contamination of food is a crucial cause of food spoilage and foodborne diseases, posing a severe threat to global public health. Although chemical preservatives are effective, their potential hazards to human health and the environment, coupled with the growing demand for “clean label” products, have driven the search for natural alternatives. Lactic acid bacteria (LAB), recognized as the Generally Recognized as Safe (GRAS) microorganisms, have emerged as the promising bio-preservatives due to their safety, effectiveness, and multifunctionality. This review systematically summarized the core antimicrobial properties of LAB, including their inhibitory spectrum against foodborne pathogens, spoilage microorganisms, viruses, parasites, and their ability to degrade toxic substances such as mycotoxins, pesticides, and heavy metals. Key inhibitory mechanisms of LAB are highlighted, encompassing the production of antimicrobial metabolites, leading to metabolism disruption and cell membrane damage, nutrition and niche competition, quorum-sensing interference, and anti-biofilm formation. Furthermore, recent advances in LAB applications in preserving various food matrices (meat, dairy products, fruits and vegetables, cereals) are integrated, including their roles in enhancing food sensory quality, extending shelf life, and retaining nutritional value. The review also discusses critical factors influencing LAB’s inhibitory activity (medium composition, culture conditions, ionic components, pathway regulator, etc.) and the challenges associated with the application of LAB. Finally, future research directions are outlined, including the novel LAB and metabolites exploration, AI-driven cultural condition optimization, genetic engineering application, nano-encapsulation and active packaging development, and building up the LAB-based cellular factories. In conclusion, LAB and their antimicrobial metabolites hold great promise as green and safe food preservatives. This review is to provide comprehensive theoretical support for the rational improvement and efficient application of LAB-based natural food preservatives, contributing to the development of a safer and more sustainable food processing and preservation systems. Full article

Game meats are particularly prone to oxidation and microbial spoilage due to their specific characteristics and the procedures required to obtain them. Various sustainable bioactive molecules derived from food industry by-products, such as olive mill wastewater, have the potential to enhance the stability and safety of game meats. The use of different levels of polyphenolic extracts from olive mill vegetation water, encapsulated through a freeze-drying process, was tested on wild boar meat patties as an antioxidant and antimicrobial. Two separate trials were performed. Trial 1 was carried out by adding different concentrations of polyphenolic extract (0, 1, and 2%) during the production of wild boar patties, and trial 2 by adding 1.5% salt and adding or not adding 2% polyphenolic extract. The first trial revealed antioxidant effects on the raw patties during storage time, both on colour (increasing in saturation index) and thiobarbituric acid-reactive substances (0.306, 0.268, and 0.254 mg MDA/kg after 5 days of storage in the control with 1% and 2% polyphenolic extract groups, respectively). Oxidation was also reduced during cold storage of cooked patties. Trial 1 also revealed a dose-dependent antimicrobial effect, mainly on Enterobacteriaceae and Pseudomonas spp. Trial 2 confirmed that salt plus extract addition had an overall higher antimicrobial effect than when singularly added, but with a moderate increase in the hardness of the products. Full article

Ewe’s milk cheese produced from raw milk holds cultural and economic importance in Southern European countries; however, it poses microbiological challenges. Among spoilage microorganisms, Pseudomonas fluorescens is particularly concerning due to thermostable enzymes that impair the texture, aroma, and stability of cheese, even under refrigeration and salinity. This study evaluated the influence of sodium chloride concentration on Pseudomonas fluorescens given the pivotal role of salt in ensuring cheese stability and safety. Cheeses inoculated with Pseudomonas fluorescens were produced under an experimental design that combined three ripening temperatures with four salt concentrations. Physicochemical composition and microbiological stability were assessed at the end of ripening (20 days). Results showed that the ripening temperature emerged as the most determinant factor, influencing microbial viability and increasing solid retention, proteolysis, and dehydration, leading to harder cheeses. Low temperatures without salt favoured surface colour defects, whereas, although high salt levels contributed to partial control of Pseudomonas spp., they also delayed ripening, resulting in cheeses with a pale, uncharacteristic appearance. Conversely, moderate salinity (2%) combined with higher ripening temperatures promoted uniform maturation, resulting in a stable texture and appearance free of defects. These findings highlight the need to balance salt and ripening conditions to optimise quality and safety in traditional raw ewe’s milk cheeses. Full article

Sulfiting agents are common preservatives in the food and beverage industry to inhibit spoilage microorganisms. Sulfite produced by the dissolution of sulfur dioxide (SO₂) in water is used as a microbial inhibitor and antioxidant during winemaking. Thus, sulfite resistance is a desirable trait for wine yeasts. However, consumer health concerns regarding SO₂ exposure require a better understanding of the molecular basis of sulfite resistance/response. In this study, we have developed a highly SO₂-stress-resistant Saccharomyces cerevisiae strain (F3) using evolutionary engineering by repeated batch selection at gradually increased potassium metabisulfite (K₂S₂O₅) levels. F3 was resistant to 1.1 mM K₂S₂O₅ stress, which was strongly inhibitory to the reference strain, and cross-resistant to oxidative, heat, and freeze–thaw stresses. F3 also had enhanced cell wall integrity and altered carbon metabolism, indicating its potential for industrial applications, including winemaking. Comparative whole genome sequencing revealed point mutations in SSU1 and FZF1 that are related to SO₂ transport; ATG14, related to autophagy; and other genes involved in vacuolar protein sorting. Comparative transcriptomic analysis showed significant upregulation of SSU1 and differential expression of genes related to transport and carbohydrate metabolism. These findings may shed light on the molecular mechanisms contributing to SO₂ resistance and industrial robustness in S. cerevisiae. Full article

Natural wines represent a new trend in winemaking without the use of preservatives and starter cultures, revealing the unique quality traits of grapes, wine, and terroir, but are susceptible to spoilage or undesirable fermentations. This study investigated the microbial populations associated with organic grapes, must, and natural wines of the Limniona red grape variety, focusing on different production stages and fermentation vessels. Samples included immature and ripe grapes, initial and fermenting must, filtered and unfiltered wines, and final bottled and filtered wines. These were analyzed in order to enumerate key groups of microorganisms and identify beneficial yeasts and bacteria of alcoholic and malolactic fermentation, respectively, as well as potential markers of off-flavors. Culture-dependent methods were used to enumerate yeasts and bacteria, while Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) and 16S rRNA sequencing provided taxonomic resolution. Beneficial fermentation microorganisms (especially Saccharomyces yeasts) were scarce in initial grapes, where other contaminants or wild yeasts were present. Gradually, as fermentation progressed, there was a prevalence of Saccharomyces cerevisiae strains of increased diversity in matured wine, as well as several lactic acid bacteria (LAB) of malolactic fermentation. Most LAB were identified as Lactobacillus and Oenococcus species. Other bacteria from environmental sources, irrelevant to alcoholic/malolactic fermentation or spoilage, like Burkholderia, were also present during the vinification process. The type of vessel affected the type of LAB that prevail, with an abundance of Oenococcus in clay vessels versus Lactobacillus species in stainless-steel vessels. Notably, Lentilactobacillus parafarraginis can be linked to off-flavors if they represent a high percentage of the wine microbiota. These findings highlight the importance of understanding, monitoring and controlling microbial succession during production stages in order to prevent sensory faults and ensure the stable quality of natural wines. Full article

Fermented sausages are popular worldwide due to their sensory and nutritional characteristics, as well as their convenience for storage and consumption. The production and consumption of meat products are associated with negative impacts from the risks of high sodium intake, such as cardiovascular disease and hypertension. Salt (NaCl) plays an important role in the preservation, water loss during drying, reduction in water activity, and sensory characteristics of meat and other fermented food products. NaCl reduction is considered a challenge because it affects the sensory properties of meat and can compromise the safety and microbiological parameters related to the spoilage of the fermented meat product. The use of microorganisms, such as LAB, has been studied as an innovative way to substitute traditional preservatives. They produce various metabolites, including bioactive and antimicrobial substances that are actively involved in health benefits and guarantee the safety of meat products. These natural substances produced by bacteria extend shelf life by inhibiting spoilage and pathogenic microorganisms. This review discusses the potential application of lactic acid bacteria in the reformulation of fermented sausages, challenges, and beneficial effects on sensorial, safety, and health properties. Full article

The presence of microorganisms in fish and fish products is a relevant factor in spoilage and food safety. Fish is considered a nutritious staple of the human diet and is produced, processed, and marketed worldwide. To describe the role of microorganisms in regard to the safety of fish and fish products, we conducted this narrative review to present information on fish production; various pollution hazards; and the causes, control, and prevention of diseases caused by food consumption. It also explores documented cases of foodborne illnesses in Mexico associated with microorganisms. Furthermore, microbiological evaluations of products that are offered for consumption in different areas and cities of Mexico are reviewed, as is the regulatory framework that has been developed regarding the safety of produced and marketed products. This was achieved through the searching for, compilation of, and analysis of information in various databases (Redalyc, Scielo, Scopus, Web of Science, ScienceDirect, Google Scholar, among others). The knowledge obtained indicates that bacteria and parasites are frequently associated with illnesses caused by the consumption of raw products or products subjected to inadequate cooking and hygiene practices. Meanwhile, a microbiological evaluation of fish and marketed products reveals contamination that compromises food safety. Therefore, it is necessary to strengthen microbiological surveillance of products and hygiene education throughout the food chain by government, industry, researchers, and end consumers to promote the availability of safe, nutritious foods for the population. Full article

Fermented vegetables, which are valued for their distinctive organoleptic properties and nutritional profile, are susceptible to quality deterioration during processing and storage because microorganisms inhabit vegetable raw materials. The metabolic processes of these microorganisms may induce texture degradation, chromatic alterations, flavor diminution, and spoilage. Conventional inactivation methods employing thermal sterilization or chemical preservatives achieve microbial control through nonselective inactivation, inevitably compromising the regional sensory characteristics conferred by indigenous fermentative microbiota. Recent advances in existing antimicrobial technologies offer promising alternatives for selective microbial management in fermented vegetable matrices. Existing modalities, including cold plasma, electromagnetic wave-based inactivation (e.g., photodynamic inactivation, pulsed light, catalytic infrared radiation, microwave, and radio frequency), natural essential oils, and lactic acid bacterial metabolites, demonstrate targeted pathogen inactivation while maintaining beneficial microbial consortia essential for quality preservation when properly optimized. This paper explores the applications, mechanisms, and targeted microbes of these technologies in fermented vegetable ingredients, aiming to provide a robust theoretical and practical framework for the use of selective inactivation strategies to manage the fermentation process. By assessing their impact on the initial microbial community, this review aims to guide the development of methods that ensure product safety while safeguarding the characteristic flavor and quality of fermented vegetables. Full article

Food spoilage and the associated organisms are a continuing concern for the food industry. The microorganisms involved with food spoilage in pasteurized milk can be introduced in a variety of ways, which include those that survive pasteurization and/or are introduced post-pasteurization. The use of bacteriophages for therapeutic regimens and as a method for the biocontrol of food-borne pathogens has been widely studied and applied; however, their use in the biocontrol against spoilage organisms is in its nascency. Bioluminescent bacteria offer the ability to act as cell-death reporters. In the case of using bacteriophage against spoilage-associated bacteria, cell death results in the loss of bioluminescence. In this study, a bioluminescent Pseudomonas species, Pseudomonas fluorescens M3A, was used to monitor the efficacy of the bacteriophage-associated biocontrol system within laboratory bacterial growth broth and fluid milk using bacteriophage ΦS1. Utilizing a bioluminescence kinetic assay with ten-fold serially diluted P. fluorescens M3A and bacteriophage ΦS1, data demonstrated rapid inactivation of bacterial growth, and at low bacteriophage titers. Cell death was indicated by the loss of bacterial bioluminescence. These data help to support the application of bacteriophage-based technologies against spoilage-associated bacteria to prolong shelf life in the event of microbial growth. Full article

Pseudomonas fragi and Aeromonas salmonicida are major spoilage microorganisms in refrigerated grass carp. This study systematically investigated the physicochemical and metabolomic characteristics of chilled grass carp that were artificially inoculated with P. fragi and A. salmonicida in mono- and co-culture. The results indicated that P. fragi was the dominant bacterium in the co-culture of grass carp. The P. fragi-inoculated group exhibited significantly higher levels of total volatile basic nitrogen and thiobarbituric acid reactive substances (TBARs, byproducts of lipid peroxidation) compared with the A. salmonicida group. Moreover, the TBAR levels were greater in the co-culture than in the A. salmonicida group at the end of storage. A metabolomic analysis revealed that 712, 424, and 465 differential metabolites were identified in grass carp inoculated with A. salmonicida, P. fragi, and their co-culture, respectively. The metabolic pathway enrichment showed that purine metabolism, aminoacyl-tRNA biosynthesis, glycerophospholipid metabolism, and amino acid metabolism were prevalent across all three inoculated groups. A total of 175 amino acids, peptides, and analogues were identified in the A. salmonicida group, indicating that A. salmonicida played a vital role in protein degradation. P. fragi was primarily enriched in linoleic acid metabolism and the biosynthesis of unsaturated fatty acids and fatty acids, demonstrating its advantages in lipid metabolism. Additionally, six potential spoilage biomarkers were identified, including inosine, cytidine, L-aspartic acid, L-tyrosine, Pro-Ile and PS(17:1(9Z)22:0). These results elucidated the complex and competitive interactions between A. salmonicida and P. fragi in the spoilage of grass carp, providing a scientific basis for the quality monitoring of grass carp and targeted preservation strategies. Full article

Lytic bacteriophages, viruses that attack and kill bacteria cells, can be used in food as biocontrol agents to prevent the growth of pathogenic bacteria. Meat is highly susceptible to bacterial growth, including pathogenic species, the control of which is crucial. Antibiotic use by breeders has resulted in bacterial resistance, which remains a huge problem; bacteriophages have emerged as an interesting alternative. In the literature, the influence of bacteriophages on common foodborne pathogens, such as Salmonella sp., Listeria monocytogenes, Campylobacter jejuni, Yersinia enterocolitica, Escherichia coli, and Shigella sp., has been described. Some phage preparations can show synergistic effects when used with other antimicrobial agents. However, data on the use of bacteriophages to inhibit the growth of meat spoilage bacteria are limited. Bacteriophages can also synthesize endolysins, which possess antimicrobial properties. Contrary to bacteriophages, which are active against only a narrow range of microorganisms (usually one bacterial species), endolysins show a broad spectrum of activity. Full article

The aim of this study was to evaluate liposomal particles as a potential delivery system for natamycin, a widely known antimicrobial agent used in the food industry. The goal was to prolong its diffusion into the surrounding medium. Natamycin-loaded liposomes were prepared using two methods (proliposome and thin-film) and two different phospholipid mixtures. The characterization of natamycin-loaded liposomes was performed in terms of their chemical composition (FT-IR analysis), encapsulation efficiency (EE), and antimicrobial potential against spoilage and pathogenic microorganisms that can be found in milk and milk products. During the 60-day storage period, their size, polydispersity index (PDI), and zeta potential were measured. The in vitro release kinetics of natamycin from liposomes were also assessed, and the results showed a significantly lower release rate of the drug when it was encapsulated. EE showed a high level of natamycin encapsulation (>80%), which was confirmed with FT-IR analysis. The stability study indicated that these systems were stable over a 60-day storage period, as the zeta potential of all formulations was ~−25 mV. Satisfactory antimicrobial performance of the developed liposomes against Listeria monocytogenes, Yersinia enterocolitica, Candida tropicalis, Candida parapsilosis, and Aspergillus flavus (MIC values from 0.00625 to 4 mg/mL) indicates that loading of natamycin into liposomal carriers was an adequate method for their encapsulation and delivery in the milk industry. Full article

Carboxymethyl cellulose (CMC) films, derived from sugarcane bagasse agricultural waste (SCB) incorporated with Betalains-nitrogen-doped carbon dots (Betalains-N–CQDs), derived from beet root waste (BR), offer a sustainable, smart and naked-eye sensor for strawberry packaging due to their excellent fluorescent and shape memory properties. These CMC-Betalains-N–CQDs aim to enhance strawberry preservation and safety by enabling visual detection of common food contaminants such as bacteria, fungi and Pb(II). Crucially, the CMC-Betalains-N–CQD film also exhibits excellent shape memory properties, capable of fixing various shapes under alkaline conditions and recovering its original form in acidic environments, thereby offering enhanced physical protection for delicate produce like strawberries. Optical studies reveal the Betalains-N–CQDs’ pH-responsive fluorescence, with distinct emission patterns observed across various pH levels, highlighting their potential for sensing applications. Scanning Electron Microscopy (SEM) confirms the successful incorporation of Betalains-N–CQDs into the CMC matrix, revealing larger pores in the composite film that facilitate better interaction with analytes such as bacteria. Crucially, the CMC-Betalains-N–CQD film demonstrates significant antibacterial activity against common foodborne pathogens like Escherichia coli, Staphylococcus aureus, and Candida albicans, as evidenced by inhibition zones and supported by molecular docking simulations showing strong binding interactions with bacterial proteins. Furthermore, the film functions as a fluorescent sensor, exhibiting distinct color changes upon contact with different microorganisms and Pb(II) heavy metals, enabling rapid, naked-eye detection. The film also acts as a pH sensor, displaying color shifts (brown in alkaline, yellow in acidic) due to the betalains, useful for monitoring food spoilage. This research presents a promising, sustainable, and multifunctional intelligent packaging solution for enhanced food safety and extended shelf life. Full article