Biogenic Amine Production by Lactic Acid Bacteria: A Review

Effects of different lactic acid bacteria on the physicochemical properties, functional characteristics and metabolic characteristics of fermented hawthorn juice

Lactic acid bacteria (LAB) fermentation enhances the flavour and functionality of juice substrates; however, research on hawthorn juice is limited. We hypothesize that due to strain specificity, the changes in hawthorn juice after fermentation with different LAB may vary. After selecting LAB strains based on pH and sensory evaluation, the physicochemical properties and anti-inflammatory potential in a lipopolysaccharide-induced RAW 264.7 macrophage model were analysed in vitro. Non-targeted metabolomics revealed fermentation-driven metabolic changes. All strains exhibited increased total acidity and decreased reducing sugar and flavonoid contents. In particular, the Lactobacillus plantarum SC-1.3 and FWDG (strain preservation number) strains suppressed the pro-inflammatory cytokines interleukin-6 and tumour necrosis factor-α, with FWDG exhibiting the strongest effect. Moreover, fermentation resulted in the enrichment of bioactive metabolites, including prunetin and glycitein, which are unique to FWDG. The results provided a basis for the industrialization of hawthorn juice as a dietary product.

Production and transformation of biogenic amines in different food products by the metabolic activity of the lactic acid bacteria

Protein-rich diets often contain high quantities of biogenic amines (BAs), notably histamine and tyramine, which pose substantial health hazards owing to their toxicity. BAs are primarily produced by the microbial decarboxylation of free amino acids. Lactic acid bacteria (LAB) can either produce BAs using substrate-specific decarboxylase enzymes or degrade them into non-toxic compounds using amine-degrading enzymes such as amine oxidase and multicopper oxidase. Furthermore, LAB may inhibit BA-producing microbes by generating bioactive metabolites, including organic acids and bacteriocins. This paper thoroughly explores the processes underlying BA production and degradation in LAB, with a focus on the diversity of enzymes involved. Metabolic mapping of LAB strains at the genus and species levels reveals their involvement in BA metabolism, from production to degradation. The phylogenetic-based evolutionary relatedness of BA-producing and BA-degrading enzymes among LAB strains sheds light on their functional adaptability to various metabolic needs and ecological settings. These findings have significant practical implications for establishing better microbial management strategies in food production, particularly through strategically using starter or bioprotective cultures to reduce BA buildup. By highlighting the evolutionary and metabolic diversity of LAB, this review helps to optimize industrial fermentation processes, improve food safety protocols, and advance future research and innovation in BA management, ultimately protecting consumer health and supporting regulatory compliance.

The Health Impact of Cocoa from Cultivation to the Formation of Biogenic Amines: An Updated Review

Cocoa and chocolate are known for their health benefits, which depend on factors like cocoa variety, post-harvest practices, and manufacturing processes, including fermentation, drying, roasting, grinding, and refining. These processing methods can influence the concentration and bioavailability of bioactive compounds, such as polyphenols that are linked to cardiovascular health and antioxidant effects. Recent scientific research has led to the development of cocoa-based products marketed as functional foods. However, despite the growing interest in the functional potential of cocoa, the literature lacks crucial information about the properties of different varieties of cocoa and their possible implications for human health. Moreover, climate change is affecting global cocoa production, potentially altering product composition and health-related characteristics. In addition to polyphenols, other compounds of interest are biogenic amines, due to their role and potential toxic effects on human health. Based on toxicological data and recent research on the complex relationship between biogenic amines and cocoa fermentation, setting limits or standards for biogenic amines in cocoa and chocolate could help ensure product safety. Finally, new trends in research on biogenic amines in chocolate suggest that these compounds might also be used as quality markers, and that product formulation and process conditions could change content and diversity of the different amines.

Physicochemical and sensory characterization of functional synbiotic Labneh fortified with the bacteriocin-producing Lactiplantibacillus plantarum strain GA7 and nano-encapsulated Tirmania pinoyi extract

BACKGROUND

Functional foods and dairy products are gaining global attention due to their nutritional value and health-promoting characteristics. Lactic acid bacteria (LAB) are one of the promising components included in these products, thanks to their probiotic properties and ability to produce bioactive compounds such as bacteriocins. On the other hand, ectomycorrhizal wild mushrooms (truffles) are known for their ethnomycological importance. Hence, we aimed to develop a functional dairy product using a bacteriocin-producing LAB isolate that has probiotic potentials together with the bioactive extract of a truffle mushroom.

RESULTS

Screening for bacteriocin-producing LAB led to the selection of four safe isolates that also showed promising probiotic potentials. Isolate No. 7 was selected due to its wider antimicrobial spectrum and was identified as Lactiplantibacillus plantarum strain GA7. Out of resulting bands from Tricine SDS-PAGE analysis, a band (its molecular mass was approximately 7 kDa) exhibited antimicrobial activity. Amino acid sequencing of this active band detected 62 amino acid residues with 100% identity to plantaricin ASM1 bacteriocin. Simultaneously, an ethyl acetate extract was prepared from a truffle sample identified as Tirmania pinoyi. Safety of this truffle was confirmed and its extract exerted promising antioxidant and hypocholesterolemic activity. Prepared functional dairy products (Labneh) fortified with L. plantarum GA7 and nano-encapsulated T. pinoyi extract exhibited superior physicochemical, sensory and antioxidant properties compared to control. Moreover, an increase in probiotic count was observed in presence of T. pinoyi extract. Furthermore, prepared Labneh using the bacteriocin-producing L. plantarum GA7 and nano-encapsulated T. pinoyi extract remained unspoiled for over 60 days, compared to control, which spoiled after 21 days.

CONCLUSION

Besides improving Labneh physicochemical, sensory and antioxidant properties, the presence of the bacteriocin-producing L. plantarum GA7 has contributed in significantly extending its shelf life, while T. pinoyi extract showed prebiotic influence on probiotic count. As far as we know this is the first study describing production of a functional synbiotic dairy product fortified with bacteriocin-producing probiotic LAB and bioactive T. pinoyi truffle extract.

Screening of Leuconostoc mesenteroides strains suitable for kimoto-style brewing of sake with high antioxidant capacity

Sake brewed using the kimoto-style exhibits high antioxidant capacity and is expected to inhibit the deterioration of sake quality due to oxidation. However, the antioxidant capacity of the added lactic acid bacteria has not been explored. We aimed to screen the lactic acid bacterium, Leuconostoc mesenteroides, with excellent brewing and antioxidant capacity, to develop sake with high antioxidant capacity. Three Le. mesenteroides strains (19-2, 19-5, and 19-23) were selected from eight screened strains based on their alcohol intolerance, growth performance in koji extract, aroma compound, and low biogenic amine production. Among these, Le. mesenteroides 19-23 exhibited a significantly higher hydrophilic-oxygen radical absorbance capacity (H-ORAC) in the culture medium than the control strain, Le. mesenteroides NBRC102481. In a medium-scale sake brewing test, sake prepared with Le. mesenteroides 19-23 had a significantly higher H-ORAC value than that prepared using the sokujo-style (without Le. mesenteroides). Additionally, metabolome analysis using capillary electrophoresis time-of-flight mass spectrometry identified ferulic acid, p-coumaric acid, 3-hydroxyanthranilic acid (3-HAA), and 6,8-thioctic acid in the main mash. High-performance liquid chromatography-based quantification revealed that antioxidants in the unrefined filtrates of the main mash prepared using the kimoto-style tended to be more abundant than in those prepared using the sokujo-style. Specifically, 3-HAA and ferulic acid were more concentrated in some unrefined filtrates of the kimoto-style than sokujo-style. In conclusion, the screened Le. mesenteroides strain demonstrated potential for brewing sake with high antioxidant capacity using the kimoto-style, offering a promising method for antioxidant-rich sake production.

A Study of Bioactivities and Composition of a Cocktail of Supernatants Derived from Lactic Acid Bacteria for Potential Food Applications

Growing interests in replacing conventional preservatives and antibiotics in food and pharmaceutical industries have driven the exploration of bacterial metabolites, especially those from strains with generally recognized as safe (GRAS) status, such as lactic acid bacteria (LAB). In this study, a supernatant cocktail derived from multiple LAB strains was prepared and its bioactivities-antimicrobial, antibiofilm, antioxidant, cytotoxicity, and stability-were thoroughly investigated. The cocktail's main components were identified using thermal and protease treatments, gas chromatography coupled to mass spectrometry (GC-MS), and flame ionization detection (GC-FID). The results demonstrated that the supernatant cocktail had a broad inhibition spectrum and was effective against food-related bacterial indicators with the highest activity observed on Bacillus cereus ATCC9634 (inhibition zone sizes 12.33 mm) and the lowest on Enterococcus faecium DSM 13590 (3.31 mm). It showed dose- and time-dependent delaying effects on the growth of tested fungi. Regarding the antibiofilm activity, it was more effective in preventing biofilm formation (40% biofilm mass reduction) than in degrading preformed biofilm (20% reduction). Additionally, the cocktail showed antioxidant capacity of 10.1 ± 0.3 g Trolox equivalent (TE)/kg and dose-dependent cytotoxicity on HEK-293 and HT-29 cell lines. The main bioactive compounds in this cocktail are organic acids (particularly acetic acid), volatiles, and bacteriocin-like compounds. The antimicrobial capacity of this supernatant cocktail was highly reproducible across different fermentation batches, and it remained highly stable at 4 °C. Overall, these findings provided novel insights into the functional potentials of LAB metabolites, broadening their application as customizable biopreservatives for food and pharmaceutical industry.

Evaluation of Safety and Probiotic Properties of Weissella spp. in Fermented Vegetables From Xi'an, Shaanxi, China

The genus Weissella, commonly found in fermented foods, is a significant group of lactic acid bacteria (LAB) with potential probiotic properties. Several Weissella strains have been proposed as probiotics due to their biotechnological capabilities. However, a few strains may exhibit opportunistic pathogenic behavior, which restricts the widespread use of all Weissella strains in food applications. This study sought to expand our understanding of the biotechnological capabilities of Weissella spp. by examining the safety and functional characteristics of strains isolated from spontaneous fermentation. In this investigation, nine Weissella strains were evaluated for their safety and probiotic potential. The safety assessment revealed that the antibiotic resistance profiles of strains 16-2, 38-3, 69-3, 91-3, 91-5, 104-4, and 106-5 were comparable or superior to the reference strain LGG. Hemolytic activity and ammonia production were also evaluated, but no positive results were observed. Further probiotic experiments demonstrated that strain 91-5 exhibited superior performance in several areas, including survival rates in simulated gastrointestinal fluids, cell surface properties (hydrophobicity and adhesion to Caco-2 cells), ABTS+ scavenging ability, antimicrobial activity, and cholesterol assimilation in vitro. Additionally, strain 104-4 produced an exopolysaccharide (EPS) yield of 35.11 g/L after 48 h of culture in MRS-sucrose (60 g/L) medium, surpassing most previously reported values. These findings suggest that strains 91-5 and 104-4 show promise as potential probiotic candidates for the development of new functional food supplements. Furthermore, this research expands the theoretical basis for considering Weissella strains as novel probiotics.

Development of a Wine Yeast Strain Capable of Malolactic Fermentation and Reducing the Ethyl Carbamate Content in Wine

In winemaking, malolactic fermentation (MLF), which converts L-malic acid to L-lactic acid, is often applied after the alcoholic fermentation stage to improve the sensory properties of the wine and its microbiological stability. MLF is usually performed by lactic acid bacteria, which, however, are sensitive to the conditions of alcoholic fermentation. Therefore, the development of wine yeast strains capable of both alcoholic fermentation and MLF is an important task. Using genome editing, we engineered a modified variant of the triploid wine yeast strain Saccharomyces cerevisiae I-328, in which the CAR1 arginase gene was replaced by the malate permease gene from Schizosaccharomyces pombe and the malolactic enzyme gene from Oenococcus oeni. Genome-wide transcriptional profiling confirmed the expression of the introduced genes and revealed a limited effect of the modification on global gene expression. Winemaking experiments show that genome editing did not affect fermentation activity and ethanol production, while use of the modified strain resulted in a tenfold reduction in malate content with simultaneous formation of lactate. The resulting wines had a softer and more harmonious taste compared to wine obtained using the parental strain. Inactivation of arginase, which forms urea and L-ornithine through the breakdown of arginine, also resulted in a twofold decrease in the content of urea and the carcinogenic ethyl carbamate in wine. Thus, the new strain with the replacement of the arginase gene with the MLF gene cassette is promising for use in winemaking.

A Review on Analytical Techniques for Quantitative Detection of Biogenic Amines in Aquatic Products

Aquatic products contain a large amount of protein, which can promote the production of a variety of biogenic amines through the function of microorganisms. Biogenic amines are a broad category of organic substances that contain nitrogen and have a low molecular weight. The presence of biogenic amines can cause the deterioration and excessive accumulation of aquatic products, which can cause damage to human health. Therefore, it is essential to discover a fast, convenient, and easy to operate method for the determination of biogenic amines in aquatic products. In this paper, the function and research significance of biogenic amines are analyzed from the aspects of their formation, toxicological properties, harm to the human body, and control methods. Several common direct detection techniques and indirect techniques for biogenic amines are briefly introduced especially sensors. This review provides references for efficient detection in the future.

Shotgun metagenomic sequencing reveals the influence of artisanal dairy environments on the microbiomes, quality, and safety of Idiazabal, a raw ewe milk PDO cheese

BACKGROUND

Numerous studies have highlighted the impact of bacterial communities on the quality and safety of raw ewe milk-derived cheeses. Despite reported differences in the microbiota among cheese types and even producers, to the best of our knowledge, no study has comprehensively assessed all potential microbial sources and their contributions to any raw ewe milk-derived cheese, which could suppose great potential for benefits from research in this area. Here, using the Protected Designation of Origin Idiazabal cheese as an example, the impact of the environment and practices of artisanal dairies (including herd feed, teat skin, dairy surfaces, and ingredients) on the microbiomes of the associated raw milk, whey, and derived cheeses was examined through shotgun metagenomic sequencing.

RESULTS

The results revealed diverse microbial ecosystems across sample types, comprising more than 1300 bacterial genera and 3400 species. SourceTracker analysis revealed commercial feed and teat skin as major contributors to the raw milk microbiota (45.6% and 33.5%, respectively), being a source of, for example, Lactococcus and Pantoea, along with rennet contributing to the composition of whey and cheese (17.4% and 41.0%, respectively), including taxa such as Streptococcus, Pseudomonas_E or Lactobacillus_H. Functional analysis linked microbial niches to cheese quality- and safety-related metabolic pathways, with brine and food contact surfaces being most relevant, related to genera like Brevibacterium, Methylobacterium, or Halomonas. With respect to the virulome (virulence-associated gene profile), in addition to whey and cheese, commercial feed and grass were the main reservoirs (related to, e.g., Brevibacillus_B or CAG-196). Similarly, grass, teat skin, or rennet were the main contributors of antimicrobial resistance genes (e.g., Bact-11 or Bacteriodes_B). In terms of cheese aroma and texture, apart from the microbiome of the cheese itself, brine, grass, and food contact surfaces were key reservoirs for hydrolase-encoding genes, originating from, for example, Lactococcus, Lactobacillus, Listeria or Chromohalobacter. Furthermore, over 300 metagenomic assembled genomes (MAGs) were generated, including 60 high-quality MAGs, yielding 28 novel putative species from several genera, e.g., Citricoccus, Corynebacterium, or Dietzia.

CONCLUSION

This study emphasizes the role of the artisanal dairy environments in determining cheese microbiota and, consequently, quality and safety. Video Abstract.

Multifunctional Applications of Lactic Acid Bacteria: Enhancing Safety, Quality, and Nutritional Value in Foods and Fermented Beverages

Lactic Acid Bacteria (LAB) have garnered significant attention in the food and beverage industry for their significant roles in enhancing safety, quality, and nutritional value. As starter cultures, probiotics, and bacteriocin producers, LAB contributes to the production of high-quality foods and beverages that meet the growing consumer demand for minimally processed functional and health-promoting food products. Industrial food processing, especially in the fresh produce and beverage sector, is shifting to the use of more natural bioproducts in food production, prioritizing not only preservation but also the enhancement of functional characteristics in the final product. Starter cultures, essential to this approach, are carefully selected for their robust adaptation to the food environment. These cultures, often combined with probiotics, contribute beyond their basic fermentation roles by improving the safety, nutritional value, and health-promoting properties of foods. Thus, their selection is critical in preserving the integrity, quality, and nutrition of foods, especially in fresh produce and fruits and vegetable beverages, which have a dynamic microbiome. In addition to reducing the risk of foodborne illnesses and spoilage through the metabolites, including bacteriocins they produce, the use of LAB in these products can contribute essential amino acids, lactic acids, and other bioproducts that directly impact food quality. As a result, LAB can significantly alter the organoleptic and nutritional quality of foods while extending their shelf life. This review is aimed at highlighting the diverse applications of LAB in enhancing safety, quality, and nutritional value across a range of food products and fermented beverages, with a specific focus on essential metabolites in fruit and vegetable beverages and their critical contributions as starter cultures, probiotics, and bacteriocin producers.

Comprehensive Safety Assessment of Lacticaseibacillus paracasei subsp. paracasei NTU 101 Through Integrated Genotypic and Phenotypic Analysis

Probiotics, as defined by the World Health Organization, are live microorganisms that, when consumed in sufficient quantities, provide health benefits to the host. Although some countries have approved specific probiotic species for use in food, safety concerns may still arise with individual strains. Lacticaseibacillus paracasei subsp. paracasei NTU 101 (NTU 101), isolated from the gut of healthy infants, has demonstrated various probiotic effects and shown safety in a prior 28-day animal feeding study. To further verify its safety and mitigate potential risks, we performed a comprehensive genotypic and phenotypic safety evaluation in accordance with the European Food Safety Authority guidelines for safety assessment through whole genome sequencing and related literature. In this research, minimum inhibitory concentration testing identified NTU 101's resistance to chloramphenicol; however, subsequent gene analysis confirmed no associated risk of resistance. Assessments of safety, including biogenic amine content, hemolytic activity, mucin degradation, and D-lactic acid production, indicated a low level of risk. Additionally, a repeated-dose 90-day oral toxicity study in Sprague-Dawley rats revealed no toxicity at a dose of 2000 mg/kg body weight, further supporting the strain's safety for consumption. Based on these comprehensive analyses, NTU 101 is considered safe for regular consumption as a health supplement.

Characterization of Human Breast Milk-Derived Limosilactobacillus reuteri MBHC 10138 with Respect to Purine Degradation, Anti-Biofilm, and Anti-Lipid Accumulation Activities

Background: Human breast milk is a valuable source of potential probiotic candidates. The bacteria isolated from human breast milk play an important role in the development of the infant gut microbiota, exhibiting diverse biological functions. Methods: In this study, Limosilactobacillus reuteri MBHC 10138 isolated from breast milk was characterized in terms of its probiotic safety characteristics and potential efficacy in hyperuricemia, obesity, lipid liver, and dental caries, conditions which Korean consumers seek to manage using probiotics. Results: Strain MBHC 10138 demonstrated a lack of D-lactate and biogenic amine production as well as a lack of bile salt deconjugation and hemolytic activity. It also exhibited susceptibility to common antibiotics, tolerance to simulated oral-gastric-intestinal conditions, and superior biological activity compared to three L. reuteri reference strains, including KACC 11452 and MJ-1, isolated from feces, and a commercial strain isolated from human breast milk. Notably, L. reuteri MBHC 10138 showed high capabilities in assimilating guanosine (69.48%), inosine (81.92%), and adenosine (95.8%), strongly inhibited 92.74% of biofilm formation by Streptococcus mutans, and reduced lipid accumulation by 32% in HepG2 cells. Conclusions: These findings suggest that strain MBHC 10138, isolated from human breast milk, has potential to be developed as a probiotic for managing hyperuricemia, obesity, and dental caries after appropriate in vivo studies.

Visual detection of biogenic monoamines based on amine oxidase-peroxidase coupling reaction using ascorbic acid as H2O2 scavenger

This study represents a visual detection for total biogenic monoamines with naked eye as a simple and rapid semi-quantitative method for biogenic amine monitoring. The equivalent reaction of H2O2 with ascorbic acid resulted in color development by an amine oxidase-peroxidase coupling reaction in the samples containing the biogenic monoamines higher than the subjected ascorbic acid by 10 μM. Upon employing the commercial doenjang extracts as a model food, an additional heating step was requested, and the expected ranges for the biogenic monoamines from 360 to 480 μM covered the real contents of the samples (360.2-407.3 μM). Therefore, this visual detection method makes it possible to decide with naked eye whether the sample contains the biogenic monoamines higher than the ascorbic acid supplemented as much as a control level on manufacturing sites without instrumental analysis.

A Comprehensive Review on the Biogenic Amines in Cheeses: Their Origin, Chemical Characteristics, Hazard and Reduction Strategies

Most of the biogenic amines are naturally found in fermented foods as a consequence of amino acid decarboxylation. Their formation is ascribable to microorganisms (starters, contaminants and autochthonous) present in the food matrix. The concentration of these molecules is important for food security reasons, as they are involved in food poisoning illnesses. The most frequent amines found in foods are histamine, putrescine, cadaverine, tyramine, tryptamine, phenylethylamine, spermine and spermidine. One of the most risk-prone foods are cheeses, mostly ripened ones, which could easily accumulate amines due to their peculiar manufacturing process and ripening. Cheeses represent a pivotal food in our diet, providing for nutrients such as amino acids, calcium, vitamins and others; thus, since they are widely consumed, it is important to evaluate the presence of toxic molecules to avoid consumers' poisoning. This review aimed to gather general information on the role of biogenic amines, their formation, the health issues and the microorganisms and processes that produce/reduce them, with a focus on their content in different types of cheese (from soft to hard cheeses) and the biotic and abiotic factors that influence their formation or reduction and concentration. Finally, a multivariate analysis was performed on the biogenic amine content, derived from data available in the literature, to obtain more information about the factors influencing their presence in cheeses.

Phenylethylamine sensing at the electrified liquid-liquid interface. Can electrochemistry be used to follow the UHT milk spoilage process?

This study involved an investigation into the electrochemical characteristic of a few biogenic amines (BAs) occurring at the polarized interface between two immiscible electrolyte solutions (ITIES) with ion transfer voltammetry (ITV). The main focus of this research was the comprehensive electroanalytical and physicochemical analysis of phenylethylamine (PEA), allowing the determined of the formal Galvani potential of the ion transfer reaction (ΔorgaqΦ'), diffusion coefficients (D), formal free Gibbs energy of the ion transfer reaction (ΔG'aq→org) and water-1,2-dichloroethane partition coefficient (logPwater/DCEPEA). Furthermore, the collected data were employed to calculate analytical parameters, including voltametric detection sensitivity, limits of detection and the target analyte quantification. Moreover, the influence of the presence of 7 other BAs (histamine, spermine, spermidine, putrescine, cadaverine, tyramine and tryptamine) on the recorded signals originating from the PEA ion transfer was checked. The feasibility of the developed method was corroborated through experimentation with milk samples. Additionally, utilizing the devised methodology, an electrochemical assessment of the spoilage progression in milk samples was undertaken.

Zinc Supplementation Improves Texture, Oxidative Stability of Caciotta Cheese and Reduces Biogenic Amines Production

Zinc is essential for animals, playing a vital role in enzyme systems and various biochemical reactions. It is crucial to ensure a sufficient intake of zinc through the diet to maintain efficient homeostasis. Only few studies on zinc effect in cow lactating diet evaluated the effects on milk and cheese quality, with conflicting findings. 24 cows of the Friesian breed were divided into two groups (CTR: control and TRT: treated group). Cows were selected for age, body weight, parity and phase of lactations (mid lactation, 140-160 days). CTR diet contained 38 mg/kg of Zn and TRT diet was supplied with 120 mg/kg of complete feed for 60 days. The objective of current investigation was to evaluate the impact of a dietary Zinc Oxide (ZnO) integration of lactating Friesian cows on chemical composition, zinc content, fatty acid and proteic profile, ammine content, pH, aw, texture, and sensory profile of cheese and to improve the chemical-nutritional quality of milk and cheese. The results showed that ZnO supplementation reduced mesophilic aerobic bacteria and Presumptive Pseudomonas spp. growth, proteolysis, biogenic amines content, lipid oxidation, odour intensity and sour and increased hardness, gumminess, chewiness, elasticity of cheese. Biogenic amines are considered an important aspect of food safety. ZnO integration in cow diet could represent a promising strategy for improving the quality, the safety and shelf-life of caciotta cheese.

The species and abundance of gut bacteria both positively impact Phortica okadai behavior

BACKGROUND

Gut bacteria, which serve as essential modulators, exert a significant impact on insect physiology and behavior and have substantial application potential in pest management. The dynamics of gut bacteria and their impact on Phortica okadai behavior remain unclear.

METHODS

In this study, the dynamics of gut bacteria at different developmental stages in P. okadai were analyzed using 16S ribosomal RNA (rRNA) gene sequencing, and the species and abundance of gut bacteria that affect host behavior were examined via behavioral experiments.

RESULTS

A total of 19 phyla, 29 classes, 74 orders, 101 species, and 169 genera were identified. The results of the behavioral experiments indicated that the species Lactiplantibacillus argentoratensis, Acetobacter tropicalis, Leuconostoc citreum, and Levilactobacillus brevis effectively influenced the feeding preference of P. okadai, and the single-bacterium-seeded P. okadai exhibited feeding preferences distinct from those of the germ-free (GF) and wild-type P. okadai.

CONCLUSIONS

The species and relative abundance of gut bacteria together positively impact P. okadai behavior. Lactiplantibacillus argentoratensis, as the most attractive bacteria to P. okadai, presents opportunities for novel pest control strategies targeting this vector and agricultural pest.

Valorization of Dairy and Fruit/Berry Industry By-Products to Sustainable Marinades for Broilers' Wooden Breast Meat Quality Improvement

The study aims to improve the quality of wooden breast meat (WBM) via the use of newly developed marinades based on selected strains of lactic acid bacteria (LAB) in combination with the by-products of the dairy and fruit/berry industries. Six distinct marinades were produced based on milk permeate (MP) fermented with Lacticaseibacillus casei (Lc) and Liquorilactobacillus uvarum (Lu) with the addition of apple (ApBp) and blackcurrant (BcBp) processing by-products. The microbiological and acidity parameters of the fermented marinades were evaluated. The effects of marinades on the microbiological, technical, and physicochemical properties of meat were assessed following 24 and 48 h of WBM treatment. It was established that LAB viable counts in marinades were higher than 7.00 log10 colony-forming units (CFU)/mL and, after 48 h of marination, enterobacteria and molds/yeasts in WBM were absent. Marinated (24 and 48 h) WBM showed lower dry-matter and protein content, as well as water holding capacity, and exhibited higher drip loss (by 8.76%) and cooking loss (by 12.3%) in comparison with controls. After WBM treatment, biogenic amines decreased; besides, the absence of spermidine and phenylethylamine was observed in meat marinated for 48 h with a marinade prepared with Lu. Overall, this study highlights the potential advantages of the developed sustainable marinades in enhancing the safety and quality attributes of WBM.

Changes in Chemical Composition of Lentils, Including Gamma-Aminobutyric Acid and Volatile Compound Formation during Submerged and Solid-State Fermentation with Pediococcus acidilactici

The aim of this study was to evaluate and compare the characteristics of non-treated and fermented [via submerged (SMF) and solid-state (SSF) fermentation using Pediococcus acidilactici] lentils (Lens culinaris) grown either in pure stands (L) or relay intercropped with winter rye (LR). It was observed that the lentils were suitable substrate for lacto-fermentation. Most of the free amino acid concentrations increased in lentils after both fermentations. The highest concentration of γ-aminobutyric acid was found in SSF LR samples. However, fermentation led to higher biogenic amines (BA) content in lentils. The most abundant fatty acid in lentils was C18:2. SSF lentils showed more complex volatile compound (VC) profiles (with between nine and seventeen new VCs formed), whereas, in SMF samples, between two and five newly VCs were formed. When comparing lentil grown types, L contained significantly higher concentrations of Na, K, Ca, P, Mn, and Se, while LR contained significantly higher concentrations of Fe and Ni. To sum up, fermentation with lactic acid bacteria (LAB) contributed to the improved biological value of lentils; still, the quantity of BA needs to be considered. Further investigations into the P. acidilactici metabolism of certain compounds (such as phenolic and antinutritional compounds) in lentils during fermentation ought to be carried out.

Microbiological safety of dry-cured fish from the raw material to the end of processing

The commercialization of processed fish products is rising in restaurants and small to medium enterprises. However, there is a lack of data related to the microbiological safety of such products. In this study total aerobic colony count and Enterobacteriaceae, as proxy of process hygiene criteria, and detection of Listeria monocytogenes and concentration of histamine, as food safety criteria, were investigated in Salmo salar (salmon), Xiphias gladius (swordfish) and Thunnus albacares (yellowfin tuna), before, during, and at the end of a dry-curing process, performed in a dedicated cabinet, at controlled temperature, relative humidity and ventilation, up to 240 h. The microbiological parameters were investigated in the tested fish products by culture methods and shotgun metagenomic, while the presence of histamine, and other biogenic amines, was quantified by High Performance Liquid Chromatography. In the raw material, and up to the end of the dry curing process, the concentration of Enterobacteriaceae was always lower than 10 CFU/g, while total aerobic colony counts ranged between 3.9 and 5.4 Log CFU/g in salmon; 5.5 and 5.9 Log CFU/g in swordfish; 4.4 and 4.8 Log CFU/g in tuna. The pH values were significantly different between fish species, in the raw materials and during processing except for T4, occurring 70 h after the start of the process for salmon and after 114 h for swordfish and tuna. Water activity was different at specific sampling points and at the end of processing. Overall, 79 % of the sequences identified in the tested fish samples were assigned to y bacteria. The most abundant phyla were Pseudomonadota, Bacillota and Mycoplasmatota. The microbial populations identified by shotgun metagenomic in the tested fish species clustered well separated one from the other. Moreover, the microbial richness was significantly higher in salmon and tuna in comparison to swordfish. Listeria monocytogenes was not detected in the raw material by using the reference cultural method and very few reads (relative abundance <0.007) were detected in swordfish and tuna by shotgun metagenomic. Histamine producing bacteria, belonging to the genera Vibrio, Morganella, Photobacterium and Klebsiella, were identified primarily in swordfish. However, histamine and other biogenic amines were not detected in any sample. To the best of our knowledge this is the first paper reporting time point determinations of microbiological quality and safety parameters in salmon, swordfish and tuna, before, during and at the end of a dry-curing process. The data collected in this paper can help to predict the risk profile of ready to eat dry-cured fish products during storage before consumption.

Brazilian indigenous nonstarter lactic acid bacteria enhance the diversification of volatile compounds in short-aged cheese

There is growing interest in using autochthonous lactic acid bacteria (LAB) that provide unique sensory characteristics to dairy products without affecting their safety and quality. This work studied the capacity of three Brazilian indigenous nonstarter LABs (NSLAB) to produce biogenic amines (BAs) and evaluated their effect on the volatile organic compounds (VOCs), microbial LAB communities, and physicochemical profile of short-aged cheese. Initially, the strain's potential for biosynthesis of BAs was assessed by PCR and in vitro assays. Then, a pilot-scale cheese was produced, including the NSLAB, and the microbial and VOC profiles were analyzed after 25 and 45 days of ripening. As a results, the strains did not present genes related to relevant BAs and did not produce them in vitro. During cheese ripening, the Lactococci counts were reduced, probably in the production of alcohols and acid compounds by the NSLAB. Each strain produces a unique VOC profile that changes over the ripening time without the main VOCs related to rancid or old cheese. Particularly, the use of the strain Lacticaseibacillus. paracasei ItalPN16 resulted in production of ester compounds with fruity notes. Thus, indigenous NSLAB could be a valuable tool for the enhancement and diversification of flavor in short-aged cheese.

Volatilome: Smells like microbial spirit

In recent years, the study of volatile compounds has sparked interest due to their implications in signaling and the enormous variety of bioactive properties attributed to them. Despite the absence of analysis methods standardization, there are a multitude of tools and databases that allow the identification and quantification of volatile compounds. These compounds are chemically heterogeneous and their diverse properties are exploited by various fields such as cosmetics, the food industry, agriculture and medicine, some of which will be discussed here. In virtue of volatile compounds being ubiquitous and fast chemical messengers, these molecules mediate a large number of interspecific and intraspecific interactions, which are key at an ecological level to maintaining the balance and correct functioning of ecosystems. This review briefly summarized the role of volatile compounds in inter- and intra-specific relationships as well as industrial applications associated with the use of these compounds that is emerging as a promising field of study.

Comparative genomics of four lactic acid bacteria identified with Vitek MS (MALDI-TOF) and whole-genome sequencing

Lactic acid bacteria (LAB) can be used as a probiotic or starter culture in dairy, meat, and vegetable fermentation. Therefore, their isolation and identification are essential. Recent advances in omics technologies and high-throughput sequencing have made the identification and characterization of bacteria. This study firstly aimed to demonstrate the sensitivity of the Vitek MS (MALDI-TOF) system in the identification of lactic acid bacteria and, secondly, to characterize bacteria using various bioinformatics approaches. Probiotic potency-related genes and secondary metabolite biosynthesis gene clusters were examined. The Vitek MS (MALDI-TOF) system was able to identify all of the bacteria at the genus level. According to whole genome sequencing, the bacteria were confirmed to be Lentilactobacillus buchneri, Levilactobacillus brevis, Lactiplantibacillus plantarum, Levilactobacillus namurensis. Bacteria had most of the probiotic potency-related genes, and different toxin-antitoxin systems such as PemIK/MazEF, Hig A/B, YdcE/YdcD, YefM/YoeB. Also, some of the secondary metabolite biosynthesis gene clusters, some toxic metabolite-related genes, and antibiotic resistance-related genes were detected. In addition, Lentilactobacillus buchneri Egmn17 had a type II-A CRISPR/Cas system. Lactiplantibacillus plantarum Gmze16 had a bacteriocin, plantaricin E/F.

Acid tolerance response of Salmonella during the squid storage and its amine production capacity analysis

Salmonella exhibits a strong inducible acid tolerance response (ATR) under weak acid conditions, and can also induce high-risk strains that are highly toxic, acid resistant, and osmotic pressure resistant to aquatic products. However, the induction mechanism is not yet clear. Therefore, this study aims to simulate the slightly acidic, low-temperature, and high-protein environment during squid processing and storage. Through λRed gene knockout, exploring the effects of low-acid induction, long-term low-temperature storage, and two-component regulation on Salmonella ATR. In this study, we found the two-component system, PhoP/PhoQ and PmrA/PmrB in Salmonella regulates the amino acid metabolism system and improves bacterial acid tolerance by controlling arginine and lysine. Compared with the two indicators of total biogenic amine and diamine content, biogenic amine index and quality index were more suitable for evaluating the quality of aquatic products. The result showed that low-temperature treatment could inhibit Salmonella-induced ATR, which further explained the ATR mechanism from the amino acid metabolism.

Safety Assessment of Levilactobacillus brevis KU15006: A Comprehensive Analysis of its Phenotypic and Genotypic Properties

Levilactobacillus brevis KU15006, isolated from kimchi, exhibits pathogen-antagonistic and anti-diabetic activities; however, the safety of this strain has not been assessed. In the present study, L. brevis KU15006 was evaluated to elucidate its safety as a probiotic strain using phenotypic and genotypic analyses. Its safety was assessed using a minimum inhibitory concentration test comprising nine antibiotics, 26 antibiotic resistance genes, a single conjugative element, virulence gene analysis, hemolysis, cell cytotoxicity, mucin degradation, and toxic metabolite production. L. brevis KU15006 exhibited equal or lower minimum inhibitory concentration for the nine antibiotics than the cut-off value established by the European Food Safety Authority. It did not harbor antibiotic resistance and virulence genes. L. brevis KU15006 lacked β-hemolysis, mucin degradation, cytotoxicity against Caco-2 cells, gelatin liquefaction, bile salt deconjugation, and toxic metabolite production abilities. Based on the results, L. brevis KU15006, which has antagonistic and anti-diabetic effects, could be marketed as a probiotic in the future.

Decarboxylase activity of the non-starter lactic acid bacterium Loigolactobacillus rennini gives crack defects in Gouda cheese through the production of γ-aminobutyric acid

Ten Gouda cheese wheels with an age of 31 weeks from six different batch productions were affected by a crack defect and displayed an unpleasant off-flavor. To unravel the causes of these defects, the concentrations of free amino acids, other organic acids, volatile organic compounds, and biogenic amines were quantified in zones around the cracks and in zones without cracks, and compared with those of similar Gouda cheeses without crack defect. The Gouda cheeses with cracks had a significantly different metabolome. The production of the non-proteinogenic amino acid γ-aminobutyric acid (GABA) could be unraveled as the key mechanism leading to crack formation, although the production of the biogenic amines cadaverine and putrescine contributed as well. High-throughput amplicon sequencing of the full-length 16S rRNA gene based on whole-community DNA revealed the presence of Loigolactobacillus rennini and Tetragenococcus halophilus as most abundant non-starter lactic acid bacteria in the zones with cracks. Shotgun metagenomic sequencing allowed to obtain a metagenome-assembled genome of both Loil. rennini and T. halophilus. However, only Loil. rennini contained genes necessary for the production of GABA, cadaverine, and putrescine. Metagenetics further revealed the brine and the rennet used during cheese manufacturing as the most plausible inoculation sources of both Loil. rennini and T. halophilus.IMPORTANCECrack defects in Gouda cheeses are still poorly understood, although they can lead to major economic losses in cheese companies. In this study, the bacterial cause of a crack defect in Gouda cheeses was identified, and the pathways involved in the crack formation were unraveled. Moreover, possible contamination sources were identified. The brine bath might be a major source of bacteria with the potential to deteriorate cheese quality, which suggests that cheese producers should regularly investigate the quality and microbial composition of their brines. This study illustrated how a multiphasic approach can understand and mitigate problems in a cheese company.

The microbial and metabolite composition of Gouda cheese made from pasteurized milk is determined by the processing chain

Gouda cheeses of different production batches and ripening times often differ in metabolite composition, which may be due to the starter culture mixture applied or the growth of non-starter lactic acid bacteria (NSLAB) upon maturation. Therefore, a single Gouda cheese production batch was systematically investigated from the thermized milk to the mature cheeses, ripened for up to 100 weeks, to identify the main bacterial species and metabolites and their dynamics during the whole production and ripening. As this seemed to be starter culture strain- and NSLAB-dependent, it requested a detailed, longitudinal, and quantitative investigation. Hereto, microbial colony enumeration, high-throughput full-length 16S rRNA gene sequencing, and a metabolomic approach were combined. Culture-dependently, Lactococcus lactis was the most abundant species from its addition as part of the starter culture up to the first two months of cheese ripening. Afterward, the NSLAB Lacticaseibacillus paracasei became the main species during ripening. The milk was a possible inoculation source for the latter species, despite pasteurization. Culture-independently, the starter LAB Lactococcus cremoris and Lc. lactis were the most abundant species in the cheese core throughout the whole fermentation and ripening phases up to 100 weeks. The cheese rind from 40 until 100 weeks of ripening was characterized by a high relative abundance of the NSLAB Tetragenococcus halophilus and Loigolactobacillus rennini, which both came from the brine. These species were linked with the production of the biogenic amines cadaverine and putrescine. The most abundant volatile organic compound was acetoin, an indicator of citrate and lactose fermentation during the production day, whereas the concentrations of free amino acids were an indicator of the ripening time.

Companilactobacillus alimentarius: An extensive characterization of strains isolated from spontaneous fermented sausages

Companilactobacillus alimentarius is a facultatively heterofermentative lactic acid bacterium (LAB) that is a significant constituent within the microbiota of various traditional fermented foods exerting several functions in fermentative or ripening processes. This species has been isolated from Spanish fermented sausages, where its frequency of isolation was comparable to those of Latilactobacillus sakei and Latilactobacillus curvatus. Despite to its presence in several niches, ecological information on this species is still scarce and only few publications report information about its safety features (i.e. antibiotic resistance). Since studies on C. alimentarius concern the analysis of a few individual traits regarding this species, a more extensive work on a larger number of isolates from the same matrix have been performed to allow a clearer interpretation of their phenotypic and technological characteristics. Specifically, 14 strains of C. alimentarius isolated from Mediterranean spontaneously fermented sausages, have been screened for their safety and technological characteristics (such as antibiotic resistance, biogenic amine production, inhibiting potential, growth at different temperatures and NaCl concentrations) and with phenotype microarrays with the aim to elucidate their potential role and contribution to sausage fermentation and ripening. In general, a wide variability was observed in relation to the parameters considered. Several of the tested strains were able to produce histamine, tyramine and putrescine while the antibiotic resistance greatly varied according to the strains, with the exception of vancomycin. In addition, C. alimentarius strains showed a relevant potential to grow in conditions of salt and temperature mimicking those found in fermented foods. In particular, the growth at 10 °C and in the presence of salt can explain the presence of C. alimentarius in sausages and its adaptation to fermented meat environment in which low temperature can be applied during ripening. The differentiation of the phenotypic profile reflected the environmental conditions that influenced the isolation source, including those derived by the raw materials. Given the species frequent association with spontaneous fermentations or the ripening microbiota of various products, despite not being intentionally used as starter cultures, the data presented in this study contribute to a deeper comprehension of their role, both advantageous and detrimental, in numerous significant fermented foods.

A review of biogenic amines in fermented foods: Occurrence and health effects

Biogenic amines (BAs) are low-molecular decarboxylation products of amino acids formed during microbial fermentation. Several fermented foods may contain BAs such as histamine, tyramine, and/or phenylethylamine, at levels above documented toxic doses. Dietary exposure to foods containing high levels of BAs is associated with many adverse health effects, such as migraines, elevated blood pressure, and tachycardia. BA-mediated toxicity may occur at levels a hundred times below regulatory and suggested toxic doses, depending on an individual's sensitivity and factors such as alcohol consumption and certain medications. Although BAs occur in a wide variety of fermented foods, food safety and public health professionals are not well informed about the potential health risks and control strategies in these foods. In this review, we highlight the health risks and symptoms linked to BA exposures, the BA levels found in different fermented foods, regulatory and suggested toxic doses, and risk mitigation strategies to inform food industry and public health professionals' practice.

In vitro study of biogenic amine production and gastrointestinal stress tolerance by some enterococci strains

BACKGROUND

Owing to the toxic effects of enterococci, their biogenic amine production is a negative aspect of safe strain selection and unfavourable activity in food. Additionally, the ability to tolerate acid and bile are two important traits for the selection of probiotic strains since they show the probiotic bacteria's capacity to survive throughout gastrointestinal transit. In the present work, six enterococci strains belonging to Enterococcus gallinarum and Enterococcus hirae were subjected to in vitro evaluation of their ability to produce biogenic amines and to tolerate gastrointestinal stress in order to investigate their possibility for future intended use as probiotics.

RESULTS

All enterococci isolates possessed good viability at low pH (pH 4) and in the presence of bile salts (0.3%), indicating their ability to survive passage through the gastrointestinal tract. In addition, selected strains had a high ability to produce tyramine in tyrosine decarboxylase broth, while medium levels of histamine were detected (below 74 mg L-1 ) in experimental media in vitro. Other biogenic amines were also formed at various levels by most of the enterococci strains.

CONCLUSION

All enterococci strains, with the exception of E. gallinarum DM 29, are powerful tyramine producers, and their capacity to create histamine is inferior to that of tyramine. However, more investigations are needed before considering their use as bio-preservatives or starter cultures in foods. © 2023 Society of Chemical Industry.

Rapid discrimination of Lentilactobacillus parabuchneri biofilms via in situ infrared spectroscopy

Microbial contamination in food industry is a source of foodborne illnesses and biofilm-related diseases. In particular, biogenic amines (BAs) accumulated in fermented foods via lactic acid bacterial activity exert toxic effects on human health. Among these, biofilms of histamine-producer Lentilactobacillus parabuchneri strains adherent at food processing equipment surfaces can cause food spoilage and poisoning. Understanding the chain of contamination is closely related to elucidating molecular mechanisms of biofilm formation. In the present study, an innovative approach using integrated chemical sensing technologies is demonstrated to fundamentally understand the temporal behavior of biofilms at the molecular level by combining mid-infrared (MIR) spectroscopy and fluorescence sensing strategies. Using these concepts, the biofilm forming capacity of six cheese-isolated L. parabuchneri strains (IPLA 11151, 11150, 11129, 11125, 11122 and 11117) was examined. The cut-off values for the biofilm production ability of each strain were quantified using crystal violet (CV) assays. Real-time infrared attenuated total reflection spectroscopy (IR-ATR) combined with fluorescence quenching oxygen sensing provides insight into distinct molecular mechanisms for each strain. IR spectra showed significant changes in characteristic bands of amides, lactate, nucleic acids, and extracellular polymeric substances (i.e., lipopolysaccharides, phospholipids, phosphodiester, peptidoglycan, etc.), which are major contributors to biofilm maturation involved in the initial adhesion processes. Chemometric methods including principal component analysis and partial least square-discriminant analysis facilitated the rapid determination and classification of cheese isolated L. parabuchneri strains unambiguously differentiating the IR signatures based on their ability to produce biofilm. All biofilms were morphologically characterized by confocal laser scanning microscopy on relevant industrial equipment surfaces. In summary, this innovative approach combining MIR spectroscopy with luminescence sensing enables real-time insight into the molecular composition and formation of L. parabuchneri biofilms.

Dissecting the Genetic Basis of the Technological, Functional, and Safety Characteristics of Lacticaseibacillus paracasei SRX10

Nonstarter lactic acid bacteria (NSLAB) are major contributors to the unique characteristics (e.g., aroma, flavor, texture) of dairy and nondairy fermented products. Lc. paracasei SRX10 is an NSLAB strain originally isolated from a traditional Greek cheese and previously shown to exhibit favorable biotechnological characteristics. More specifically, the strain showed tolerance to simulated gastrointestinal conditions, exopolysaccharide (EPS) biosynthetic capacity, and lack of hemolytic activity and was used in the production of yoghurt and feta cheese with distinct organoleptic characteristics. The aim of the present study was to investigate these traits at the genome level through whole-genome sequencing (WGS), annotation, and comparative genomics. Functional annotation of the genome revealed that Lc. paracasei SRX10 can utilize different carbon sources, leading to the generation of flavor compounds, including lactic acid, acetate, ethanol, and acetoin. Similarly, full clusters for fatty acid biosynthesis, protein and peptide degradation, as well as genes related to survival under extreme temperatures, osmotic shock, and oxidative stress were annotated. Importantly, no transferable antibiotic resistance genes or virulence factors were identified. Finally, strain-specific primers based on genome-wide polymorphisms were designed for the efficient and rapid identification of Lc. paracasei SRX10 via multiplex PCR in fermented products.

Charge-Reversible Nanoparticles: Advanced Delivery Systems for Therapy and Diagnosis

The past two decades have witnessed a rapid progress in the development of surface charge-reversible nanoparticles (NPs) for drug delivery and diagnosis. These NPs are able to elegantly address the polycation dilemma. Converting their surface charge from negative/neutral to positive at the target site, they can substantially improve delivery of drugs and diagnostic agents. By specific stimuli like a shift in pH and redox potential, enzymes, or exogenous stimuli such as light or heat, charge reversal of NP surface can be achieved at the target site. The activated positive surface charge enhances the adhesion of NPs to target cells and facilitates cellular uptake, endosomal escape, and mitochondrial targeting. Because of these properties, the efficacy of incorporated drugs as well as the sensitivity of diagnostic agents can be essentially enhanced. Furthermore, charge-reversible NPs are shown to overcome the biofilm formed by pathogenic bacteria and to shuttle antibiotics directly to the cell membrane of these microorganisms. In this review, the up-to-date design of charge-reversible NPs and their emerging applications in drug delivery and diagnosis are highlighted.

Benefits and concerns of probiotics: an overview of the potential genotoxicity of the colibactin-producing Escherichia coli Nissle 1917 strain

Recently, the mounting integration of probiotics into human health strategies has gathered considerable attention. Although the benefits of probiotics have been widely recognized in patients with gastrointestinal disorders, immune system modulation, and chronic-degenerative diseases, there is a growing need to evaluate their potential risks. In this context, new concerns have arisen regarding the safety of probiotics as some strains may have adverse effects in humans. Among these strains, Escherichia coli Nissle 1917 (EcN) exhibited traits of concern due to a pathogenic locus in its genome that produces potentially genotoxic metabolites. As the use of probiotics for therapeutic purposes is increasing, the effects of potentially harmful probiotics must be carefully evaluated. To this end, in this narrative review article, we reported the findings of the most relevant in vitro and in vivo studies investigating the expanding applications of probiotics and their impact on human well-being addressing concerns arising from the presence of antibiotic resistance and pathogenic elements, with a focus on the polyketide synthase (pks) pathogenic island of EcN. In this context, the literature data here discussed encourages a thorough profiling of probiotics to identify potential harmful elements as done for EcN where potential genotoxic effects of colibactin, a secondary metabolite, were observed. Specifically, while some studies suggest EcN is safe for gastrointestinal health, conflicting findings highlight the need for further research to clarify its safety and optimize its use in therapy. Overall, the data here presented suggest that a comprehensive assessment of the evolving landscape of probiotics is essential to make evidence-based decisions and ensure their correct use in humans.

Material Breakthroughs in Smart Food Monitoring: Intelligent Packaging and On-Site Testing Technologies for Spoilage and Contamination Detection

Despite extensive commercial and regulatory interventions, food spoilage and contamination continue to impose massive ramifications on human health and the global economy. Recognizing that such issues will be significantly eliminated by the accurate and timely monitoring of food quality markers, smart food sensors have garnered significant interest as platforms for both real-time, in-package food monitoring and on-site commercial testing. In both cases, the sensitivity, stability, and efficiency of the developed sensors are largely informed by underlying material design, driving focus toward the creation of advanced materials optimized for such applications. Herein, a comprehensive review of emerging intelligent materials and sensors developed in this space is provided, through the lens of three key food quality markers - biogenic amines, pH, and pathogenic microbes. Each sensing platform is presented with targeted consideration toward the contributions of the underlying metallic or polymeric substrate to the sensing mechanism and detection performance. Further, the real-world applicability of presented works is considered with respect to their capabilities, regulatory adherence, and commercial potential. Finally, a situational assessment of the current state of intelligent food monitoring technologies is provided, discussing material-centric strategies to address their existing limitations, regulatory concerns, and commercial considerations.

In-situ substitution and community dynamics modeling for enhanced safety in Chinese rice wine brewing

This research paper focuses on the application of the "Design-Build-Test-Learn" framework to design and evaluate a synthetic microbial community aimed at studying the impact of Lactic Acid Bacteria (LAB) interactions and fitness on the formation of biogenic amines (BAs) in Chinese rice wine (CRW). The study reveals a close correlation between the assembly model of LAB and the accumulation of BAs in CRW, and multiple interactions were observed between amine-producing and non-amine-producing LAB, including commensalism, amensalism, and competition. The commensalism among amine-producing LAB was found to promote BAs accumulation through metabolic cross-feeding of amino acids. Moreover, the higher-order interaction community was designed to regulate the BAs formation effectively. For instance, the interference of Lactiplantibacillus plantarum (ACBC271) resulted in the elimination of amine-producing LAB viability, resulting in a 22% decrease (not exceeding 43.54 mg/L) in the total amount of BAs. Simulation of community dynamics models further suggests that LAB with quantitative social interactions can effectively control LAB accumulation in CRW by forecasting fluctuation in BAs generation through fitness competition and metabolic interference. Overall, this study provides valuable insights into the complex interaction networks within microbial communities in traditional fermentation ecosystems. It also proposes a novel approach for quality control of nitrogen food safety factors in fermented foods.

Potential of γ-Aminobutyric Acid-Producing Leuconostoc mesenteroides Strains Isolated from Kimchi as a Starter for High-γ-Aminobutyric Acid Kimchi Fermentation

γ-Aminobutyric acid (GABA)-producing Leuconostoc mesenteroides K1501 and K1627, isolated from kimchi, exhibited the highest GABA production in 1% monosodium glutamic acid. Both strains showed high survival rates of approximately 87% in artificial gastric juice (pH 3.0) and >80% in 0.1% artificial bile salt fluid. The survival rate was approximately 28% in 0.3% artificial bile salt fluid and 0% in 0.5% artificial bile salts. Both strains showed excellent adhesion to intestinal epithelial cells (>99%). Furthermore, it was observed that growth was not inhibited at 2% salt concentration; however, it was slightly retarded at salt concentrations of 3% and 4%. Moreover, L. mesenteroides K1501 and K1627 inhibited the growth of certain species of Lactobacillus, whose presence in kimchi fermentation is undesirable. Therefore, L. mesenteroides K1501 and K1627 have the potential to be used as starter organisms for functional GABA-rich kimchi.

Evaluation of Safety and Probiotic Traits from a Comprehensive Genome-Based In Silico Analysis of Ligilactobacillus salivarius P1CEA3, Isolated from Pigs and Producer of Nisin S

Ligilactobacillus salivarius is an important member of the porcine gastrointestinal tract (GIT). Some L. salivarius strains are considered to have a beneficial effect on the host by exerting different probiotic properties, including the production of antimicrobial peptides which help maintain a healthy gut microbiota. L. salivarius P1CEA3, a porcine isolated strain, was first selected and identified by its antimicrobial activity against a broad range of pathogenic bacteria due to the production of the novel bacteriocin nisin S. The assembled L. salivarius P1CEA3 genome includes a circular chromosome, a megaplasmid (pMP1CEA3) encoding the nisin S gene cluster, and two small plasmids. A comprehensive genome-based in silico analysis of the L. salivarius P1CEA3 genome reveals the presence of genes related to probiotic features such as bacteriocin synthesis, regulation and production, adhesion and aggregation, the production of lactic acid, amino acids metabolism, vitamin biosynthesis, and tolerance to temperature, acid, bile salts and osmotic and oxidative stress. Furthermore, the strain is absent of risk-related genes for acquired antibiotic resistance traits, virulence factors, toxic metabolites and detrimental metabolic or enzymatic activities. Resistance to common antibiotics and gelatinase and hemolytic activities have been discarded by in vitro experiments. This study identifies several probiotic and safety traits of L. salivarius P1CEA3 and suggests its potential as a promising probiotic in swine production.

Fermented Vegetables: Health Benefits, Defects, and Current Technological Solutions

This review summarizes current studies on fermented vegetables, analyzing the changes in nutritional components during pickling, the health benefits of fermented vegetables, and their safety concerns. Additionally, the review provides an overview of the applications of emergent non-thermal technologies for addressing these safety concerns during the production and processing of fermented vegetables. It was found that vitamin C would commonly be lost, the soluble protein would degrade into free amino acids, new nutrient compositions would be produced, and the flavor correlated with the chemical changes. These changes would be influenced by the variety/location of raw materials, the original bacterial population, starter cultures, fermentation conditions, seasoning additions, and post-fermentation processing. Consuming fermented vegetables benefits human health, including antibacterial effects, regulating intestinal bacterial populations, and promoting health (anti-cancer effects, anti-diabetes effects, and immune regulation). However, fermented vegetables have chemical and biological safety concerns, such as biogenic amines and the formation of nitrites, as well as the existence of pathogenic microorganisms. To reduce hazardous components and control the quality of fermented vegetables, unique starter cultures, high pressure, ultrasound, cold plasma, photodynamic, and other technologies can be used to solve these problems.

Characterization of Lactococcus lactis 11/19-B1 Isolated from Kiwi Fruit as a Potential Probiotic and Paraprobiotic

Probiotics are live bacteria used as food additives that are beneficial to human health. Lactococcus lactis 11/19-B1 strain isolated from kiwi fruit stimulates innate immunity in silkworms. Intake of yogurt containing the living 11/19-B1 strain significantly decreases the level of low-density lipoproteins (LDLs) in high-LDL volunteers and improves atopic dermatitis in humans. In this study, the probiotic properties of the 11/19-B1 strain, such as sensitivity to antimicrobial compounds, biogenic amine production, some virulence genes for human health, antimicrobial activity, tolerance to gastric acid and bile acids, and ability to adhere to the intestinal mucosa, were evaluated. The 11/19-B1 strain did not show resistance to the tested antimicrobial compounds except cefoxitin and fosfomycin. In addition, no production of amines that can harm humans, the antimicrobial activity required for probiotics, and the absence of adhesion to Caco-2 cells suggest that it is unlikely to attach to the intestinal epithelium. The 11/19-B1 strain grew in 0.3% but not in 1% bile salt. In the presence of 2% skim milk, the survival rate of the 11/19-B1 strain under simulated gastrointestinal tract conditions was 67% even after 4 h. These results indicate that the 11/19-B1 strain may function as a probiotic or paraprobiotic to be utilized in the food industry.

Total and Free Hydrogen Cyanide Content and Profile of Bioactive Amines in Commercial Tucupi, a Traditionally Derived Cassava Product Widely Consumed in Northern Brazil

Tucupi is a broth derived from cassava roots which is produced after the spontaneous fermentation of manipueira (the liquid portion obtained by pressing cassava roots), followed by cooking. This product is widely consumed along with traditional dishes in the Brazilian Amazonia and is already used in different places worldwide. In this study, tucupi obtained from the markets of Belém (Pará, Brazil) and produced using agroindustrial (11 samples) and non-agroindustrial (11 samples) units were investigated to determine their physicochemical characteristics, total and free HCN contents, and free bioactive amine profiles. Most of the samples showed significant variations (p ≤ 0.05) in pH (2.82-4.67), total acidity (0.14-1.36 g lactic acid/100 mL), reducing sugars (up to 2.33 g/100 mL), and total sugars (up to 4.35 g/100 mL). Regarding the amines, four biogenic amines (0.5-4.2 mg/L tyramine, 1.0-23.1 mg/L putrescine, 0.5-66.8 mg/L histamine, and 0.6-2.9 mg/L tryptamine) and one polyamine (0.4-1.7 mg/L spermidine) were identified in the tucupi samples. Even in the tucupi produced using the agroindustrial units, which had quality seals provided by the local regulatory agency, high levels of biogenic amines (4.4-78.2 mg/L) were observed, as well as high dosages of total (8.87-114.66 mg/L) and free (0.80-38.38 mg/L) HCN. These facts highlight the need for better knowledge regarding the product manufacturing process to establish standardization and high-quality conditions for tucupi processing since high contents of biogenic amines and HCN are commonly associated with adverse health effects.

Multi-omics analysis reveals the microbial interactions of S. cerevisiae and L. plantarum on Suanyu, Chinese traditional fermented fish

S. cerevisiae and L. plantarum play important roles in Suanyu fermentation. This study investigated the interaction between S. cerevisiae and L. plantarum during fermentation and its impact on metabolic pathways. Co-culturing S. cerevisiae and L. plantarum increased pH to 5.72, reduced TVB-N to 9.47 mg/mL, and achieved high utilization rates of sugars (98.9%) and proteins (73.7%). During microbial interactions, S. cerevisiae and L. plantarum produced antibiotics, including phenyllactate and Gentamicin C1a, inhibiting the growth of each other. S. cerevisiae used S-adenosyl-l-methionine to counteract acid production of L. plantarum, establishing dominance in Suanyu fermentation. Microbial interactions influenced carbohydrate and energy metabolism pathways, such as nicotinate and nicotinamide metabolism and purine metabolism. S. cerevisiae significantly impacted gene expression in protein synthesis and cell growth pathways, including ribosome, SNARE interactions, basal transcription factors, and MAPK signaling. These findings offer insights into microbial interactions and metabolic processes during Suanyu fermentation.

Mitigation of microbial nitrogen-derived metabolic hazards as a driver for safer alcoholic beverage choices: An evidence-based review and future perspectives

Alcoholic beverages have been enjoyed worldwide as hedonistic commodities for thousands of years. The unique quality and flavor are attributed to the rich microbiota and nutritional materials involved in fermentation. However, the metabolism of these microbiota can also introduce toxic compounds into foods. Nitrogen-derived metabolic hazards (NMH) are toxic metabolic hazards produced by microorganisms metabolizing nitrogen sources that can contaminate alcoholic beverages during fermentation and processing. NMH contamination poses a risk to dietary safety and human health without effective preventive strategies. Existing literature has primarily focused on investigating the causes of NMH formation, detection methods, and abatement techniques for NMH in fermentation end-products. Devising effective process regulation strategies represents a major challenge for the alcoholic beverage industry considering our current lack of understanding regarding the processes whereby NMH are generated, real-time and online detection, and the high degradation rate after NMH formation. This review summarizes the types and mechanisms of nitrogenous hazard contamination, the potential risk points, and the analytical techniques to detect NMH contamination. We discussed the changing patterns of NMH contamination and effective strategies to prevent contamination at different stages in the production of alcoholic beverages. Moreover, we also discussed the advanced technologies and methods to control NMH contamination in alcoholic beverages based on intelligent monitoring, synthetic ecology, and computational assistance. Overall, this review highlights the risks of NMH contamination during alcoholic beverage production and proposes promising strategies that could be adopted to eliminate the risk of NMH contamination.

Formation of Histamine, phenylethylamine and γ-Aminobutyric acid during sprouting and fermenting of selected wholegrains

Sprouting and fermentation are known to cause hydrolysis of proteins into amino acids in grains, which in turn can be converted into some neuroactive compounds by some specific enzymes.One of these compounds is γ-aminobutyric acid, which is directly related to stress management. This study invesitgatesthe effects of sprouting and fermentation processes performed under different conditions on the formation of γ-aminobutyric acid.. Concomitant phenylethylamine and histamine formations were also investigated from the food safety point of view. The combined application of sprouting and fermentation increased the concentrations of histamine and phenylethylamine to a maximum of 44 ± 5 ​​ and 3.9 ± 0.002 mg/kg, respectively. Nevertheless, these values ​​did not reach the level that would cause undesirable effects. γ-Aminobutyric acid concentrations were found to reach levels comparable to γ-Aminobutyric acid -rich foods (maximum 674 ± 31 mg/kg) both with separate and combined application of sprouting and fermentation.

Use of two autochthonous bacteriocinogenic strains as starter cultures in the production of salchichónes, a type of Spanish fermented sausages

In this work, two autochthonous LAB strains (Lactiplantibacillus paraplantarum BPF2 and Pediococcus acidilactici ST6), isolated from spontaneously fermented sausages produced in Spain, were tested to produce Spanish fermented sausages (salchichón) in pilot plants, due to their promising technological and anti-listerial activity. These products were compared with a sample obtained with a commercial starter (RAP) and a spontaneously fermented control sample. Physico-chemical parameters, microbial counts, metagenomic analysis, biogenic amines content and organoleptic profile of the obtained samples were studied to assess the performances of the native starters. In fact, traditional and artisanal products obtained through spontaneous fermentations can represent an important biodiversity reservoir of strains to be exploited as new potential starter cultures, to improve the safety, quality and local differentiation of traditional products. The data underlined that ST6 strain resulted in a final lower percentage if compared with the other LAB used as starter cultures. The use of starters reduced the BA concentration observed in the sausages obtained with spontaneous fermentation and the BPF2 and ST6 strains were able to decrease the level of products rancidity. Moreover, a challenge test against L. monocytogenes were performed. The data confirmed the effectiveness in the inhibition of L. monocytogenes by the two bacteriocinogenic strains tested, with respect to RAP and control samples, highlighting their ability to produce bacteriocins in real food systems. This work demonstrated the promising application in meat industry of these autochthonous strains as starter cultures to improve sensory differentiation and recognizability of typical fermented sausages.

Ascertaining the Influence of Lacto-Fermentation on Changes in Bovine Colostrum Amino and Fatty Acid Profiles

The aim of this study was to collect samples of bovine colostrum (BCOL) from different sources (agricultural companies A, B, C, D and E) in Lithuania and to ascertain the influence of lacto-fermentation with Lactiplantibacillus plantarum strain 135 and Lacticaseibacillus paracasei strain 244 on the changes in bovine colostrum amino (AA), biogenic amine (BA), and fatty acid (FA) profiles. It was established that the source of the bovine colostrum, the used LAB, and their interaction had significant effects (p < 0.05) on AA contents; lactic acid bacteria (LAB) used for fermentation was a significant factor for aspartic acid, threonine, glycine, alanine, methionine, phenylalanine, lysine, histidine, and tyrosine; and these factor's interaction is significant on most of the detected AA concentrations. Total BA content showed significant correlations with glutamic acid, serine, aspartic acid, valine, methionine, phenylalanine, histidine, and gamma amino-butyric acid content in bovine colostrum. Despite the differences in individual FA contents in bovine colostrum, significant differences were not found in total saturated (SFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids. Finally, the utilization of bovine colostrum proved to be challenging because of the variability on its composition. These results suggest that processing bovine colostrum into value-added formulations for human consumption requires the adjustment of its composition since the primary production stage. Consequently, animal rearing should be considered in the employed bovine colostrum processing technologies.

Effect of alginate-gallic acid coating on freshness and flavor properties of Mackerel (Scomberomorus commerson) fillets under refrigerated storage

This study investigates the effect of sodium alginate-gallic acid (ALG-GAL) coating on mackerel's flavor compounds and quality properties during cold storage at 4 °C for 12 days. To this end, freshness quality indicators, including biogenic amines (BAs), volatile organic compounds (VOCs), ATP-related compounds, K value, total viable counts (TVC), thiobarbituric acid (TBA), and sensory assessment, were measured. During storage, eight BAs, i.e., histamine (HIS), tyramine (TYR), putrescine (PUT), cadaverine (CAD), 2-phenylethylamine (2-PHE), agimation, spermine (SPM), and spermidine (SPD) were identified in control and treated samples. The biogenic amine index (BAI) for control samples was 56.25 at the time of sensory rejection (day 6). BAI for samples coated with ALG-GAL did not exceed 20 mg/100 g at the time of sensory rejection (day 12). The fillets treated with the ALG alone or incorporated with GAL possessed a different trend in the retardation of VOCs, including aldehydes, ketones, alcohols, and hydrocarbons. Seven key flavors VOCs, including 3-methylbutanal, phenylacetaldehyde, E-2-hexanal, 1-hexanol, 1-octen-3-ol, 2,3 pentanedione, and hydroxyl-2-butanone, were identified in control and coated samples. Samples coated with ALG and GAL were of significantly higher quality (p < 0.05) throughout storage, which could result in lower Inosine (HxR) concentrations and K values. The results of TVC showed that use ALG-GAL had lower bacterial counts compared to control (p < 0.05). The ALG-GAL-coated samples retarded the increase in the contents of TBA during storage. In addition, significant differences in sensory scores between ALG and ALG-GAL were observed (p < 0.05). In this study, aldehydes and hypoxanthine (Hx) were the main compounds in the formation of off-flavor. These results revealed that ALG coating combined with GAL improved the quality of refrigerated mackerel fillets by decreasing off-flavor compounds and TVC population.

Depiction of the In Vitro and Genomic Basis of Resistance to Hop and High Hydrostatic Pressure of Lactiplantibacillus plantarum Isolated from Spoiled Beer

Among the beer-spoiling microorganisms, the dominant ones belong to the genera Lactobacillus, Leuconostoc, Oenococcus, and Pediococcus. It is assumed that resistance to hop bitters correlates with resistance to other factors and can significantly impact the brewing industry. Beer preservation with high hydrostatic pressure eliminates the spoiling microorganisms while preserving all desired properties of the beer. Here, we present comprehensive in vitro and genomic analysis of the beer-spoiling Lactiplantibacillus plantarum KKP 3573 capacity to resist hop and high hydrostatic pressure. Lp. plantarum KKP 3573 is a strain isolated from spoiled beer. Our finding suggests that the growth rate of the strain depends on the medium variant, where a small concentration of beer (5 IBU) stimulates the growth, suggesting that the limited concentration has a positive effect on cell growth. At the same time, increased concentrations of 20 IBU, 30 IBU, and pure beer 43.6 IBU decreased the growth rate of the KKP 3573 strain. We observed that higher extract content in the pressurized beer increased microbial survivability. The wort and Vienna Lager beer can stimulate the baroprotective effect. The taxonomy of the novel strain was confirmed after whole genome sequencing (WGS) and comparative genomic analysis. More specifically, it contains a chromosome of 3.3 Mb with a GC content of 44.4%, indicative of the Lp. plantarum species. Accordingly, it possesses high genomic similarity (>98%) with other species members. Annotation algorithms revealed that the strain carries several genes involved in resistance to stress, including extreme temperature, hop bitters and high pressure, and adaptation to the brewing environment. Lastly, the strain does not code for toxins and virulence proteins and cannot produce biogenic amines.

Metagenomic Insights into the Regulatory Effects of Microbial Community on the Formation of Biogenic Amines and Volatile Flavor Components during the Brewing of Hongqu Rice Wine

As one of the typical representatives of Chinese rice wine (Huangjiu), Hongqu rice wine is produced with glutinous rice as the main raw material and Hongqu as the fermentation starter. The complex microbial flora in the brewing process may have a great influence on the formation of the flavor quality and drinking safety of Hongqu rice wine. Previous studies have shown that high biogenic amine (BA) content in rice wine has potential physiological toxicity and has become a bottleneck problem restricting the development of the rice wine industry. This study aimed to evaluate the regulatory effects of the microbial community on the formation of BAs and volatile flavor components during the brewing of Hongqu rice wine. The results demonstrated that histamine, putrescine, cadaverine, tyramine, tryptamine, spermine, and spermidine were the main BAs in Hongqu rice wine. The contents of putrescine, cadaverine, histamine, tyramine, and spermidine in Hongqu rice wine of HBAs (with higher BAs content) were significantly higher than those in LBAs (with lower BAs content). GC-MS testing results showed that there were significant differences in the composition of volatile organic compounds (VOCs) between HBAs and LBAs. Among them, VOCs such as 2-methoxy-4-vinylphenol, ethyl caprate, phenethyl acetate, ethyl lactate, ethyl myristate, ethyl palmitate, ethyl n-octadecanoate, ethyl oleate, and ethyl linoleate were identified as the characteristic volatile components with significant differences between HBAs and LBAs. Microbiome analysis based on metagenomic sequencing revealed that unclassified_g_Pantoea, Klebsiella pneumoniae, Panobacter disperse, unclassified_f_Enterobacteriaceae, Leuconostoc mesenteroides, and Saccharomyces cerevisiae were the dominant microbial species in the HBA brewing process, while Weissella confuse, Pediococcus acidilactici, Saccharomyces cerevisiae, and Aspergillus niger were the dominant microbial species in the LBA brewing process. Furthermore, correlation heatmap analysis demonstrated that BAs were positively related to Lactobacillus curvatus, Lactococcus lactis, and Leuconostoc mesenteroides. Bioinformatical analysis based on the KEGG database revealed that the microbial genes encoding enzymes involved in BAs' synthesis were more abundant in HBAs, and the abundances of microbial genes encoding enzymes related to BAs' degradation and the metabolism of characteristic volatile components were higher in LBAs. Overall, this work provides important scientific data for enhancing the flavor quality of Hongqu rice wine and lays a solid foundation for the healthy development of the Hongqu rice wine industry.