Analytical strategies for the determination of biogenic amines in dairy products

A dummy template molecularly imprinted polymer-coated fiber array extraction for simultaneous HPLC analysis of eight biogenic amines in fermented horse milk

BACKGROUND

Biogenic amines (BAs) are low molecular weight nitrogenous compounds present in various foods. While physiologically essential in trace amounts, elevated concentrations of BAs pose health risks, including serving as precursors to carcinogens. In fermented foods such as kumiss-a traditional fermented horse milk-the quantitative assessment of BAs is critical due to their health implications. However, the wide range of logP and pKa values among BAs presents significant challenges for their simultaneous extraction and accurate analysis.

RESULT

This study introduces a novel approach for the simultaneous extraction of eight BAs in kumiss using dummy molecularly imprinted polymer (DMIP) coated fibers. The DMIP was synthesized using diethylamine dansyl chloride as a derivatized template, enabling selective recognition of eight BA derivatives. The fabricated coated fibers, which are reusable and cost-effective, were integrated into an array device for high-throughput solid-phase microextraction (SPME), achieving an average extraction time of less than 2 min per sample. The SPME method demonstrated high recoveries (70.06-110.92 %) when coupled with high-performance liquid chromatography (HPLC) analysis. Linear calibration curves were established between the peak area and the concentration of BAs over the range of 0.2-10 mg L-1, with high regression coefficients (>0.99) and low detection limits (0.025-0.123 mg L-1). The DMIP coated fiber array extraction device provided highly selective and efficient separation of BA derivatives from complex matrices, as successfully demonstrated using kumiss samples.

SIGNIFICANCE AND NOVELTY

This study presents a novel dummy molecular imprinting strategy for the fabrication of DMIP coated fiber array for SPME, addressing the limitations of traditional methods in the simultaneous recognition of structurally diverse BAs. This approach significantly enhances the efficiency and selectivity of BA analysis, which is essential for the quality control of fermented foods.

Molecular characterization of histidine and tyrosine decarboxylating Enterococcus species isolated from some milk products

BACKGROUND

Fermented foods can cause adverse effects on human health because of the biogenic amines (BAs) accumulating through amino acid decarboxylation. This study investigated the presence of BAs including tyramine and histamine in 240 samples of some cheese and fermented milk samples using high-performance liquid chromatography. Another aim of this study is to isolate and identify Enterococcus spp. as the most important and frequent BA producer in the examined samples. The isolated Enterococcus spp. was investigated phenotypically for their capacity to produce amino acid decarboxylase enzyme using decarboxylase microplate assay, and genotypically through molecular detection of some genes encoding amino acid decarboxylation (tyrdc and hdc). Biogenic amines producing enterococci were then investigated for their antimicrobial resistance, biofilm production as well as their virulence determinants.

RESULTS

Tyramine and histamine could be detected in 86.7 and 87.9% of the investigated samples with 52.9% being contaminated with Enterococcus spp. Significant correlation between the incidence of Enterococci enterococci and BAs formed in the examined samples (P < 0.0001). tyrdc and hdc genes were detected in 85 and 5% of amino acid decarboxylating Enterococcus spp., respectively. A high percentage of Enterococcus isolates (57.5%) were multidrug-resistant and resistance against penicillin was widespread among isolates followed by tetracycline, vancomycin, erythromycin and linezolid. Also, 77.5% of the isolates were capable of forming biofilms and a highly significant correlation (P < 0.0001) was found between biofilm formation and multidrug resistance. The results showed that the rates of most virulence genes gelE, esp, ace, asa1, and cylA were 77.5. 47.5, 47.5, 35 and 7.5%, respectively, while the hyl gene was not detected in any isolates.

CONCLUSION

The study highlights the significant presence of BAs (TYM and HIS) in cheese and fermented milk samples, with a strong correlation between enterococci contamination and TYM production. The high prevalence of tyramine-producing Enterococcus species poses a notable public health concern especially with the high prevalence of multidrug-resistant, biofilm production and virulence in BAs producing Enterococcus spp. in dairy products, emphasizing the urgent need for improved antimicrobial stewardship among food producers and veterinarians to mitigate the risk of transferring resistant strains to humans.

Sensitive analysis of polyamines by micellar-electrokinetic chromatography with laser-induced fluorescence (MEKC-LIF) in mineral media samples

A micellar electrokinetic chromatography (MEKC) method coupled with laser-induced fluorescence (LIF) detection was developed and validated for the determination of five aliphatic polyamines in mineral media samples. Since polyamines lack inherent UV chromophores or fluorophores, fluorescence detection was enhanced using precapillary derivatization with fluorescein isothiocyanate isomer I (FITC). Key parameters affecting the derivatization, including reagent concentration, reaction time, and temperature, were optimized to improve sensitivity. Under optimal conditions, with a background electrolyte (BGE) of 20 mM borax and 20 mM SDS, polyamines were successfully separated, achieving limits of detection as low as 0.03 μM for cadaverine and 0.09 μM for putrescine, spermine, spermidine, and norspermidine. The method demonstrated the importance of borate complexation and the use of anionic surfactants for improving both sweeping and fluorescence signal intensity. The MEKC-LIF method was applied to analyze polyamines in mineral media from in vitro cultures of Arabidopsis thaliana and Pectobacterium betavasculorum, grown individually and in co-culture. Results showed that bacteria can synthesize or degrade polyamines, suggesting their importance in plant-bacteria interactions. The method enables sensitive analysis of polyamine metabolism, and its use provides insights into inter-kingdom communication.

The Determination of Eight Biogenic Amines Using MSPE-UHPLC-MS/MS and Their Application in Regard to Changes in These Biogenic Amines in Traditional Chinese Dish-Pickled Swimming Crabs

In this study, a method for the determination of eight biogenic amines (BAs), including tyramine (Tyr), 2-phenylethylamine (2-Phe), histamine (His), tryptamine (Trp), spermidine (Spd), spermine (Spm), cadaverine (Cad), and putrescine (Put), in crab was established using ultra-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS), using a magnetic solid-phase extraction (MSPE) pretreatment, without derivatization, and the content changes in regard to these eight biogenic amines in the traditional Chinese dish, pickled swimming crabs, were investigated. The samples were purified via MSPE, using C nanofiber-coated magnetic nanoparticles (Fe3O4@C-NFs) as sorbents. The experimental variables involved in the MSPE, including the solution pH, adsorption and desorption time, adsorbent usage, and type and volume of the eluent, were investigated and optimized. Method validation indicated that the developed method showed good linearity (R2 > 0.995); the average recovery rates were 84.7% to 115%, with the intra-day and inter-day relative standard deviations (RSD, n = 6) ranging from 3.7% to 7.5% and 4.2% to 7.7%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) for the eight BAs were 0.1 mg/kg~1.0 mg/kg and 0.3 mg/kg~3.0 mg/kg, respectively. Finally, this method was applied to determine the changes in the eight biogenic amines in pickled swimming crabs (Portunus trituberculatus) during storage at 20 °C and 400 BAC. Among the BAs evaluated, Cad, Put, and Tyr were the predominant amines formed during storage. The final content of Cad, Put, and Tyr reached 22.9, 20.1, and 29.0 mg/100 g at 4 °C for 16 d, and 47.1, 52.3, and 72.0 mg/100 g at 20 °C for 96 h, respectively. The results from this study can be used to expand the application range of magnetic materials in biogenic amine pretreatment and to strengthen the quality control of the traditional Chinese dish, pickled swimming crabs.

Multiphase detection of crucial biological amines using a 2,4,6-tristyrylpyrylium dye

The strong electrophilicity of arylpyrylium salts was recognized for the colorimetric detection of vital amine analytes, limited to ammonia or methylamines and putrescine as biogenic amine. This report presents conformationally twisted, electrophilic triphenylamine-linked 2,4,6-tristyrylpyrylium salt PyTPA as a single dye to sense various aliphatic/aromatic biogenic amines, nicotine, and guanidine rapidly in nanomolar concentrations. This unexplored styrylpyrylium design offers specific electronic conjugations, steric/geometric constraints with hydrophobicity, and decent thermal/photostability, facilitating precise diverse amines detection in unique fashions. The deep-violet solution/solid dye responded remarkably at 298 K with quick decoloration against putrescine, cadaverine, spermidine, spermine, histamines, serotonin, and 2-phenylethylamine. Further, this dye could detect nicotine at 313 K and guanidine at 298 K distinctively with diminished absorption and unexpected red-shifted emission enhancement. Variation in mechanistic path is recognized in detecting amines holding mono/di-NH2 groups and short/ long alkane chains, elucidated by mass, 1H-NMR, FT-IR, SEM, PXRD, and XPS studies. The notable detection of these biogenic amines in different phases is employed for onsite applications to detect fresh chicken and tuna. Nicotine in natural tobacco leaves was identified. Such pyrylium salt provides promising advancements in this class of molecules in detecting diverse biologically significant amines.

Construction of flexible paper-based sensor for label-free recognition of histamine in cow meat samples by conductive nano-silver ink: a new platform for the analysis of biogenic amines towards early diagnosis of meat spoil

Biogenic amines are organic nitrogen compounds that play key roles in various biological processes and are produced through amino acid decarboxylation. Among these, histamine stands out as a toxic biogenic amine with the potential to cause serious health issues when present at elevated levels in food, highlighting the importance of effective detection methods. However, current histamine detection approaches are often hindered by high costs, lengthy analysis times, and intricate procedures. This research introduces a novel, label-free method for detecting histamine in meat samples using highly conductive nano-silver inks to develop miniaturized sensors based on paper microdevice technology. The proposed paper-based electrochemical sensors offer significant advantages, including affordability, reproducibility, and environmental sustainability. A newly designed paper-based microsensor was developed for label-free histamine detection employing conductive nano-silver ink via a pen-on-paper technique. The fabrication process of the microsensor was thoroughly characterized through methods like field emission scanning electron microscope (FE-SEM), Energy Dispersive X-ray (EDAX), and Atomic Force microscopy (AFM). Key findings indicate that the microsensor successfully detects histamine concentrations across a broad dynamic range of 10 to 1000 nM, with a lower limit of quantification set at 10 nM. Validation of the sensor's performance was conducted using electrochemical tools such as cyclic voltammetry and square wave voltammetry, confirming its efficacy for real-time histamine monitoring in food products and biological environments. Additionally, the study underscores the sensor's excellent selectivity, long-term stability, and lightning-fast responsiveness, positioning it as a highly promising tool to enhance food safety and quality assurance.

Fully Integrated Recognition and Enrichment Electrospray Ionization Source for High-Sensitivity Mass Spectrometry Determination of Bioamine

The development of a highly specific recognition electrospray ionization source presents a major challenge for achieving rapid ambient mass spectrometry (AMS) detection of trace harmful substances in complex samples. In this study, we constructed a molecular imprinting nanofiber electrospinning membrane-coated steel substrate (MINMCS) based on the electrospinning strategy. This was designed as a highly specific recognition and enrichment electrospray ionization source module for AMS, where the molecular imprinting nanofiber membrane served as an excellent extraction and enrichment layer. The prepared ionization source demonstrated a sufficient loading capacity for three bioamines (BAs): histamine (HIS), tyramine (TYR), and tryptamine (TRY). With simplified sample pretreatment, this ionization source exhibited sensitivity comparable to that of high performance liquid chromatography-mass spectrometry (HPLC-MS/MS). Moreover, the entire analysis process could be completed within 1 min with acceptable recoveries (83.21-101.80%). In brief, this study introduces a new integrated recognition and enrichment electrospray ionization source for the detection of harmful substances such as bioamines, showcasing significant commercial potential for the rapid detection of foodborne harmful compounds.

Invited review: Current perspectives for analyzing the dairy biofilms by integrated multiomics

Biofilms formed by pathogenic or spoilage microorganisms have become serious issues in the dairy industry, as this mode of life renders such microorganisms highly resistant to cleaning-in-place (CIP) procedures, disinfectants, desiccation, and other control strategies. The advent of omics techniques, especially the integration of different omics tools, has greatly improved our understanding of the features of microbial biofilms, and provided in-depth knowledge on developing effective methods that are directly against deleterious biofilms. This review provides novel insights into the single use of each omics tool and the application of multiomics tools to unravel the mechanisms of biofilm formation, specific molecular phenotypes exhibited by biofilms, and biofilm control strategies. Challenges and future perspective on the integration of omics tools for biofilm studies are also addressed.

Specific Gene Expression in Pseudomonas Putida U Shows New Alternatives for Cadaverine and Putrescine Catabolism

Pseudomonas putida strain U can be grown using, as sole carbon sources, the biogenic amines putrescine or cadaverine, as well as their catabolic intermediates, ɣ-aminobutyrate or δ-aminovalerate, respectively. Several paralogs for the genes that encode some of the activities involved in the catabolism of these compounds, such as a putrescine-pyruvate aminotransferase (spuC1 and spuC2 genes) and a ɣ-aminobutyrate aminotransferase (gabT1 and gabT2 genes) have been identified in this bacterium. When the expression pattern of these genes is analyzed by qPCR, it is drastically conditioned by supplying the carbon sources. Thus, spuC1 is upregulated by putrescine, whereas spuC2 seems to be exclusively induced by cadaverine. However, gabT1 increases its expression in response to different polyamines or aminated catabolic derivatives from them (i.e., ɣ-aminobutyrate or δ-aminovalerate), although gabT2 does not change its expression level concerning no-amine unrelated carbon sources (citrate). These results reveal differences between the mechanisms proposed for polyamine catabolism in P. aeruginosa and Escherichia coli concerning P. putida strain U, as well as allow a deeper understanding of the enzymatic systems used by this last strain during polyamine metabolism.

Gut microbiota and anti-aging: Focusing on spermidine

The human gut microbiota plays numerous roles in regulating host growth, the immune system, and metabolism. Age-related changes in the gut environment lead to chronic inflammation, metabolic dysfunction, and illness, which in turn affect aging and increase the risk of neurodegenerative disorders. Local immunity is also affected by changes in the gut environment. Polyamines are crucial for cell development, proliferation, and tissue regeneration. They regulate enzyme activity, bind to and stabilize DNA and RNA, have antioxidative properties, and are necessary for the control of translation. All living organisms contain the natural polyamine spermidine, which has anti-inflammatory and antioxidant properties. It can regulate protein expression, prolong life, and improve mitochondrial metabolic activity and respiration. Spermidine levels experience an age-related decrease, and the development of age-related diseases is correlated with decreased endogenous spermidine concentrations. As more than just a consequence, this review explores the connection between polyamine metabolism and aging and identifies advantageous bacteria for anti-aging and metabolites they produce. Further research is being conducted on probiotics and prebiotics that support the uptake and ingestion of spermidine from food extracts or stimulate the production of polyamines by gut microbiota. This provides a successful strategy to increase spermidine levels.

Combination of SPE and fluorescent detection of AQC-derivatives for the determination at sub-mg/L levels of biogenic amines in dairy products

Biogenic amines (BAs) are compounds generated by decarboxylation of their amino acid precursors. Their intake, even at low concentrations, can lead to several types of health problems in sensitive individuals. As they can be easily formed in fermented dairy products, their quantitative determination is very relevant. In the present paper, a method for the quantitative determination of four biogenic amines in different dairy products has been developed, validated and applied to 37 samples of milk, 23 of yogurt, and 14 of kefir. Amines were selectively extracted using solid phase extraction, subsequently derivatizatized with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate and further determined by High Performance Liquid Chromatography with fluorescence detection. The method's sensitivity was highly satisfactory, with limits of detection lower than 0.2 mg/L. Optimal linearity and repeatability were also achieved. BAs were not detected in most of the milk samples, but they were found frequently at high levels in yogurt and kefir samples, reaching values of up to 79 mg/kg total BAs in kefir samples. Levels measured should not be a cause for concern for the population at large, but should be known by BAs-sensitive individuals.

The Selection of the Best Derivatization Reagents for the Determination of Polyamines in Home-Made Wine Samples

The procedures of putrescine, spermine, spermidine, and cadaverine derivatization using 2-chloro-1,3-dinitro-5-(trifluoromethyl)benzene, 1-fluoro-2-nitro-4-(trifluoromethyl) benzene, and 3,5-bis-(trifluoromethyl)phenyl isothiocyanate for chromatographic determination in home-made wine samples are compared in the present study. The procedures discussed were compared regarding simplicity, linearity, precision, and accuracy. The polyamines derivatives were isolated and characterized by X-ray crystallography and ¹H, ¹³C, and ¹⁹F NMR spectroscopy. The obtained structures of aliphatic amines showed that all amino groups, four in spermine, two in putrescine and cadaverine, and three in spermidine, regardless of the applied reagent, were substituted. The applicability of the described procedures was tested during the chromatographic analysis of the compounds' content in home-made wines. For this purpose, a simple and environmentally friendly sample preparation procedure was developed. The obtained results present the derivatization of polyamines with 1-fluoro-2-nitro-4-(trifluoromethyl)benzene as a better choice for the determination of these compounds in food samples.

A Review on Bio- and Chemosensors for the Detection of Biogenic Amines in Food Safety Applications: The Status in 2022

This article provides an overview on the broad topic of biogenic amines (BAs) that are a persistent concern in the context of food quality and safety. They emerge mainly from the decomposition of amino acids in protein-rich food due to enzymes excreted by pathogenic bacteria that infect food under inappropriate storage conditions. While there are food authority regulations on the maximum allowed amounts of, e.g., histamine in fish, sensitive individuals can still suffer from medical conditions triggered by biogenic amines, and mass outbreaks of scombroid poisoning are reported regularly. We review first the classical techniques used for selective BA detection and quantification in analytical laboratories and focus then on sensor-based solutions aiming at on-site BA detection throughout the food chain. There are receptor-free chemosensors for BA detection and a vastly growing range of bio- and biomimetic sensors that employ receptors to enable selective molecular recognition. Regarding the receptors, we address enzymes, antibodies, molecularly imprinted polymers (MIPs), and aptamers as the most recent class of BA receptors. Furthermore, we address the underlying transducer technologies, including optical, electrochemical, mass-sensitive, and thermal-based sensing principles. The review concludes with an assessment on the persistent limitations of BA sensors, a technological forecast, and thoughts on short-term solutions.