Optical sensors for determination of biogenic amines in food

A colorimetric and NIR fluorescent probe for ultrafast detecting bisulfite and organic amines and its applications in food, imaging, and monitoring fish freshness

Herein, for the first time, we have successfully constructed a novel near-infrared (NIR) emission fluorescent probe Dpyt for ultrafast detecting (within 5 s) bisulfate and organic amines based on a 1,2-dihydrocyclopenta[b]chromene-barbiturate conjugation system. Upon addition of bisulfate or organic amines, Dpyt displayed a distinct color change from blue to colorless or from purple to blue, respectively, suggesting that the Dpyt can be used to detect two analytes by the naked eye. Based on quantum chemistry calculations, the fluorescence quenching of Dpyt after the addition of HSO3- is caused by the photoinduced electron transfer (PET) process of the adduct Dpyt-HSO3-. The fluorescence enhancement of Dpyt caused by most organic amines is due to the enhanced intramolecular charge transfer (ICT) process of deprotonated Dpyt. Notably, Dpyt can be applied for detecting HSO3- in actual food samples such as red wine and sugar, as well as for imaging of HSO3- and representative propylamine in living cells. And more importantly, indicator labels constructed by filter paper loaded with Dpyt can visually monitor the freshness of salmon in real-time by daylight and fluorescence dual-mode. The comparison with national standard method of China manifests that indicator labels are a valid tool to assess the freshness of seafood.

Isomeric Benzenediol-Linked Organophosphonates as a Handy Reusable Emitting Platform: Diversity in Polyamine Vapor Detection

This work introduces metal/column-free facile quantitative access to conformationally twisted catechol-linked organophosphonate (CAP) as a blue-emitting solid that could reversibly detect only 1,3-diaminopropane (DAP) and 1,2-ethylenediamine (EDA) vapors, belonging to industrially and pharmaceutically abundant crucial diamines. In CAP, two adjacent hydroxy groups in a benzene ring facilitate selective diamine-dihydroxy (amine-phenol type) interactions in the solid phase, leading to a quenched emission with selectively smaller aliphatic PAs, that is, DAP and EDA. The disparity was noticed with an isomeric resorcinol-linked emitter (RAP), detecting various polyamine vapors with superior sensitivity. A one-carbon-away placed hydroxy group in RAP can only generate a monoamine-hydroxy complex, not diamine-dihydroxy. The more acidic nature of resorcinol would prefer ionizing the amines and, consequently, creating amine/hydroxy interactions. More systematic investigations reveal an exciting role of amine-hydroxy realization for the catechol analog in the solid phase with a syn-anti conformation for CAP. Unlike CAP, RAP's available crystal void space creates considerable room in which to come closer and facilitates amine-phenol interactions. The role of phosphonates in the selective detection of PAs is also examined. Observed outcomes are substantiated by FT-IR, single-crystal X-ray diffraction, SEM, XPS, and mass spectroscopic studies. The proposed amine-hydroxy interactions are further supported by DFT-optimized molecular structures.

The highly selective rhodol-based putrescine probe and visual sensors for on-site detection of putrescine in food spoilage

Putrescine (Butane-1,4-diamine) has been regarded as a vital marker of spoiling protein-rich foods, especially meat and seafood. The detection of putrescine in food is considered a convenient and powerful method for evaluating the degree of spoilage of protein-rich foods. Herein, a novel rhodol-based fluorescent probe RSMA (formyl-rhodol Schiff base with methoxyaniline) was developed to detect putrescine. RSMA exhibited excellent linearity (R2 = 0.9912) in the concentration range of 0-45 μM of putrescine with a detection limit as low as 0.45 μM. Although RSMA had moderate responses to some aliphatic diamines, the selectivity of RSMA for putrescine was one of the best reported in the literature so far. Moreover, RSMA was successfully fabricated to solid-state sensors for on-site detection of putrescine in shrimp, that demonstrated its application in monitoring food spoilage.

Facile Synthesis of PEGylated Gold Nanoparticles for Enhanced Colorimetric Detection of Histamine

Histamine is among the biogenic amines that are formed during the microbial decarboxylation of amino acids in various food products, posing a significant threat to both food safety and human health. Herein, we present a one-step synthesis of PEGylated gold nanoparticles (PEG-AuNPs) for rapid, simple, and cost-effective colorimetric histamine detection. PEG-AuNPs' surface plasmon resonance (SPR) range at 520-530 nm with a hydrodynamic size distribution of 20-40 nm. Fourier transform infrared (FT-IR) spectra confirmed the reduction of AuNPs at 1645 cm-1 along with the other observed peaks at 2870, 1350, and 1100 cm-1 as a strong evidence for the presence of PEG. Upon the addition of histamine to the PEG-AuNP solution, transmission electron microscopy (TEM) highlighted the aggregation of nanoparticles. In addition, red shifting and a decrease in the absorbance of the SPR peak along with the appearance of an additional peak at ∼690 nm was observed in the PEG-AuNP absorption spectra in the presence of histamine. Increasing the PEG concentration in the gold colloids leads to the formation of a protective barrier around the surface of nanoparticles, which influences the colloidal stability by impeding the aggregation of PEG-AuNPs upon histamine addition. The minimum colorimetric response of PEG-AuNPs to histamine concentration is 30 ppm, as assessed by the naked eye. The absorption ratio (A690/A526) showed a linear dynamic range from 20 to 100 ppm with a limit of detection of 9.357 μM. Additionally, the assay demonstrates a commendable selectivity toward histamine analyte.

Recent advancements in chemosensors for the detection of food spoilage

The need for reliable sensors has become a major requirement to confirm the quality and safety of food commodities. Chemosensors are promising sensing tools to identify contaminants and food spoilage to ensure food safety. Chemosensing materials are evolving and becoming potential mechanisms to enable onsite and real-time monitoring of food safety. This review summarizes the information about the basic four types of chemosensors (colorimetric, optical, electrochemical, and piezoelectric) employed in the food sector, the latest advancements in the development of chemo-sensing mechanisms, and their food applications, with special emphasis on the future outlook of them. In this review, we discuss the novel chemosensors developed from the year 2018 to 2022 to detect spoilage in some common types of food like fish, meat, milk, cheese and soy sauce. This work will provide a fundamental step toward further development and innovations of chemosensors targeting different arenas in the food industry.

Optical dِِِِiscrimination of histamine and ethylenediamine in meat samples using a colorimetric affordable test strip (CATS): introducing a novel lab-on paper sensing strategy for low-cost ensuring food safety by rapid and accurate monitoring of biogenic amines

Biogenic amines (BAs) are a group of organic compounds that are produced through the decarboxylation of amino acids by microorganisms. These compounds are commonly found in a variety of foods and are known to cause adverse health effects if consumed in high concentrations. Therefore, the development of sensitive and rapid detection methods for detection and determination of BAs is essential for ensuring food safety. In this study, a novel colorimetric affordable test strip (CATS) was developed for the colorimetric and naked-eye detection of two BAs of ethylenediamine (EDA) and histamine (HIS) in meat samples. Also, triangular silver nanoparticles (AgNPrs) were used as a diagnostic optical probe, and CATS used as a simple, environmentally friendly, inexpensive diagnostic substrate for on-site recognition of meat spoil. The AgNPrs-based optosensor demonstrated high sensitivity and selectivity towards EDA and HIS, allowing for the detection of low concentrations of the BAs in real food samples such as raw chicken and beef. The system presented a UV-vis technique for HIS and EDA analysis in the linear range of 0.1 μM to 0.01 mM, with an LLOQ of 0.1 μM, and 0.05 to 1 μM, with an LLOQ of 0.05 μM, respectively. Additionally, the performance of the designed CATS in the analysis of produced gases was evaluated, highlighting the potential of this simple and cost-effective strategy for the development of BAs diagnostic kits. This approach provides a simple and cost-effective method for detecting BAs in food, which could be beneficial for ensuring food safety and preventing the harmful effects associated with their consumption.

Concentration-tuned diverse response to selective biogenic amines using a reusable fluorophore: monitoring protein-rich food spoilage

Maintaining the freshness of food is essential for a healthy and quality life. Nevertheless, it remains a global challenge. Hence, an easy detection and monitoring protocol would be highly desirable. A cyanoacrylic acid (CAA)-based fluorophore is manifested as a reusable platform that responds diversely against different concentrations of selective aliphatic biogenic amines (BAs) in both solution and vapor phases. Slow spoilage of the protein-rich food is progressively monitored through emission shifts visible to the naked eye. This fluorophore provides easy and naked-eye detection of the BA vapor through a change in emission, i.e., red → orange → orange-yellow → cyan → green and quantum yield enhancement, which occur in stepwise increments of vapor concentrations. The probe design includes π-conjugated functionalized fluorescent molecules linked to multiple twisting sites, resulting in both solid and solution-state emission. The attached carboxylic acid responds quickly with selective BAs, mainly putrescine (PUT), cadaverine (CAD), and spermidine (SPM), where the concentration-based emission variation has appeared to be distinct and prominent against PUT [sensitivity (μM): 2 (solution); 3.3 (vapour)]. The selectivity towards diamine can be clarified by the formation of carboxylic acid salts and the consequent proton exchanges between free and protonated amines. In addition, -CN···H interaction is likely to develop within this ammonium carboxylate system, providing extra stability. Such ammonium carboxylate salt formation and gradual change in the molecular arrangement, resulting in symmetry development, are validated by FT-IR and wide-angle X-ray diffraction studies. Besides, this fact is supported by DFT studies that validate intramolecular H-atom exchange between free amine and ammonium salt units. A fluorophore-coated coverslip, filter paper, or silica gel-coated Al-plate is fruitfully utilized to detect the freshness of fish and chicken, which reveals the potential of this probe to prevent food waste and control food safety.

Biosensors for Odor Detection: A Review

Animals can easily detect hundreds of thousands of odors in the environment with high sensitivity and selectivity. With the progress of biological olfactory research, scientists have extracted multiple biomaterials and integrated them with different transducers thus generating numerous biosensors. Those biosensors inherit the sensing ability of living organisms and present excellent detection performance. In this paper, we mainly introduce odor biosensors based on substances from animal olfactory systems. Several instances of organ/tissue-based, cell-based, and protein-based biosensors are described and compared. Furthermore, we list some other biological materials such as peptide, nanovesicle, enzyme, and aptamer that are also utilized in odor biosensors. In addition, we illustrate the further developments of odor biosensors.

Meldrum's Acid Furfural Conjugate MAFC: A New Entry as Chromogenic Sensor for Specific Amine Identification

Bioactive amines are highly relevant for clinical and industrial application to ensure the metabolic status of a biological process. Apart from this, generally, amine identification is a key step in various bioorganic processes ranging from protein chemistry to biomaterial fabrication. However, many amines have a negative impact on the environment and the excess intake of amines can have tremendous adverse health effects. Thus, easy, fast, sensitive, and reliable sensing methods for amine identification are strongly searched for. In the past few years, Meldrum's acid furfural conjugate (MAFC) has been extensively explored as a starting material for the synthesis of photoswitchable donor-acceptor Stenhouse adducts (DASA). DASA formation hereby results from the rapid reaction of MAFC with primary and secondary amines, which has so far been demonstrated through numerous publications for different applications. The linear form of the MAFC-based DASA exhibits intense pink coloration due to its linear conjugated triene-2-ol conformation, which has inspired researchers to use this easy synthesizable molecule as an optical sensor for primary, secondary, and biogenic amines. Due to its new entry into amine identification, a collection of the literature exclusively on MAFC is demanded. In this mini review, we intend to present the state-of-the-art of MAFC as an optical molecular sensor in hopes to motivate researchers to find even more applications of MAFC-based sensors and methods that pave the way to their usage in medicinal applications.

Biogenic Amine Content Analysis of Three Chicken-Based Dry Pet Food Formulations

The pet food market is constantly expanding, and more and more attention is paid to the feeding of pets. Dry foods stand out and are often preferred due to their long shelf life, ease of administration, and low cost. In this context, dry foods are formulated from fresh meats, meat meals, or a mix of the two. These raw materials are often meat not fit for human consumption; they might be subject to contamination and proliferation of microorganisms which, by degrading the organic component, can lead to the formation of undesirable by-products such as biogenic amines. These nitrogenous compounds obtained by decarboxylation of amino acids can therefore be found in high-protein foods, and their ingestion in large quantities can cause intoxication and be harmful. This study aims at analyzing the possible presence of biogenic amines in three different formulations of chicken-based kibbles for pets: one obtained from fresh meat, one from meat meal, and one from a mix of the two. This study is also focused on the presence of free amino acids as they represent the key substrate for decarboxylating enzymes. Mass spectrometry (Q-TOF LC/MS) was used to analyze the presence of biogenic amines and free amino acids. The results show that fresh-meat-based products have a lower content of biogenic amines, and at the same time a higher quantity of free amino acids; on the contrary, meat-meal- and mix-based products have a greater quantity of biogenic amines and a lower concentration of free amino acids, suggesting that there has been a higher microbial proliferation as proved by the total aerobic mesophilic bacteria counts. It is therefore clear that fresh-meat-based kibbles are to be preferred when they are used for preparing dry pet food due to the lowest concentration of biogenic amines.

Fabrication of an Ag-based SERS nanotag for histamine quantitative detection

A crucial issue in analytical science and physiology is the detection of histamine with high sensitivity, specificity and credibility, which served as an important neurotransmitter in biofluids. Despite the high sensitivity of surface-enhanced Raman spectroscopy (SERS) at the level of single molecule, there are still challenges in providing high sensitivity for histamine with a small cross section. For the selective detection of histamine using SERS, a highly sensitive sandwich structure substrate combining Fe₃O₄ and an Ag-based SERS nanotag was developed. The Fe₃O₄@SiO₂-COOH served as a capture component for enriching histamine. Upon functionalized Ag nanoparticles with glycine (Gly) and (3-Aminopheyonyl) boronic acid (APBA), they were then used to connect with histamine and serve as a SERS nanotag, respectively. A linear relationship between the Raman intensity and the histamine concentration was observed over the range 10^-4-10^-8 M with a limit of detection of 7.24 × 10^-9 M. This methodology also exhibited good selectivity in the presence of other neurotransmitters. With our new approach, histamine can be detected sensitively and reliably in fish samples, which indicates the potential prospect of an effective method for analyzing histamine in complex specimens.

Concentration-Guided Visual Detection of Multiphase Aliphatic Biogenic Amines through Amine-Phenol Recognition Using a Dual-State Emitter

Intermolecular amine-phenol interactions are largely recognized as unique models with diverse supramolecular interactions. However, fluorescence (FL) variations originating from such interactions are rare. Herein, FL changes are well realized from amine-phenol interactions to identify an important biomarker, biogenic amines (BAs). A simple, inexpensive, and thermally stable anthracenylphosphonate is linked with 2,2'-biphenol to design a functional dual-state emitter. Among the various amines tested, this emitter displays superior sensitivity with the lowest possible limit of detection as 5.8-9.7 ppb with aliphatic polyamines such as 1,3-, 1,4-, 1,5-, and 1,6- diamines and spermidine in the solution phase. Fast, on-spot detection of the BA vapors was visually conducted through a notable high-contrast change from blue to yellow emission in the solid state. FT-IR, ¹H/³¹P NMR, and mass spectroscopic studies identify the ground-state amine-phenol interactions. The failure in BA detection with the 2,2'-dimethoxy-biphenyl-linked analog verifies the role of amine-phenol interactions. Mechanistic studies determine amine-phenol interactions in the ground and excited states. The molecular structure and packing of the doubly twisted probe are documented with a substantial void space facilitating close contact of the BAs with the strong amine-phenol interactions desired for efficient detection. Finally, this probe governs the freshness of a piece of Catla catla fish and prawn. Further, a remarkable concentration-controlled diverse emission with a red shift difference of 141 nm is detected with 1,3-diaminopropane (1,3-DAP) vapor (from 29 to 319 mg/L) for the first time. Thus, a cost-effective device is developed to detect 1,3-DAP at a precise concentration, visible through the naked eye.

Portable colorimetric enzymatic disposable biosensor for histamine and simultaneous histamine/tyramine determination using a smartphone

Tyramine oxidase (TAO), peroxidase (HRP), and Amplex Red (AR) have been immobilized on cellulose to obtain disposable biosensors for the determination of histamine. During the enzymatic reaction, AR is oxidized and a pink spot is obtained. Using a smartphone and measuring the G (green) color coordinate, histamine can be determined in the presence of other biogenic amines (putrescine and cadaverine) in concentrations ranging from 2·10^-5 M to 5·10^-4 M with a 7.5·10^-6 M limit of detection (LoD). Despite tyramine interference, experimental conditions are provided which allow rapid and simple histamine and simultaneous histamine/tyramine (semi)quantitative determination in mixtures. Finally, tyramine and histamine were determined in a tuna extract with good results (compared to the reference HPLC-MS method). The methodology can also be applied in solution allowing histamine (and simultaneous histamine/tyramine) determination with a lower LoD (1.8·10^-7 M) and a similar selectivity.

Colorimetric Paper Sensor for Food Spoilage Based on Biogenic Amine Monitoring

Biogenic amines (BAs), nitrogenous molecules usually present in different foods, can be considered an indicator of freshness and food quality since their amount increases during food spoilage. Their detection, possibly in real time via the use of smart packaging, is therefore of crucial importance to ensure food safety and to fulfill consumers' demand. To this end, colorimetric sensors are considered one of the most feasible solutions. Here, we report a user-friendly colorimetric sensing paper able to detect BAs via the naked eye. The sensing molecule is the aglycone genipin, a natural cross-linking agent extracted from gardenia fruit, able to bind BAs producing water-soluble blue pigments. The paper sensor was applied to chicken meat quality monitoring and a quantitative analysis was performed with image acquisition via a smartphone camera, achieving a limit of detection equivalent to 0.1 mM of putrescine. The suitability of the BA sensing paper was assessed by integrating the sensor into smart packaging and analyzing commercial chicken meat samples stored at different temperatures; the results of the sensor paralleled the "best before date" indicated on the label, confirming the potential applicability of the sensor as a smart label.

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.

Progress in Plasmonic Sensors as Monitoring Tools for Aquaculture Quality Control

Aquaculture is an expanding economic sector that nourishes the world's growing population due to its nutritional significance over the years as a source of high-quality proteins. However, it has faced severe challenges due to significant cases of environmental pollution, pathogen outbreaks, and the lack of traceability that guarantees the quality assurance of its products. Such context has prompted many researchers to work on the development of novel, affordable, and reliable technologies, many based on nanophotonic sensing methodologies. These emerging technologies, such as surface plasmon resonance (SPR), localised SPR (LSPR), and fibre-optic SPR (FO-SPR) systems, overcome many of the drawbacks of conventional analytical tools in terms of portability, reagent and solvent use, and the simplicity of sample pre-treatments, which would benefit a more sustainable and profitable aquaculture. To highlight the current progress made in these technologies that would allow them to be transferred for implementation in the field, along with the lag with respect to the most cutting-edge plasmonic sensing, this review provides a variety of information on recent advances in these emerging methodologies that can be used to comprehensively monitor the various operations involving the different commercial stages of farmed aquaculture. For example, to detect environmental hazards, track fish health through biochemical indicators, and monitor disease and biosecurity of fish meat products. Furthermore, it highlights the critical issues associated with these technologies, how to integrate them into farming facilities, and the challenges and prospects of developing plasmonic-based sensors for aquaculture.

Critical review of polymer and hydrogel deposition methods for optical and electrochemical bioanalytical sensors correlated to the sensor's applicability in real samples

Sensors, ranging from in vivo through to single-use systems, employ protective membranes or hydrogels to enhance sample collection or serve as filters, to immobilize or entrap probes or receptors, or to stabilize and enhance a sensor's lifetime. Furthermore, many applications demand specific requirements such as biocompatibility and non-fouling properties for in vivo applications, or fast and inexpensive mass production capabilities for single-use sensors. We critically evaluated how membrane materials and their deposition methods impact optical and electrochemical systems with special focus on analytical figures of merit and potential toward large-scale production. With some chosen examples, we highlight the fact that often a sensor's performance relies heavily on the deposition method, even though other methods or materials could in fact improve the sensor. Over the course of the last 5 years, most sensing applications within healthcare diagnostics included glucose, lactate, uric acid, O₂, H⁺ ions, and many specific metabolites and markers. In the case of food safety and environmental monitoring, the choice of analytes was much more comprehensive regarding a variety of natural and synthetic toxicants like bacteria, pesticides, or pollutants and other relevant substances. We conclude that more attention must be paid toward deposition techniques as these may in the end become a major hurdle in a sensor's likelihood of moving from an academic lab into a real-world product.

Biogenic Amine Sensing Based on Rosamine a N-Methylpyridinium Derivative Supported on Silica Materials from Rice Husk

In this work new rosamine-silica composites were prepared and their sensing ability towards different amines was assessed. Rice husk wastes were used as a biogenic silica source. Silica was extracted by thermal treatment, before rice husk ash and after acid leaching with citric acid-treated rice husk ash. Mesoporous material (SBA-15) was also prepared using the extracted silica. The prepared materials were characterized by several techniques such as FTIR, XRD, SEM and N₂ adsorption. The materials were then used as adsorbents of the chromophore N-methylpyridinium rosamine (Ros4PyMe). The obtained loaded composites were tested in solution for amines sensing (n-butylamine, aniline, putrescine and cadaverine). The detection studies were analyzed by fluorescence and revealed 40% and 48% quenching in fluorescence intensity for the composite Ros4PyMe@SBA in the presence of the biogenic amines cadaverine and putrescine, respectively. The composite was also sensitive in the powder form, changing the color from violet to pale pink in the presence of putrescine vapors with a fast response (around 2 min), the process being reversible by exposure to air.

Real-Time Measurement of Refractive Index Using 3D-Printed Optofluidic Fiber Sensor

This work describes a 3D-printed optofluidic fiber sensor to measure refractive index in real time, combining a microfluidic system with an optical fiber extrinsic Fabry-Perot interferometer. The microfluidic chip platform was developed for this purpose through 3D printing. The Fabry-Perot cavity was incorporated in the microfluidic chip perpendicularly to the sample flow, which was of approximately 3.7 µL/s. The optofluidic fiber sensor platform coupled with a low-cost optical power meter detector was characterized using different concentrations of glucose solutions. In the linear regression analysis, the optical power shift was correlated with the refractive index and a sensitivity of -86.6 dB/RIU (r² = 0.996) was obtained. Good results were obtained in terms of stability with a maximum standard deviation of 0.03 dB and a sensor resolution of 5.2 × 10^-4 RIU. The feasibility of the optofluidic fiber sensor for dynamic analyses of refractive index with low sample usage was confirmed through real-time measurements.

Systematic bio-fabrication of aptamers and their applications in engineering biology

Aptamers are single-stranded DNA or RNA molecules that have high affinity and selectivity to bind to specific targets. Compared to antibodies, aptamers are easy to in vitro synthesize with low cost, and exhibit excellent thermal stability and programmability. With these features, aptamers have been widely used in biology and medicine-related fields. In the meantime, a variety of systematic evolution of ligands by exponential enrichment (SELEX) technologies have been developed to screen aptamers for various targets. According to the characteristics of targets, customizing appropriate SELEX technology and post-SELEX optimization helps to obtain ideal aptamers with high affinity and specificity. In this review, we first summarize the latest research on the systematic bio-fabrication of aptamers, including various SELEX technologies, post-SELEX optimization, and aptamer modification technology. These procedures not only help to gain the aptamer sequences but also provide insights into the relationship between structure and function of the aptamers. The latter provides a new perspective for the systems bio-fabrication of aptamers. Furthermore, on this basis, we review the applications of aptamers, particularly in the fields of engineering biology, including industrial biotechnology, medical and health engineering, and environmental and food safety monitoring. And the encountered challenges and prospects are discussed, providing an outlook for the future development of aptamers.

Recent Progress in Amine Gas Sensors for Food Quality Monitoring: Novel Architectures for Sensing Materials and Systems

The increasing demand for food production has necessitated the development of sensitive and reliable methods of analysis, which allow for the optimization of storage and distribution while ensuring food safety. Methods to quantify and monitor volatile and biogenic amines are key to minimizing the waste of high-protein foods and to enable the safe consumption of fresh products. Novel materials and device designs have allowed the development of portable and reliable sensors that make use of different transduction methods for amine detection and food quality monitoring. Herein, we review the past decade's advances in volatile amine sensors for food quality monitoring. First, the role of volatile and biogenic amines as a food-quality index is presented. Moreover, a comprehensive overview of the distinct amine gas sensors is provided according to the transduction method, operation strategies, and distinct materials (e.g., metal oxide semiconductors, conjugated polymers, carbon nanotubes, graphene and its derivatives, transition metal dichalcogenides, metal organic frameworks, MXenes, quantum dots, and dyes, among others) employed in each case. These include chemoresistive, fluorometric, colorimetric, and microgravimetric sensors. Emphasis is also given to sensor arrays that record the food quality fingerprints and wireless devices that operate as radiofrequency identification (RFID) tags. Finally, challenges and future opportunities on the development of new amine sensors are presented aiming to encourage further research and technological development of reliable, integrated, and remotely accessible devices for food-quality monitoring.

Biogenic Amines in Poultry Meat and Poultry Products: Formation, Appearance, and Methods of Reduction

Simple Summary

Meat consumption is on the rise, including poultry meat. With the storage of meat and the progressing process of food spoilage, the content of biogenic amines increases. Methods to prevent the formation of amines include: starter cultures, packaging methods, high hydrostatic pressure (HHP), ozonisation, radiation, use of essential oils, phytobiotics, and organic acids in food. The aim of this study was to compare the content of biogenic amines in poultry meat on the basis of the latest scientific reports and to present methods for preventing the formation of biogenic amines.The use of herbal extracts can not only reduce the occurrence of biogenic amines, but also improve production results and meat quality.

Abstract

Poultry meat is a source of many important nutrients, micro- and macro-elements, and biologically active substances. During meat storage, many physicochemical changes take place, also affecting the content of biologically active substances, including biogenic amines.They are formed as a result of three processes: decarboxylation of amino acids by microorganisms, reductive amination, and transamination of aldehydes and ketones, and as a result of activity of body tissues. Excessive consumption of biogenic amines shows toxic properties. The increasing consumption of poultry meat and the lack of established limits for biogenic amine content is a major challenge for scientists, producers, and consumer organisations, which have not yet established limits for biogenic amine content in meat (including poultry meat). Analyses of biogenic amine content in meat account for less than 10% of scientific papers, which raises the scope of the problem of limiting biogenic amines in meat. Among the methods of amine reduction are methods of destroying or reducing microorganisms’ high hydrostatic pressure (HHP), ozonisation, radiation, or the use of essential oils.

IoT-Based Fumigation for Insect Repellent in Food Storages: Breaking the Trade-Off between Efficiency and Safety

Insect infestation in food can cause various health risks when ingested by humans, as well as damage to food itself. To tackle this, food safety can be secured by fumigating the food storage, using specific materials containing pesticides. However, because most fumigation is toxic to human health, there is a trade-off relationship between insect repellency and safety assurance. In this paper, to overcome this problem, first, organic fumigation is proposed, in which a relatively low-risk pyrethrin oil is developed. Second, a novel system which can remotely monitor and control fumigation using IoT is proposed for mitigating the fact that pyrethrin can also be dangerous when inhaled directly. Third, an insect repellent LED lamp system, which can replace insecticide through direct fumigation and ensure safety, has been proposed. Fourth, a camera-based human access detection system is developed for more efficient and safe controls during the fumigation. The performance of the proposed system has been verified through implemented test-bed, and it is revealed that the trade-off relationship between efficiency and safety can be overcome.

A pyrylium salt-based fluorescent probe for the highly sensitive detection of methylamine vapour

The MTPY exhibits an obvious fluorescence response from yellow to cyan when reacted with CH3NH2 with a low detection limit (2.6 ppt, 8.4 × 10−8 M). The sensing mechanism was traced by mass spectrometry.

Development of a novel chromophore reaction-based fluorescent probe for biogenic amines detection

Biogenic amines (BAs) are important biomarkers to monitor meat spoilage. However, the design of efficient BA fluorescent probes with distinct colorimetric and ratiometric fluorescent dual-channels is still a critical challenge because of similar chemical properties and basicity between BAs and other amines. Herein, pyrrolopyrrole cyanine (PPCy-1) is reported to display distinctly high reactivity toward BAs through an ultrasensitive irreversible chromophore reaction for the first time. The reaction mechanism is ascribed to synergistic aza-Michael addition and B-N detachment, followed by hydrolysis to produce low-conjugated diketopyrrolopyrrole and heteroaromatic acetonitrile compounds. As a result, colorimetric and ratiometric fluorescent dual-channel (Δλ_ab = 188 nm and Δλ_em = 151 nm) signals and a limit of detection up to 62.1 nM level for BA solution are acquired. In addition, the colorimetric detection of volatile amine vapor using the PPCy-1-loaded filter paper, showing a color change from green to yellow, is feasible. A simple and cost-effective fluorescence "turn on" method using the filter paper or the CAD-40 resin loaded with PPCy-1 to detect TVB (total volatile bases) originating from shrimp spoilage is further demonstrated.

Synthesis of Catechol Derived Rosamine Dyes and Their Reactivity toward Biogenic Amines

Functional organic dyes play a key role in many fields, namely in biotechnology and medical diagnosis. Herein, we report two novel 2,3- and 3,4-dihydroxyphenyl substituted rosamines (3 and 4, respectively) that were successfully synthesized through a microwave-assisted protocol. The best reaction yields were obtained for rosamine 4, which also showed the most interesting photophysical properties, specially toward biogenic amines (BAs). Several amines including n- and t-butylamine, cadaverine, and putrescine cause spectral changes of 4, in UV–Vis and fluorescence spectra, which are indicative of their potential application as an effective tool to detect amines in acetonitrile solutions. In the gas phase, the probe response is more expressive for spermine and putrescine. Additionally, we found that methanolic solutions of rosamine 4 and n-butylamine undergo a pink to yellow color change over time, which has been attributed to the formation of a new compound. The latter was isolated and identified as 5 (9−aminopyronin), whose solutions exhibit a remarkable increase in fluorescence intensity together with a shift toward more energetic wavelengths. Other 9-aminopyronins 6a, 6b, 7a, and 7b were obtained from methanolic solutions of 4 with putrescine and cadaverine, demonstrating the potential of this new xanthene entity to react with primary amines.

Highly selective and sensitive colorimetric/fluorometric dual mode detection of relevant biogenic amines

Biogenic amines are involved in physiological roles in living organisms, but their excessive production or intake can induce undesired toxicological effects. As biogenic amines can be found in the process of food spoilage, they are considered an indicator of food quality and freshness, and their detection is of crucial importance in food safety. In this contribution, we report the fast and direct colorimetric and fluorometric sensing of biogenic amines by means of a dinuclear Zn(ii) Schiff-base complex. The selective and sensitive detection involves the formation of stable adducts between the dinuclear complex, acting as the Lewis acidic molecular tweezer, and biogenic di- or polyamines. The selectivity towards biogenic amines, even in the presence of common aliphatic, primary, secondary, or tertiary monoamines, heterocyclic amines, and amino acids, is demonstrated by competitive experiments. The quantitation of histamine in a fish matrix is easily achieved using a standard extraction procedure followed by simple colorimetric or fluorometric measurements.

Biogenic amines levels in food processing: Efforts for their control in foodstuffs

Fermented and/or protein-rich foods, the most widely consumed worldwide, are the most susceptible to the presence of high levels of biogenic amines (BAs). Many reviews have focused on BAs toxicity and presence in foods; however, technological strategies such as evaluation of physical parameters, the addition of natural or synthetic compounds or the use of specific starter cultures of BAs reduction, and quick detection methods have been scarcely approached. In current research, there has been a focus on fast detection of BAs through colorimetric methods that allow these compounds to be quickly and easily identified by consumers. To reduce BAs presence in food, several alternatives have been developed and investigated with the aim of preventing negative effects caused by their intake, which can be applied before, during, or after processing. Food safety is one of the most important concerns of consumer and sanitary authorities. Therefore, detecting toxins such as BAs in food has become a priority for research. Recent reports that focus on the development of rapid detection methods of BAs are reviewed in this analysis. These methods have been successfully applied to food matrices with little to no sample pretreatment. Several alternatives for BAs reduction in food was also summarized. These findings will help the food industry to improve its processes for developing safe food.

Histamine detection in fish samples based on indirect competitive ELISA method using iron-cobalt co-doped carbon dots labeled histamine antibody

Due to complex matrixes and specific reagent deficiency, the rapid detection of histamine is still a challenge to date. Based on the high peroxidase-like activity of iron-cobalt co-doped carbon dots, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was established for histamine detection using the mimic enzyme labeled with histamine antibody (His-Ab). Through the competitive binding of the labeled His-Ab to solid-phase and sample antigens, histamine content was detected with a linear range of 2.5-150 μg mL^-1. The detection limit based on 3σ/K was 0.50 mg kg^-1, which was much lower than those of commercial His-kit and HPLC methods. The ic-ELISA method was applied to histamine detection in fish samples with the recovery of (103.4 ± 0.5)%, which was in accord with those of commercial His-kit and HPLC methods. The results indicated that the established ic-ELISA method was suitable for rapid detection of histamine in fish samples with high accuracy, sensitivity and stability.

Dipsticks with Reflectometric Readout of an NIR Dye for Determination of Biogenic Amines

Electrospun nanofibers (ENFs) are remarkable analytical tools for quantitative analysis since they are inexpensive, easily produced in uniform homogenous mats, and provide a high surface area-to-volume ratio. Taking advantage of these characteristics, a near-infrared (NIR)-dye was doped as chemosensor into ENFs of about 500 nm in diameter electrospun into 50 µm thick mats on indium tin oxide (ITO) supports. The mats were made of cellulose acetate (CA) and used as a sensor layer on optical dipsticks for the determination of biogenic amines (BAs) in food. The ENFs contained the chromogenic amine-reactive chameleon dye S0378 which is green and turns blue upon formation of a dye-BA conjugate. This SN1-reaction of the S0378 dye with various BAs was monitored by reflectance measurements at 635 nm where the intrinsic absorption of biological material is low. The difference of the reflectance before and after the reaction is proportional to BA levels from 0.04–1 mM. The LODs are in the range from 0.03–0.09 mM, concentrations that can induce food poisoning but are not recognized by the human nose. The calibration plots of histamine, putrescine, spermidine, and tyramine are very similar and suggesting the use of the dipsticks to monitor the total sample BA content. Furthermore, the dipsticks are selective to primary amines (both mono- and diamines) and show low interference towards most nucleophiles. A minute interference of proteins in real samples can be overcome by appropriate sample pretreatment. Hence, the ageing of seafood samples could be monitored via their total BA content which rose up to 21.7 ± 3.2 µmol/g over six days of storage. This demonstrates that optically doped NFs represent viable sensor and transducer materials for food analysis with dipsticks.