Characterization and application of a diamine oxidase from Lathyrus sativus as component of an electrochemical biosensor for the determination of biogenic amines in wine and beer

Enzymatic reactions towards aldehydes: An overview

Many aldehydes are volatile compounds with distinct and characteristic olfactory properties. The aldehydic functional group is reactive and, as such, an invaluable chemical multi-tool to make all sorts of products. Owing to the reactivity, the selective synthesis of aldehydic is a challenging task. Nature has evolved a number of enzymatic reactions to produce aldehydes, and this review provides an overview of aldehyde-forming reactions in biological systems and beyond. Whereas some of these biotransformations are still in their infancy in terms of synthetic applicability, others are developed to an extent that allows their implementation as industrial biocatalysts.

Current State of Sensors and Sensing Systems Utilized in Beer Analysis

Beer is one of the most consumed beverages in the world. Advances in instrumental techniques have allowed the analysis and characterization of a large number of beers. However, review studies that outline the methodologies used in beer characterization are scarce. Herein, a systematic review investigating the molecular targets and sensometric techniques in beer characterization was performed following the PRISMA protocol. The study reviewed 270 articles related to beer analysis in order to provide a comprehensive summary of the recent advances in beer analysis, including methods using sensors and sensing systems. The results revealed the use of various techniques that include several technologies, such as nanotechnology and electronics, often combined with scientific data analysis tools. To our knowledge, this study is the first of its kind and provides the reader with a faithful overview of what has been done in the sensor field regarding beer characterization.

Recent advances in development of electrochemical biosensors for the detection of biogenic amines

Biogenic amines (BAs) are widely found in food as a consequence of diverse factors including free amino acid availability, microbial production of decarboxylases, and variations in processing and storage conditions. Hence, BAs are considered as an important marker for determining the freshness and quality of food. Owing to the documentation of BAs in different dietary products, their numerous negative impacts on human health have reported to be a serious concern in past few decades. Therefore, the quantification of these chemical species in food becomes crucial as it can immensely contributes toward control of new episodes on food intoxication in humans. In this line, various chromatographic and colorimetric methods have been developed to detect BAs. However, these methods are in use from a longer time, still are limited by high cost, lengthy procedures, huge infrastructure and skilled personnel requirements that hinder their on-field application. In pursuit of a reliable method offering accurate detection of BAs, this review presents the state-of-the-art of electrochemical strategies for BAs sensing in food. The core of the review discusses about the widely employed electrochemical transducers, such as amperometric, potentiometric, impedimetric and conductometric-based BAs biosensors with significant findings of research work conducted previously. The application of electrochemical sensors to analyze BAs in different fields including food systems (fermented and non-fermented types) and smart packaging systems has been reviewed. Moreover, existing challenges and further available prospects for the development of rapid, facile, and sensitive electrochemical strategies for on-site determination of BAs have also been discussed.

A Multipurpose and Multilayered Microneedle Sensor for Redox Potential Monitoring in Diverse Food Analysis

This work presents a multipurpose and multilayered stainless steel microneedle sensor for the in situ redox potential monitoring in food and drink samples, termed MN redox sensor. The MN redox sensor was fabricated by layer-by-layer (LbL) approach. The in-tube multilayer coating comprised carbon nanotubes (CNTs)/cellulose nanocrystals (CNCs) as the first layer, polyaniline (PANI) as the second layer, and the ferrocyanide redox couple as the third layer. Using cyclic voltammetry (CV) as a transduction method, the MN redox sensor showed facile electron transfer for probing both electrical capacitance and redox potential, useful for both analyte specific and bulk quantification of redox species in various food and drink samples. The bulk redox species were quantified based on the anodic/cathodic redox peak shifts (E_a/E_c) on the voltammograms resulting from the presence of redox-active species. The MN redox sensor was applied to detect selected redox species including ascorbic acid, H₂O₂, and putrescine, with capacitive limits of detection (LOD) of 49.9, 17.8, and 263 ng/mL for each species, respectively. For the bulk determination of redox species, the MN redox sensor displayed LOD of 5.27 × 10³, 55.4, and 25.8 ng/mL in ascorbic acid, H₂O₂, and putrescine equivalents, respectively. The sensor exhibited reproducibility of ~ 1.8% relative standard deviation (%RSD). The MN redox sensor was successfully employed for the detection of fish spoilage and antioxidant quantification in king mushroom and brewed coffee samples, thereby justifying its potential for food quality and food safety applications. Lastly, the portability, reusability, rapid sampling time, and capability of in situ analysis of food and drink samples makes it amenable for real-time sensing applications.

Recent advances in the application of microbial diamine oxidases and other histamine-oxidizing enzymes

The consumption of foods fraught with histamine can lead to various allergy-like symptoms if the histamine is not sufficiently degraded in the human body. The degradation occurs primarily in the small intestine, naturally catalyzed by the human diamine oxidase (DAO). An inherent or acquired deficiency in human DAO function causes the accumulation of histamine and subsequent intrusion of histamine into the bloodstream. The histamine exerts its effects acting on different histamine receptors all over the body but also directly in the intestinal lumen. The inability to degrade sufficient amounts of dietary histamine is known as the ‘histamine intolerance’. It would be preferable to solve this problem initially by the production of histamine-free or -reduced foods and by the oral supplementation of exogenous DAO supporting the human DAO in the small intestine. For the latter, DAOs from mammalian, herbal and microbial sources may be applicable. Microbial DAOs seem to be the most promising choice due to their possibility of an efficient biotechnological production in suitable microbial hosts. However, their biochemical properties, such as activity and stability under process conditions and substrate selectivity, play important roles for their successful application. This review deals with the advances and challenges of DAOs and other histamine-oxidizing enzymes for their potential application as processing aids for the production of histamine-reduced foods or as orally administered adjuvants to humans who have been eating food fraught with histamine.

Rediscovering the Potential of Multifaceted Orphan Legume Grasspea- a Sustainable Resource With High Nutritional Values

The genus Lathyrus consists of more than 184 herbaceous annual and perennial species suitable for multifaceted sustainable food and feed production system in the arid and semi-arid regions of the world. The grasspea is a promising source of protein nutrition. However, its potential is not being utilized fully due to the presence of neurotoxin content (β-N-oxalyl-l-α, β diaminopropionic acid, β-ODAP), a causal agent of non-reversible lower limbs paralysis. The high protein contents in seeds and leaves with ~90% digestibility make it sustainable super food to beat protein malnutrition in future. Therefore, it is desired to breed new grasspea cultivars with low β-ODAP contents. Limited research has been carried out to date about this feature. A draft genome sequence of grasspea has been recently published that is expected to play a vital role in breeding and identifying the genes responsible for biosynthesis pathway of β-ODAP contents in grasspea. Efforts to increase awareness about the importance of genus Lathyrus and detoxify β-ODAP in grasspea are desired and are in progress. Presently, in South Asia, systematic and dedicated efforts to support the farmers in the grasspea growing regions by disseminating low β-ODAP varieties has resulted in a considerable improvement in reducing the incidence of neurolathyrism. It is expected that the situation will improve further by mainstreaming grasspea cultivation by implementing different approaches such as the development and use of low β-ODAP varieties, strengthening government policies and improved detox methods. The present review provides insight into the multifaceted characteristics of sustainable nutritious grasspea in the global and Indian perspective.

Screen-Printed Electrode-Based Sensors for Food Spoilage Control: Bacteria and Biogenic Amines Detection

Food spoilage is caused by the development of microorganisms, biogenic amines, and other harmful substances, which, when consumed, can lead to different health problems. Foodborne diseases can be avoided by assessing the safety and freshness of food along the production and supply chains. The routine methods for food analysis usually involve long analysis times and complex instrumentation and are performed in centralized laboratories. In this context, sensors based on screen-printed electrodes (SPEs) have gained increasing importance because of their advantageous characteristics, such as ease of use and portability, which allow fast analysis in point-of-need scenarios. This review provides a comprehensive overview of SPE-based sensors for the evaluation of food safety and freshness, focusing on the determination of bacteria and biogenic amines. After discussing the characteristics of SPEs as transducers, the main bacteria, and biogenic amines responsible for important and common foodborne diseases are described. Then, SPE-based sensors for the analysis of these bacteria and biogenic amines in food samples are discussed, comparing several parameters, such as limit of detection, analysis time, and sample type.

A review on chemical and electrochemical methodologies for the sensing of biogenic amines

Biogenic amines (BA) are biomolecules of low molecular weight with organic basic functionalities (amine group) that are formed by the microbial decarboxylation of amino acids of fermented food/beverages. Hence BAs are an important indicator in estimating the freshness and quality of meat, seafood, and industrial food products with high protein content. The reaction of BAs with nitrites available in certain meat products forms nitrosoamine, a carcinogenic compound. Hence BAs are in general considered to be a food hazard and monitoring the level of BAs in food samples becomes crucial as their high concentrations may lead to health problems. This review offers an overview of the available chemical and electrochemical methods that are typically used for the sensing of BAs in food samples. Certain compounds are known to selectively interact with BAs via chemical or non-covalent interactions and these interactions are often accompanied by fluorescence or visible color changes (sometimes visual detection) that could be monitored/assessed using a fluorescence spectrophotometer or UV-vis spectrophotometer (colorimetric methods). The colorimetric methods are limited by sensitivity and selectivity as they are based on straight-forward chemical reactions. In the case of electrochemical sensing of BAs, mediators are often used which undergo oxidation/reduction to produce intermediates that could interact with BAs accompanied by changes in their electrochemical potential. Overall, this review summarizes the available chemical and electrochemical strategies towards the sensing of BAs with a discussion on further prospects.

Zinc(II) salphen complex-based fluorescence optical sensor for biogenic amine detection

Biogenic amines have attracted interest among researchers because of their importance as biomarkers in determining the quality of food freshness in the food industry. A rapid and simple technique that is able to detect biogenic amines is needed. In this work, a new optical sensing material for one of the biogenic amines, histamine, based on a new zinc(II) salphen complex was developed. The binding of zinc(II) complexes without an electron-withdrawing group (complex 1) and with electron-withdrawing groups (F, complex 2; Cl, complex 3) to histamine resulted in enhancement of fluorescence. All complexes exhibited high affinity for histamine [binding constant of (7.14 ± 0.80) × 10⁴, (3.33 ± 0.03) × 10⁵, and (2.35 ± 0.14) × 10⁵ M^-1, respectively]. Complex 2 was chosen as the sensing material for further development of an optical sensor for biogenic amines in the following step since it displayed enhanced optical properties in comparison with complexes 1 and 3. The optical sensor for biogenic amines used silica microparticles as the immobilisation support and histamine as the analyte. The optical sensor had a limit of detection for histamine of 4.4 × 10^-12 M, with a linear working range between 1.0 × 10^-11 and 1.0 × 10^-6 M (R² = 0.9844). The sensor showed good reproducibility, with a low relative standard deviation (5.5 %). In addition, the sensor exhibited good selectivity towards histamine and cadaverine over other amines, such as 1,2-phenylenediamine, triethylamine, and trimethylamine. Recovery and real sample studies suggested that complex 2 could be a promising biogenic amine optical sensing material that can be applied in the food industry, especially in controlling the safety of food for it to remain fresh and healthy for consumption.

An Overview on Biogenic Amines in Wine

Biogenic amines (BAs) are low molecular weight compounds formed from precursor amino acids, mainly by microbial decarboxylation. The presence of these compounds is important in the food and beverage industry because, in high amounts, they can lead to negative effects on consumers. In this review, we illustrate the critical aspects needed to control the formation of BAs during winemaking and their presence in the final product. Recent biotechnological approaches related to microorganisms and their ability to reduce BAs are illustrated. The current methods used for BA detection and quantification are also presented. These methods are very important to consider, as BAs can serve as markers for the quality assessment of products. The information presented here offers an overview useful for identifying specific parameters and conditions which should be controlled to minimise BA content in wine; knowledge about BAs in foods and beverages has been accumulating in recent years, not only to ensure and improve quality (since BAs have been used as an indicator of spoilage) but especially to guarantee consumer safety due to the potential toxic effects of BAs on humans.

Development of Amine-Oxidase-Based Biosensors for Spermine and Spermidine Analysis

In this work a detailed description of the development of amine oxidase-based electrochemical biosensors for the selective determination of the biogenic amines is presented. The enzymes required for this operation are Polyamine Oxidase (PAO) and Spermine Oxidase (SMO) which are physically entrapped in poly(vinyl alcohol) bearing styrylpyridinium groups (PVA-SbQ), a photo-cross-linkable gel, onto screen printed electrode (SPE) surface. The developed biosensors are deeply characterized in the analysis of biogenic amines by using flow injection amperometric (FIA) technique. The enzymatic electrodes are characterized by good sensitivity, long-term stability, and reproducibility. To test the feasibility of the developed biosensors in the analysis of real matrices, they are used for the analysis of blood samples. The results obtained are in good agreement with those obtained with the GC-MS reference method.

Portable Bio/Chemosensoristic Devices: Innovative Systems for Environmental Health and Food Safety Diagnostics

This mini-review covers the newly developed biosensoristic and chemosensoristic devices described in recent literature for detection of contaminants in both environmental and food real matrices. Current needs in environmental and food surveillance of contaminants require new simplified, sensitive systems, which are portable and allow for rapid and on-site monitoring and diagnostics. Here, we focus on optical and electrochemical bio/chemosensoristic devices as promising tools with interesting analytical features that can be potentially exploited for innovative on-site and real-time applications for diagnostics and monitoring of environmental and food matrices (e.g., agricultural waters and milk). In near future, suitably developed and implemented bio/chemosensoristic devices will be a new and modern technological solution for the identification of new quality and safety marker indexes as well as for a more proper and complete characterization of abovementioned environmental and food matrices. Integrated bio/chemosensoristic devices can also allow an “holistic approach” that may prove to be more suitable for diagnostics of environmental and food real matrices, where the copresence of more bioactive substances is frequent. Therefore, this approach can be focused on the determination of net effect (mixture effect) of bioactive substances present in real matrices.

Optimizing the preparation conditions and characterization of cross-linked enzyme aggregates of a monoamine oxidase

Monoamine oxidases are useful in determination of biogenic monoamines, particularly histamine and tyramine. In this study, cross-linked enzyme aggregates (CLEAs) technique was applied to improve the stability of a monoamine oxidase from Arthrobacter aurescens (AMAO). Under the optimized condition (50% of saturated ammonium sulfate, 5 mM glutaraldehyde, 2.0 mg/mL AMAO, 4 h-cross-linking at 25°C, pH 8.0), CLEAs-AMAO was recovered with a yield of 82% based on the subjected total enzyme activity. Both pH activity and stability at alkaline pHs of CLEAs-AMAO were significantly improved compared to those of the free enzyme, resulting in the shift of optimum pH to pH 8.0 and a broader pH profile. The half-life of the CLEAs at 65°C was elongated by 1.7-fold compared to that of the free enzyme, suggesting the thermal stability of AMAO was also improved by the CLEAs formation.

Amperometric Biosensor Based on Diamine Oxidase/Platinum Nanoparticles/Graphene/Chitosan Modified Screen-Printed Carbon Electrode for Histamine Detection

This work describes the development and optimization studies of a novel biosensor employed in the detection and quantification of histamine in freshwater fish samples. The proposed biosensor is based on a modified carbon screen-printed electrode with diamineoxidase, graphene and platinum nanoparticles, which detects the hydrogen peroxide formed by the chemical process biocatalysed by the enzyme diamine oxidase and immobilized onto the nanostructurated surface of the receptor element. The amperometric measurements with the biosensor have been implemented in buffer solution of pH 7.4, applying an optimal low potential of +0.4 V. The novel biosensor shows high sensitivity (0.0631 μA·μM), low detection limit (2.54 × 10⁻⁸ M) and a broad linear domain from 0.1 to 300 μM. The applicability in natural complex samples and the analytical parameters of this enzyme sensor have been performed in the quantification of histamine in freshwater fish. An excellent correlation among results achieved with the developed biosensor and results found with the standard method for all freshwater fish samples has been achieved.

A novel enzyme with spermine oxidase properties in bovine liver mitochondria: identification and kinetic characterization

The uptake of spermine into mammalian mitochondria indicated the need to identify its catabolic pathway in these organelles. Bovine liver mitochondria were therefore purified and their capacity for natural polyamine uptake was verified. A kinetic approach was then used to determine the presence of an MDL 72527-sensitive enzyme with spermine oxidase activity in the matrix of bovine liver mitochondria. Western blot analysis of mitochondrial fractions and immunogold electron microscopy observations of purified mitochondria unequivocally confirmed the presence of a protein recognized by anti-spermine oxidase antibodies in the mitochondrial matrix. Preliminary kinetic characterization showed that spermine is the preferred substrate of this enzyme; lower activity was detected with spermidine and acetylated polyamines. Catalytic efficiency comparable to that of spermine was also found for 1-aminododecane. The considerable effect of ionic strength on the Vmax/KM ratio suggested the presence of more than one negatively charged zone inside the active site cavity of this mitochondrial enzyme, which is probably involved in the docking of positively charged substrates. These findings indicate that the bovine liver mitochondrial matrix contains an enzyme belonging to the spermine oxidase class. Because H2O2 is generated by spermine oxidase activity, the possible involvement of the latter as an important signaling transducer under both physiological and pathological conditions should be considered.

Quantification of histamine in various fish samples using square wave stripping voltammetric method

The objective of this study was to describe a new and simple method for the determination of histamine so that it can be used in routine food analysis. A square wave stripping voltammetric (SWSV) method has been used for the indirect determination of histamine. The method is based on accumulation copper (II) - histamine complex onto a hanging mercury drop electrode and reduction of complex. The optimum conditions include an accumulation potential of -420 mV (versus Ag/AgCl), an accumulation time of 10 s. Two linear calibration graphs were obtained with slopes of 0.078 (μM/μA) and 0.014 (μM/μA), respectively. The detection limits were found to be 3 × 10(-7) and 1 × 10(-5) M for histamine (S/N = 3), respectively. The validated SWSV method showed good linearity as well as satisfactory repeatability and immediate precision values, for both instrument and method. The effect of common excipients and metal ions on the peak height of Cu-histamine complex peak was studied. The method was successfully, applied to the determination of histamine in canned anchovy (Engraulis encrasicholus), frozen Tinca tinca (L.) and Cyprinus carpio fish samples.

Amine oxidase-based biosensors for spermine and spermidine determination

The present work describes the development and optimization of electrochemical biosensors for specific determination of the biogenic polyamine spermine (Spm) and spermidine (Spmd) whose assessment represents a novel important analytical tool in food analysis and human diagnostics. These biosensors have been prepared using novel engineered enzymes: polyamine oxidase (PAO) endowed with selectivity towards Spm and Spmd and spermine oxidase (SMO) characterized by strict specificity towards Spm. The current design entails biosensors in which the enzymes were entrapped in poly(vinyl alcohol) bearing styrylpyridinium groups (PVA-SbQ), a photocrosslinkable gel, onto an electrode surface. Screen-printed electrodes (SPEs) were used as electrochemical transducers for enzymatically produced hydrogen peroxide, operating at different potential vs Ag/AgCl according to the material of the working electrode (WE): +700 mV for graphite (GP) or -100 mV for Prussian blue (PB)-modified SPE, respectively. Biosensor performances were evaluated by means of flow injection amperometric (FIA) measurements. The modified electrodes showed good sensitivity, long-term stability and reproducibility. Under optimal conditions, the PAO biosensor showed a linear range 0.003-0.3 mM for Spm and 0.01-0.4 mM for Spmd, while with the SMO biosensor, a linear range of 0.004-0.5 mM for Spm has been obtained. The main kinetic parameters apparent Michaelis constant (K M), turnover number (K cat) and steady-state current (I max) were determined. The proposed device was then applied to the determination of biogenic amines in blood samples. The results obtained were in good agreement with those obtained with the GC-MS reference method.

Simultaneous determination of cadaverine and putrescine using a disposable monoamine oxidase based biosensor

The selective and simultaneous amperometric determination of putrescine (Put) and cadaverine (Cad) has been carried out using a novel design of screen-printed carbon electrode (SPCE) with two working electrodes connected in array mode. A mixture of 3% of tetrathiafulvalene (TTF), as mediator, and carbon ink was used for the construction of the screen-printed working electrode. The employment of different amounts of monoamine oxidase (MAO) enzyme on these modified TTF/SPCEs and the use of gold nanoparticles (AuNPs) allowed performing the simultaneous determination of both analytes. The amperometric detection has been performed by measuring the oxidation current of the mediator at a potential of+250 mV vs. screen-printed Ag/AgCl reference electrode. A linear response in the Cad concentration range from 19.6 till 107.1 µM and from 9.9 till 74.1 μM for Put was obtained at the MAO/AuNPs/TTF/SPCE biosensor. This device showed a capability of detection of 9.9 and 19.9±0.9 µM (n=4 α=β=0.05) and a precision of 4.9% and 10.3% in terms of relative standard deviation for Put and Cad, respectively. The developed biosensor was successfully applied to the simultaneous determination of Put and Cad in octopus samples.

Construction of a bifunctional enzyme fusion for the combined determination of biogenic amines in foods

Biogenic amines (BAs) are a group of low-molecular-mass organic bases derived from free amino acids. Due to the undesirable effects of BAs on human health, amine oxidase-based detection methods for BAs in foods have been developed. Here, we developed a bifunctional enzyme fusion (MAPO) using a Cu(2+)-containing monoamine oxidase (AMAO2) and a flavin adenine dinucleotide-containing putrescine oxidase (APUO) from Arthrobacter aurescens. It was necessary to activate MAPO with supplementary Cu(2+) ions, leading to a 6- to 12-fold improvement in catalytic efficiency (kcat/KM) for monoamines. The optimal temperatures of Cu(2+)-activated MAPO (cMAPO) for both tyramine and putrescine were 50 °C, and the optimal pH values for tyramine and putrescine were pH 7.0 and pH 8.0, respectively, consistent with those of AMAO2 and APUO, respectively. The cMAPO showed relative specific activities of 100, 99, 32, and 32 for 2-phenylethylamine, tyramine, histamine, and putrescine, respectively. The tyramine-equivalent BA contents of fermented soybean pastes by cMAPO were more than 90% of the total BA determined by HPLC. In conclusion, cMAPO is fully bifunctional toward biogenic monoamines and putrescine, allowing the combined determination of multiple BAs in foods. This colorimetric determination method could be useful for point-of-care testing to screen safety-guaranteed products prior to instrumental analyses.

Amperometric biosensor for the determination of histamine in fish samples

A bienzymatic biosensor employing diamine oxidase (DOx) and horseradish peroxidase (HRP) for the detection of histamine in fish samples has been developed and optimized in this work. These enzymes have been co-immobilized into a polysulfone/carbon nanotubes/ferrocene membrane by means of phase inversion technique onto screen-printed electrodes. The electrochemical measurements have been carried out in phosphate buffer solution at pH 8.0 in batch mode and low applied potential (-50 mV vs. Ag/AgCl, KCl 0.1 M) to minimize the interferences. Developed biosensor exhibits high sensitivity (1.9×10(7) nA(-1)), low limit of detection (1.7×10(-7) M), high storage stability and excellent reproducibility, obtaining a linear interval range from 3×10(-7) to 2×10(-5) M. Finally, applicability of the biosensor to the estimation of histamine content in different fish samples has been assessed; obtaining a good correlation between results obtained with the biosensor and those obtained with the reference method (ELISA) in case of sardines, mackerel and greater weever.