RESUMO
3D-printing technology allows scientist to fabricate easily electrochemical sensors. Until now, these sensors were designed employing a large amount of material, which increases the cost and decreases manufacturing throughput. In this work, a low-cost 3D-printed on-drop electrochemical sensor (3D-PES) was fully manufactured by fused filament fabrication, minimizing the number of printing layers. Carbon black/polylactic acid filament was employed, and the design and several printing parameters were optimized to yield the maximum electroanalytical performance using the minimal amount of material. Print speed and extrusion width showed a critical influence on the electroanalytical performance of 3D-PES. Under optimized conditions, the fabrication procedure offered excellent reproducibility (RSD 1.3% in working electrode diameter), speed (< 3 min/unit), and costs (< 0.01 $ in material cost). The 3D-PES was successfully applied to the determination of phloridzin in apple juice. The analytical performance of 3D-PES was compared with an equivalent commercial on-drop screen-printed electrode, yielding similar precision and accuracy but lower sensitivity. However, 3D-PES provides interesting features such as recyclability, biodegradability, low-cost, and the possibility of being manufactured near the point of need, some of which meets several demands of Green Chemistry. This cost-effective printing approach is a green and promising alternative for manufacturing disposable and portable electroanalytical devices, opening new possibilities not only in on-site food analysis but also in point-of-care testing.
Assuntos
Técnicas Eletroquímicas , Análise de Alimentos , Sucos de Frutas e Vegetais , Poliésteres , Impressão Tridimensional , Fuligem , Fuligem/química , Poliésteres/química , Técnicas Eletroquímicas/métodos , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/economia , Sucos de Frutas e Vegetais/análise , Análise de Alimentos/instrumentação , Análise de Alimentos/economia , Análise de Alimentos/métodos , Eletrodos , Malus/química , Análise Custo-Benefício , Limite de DetecçãoRESUMO
In multiresidue analysis, the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) is one of the most popular techniques routinely used by researchers during pesticide analysis of food and vegetable samples. Originally, the QuEChERS method was developed for analysis of pesticide residues from fruits and vegetables, but rapidly gained popularity in the extraction of analytes from different matrices. This analytical approach shows several advantages over traditional extraction techniques: it requires lower sample and solvent amounts while shortening the time of sample preparation. However, it presents some limitations for complex matrices such as those containing high amounts of chlorophyll. To overcome the problem of strong matrix effect and influence of interferences, different approaches are applied. Most are concerning modifications of the cleanup step, that is, sorbent type and its amount. Optimization of other parameters, such as sample size, hydration level, extraction solvent, and buffering, also has an impact on overall performance. Combining proper sample preparation with modern highly sensitive and selective detection techniques enables receiving desired limits of quantification. This article presents an overview of strategies employed by researchers for analysis of green, high chlorophyll content commodities and results obtained in their studies.
Assuntos
Clorofila/análise , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Resíduos de Praguicidas/análise , Resíduos de Praguicidas/isolamento & purificação , Extração em Fase Sólida/métodos , Análise de Alimentos/economia , Contaminação de Alimentos/economia , Extração em Fase Sólida/economia , Extração em Fase Sólida/instrumentaçãoRESUMO
Ultrasonic-enhanced surface-active bismuth trisulfide based core-shell nanomaterials were developed and used as an efficient modified electrode material to construct a highly sensitive antibiotic sensor. The core-shell Bi2S3@GCN electrode material was directly synthesized by in-situ growth of GCN on Bi2S3 to form core-shell like nanostar (Ti-horn, 30 kHz, and 70 W/cm2). The electrocatalyst of Bi2S3@GCN nanocomposites was efficaciously broadened towards electrochemical applications. As synthesized Bi2S3@GCN promoted the catalytic ability and electrons of GCN to transfer to Bi2S3. The single-crystalline GCN layers were uniformly grown on the surface of the Bi2S3 nanostars. Under the optimal conditions of electrochemical analysis, the CPL sensor exhibited responses directly proportional to concentrations (toxic chemical) over a range of 0.02-374.4 µM, with a nanomolar detection limit of 1.2 nM (signal-to-noise ratio S/N = 3). In addition, the modified sensor has exhibited outstanding selectivity under high concentrations of interfering chemicals and biomolecules. The satisfactory CPL recoveries in milk product illustrated the credible real-time application of the proposed Bi2S3@GCN sensors for real samples, indicating promising potential in food safety department and control. Additionally, the proposed electrochemical antibiotic sensor exhibited outstanding performance of anti-interfering ability, high stability and reproducibility.
Assuntos
Antibacterianos/análise , Bismuto/química , Eletroquímica/instrumentação , Análise de Alimentos/instrumentação , Contaminação de Alimentos/análise , Grafite/química , Compostos de Nitrogênio/química , Sulfetos/química , Ondas Ultrassônicas , Catálise , Custos e Análise de Custo , Resíduos de Drogas/análise , Eletroquímica/economia , Eletrodos , Análise de Alimentos/economia , Limite de DetecçãoRESUMO
Studies about the phenolic composition of yellow (Brassica alba), brown (Brassica juncea), and black (Brassica nigra) mustard seeds are still scarce in the literature. Hence, this study describes, for the first time, the use of the QuEChERS extraction method followed by UHPLC-MS/MS analysis for phenolic compound determination in the seeds of these mustard species. Under the optimized extraction and analysis conditions, twenty-one phenolic compounds were evaluated. Six, eleven, and seven were found in B. alba, B. juncea, and B. nigra seeds, respectively. The most abundant phenolic compound was sinapic acid, which was found in amounts ranging from 44 to 82 times higher than the other major compounds found in the mustard seeds, ferulic, 4-hydroxybenzoic and protocatechuic acids. Overall, these results are an important contribution to the characterization of the phenolic composition of the three in natura mustard seeds species, and support future reliable phenolic compounds determination with the QuEChERS method.
Assuntos
Custos e Análise de Custo , Análise de Alimentos/métodos , Mostardeira/química , Fenóis/análise , Segurança , Sementes/química , Sinapis/química , Análise de Alimentos/economia , Humanos , Pigmentação , Espectrometria de Massas em Tandem , Fatores de TempoRESUMO
An extraction procedure was developed for the determination of aflatoxin M1 in milk and dairy products. A sorbent based on UVM-7 mesoporous silica was used as solid phase for the sample clean-up, and the analyte determination was carried out by HPLC coupled to a fluorescence detector. The material architecture was characterized by transmission electronic microscopy, X-ray diffraction, 29Si NMR and nitrogen adsorption-desorption. After the optimization of extraction parameters, the influence of the matrix has been evaluated, obtaining recoveries in the range 78-105% for whole and skimmed milk and yogurt matrix. The reusability of the material was also proved. The sensitivity of the method was also evaluated, and a LOQ (0.015 µg kg-1) below the European legislation limit was obtained. The procedure was successfully applied for the determination of aflatoxin M1 in real samples. The results were compared with those obtained with a reference method, being the results statistically comparable.
Assuntos
Aflatoxina M1/análise , Custos e Análise de Custo , Análise de Alimentos/métodos , Leite/química , Nanoestruturas/química , Dióxido de Silício/química , Iogurte/análise , Adsorção , Aflatoxina M1/química , Animais , Fluorescência , Análise de Alimentos/economia , Contaminação de Alimentos/análise , Limite de Detecção , PorosidadeRESUMO
Chia (Salvia hispanica) and quinoa (Chenopodium quinoa) seeds are often referred to as a "superfood" or functional food as a result of the claims of numerous health benefits. This often resulted in a sudden increase in demand, which frequently exceeds existing supply capacities, fostering fraudulent practices, such as mislabeling and use of other species of inferior quality. To assess the authenticity of food products containing chia and quinoa, we developed real-time polymerase chain reaction systems for the detection of seeds of these plant species. The developed methodology using chia- and quinoa-specific primer-probe sets based on TaqMan technology was validated, and specificity, cross-reactivity, limit of detection, efficiency, and robustness were determined. The methods were successfully applied to 12 (chia) and 7 (quinoa) commercial samples, proving its suitability for the verification of the authenticity of chia- and quinoa-containing products in commercial trade.
Assuntos
Chenopodium quinoa/genética , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Reação em Cadeia da Polimerase em Tempo Real/métodos , Salvia/genética , Análise de Alimentos/economia , Sementes/genéticaRESUMO
In view of the high polarity and ubiquitous occurrence of perchlorate, achieving an ultra-trace analysis has become a challenging task. The present study aimed to develop a simple and generic pretreatment protocol based on cold-induced liquid-liquid extraction to efficiently extract perchlorate from tea and dairy products and remarkably decrease potential matrix interferences and laborious cleanup. By optimizing the pretreatment conditions, the enrichment factor of perchlorate increased by 7.79 times under the compromise between the matrix effect and extraction recovery. The validated method presented satisfactory selectivity, linearity, accuracy, precision, and matrix effect, providing recoveries of 78.2%-106.2% with RSDr ranging from 1.2% to 7.9% and RSDR less than 10.7% for tea and dairy products. This pretreatment protocol depended only on shaking, freezing, and centrifugation in one step, without additional equipment or tedious operations, which will be explored to a greater extent in complex biological or food matrices.
Assuntos
Laticínios/análise , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Extração Líquido-Líquido/métodos , Percloratos/análise , Chá/química , Centrifugação/métodos , Análise Custo-Benefício , Análise de Alimentos/economia , Congelamento , Extração Líquido-Líquido/economia , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Fatores de TempoRESUMO
Salmonella spp. are zoonotic pathogens of substantial public health concern. To enable detection in the field or under instrument-free conditions, we developed a rapid and robust lateral flow fluorescent immunoassay based on strand exchange amplification (SEA-LFIA) for the quantitative detection of Salmonella spp. As far as we know, this work is the first report regarding the use of Bst DNA polymerase-assisted SEA for fluorescence sensing to detect Salmonella spp. The SEA method was further confirmed by enzymatic digestion and Sanger dideoxy sequencing. The specificity of SEA-LFIA assay was verified by 89 Salmonella strains (18 Salmonella reference strains and 71 clinical isolates) and 15 non-Salmonella reference strains (different genera). The sensitivity of SEA-LFIA assay was 6 × 100 CFU mL-1 of Salmonella pure culture or 3 × 104 CFU 25 g-1 of artificially spiked raw chicken meat. Using this assay, it was found that 37 (16%) of the 236 samples collected were positive, which was consistent with the results of conventional PCR. The cutoff value is 15 and SEA-LFIA assay only takes â¼30 min without high equipment and reagent cost. In addition, the proposed strategy can be easily extended by redesigning the corresponding amplification primers to detect target analytes. In conclusion, the optimized SEA-LFIA assay is an efficient and specific method for the detection of Salmonella spp., and can potentially serve as a new on-site diagnostic tool in life sciences.
Assuntos
Fluorimunoensaio/métodos , Aves Domésticas/microbiologia , Infecções por Salmonella/microbiologia , Salmonella/isolamento & purificação , Animais , Galinhas/microbiologia , DNA Bacteriano/análise , DNA Bacteriano/genética , Desenho de Equipamento , Imunofluorescência/economia , Imunofluorescência/métodos , Fluorimunoensaio/economia , Análise de Alimentos/economia , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Humanos , Técnicas de Amplificação de Ácido Nucleico/economia , Técnicas de Amplificação de Ácido Nucleico/métodos , Salmonella/genética , Fatores de TempoRESUMO
Simple, effective, and rapid detection of chemically relevant hazards is a highly desirable research goal, which can provide early-warning information to improve the patient-care outcomes for public health. Here, we introduce a microdroplet-captured tape toward rapid SERS screening of food contaminants. The dominant sensing unit lies on functionalized microwell in conductive carbon tapes, which is simply prepared by physical punching, magnetron sputtering and electrochemical deposition of Au nanodendrites. The tape-based sensors not only possess highly branched Au nanodendrites in microwell for promoting SERS activity, but also enable anchoring the microdroplets via direct dip-pulling from pristine analytes solutions upon sticky incorporated on a glove. Early-warning SERS detection of food contaminants including Sudan-1, thiram, and thiabendazole from the real samples can be achieved by such simple sampling method. These tape-based sensors with a facile operation module and accessible signal read-out represent an innovative point-of-care testing (POCT) device for forensic, military, consumer protection, environmental monitoring, and food safety applications.
Assuntos
Análise de Alimentos/instrumentação , Contaminação de Alimentos/análise , Ouro/química , Nanopartículas Metálicas/química , Análise Espectral Raman/instrumentação , Anti-Helmínticos/análise , Corantes/análise , Desenho de Equipamento , Análise de Alimentos/economia , Fungicidas Industriais/análise , Naftóis/análise , Tiabendazol/análise , Tiram/análise , Fatores de TempoRESUMO
Ascorbic Acid (AA) is a natural and powerful water-soluble antioxidant associated with long-lasting food products. As time passes, the AA content in products sharply decreases, and they become increasingly degraded. There are several techniques to precisely quantify AA concentrations. However, most of them employ costly laboratory instruments, such as High-Performance Liquid Chromatography (HPLC) or complex electrochemical methods, which make unfeasible recurrent AA measurements along the entire supply chain. To address this issue, we contribute with an in-field and real-time voltammetric method, carried out with a low-cost, easy-to-use, and portable device. An unmodified Screen-Printed Electrode (SPE) is used together with the device to achieve short reading times. Our method has been extensively tested in two multifruit juices using three different SPEs. Calibration curves and Limit of Detection were derived for each SPE. Furthermore, periodic experiments were conducted to study the shelf life of juices under consideration. During the analysis, a set of assays for each SPE were implemented to determine the remaining AA amount per juice and compare it with that obtained using HPLC under the same conditions. Results revealed that our cost-effective device is fully comparable to the HPLC equipment, as long as the juice does not include certain interferents; a scenario also contemplated in this article.
Assuntos
Ácido Ascórbico/análise , Técnicas Eletroquímicas/métodos , Análise de Alimentos/métodos , Sucos de Frutas e Vegetais/análise , Calibragem , Cromatografia Líquida de Alta Pressão , Análise Custo-Benefício , Técnicas Eletroquímicas/economia , Técnicas Eletroquímicas/instrumentação , Eletrodos , Desenho de Equipamento , Análise de Alimentos/economia , Análise de Alimentos/instrumentação , Limite de DetecçãoRESUMO
A rapid method for detecting fatty acids (FAs) using terahertz time-domain spectroscopy (THz-TDS) technology combined with a metamaterial-based THz sensor was developed. We measured the THz responses to oleic acid, linoleic acid and α-linoleic acid with different numbers of double-bond, α-linoleic acid and γ-linoleic acid with different conformations. In addition, in order to explore the reason for the observed redshifts of the resonance frequencies of the four FAs, the dielectric constants of the FAs were measured in the THz region. Furthermore, the four fatty acids were also attempted to be identified by Raman spectroscopy, which was difficult to accomplish unambiguously because of the effect of fluorescence. This result thus demonstrates the power and usefulness of metamaterial-assisted THz-TDS in the rapid determination of the FAs, and its potential as a versatile tool for investigation of biological metabolism, and for food product quality, safety inspection and control.
Assuntos
Técnicas Biossensoriais/instrumentação , Ácidos Graxos/análise , Espectroscopia Terahertz/instrumentação , Técnicas Biossensoriais/economia , Desenho de Equipamento , Análise de Elementos Finitos , Análise de Alimentos/economia , Análise de Alimentos/instrumentação , Espectroscopia Terahertz/economia , Fatores de TempoRESUMO
Mycotoxin contamination causes over $5 billion of economic loss per year in the North American food and feed industry. A rapid, low-cost, portable, and reliable method for on-site detection of deoxynivalenol (DON), a representative mycotoxin predominantly occurring in grains, would be helpful to control mycotoxin contamination. In this study, a paper-based microfluidic chip capable of measuring DON (DON-Chip) in food, feed, and feed ingredients was developed. The DON-Chip incorporated a colorimetric competitive immunoassay into a paper microfluidic device and used gold nanoparticles as a signal indicator. Furthermore, a novel ratiometric analysis method was proposed to improve detection resolvability. Detection of DON in the aqueous extracts from solid food, feed, or feed ingredients was successfully validated with a detection range of 0.01-20 ppm (using dilution factors from 10 to 104). Compared with conventional methods, the DON-Chip method could greatly reduce the cost and time of mycotoxin detection in the food and feed industry.
Assuntos
Análise de Alimentos/economia , Contaminação de Alimentos/análise , Dispositivos Lab-On-A-Chip/economia , Papel , Tricotecenos/análise , Poluentes Químicos da Água/química , Indústria AlimentíciaRESUMO
The adulteration of meat products by the undeclared addition of commercially available blood plasma powder is quite conceivable due to low costs, high protein contents (about 70%), and advantageous functional properties. This applies particularly to pork, which has the highest meat production rate in the European Union. Evidence of this type of food fraud has been rather difficult to identify due to the lack of appropriate analytical methods, especially when adding plasma to meat of the same animal species. Consequently, a rapid UHPLC-MS/MS method for the detection of porcine blood plasma in emulsion-type pork sausages was developed. After protein extraction and tryptic digestion in a quick and simple one-pot process, species-specific marker peptides for porcine blood cell proteins (four markers) and plasma proteins (12 markers) were measured by UHPLC-MS/MS. Emulsion-type pork sausages were produced from a variety of raw materials that differed in the age or sex of the slaughtered pigs. Sausages were spiked with 0.5, 1, 1.5, 2, 3, or 5% meat substitution by one of two plasma powders, or produced as corresponding blank samples, and subjected to different thermal treatments as full or semi-preserves. Four plasma peptides were identified for the overall sample that allowed detection down to 0.7% meat substitution from the sum of their peak areas, with 5% error probability for both false positives and negatives.
Assuntos
Proteínas Sanguíneas/análise , Contaminação de Alimentos/análise , Produtos da Carne/análise , Carne Vermelha/análise , Animais , Cromatografia Líquida de Alta Pressão/economia , Cromatografia Líquida de Alta Pressão/métodos , Emulsões/química , Feminino , Análise de Alimentos/economia , Análise de Alimentos/métodos , Masculino , Peptídeos/análise , Plasma/química , Suínos , Espectrometria de Massas em Tandem/economia , Espectrometria de Massas em Tandem/métodos , Fatores de TempoRESUMO
Incorporation of new readout methods with established analytical devices allows methodological innovations in analytical sciences. Herein, we present a new sensing platform by combining an ultrasensitive element analyzer, namely the laser-induced breakdown spectroscopy (LIBS) and a lateral flow strip (LFS). AgxAuy bimetallic nanoparticles (AgxAuyBNPs) are selected as the labels to deliver the optimal quantitative performance by analyzing the Ag (I) signal from the test (T) line of LFS. For prototypical application in pathogen detection, the LIBS-LFS sensor can achieve a detection limit of 1.6â¯cfuâ¯mL-1 of Staphylococcus aureus (S. aureus) within 10â¯min, which is superior to conventional methods. Importantly, the signals of AgxAuyBNPs for visual and LIBS analysis are stable and still readable after the detection is finished and the test strip is stored for up to 13 days, suggesting a potential for long-term data preservation. This combination of LIBS with LFS provides a new concept toward integrated nano/analytical devices that can benefit various application scenarios.
Assuntos
Técnicas Biossensoriais/instrumentação , Nanopartículas Metálicas/química , Fitas Reagentes/análise , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/isolamento & purificação , Animais , Técnicas Biossensoriais/economia , Água Potável/microbiologia , Desenho de Equipamento , Análise de Alimentos/economia , Análise de Alimentos/instrumentação , Microbiologia de Alimentos , Ouro/química , Humanos , Lasers , Limite de Detecção , Leite/microbiologia , Fitas Reagentes/economia , Prata/química , Análise Espectral/economia , Análise Espectral/instrumentação , Infecções Estafilocócicas/diagnósticoRESUMO
Nitrite ions (NO2-) have been widely used in the food and drink industry as preservatives. However, the NO2- discharged into the environment is harmful to the ecosystem and human health. Due to its potential toxicity, selective and sensitive detection of nitrite is important. In this work, a rose-like Au nanoparticles/MoS2 nanoflower/graphene (AuNPs/MoS2/GN) composite was fabricated using a one-pot hydrothermal method without the addition of any extra reductant for use in nitrite detection. Graphene acts as an efficient matrix for the growth of MoS2 nanoflower (NF), and the edges of the MoS2 NF subsequently load AuNPs. The obtained AuNPs/MoS2/GN composite exhibits excellent electrooxidative activity toward nitrite ions, which is attributable to its large specific surface area, good conductivity, and the synergistic catalysis of each component. Accordingly, we propose a rapid, sensitive, and cost-effective electrochemical method for nitrite detection, which achieved a linear dynamic range of 5.0⯵M to 5.0â¯mM with a detection limit of 1.0⯵M. The present work provides not only a general one-pot synthesis method for a variety of noble-transition metal dichalcogenides nanohybrids, but also an example of the fabrication of an electrochemical nitrite sensor using a nanohybrid as an enhanced material, an approach that can easily be extended to other sensors.
Assuntos
Dissulfetos/química , Ouro/química , Grafite/química , Molibdênio/química , Nanocompostos/química , Nitritos/análise , Técnicas Eletroquímicas/economia , Técnicas Eletroquímicas/métodos , Análise de Alimentos/economia , Análise de Alimentos/métodos , Limite de Detecção , Nanopartículas Metálicas/química , Nanopartículas Metálicas/ultraestrutura , Nanocompostos/ultraestrutura , Fatores de TempoRESUMO
We focused on the development of a hand-held pathogen-detection device using smartphone-embedded electronic elements combined with functionalized magnetic particles (MPs) and sepharose. To perform affinity chromatography for evaluating DNA amplicons, avidin-conjugated MPs and succinimide-linked sepharose were used with biotin-primers. To mimic the centrifugal-based affinity ligand chromatography, a smartphone-mountable low-power fan was plugged into the charging port of a smartphone. The charging port stably emitted electric current at 3.0â¯V, and the fan blades were modified for use as a portable rotor. Based on the binding variation of MPs with DNA amplicons, the position of MPs in sepharose changed significantly during centrifugation. The change in distance was optically analyzed using the illumination sensor of the smartphone with respect to the altered transmittance due to the MPs. Amplified genes from Escherichia. coli O157:H7 samples ranging from 1.0â¯×â¯101 to 1.0â¯×â¯106â¯colony-forming units could be rapidly and immediately detected by the naked eye using a simple smartphone-based optical device. The results indicated that this novel biosensing technique is suitable for use as a point-of-care testing device in both industrial and clinical fields.
Assuntos
Técnicas Biossensoriais/instrumentação , Infecções por Escherichia coli/microbiologia , Escherichia coli O157/isolamento & purificação , Reação em Cadeia da Polimerase/instrumentação , Smartphone/instrumentação , Animais , Técnicas Biossensoriais/economia , DNA Bacteriano/análise , DNA Bacteriano/genética , Escherichia coli O157/genética , Análise de Alimentos/economia , Análise de Alimentos/instrumentação , Humanos , Leite/microbiologia , Sistemas Automatizados de Assistência Junto ao Leito/economia , Reação em Cadeia da Polimerase/economia , Smartphone/economia , Fatores de TempoRESUMO
A novel, rapid and convenient competitive immunoassay for ultrasensitive detection of chloramphenicol residues in shrimp and honey was established combined with flow injection chemiluminescence. The carboxylic resin beads were used as solid phase carriers to load with more coating antigen due to their larger specific surface area and good biocompatibility. The surface of the silica dioxide nanoparticles was modified with aldehyde group to combine with more horseradish peroxidase and the chloramphenicol antibody. There was a competitive process between the chloramphenicol in solution and the immobilized coating antigen to combine with the limited binding site of antibody to form the immunocomplex. Silica dioxide nanoparticles played an important role in enhancing chemiluminescence signal, because the horseradish peroxidase on SiO2 effectively catalyzed the system of luminol-PIP-H2O2. Under optimal conditions, the chemiluminescence intensity decreased linearly with the logarithm of the chloramphenicol concentration in the range of 0.0001 to 100â¯ngâ¯mL-1 and the detection limit (3σ) was 0.033â¯pgâ¯mL-1. This immunosensor demonstrated acceptable stability, high specificity and reproducibility. The horseradish peroxidase-silica dioxide nanoparticle-chloramphenicol antibody complex successfully prepared in this article was firstly applied to the detection of chloramphenicol, and had extremely important meanings for the application of nanoparticles and enzymatic catalysis in the field of chemiluminescence.
Assuntos
Antibacterianos/análise , Cloranfenicol/análise , Análise de Alimentos/instrumentação , Medições Luminescentes/instrumentação , Nanopartículas/química , Dióxido de Silício/química , Animais , Anticorpos Monoclonais/química , Técnicas Biossensoriais/economia , Técnicas Biossensoriais/instrumentação , Desenho de Equipamento , Análise de Injeção de Fluxo/economia , Análise de Injeção de Fluxo/instrumentação , Análise de Alimentos/economia , Mel/análise , Imunoensaio/economia , Imunoensaio/instrumentação , Limite de Detecção , Medições Luminescentes/economia , Penaeidae/química , Reprodutibilidade dos Testes , Resinas Sintéticas/química , Frutos do Mar/análiseRESUMO
Mid-infrared analysis of reconstituted milk is proposed as a feasible solution for the detection of milk powder adulteration regardless of the blending practice. To challenge the concept, skim milk powders were spiked with three of the most reactive/unstable of potential milk adulterants: semicarbazide hydrochloride, ammonium sulfate and cornstarch. To create the wet-blended set, a fraction of each sample was reconstituted and re-spray dried at laboratory scale with a benchtop spray dryer. Dry and wet-blended adulterated samples were reconstituted prior to mid-infrared measurement and projected onto a one-class classifier SIMCA model for reconstituted skim milk. Quantitative sensitivities, determined from the normalized orthogonal distances, were compared. Although the non-industrial spray drying introduced a spectroscopic bias, as revealed by the control samples, the non-targeted mid-infrared model showed comparable sensitivities for both blending practices once the main bias-rich spectral regions were removed, validating thereby the proposed concept.
Assuntos
Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Leite/química , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Sulfato de Amônio/química , Animais , Análise de Alimentos/economia , Modelos Teóricos , Pós/química , Semicarbazidas/química , Amido/químicaRESUMO
Monitoring of food quality, in particular, milk quality, is critical in order to maintain food safety and human health. To guarantee quality and safety of milk products and at the same time deliver those as soon as possible, rapid analysis methods as well as sensitive, reliable, cost-effective, easy-to-use devices and systems for process control and milk spoilage detection are needed. In this paper, we review different rapid methods, sensors and commercial systems for milk spoilage and microorganism detection. The main focus lies on chemical sensors and biosensors for detection/monitoring of the well-known indicators associated with bacterial growth and milk spoilage such as changes in pH value, conductivity/impedance, adenosine triphosphate level, concentration of dissolved oxygen and produced CO2. These sensors offer several advantages, like high sensitivity, fast response time, minimal sample preparation, miniaturization and ability for real-time monitoring of milk spoilage. In addition, electronic-nose- and electronic-tongue systems for the detection of characteristic volatile and non-volatile compounds related to microbial growth and milk spoilage are described. Finally, wireless sensors and color indicators for intelligent packaging are discussed.
Assuntos
Técnicas Biossensoriais/instrumentação , Análise de Alimentos/instrumentação , Leite/química , Animais , Técnicas Biossensoriais/economia , Técnicas Biossensoriais/métodos , Nariz Eletrônico/economia , Análise de Alimentos/economia , Análise de Alimentos/métodos , Qualidade dos Alimentos , Inocuidade dos Alimentos , Humanos , Leite/microbiologia , Fatores de Tempo , Tecnologia sem Fio/economia , Tecnologia sem Fio/instrumentaçãoRESUMO
An impedance based microfluidic biosensor for simultaneous and rapid detection of Salmonella serotypes B and D in ready-to-eat (RTE) Turkey matrix has been presented. Detection of Salmonella at a concentration as low as 300 cells/ml with a total detection time of 1 hour has been achieved. The sensor has two sensing regions, with each formed from one interdigitated electrode array (IDE array) consisting of 50 finger pairs. First, Salmonella antibody type B and D were prepared and delivered to the sensor to functionalize each sensing region without causing any cross contamination. Then the RTE Turkey samples spiked with Salmonella types B and D were introduced into the biosensor via the antigen inlet. The response signal resulted from the binding between Salmonella and its specific antibody demonstrated the sensor's ability to detect a single type of pathogen, and multiple pathogens simultaneously. In addition, the biosensor's selectivity was tested using non-specific binding of E. coli O157 and E. coli DH5 Alpha while the IDE array was coated with the Salmonella antibody. The results also showed the sensor is capable to differentiate low concentration of live Salmonella cells from high concentration of dead Salmonella cells, and high concentration of E. coli cells. A detailed study on antibody immobilization that includes antibody concentration, antibody coating time (0.5-3 hours) and use of cross-linker has been performed. The study showed that Salmonella antibody to Salmonella antigen is not a factor of antibody concentration after electrodes were saturated with antibody, while the optimal coating time was found to be 1.5 hours, and the use of cross-linker has improved the signal response by 45-60%.