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1.
Food Chem ; 331: 127348, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32619908

RESUMO

Information concerning food composition, including information on its glucose content, is essential for modern food industry due to greater consumer awareness and expectations. In this work, the gene encoding d-glucose dehydrogenase (GDH) from Bacillus Natto was expressed in Escherichia coli BL21(DE3) firstly. Ni-IDA column was used for the purification of GDH. Then, the purified GDH was used to construct a color system with stable and effective measurement of concentration of d-glucose. The smart phone photographing and the software Microsoft Photoshop have been used in the system for determination of the color. The enzymatic analysis system can detect the concentration of d-glucose from 5 mM to 40 mM, and other various sugars has no interference to the system. The system was used to quantitatively detect the concentration of d-glucose in honey. The system can be used for convenient and rapid detection of d-glucose in food, especially for large numbers of samples.


Assuntos
Análise de Alimentos/métodos , Glucose/análise , Mel/análise , Smartphone , Bacillus/genética , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Cor , Escherichia coli/genética , Análise de Alimentos/instrumentação , Glucose 1-Desidrogenase/genética , Glucose 1-Desidrogenase/metabolismo , Concentração de Íons de Hidrogênio , Limite de Detecção , Software
2.
Food Chem ; 331: 127361, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32650229

RESUMO

A low cost hand-held spectral analytical system was developed for in situ screening of phenolics and flavonoids in puff dried Ziziphus jujuba (Z. Jujuba) samples. Standards of gallic acid, caffeic acid, l-epicatechin, phloridzin and cianidanol were used to quantify the individual phenolics and flavonoids using high performance liquid chromatography-diode array detector (HPLC-DAD). The synergy interval partial least square with ant colony optimization (Si-ACO-PLS) was attempted to optimize and capture informative variables for the prediction of target compounds. The model performance was evaluated using correlation coefficients of prediction (Rp); root mean square error of prediction (RMSEP) and residual predictive deviation (RPD). The Si-ACO-PLS yielded optimal performance, 0.8540 ≤ Rc ≤ 0.9250, 0.8360 ≤ Rp ≤ 0.9056, 0.84 ≤ RMSEP ≤ 16.30 and 2.03 ≤ RPD ≤ 2.26. The hand-held spectral analytical system coupled with Si-ACO-PLS proved to the reliable, rapid and cost-effective method to quantify the phenolics and flavonoids in Z. Jujuba.


Assuntos
Flavonoides/análise , Análise de Alimentos/instrumentação , Análise de Alimentos/métodos , Fenóis/análise , Ziziphus/química , Algoritmos , Cromatografia Líquida de Alta Pressão , Dessecação/métodos , Análise de Alimentos/estatística & dados numéricos , Análise dos Mínimos Quadrados , Análise Espectral/instrumentação , Análise Espectral/métodos
3.
Food Chem ; 328: 127106, 2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-32485584

RESUMO

In this work, based on the strawberry-like SiO2/Ag nanocomposites (SANC) immersed filter paper, a newly surface-enhanced Raman scattering (SERS) substrate was constructed for the detection of acrylamide (AAm) in food products. To construct filter paper-based SANC (F-SANC) SERS substrates, SiO2 nanoparticles (SNP) were firstly synthesized and acted as carriers. After that, the in-situ preparation of silver nanoparticles (Ag NP) on SNP surface was carried out to form the strawberry-like three-dimensional (3D) structure of SANC. Finally, SANC were entangled into the filter paper to produce nanoarchitecture, thus providing enhanced plasmon resonance between SANC with strong SERS signal. Under the optimized conditions, the method exhibited good performance toward AAm with a vast linear response from 0.1 nM to 50 µM (R = 0.9935), limit of detection (LOD) of 0.02 nM (S/N = 3), and the recoveries of 80.5%~105.6% for practical samples. This strategy showed good robustness in the rapid and sensitive detection of AAm, which could be a promising strategy in food analysis and verification.


Assuntos
Acrilamida/análise , Análise de Alimentos/métodos , Nanopartículas Metálicas/química , Nanocompostos/química , Análise Espectral Raman/métodos , Filtração/instrumentação , Análise de Alimentos/instrumentação , Fragaria/química , Limite de Detecção , Dióxido de Silício/química , Prata/química
4.
Food Chem ; 329: 127162, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32492599

RESUMO

We report for the first time the use of biochar as a stabilizer for oil-in-water (o/w) Pickering emulsion. The emulsion is subsequently used to prepare tetracycline-imprinted biochar composite microspheres (MIPMs) with tailored sizes and good uniformity. The adsorption properties of tetracycline to the MIPMs were investigated using different adsorption experiments including adsorption kinetic experiment, equilibrium binding experiment, selectivity evaluation and competitive adsorption tests. The MIPMs were used as adsorbent for solid phase extraction (SPE) for the extraction of tetracycline present in drinking water, fish, and chicken samples. Under optimal conditions, the results showed good recovery yield ranging from ~73% to ~95% with a relative standard deviation (RSD) ranging from ~0.3% to ~8.4%, respectively.


Assuntos
Carvão Vegetal/química , Emulsões/química , Contaminação de Alimentos/análise , Extração em Fase Sólida/métodos , Tetraciclina/isolamento & purificação , Adsorção , Antibacterianos/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Análise de Alimentos/instrumentação , Análise de Alimentos/métodos , Microesferas , Impressão Molecular/métodos , Extração em Fase Sólida/instrumentação , Poluentes Químicos da Água/isolamento & purificação
5.
Food Chem ; 331: 127050, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32569961

RESUMO

A visualization and quantification image analysis method is developed to evaluate the water-absorbing characteristics of rice. A projected image of soaked rice was obtained by a scanner in real time, the expansion ratio of the soaked rice in the projected image was calculated with computer software, and the change in the internal structure was analyzed. The results showed that water absorption had a positive correlation with expansion and the cracks occurred in the internal structure of rice could accelerate the water absorption. The maximum expansion ratio of Japonica rice gradually increased with increased milling time, but that of Japonica glutinous rice was not significantly different (P > 0.05). A high soaking temperature shortened the time to reach the maximum expansion ratio and resulted in a lower expansion ratio in the Indica and Indica glutinous rice but had no significant effect (P > 0.05) in the Japonica and Japonica glutinous rice.


Assuntos
Visualização de Dados , Análise de Alimentos/métodos , Oryza/química , Sementes/química , Água/química , Adsorção , Análise de Alimentos/instrumentação , Genótipo , Oryza/genética , Software , Temperatura
6.
Food Chem ; 331: 127051, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32569974

RESUMO

A simple, fast, and efficient spark discharge-laser-induced breakdown spectroscopy (SD-LIBS) method was developed for determining rice botanic origin using predictive modeling based on support vector machine (SVM). Seventy-two samples from four rice varieties (Guri, Irga 424, Puitá, and Taim) were analyzed by SD-LIBS. Spectral lines of C, Ca, Fe, Mg, N and Na were selected as input variables for prediction model fitting. The SVM algorithm parameters were optimized using a central composite design (CCD) to find the better classification performance. The optimum model for discriminating rice samples according to their botanical variety was obtained using C = 5.25 and γ = 0.119. This model achieved 96.4% of correct predictions in test samples and showed sensitivities and specificities per class within the range of 92-100%. The developed method is robust and eco-friendly for rice botanic identification since its prediction results are consistent and reproducible and its application does not generate chemical waste.


Assuntos
Análise de Alimentos/métodos , Oryza/química , Análise Espectral/métodos , Algoritmos , Análise de Alimentos/instrumentação , Análise de Alimentos/estatística & dados numéricos , Lasers , Aprendizado de Máquina , Metais/análise , Sensibilidade e Especificidade , Análise Espectral/instrumentação , Análise Espectral/estatística & dados numéricos , Máquina de Vetores de Suporte
7.
Food Chem ; 331: 127090, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32593035

RESUMO

Chlorothalonil is a class of 2B carcinogen which is widely used in the prevention and treatment of fungal diseases in food samples. Its residual problem has been increasingly concerned by society. In this paper, a fast and simple colorimetric assay based on Manganese dioxide nanosheets (MnO2 NSs)-oxidize 3,3',5,5'-tetramethylbenzidine (TMB) platform was used to detect residual pesticide chlorothalonil in food samples. Under optimal conditions, the half maximal inhibitory concentration and the limit of detection of chlorothalonil were 3.27 and 0.024 ng/mL. There were no obvious cross-reactivity between chlorothalonil and interference substances. The recoveries shown the satisfactory results. The results of colorimetric assay for the authentic samples were largely consistent with gas chromatography. Therefore, the proposed method would be convenient and satisfactory analytical methods for the monitoring of chlorothalonil. Furthermore, the MnO2 - TMB system was used to produce test strips for quick and convenient visual detection of chlorothalonil with good performance.


Assuntos
Colorimetria/métodos , Análise de Alimentos/métodos , Compostos de Manganês/química , Nanoestruturas/química , Nitrilos/análise , Óxidos/química , Benzidinas/química , Colorimetria/instrumentação , Análise de Alimentos/instrumentação , Contaminação de Alimentos/análise , Fungicidas Industriais/análise , Limite de Detecção , Oxirredução , Oxirredutases/química
8.
Food Chem ; 331: 127163, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32593037

RESUMO

Herein, a surface plasmon resonance (SPR) enhanced DNA biosensor has been developed for real-time detection of donkey meat marker using biotinylated reporter and streptavidin functionalized gold nanostars (Stre@GNSs). Compared to the direct detection assay, this sandwich format for the enhancement of the signal, resulted in 6-folds orders increase in the sensitivity. Target DNA could be detected with the lower limit of quantification (LLOQ) of 1.0 nM with a relative standard deviation (RSD, n = 3) of 0.85%. In addition, the fabricated SPR sensor showed good selectivity for the target analyte over full complementary, single-base mismatch, three base-mismatch and non-complementary oligonucleotides. Finally, the proposed sensor was successfully applied for detection of donkey meat adulteration with various percentages in homemade beef sausage, as a real sample. The results indicated that the proposed biosensor provides a high specificity, easy, good sensitivity and fast approach for identification of donkey meat adulteration in food samples.


Assuntos
Técnicas Biossensoriais/métodos , Equidae/genética , Contaminação de Alimentos/análise , Carne/análise , Animais , Técnicas Biossensoriais/instrumentação , DNA/análise , Análise de Alimentos/instrumentação , Análise de Alimentos/métodos , Ouro/química , Limite de Detecção , Microscopia Eletrônica de Transmissão , Nanoestruturas/química , Espectrofotometria Ultravioleta , Estreptavidina/química , Ressonância de Plasmônio de Superfície/métodos
9.
Food Chem ; 324: 126664, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32380410

RESUMO

Authentication of meat products is critical in the food industry. Meat adulteration may lead to religious apprehensions, financial gain and food-toxicities such as meat allergies. Thus, empirical validation of the quality and constituents of meat is paramount. Various analytical methods often based on protein or DNA measurements are utilized to identify meat species. Protein-based methods, including electrophoretic and immunological techniques, are at times unsuitable for discriminating closely related species. Most of these methods have been replaced by more accurate and sensitive detection methods, such as DNA-based techniques. Emerging technologies like DNA barcoding and mass spectrometry are still in their infancy when it comes to their utilization in meat detection. Gold nanobiosensors have shown some promise in this regard. However, its applicability in small scale industries is distant. This article comprehensively reviews the recent developments in the field of analytical methods used for porcine identification.


Assuntos
Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Produtos da Carne/análise , Suínos , Animais , Técnicas Biossensoriais , Cromatografia/métodos , DNA/análise , Análise de Alimentos/instrumentação , Espectrometria de Massas , Carne/análise , Reação em Cadeia da Polimerase , Proteínas/análise , Análise Espectral/métodos , Suínos/genética
10.
Food Chem ; 328: 127081, 2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-32454260

RESUMO

Mycotoxin contaminations of tea have been considered serious problems. The presence of interfering substances presents enormous challenges to accurate detection of hazardous analytes in tea soups. In this work, we have carefully predicted, evaluated, and confirmed the matrix effects in tea that have an undesired influence on the detection of aflatoxin B1 (AFB1) in tea soups by lateral flow test strips (LFTS). After pretreatment of tea samples by simple dilution to change the acidic tea soups to alkaline environments, the matrix effects can be completely eliminated and the reliability of AFB1 analysis in tea soups can be effectively guaranteed. AFB1 contaminated samples of different tea soups can be accurately measured with detection limits down to 0.05 ppb. As the first pioneering report to study the matrix effects on AFB1 monitoring in tea soups by LFTS, we definitely expect this work to further widen the application of LFTS for hazard screening in food safety.


Assuntos
Aflatoxina B1/análise , Análise de Alimentos/instrumentação , Contaminação de Alimentos/análise , Chá/química , Limite de Detecção , Fitas Reagentes/química , Fatores de Tempo
11.
Food Chem ; 321: 126697, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32244141

RESUMO

Based on colloidal gold and broad-spectrum monoclonal antibody that binds to zeranol and its five analogues with high sensitivity, a lateral flow immunochromatographic assay (LFIA) in a competitive format was developed to specifically determine residues of zeranol, an illegal growth promoter in livestock. In this study, the assay had high sensitivity and was broad-spectrum only for zeranol and its five analogues, and the results were obtained within 10 min without needing sophisticated procedures. The cutoff values for zeranol and its five analogues were 10 ng/mL, and the IC50 values for zeranol, ß-zearalanol, zearalanone, α-zearalenol, ß-zearalenol and zearalenone were 1.250, 1.800, 1.775, 1.225, 1.709 and 1.319 ng/mL, respectively. The recovery rates were ranged from 85.6 to 93.9%, with the coefficient of variations less than 12.4%. The results demonstrated that the LFIA could be used for rapid, simultaneous, semi-quantitative and quantitative detection of residues of zeranol and its five analogous in milk.


Assuntos
Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Imunoensaio/métodos , Leite/química , Zeranol/análise , Animais , Anticorpos Monoclonais/imunologia , Desenho de Equipamento , Análise de Alimentos/instrumentação , Coloide de Ouro/química , Imunoensaio/instrumentação , Sensibilidade e Especificidade , Zearalenona/análise , Zeranol/análogos & derivados , Zeranol/imunologia
12.
Food Chem ; 322: 126762, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32283369

RESUMO

A novel electrochemical aptasensor modified with highly porous gold and aptamer was prepared for the determination of acetamiprid in fruits and vegetables. Highly porous gold was synthesized by electroreduction at -4 V in an electrolyte containing 2.5 mol/L NH4Cl and 10 mmol/L HAuCl4. Acetamiprid-binding aptamer was immobilized on highly porous gold by self-assembly. Acetamiprid could be captured by aptamer on the sensing interface, resulting in an increment of electron transfer resistance. Thanks to the large specific surface area of highly porous gold and the high affinity of aptamer, the aptasensor exhibited a highly sensitive impedance response for acetamiprid. Under optimal condition, the aptasensor displayed a linear response for acetamiprid in the concentration range of 0.5-300 nmol/L, and the detection limit was 0.34 nmol/L. Furthermore, the aptasensor showed high selectivity, good reproducibility and stability. Finally, the aptasensor was applied for the determination of acetamiprid in fruits and vegetables with satisfactory results.


Assuntos
Aptâmeros de Nucleotídeos/química , Técnicas Eletroquímicas/métodos , Análise de Alimentos/métodos , Neonicotinoides/análise , Impedância Elétrica , Técnicas Eletroquímicas/instrumentação , Análise de Alimentos/instrumentação , Contaminação de Alimentos/análise , Frutas/química , Ouro/química , Limite de Detecção , Praguicidas/análise , Porosidade , Reprodutibilidade dos Testes , Verduras/química
13.
Food Chem ; 320: 126683, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32229401

RESUMO

Here, we demonstrate use of acetylcholinesterase (AChE)-responsive polyoxometalate (POM)/surfactant supramolecular spheres to build a liquid crystal (LC)-based sensing platform for detection of organophosphorus pesticides. The self-assembled spheres are composed of hybrid materials of a POM, sodium dodecatungstophosphate (PW12), and a surfactant, myristoylcholine (Myr). It displays dark appearance when the aqueous solution is in contact with LCs supported on the octadecyltrichlorosilane-treated glass deposited with the supramolecular spheres, suggesting perpendicular orientation of LCs at the aqueous/LC interface. In contrast, LCs show bright appearance when the surface-deposited supramolecular spheres are enzymatically hydrolyzed by AChE, corresponding to planar orientation of LCs at the aqueous/LC interface. Detection of organophosphates are successfully achieved as they are potent inhibitors of AChE. The detection limit of the sensing platform reached 0.9 ng/mL for dimethoate. This method can avoid disturbance of external interference with excellent specificity and sensitivity, which makes it very promise in detection of organophosphorus pesticides.


Assuntos
Acetilcolinesterase/metabolismo , Análise de Alimentos/métodos , Cristais Líquidos/química , Praguicidas/análise , Análise de Alimentos/instrumentação , Hidrólise , Lagos/análise , Limite de Detecção , Compostos Organofosforados/análise , Silanos/química , Tensoativos/química , Compostos de Tungstênio/química , Água/química , Poluentes Químicos da Água/análise
14.
J Environ Sci Health B ; 55(6): 583-591, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32238102

RESUMO

An original voltammetric screening method, employing glassy carbon electrode (GCE) with the differential-pulse voltammetry technique (DPV), has been developed to determine residues of the anti-parasitic agent Ronidazole (RNZ) in bovine meat. By using cyclic voltammetry (CV), it has been demonstrated that an irreversible cathodic process occurs at approximately -0.740 V (vs. Ag|AgCl, KCl 3 mol L-1) in a 0.100 mol L-1 phosphate buffer at pH 6.5 as supporting electrolyte. Furthermore, the behavior of RNZ in CV indicates the occurrence of a diffusion mass transfer process to the working electrode surface. The RNZ reduction mechanism was proposed as a 6-electron transfer, similar to Metronidazole under the same pH range. Quantification of RNZ and method validation were then carried out by DPV. The relative standard deviation (RSD) were 3.21% for intraday precision of 10 consecutive repetitions and 6.78% for interday precision after five analysis. Limits of detection and quantification were also obtained, and the values were 0.107 and 0.358 mg kg-1, respectively. The recovery percentage for three different concentrations of RNZ in the bovine meat matrix ranged between 98.1% and 100.3%. The method proved to be efficient for screening RNZ in bovine meat.


Assuntos
Eletroquímica/métodos , Análise de Alimentos/métodos , Carne Vermelha/análise , Ronidazole/análise , Animais , Carbono , Bovinos , Eletroquímica/instrumentação , Eletrodos , Análise de Alimentos/instrumentação , Contaminação de Alimentos/análise , Limite de Detecção , Reprodutibilidade dos Testes
15.
Food Chem ; 317: 126459, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32113141

RESUMO

The widespread exposure of bisphenol A (BPA) presents a significant risk to human health. A rapid, ultra-sensitive and label-free colorimetric aptasensor using high affinity truncated aptamers was developed for BPA detection. Truncated 38-mer and 12-mer aptamers specific for BPA were obtained through rationally truncation from 63-mer BPA aptamer. The dissociation constants (Kd) of 38-mer and 12-mer aptamers were determined to be 13.17 nM and 27.05 nM. Then, truncated aptamers were used in label-free colorimetric detection assays based on gold nanoparticles (AuNPs). The limit of detections of aptasensors using 38-mer and 12-mer aptamers were 7.60 pM and 14.41 pM, which were 265-fold and 140-fold lower than that of the aptasensor using 63-mer aptamer, respectively. The recovery rates in milk, orange juice and mineralized water samples were 93.88% to 107.30%. Therefore, the developed BPA colorimetric aptasensor using truncated aptamers has great application prospects in food safety control and environmental monitoring.


Assuntos
Aptâmeros de Nucleotídeos/química , Compostos Benzidrílicos/análise , Colorimetria/métodos , Análise de Alimentos/métodos , Fenóis/análise , Animais , Aptâmeros de Nucleotídeos/metabolismo , Compostos Benzidrílicos/química , Compostos Benzidrílicos/metabolismo , Análise de Alimentos/instrumentação , Contaminação de Alimentos/análise , Sucos de Frutas e Vegetais/análise , Ouro/química , Limite de Detecção , Nanopartículas Metálicas/química , Leite/química , Simulação de Acoplamento Molecular , Fenóis/química , Fenóis/metabolismo , Sensibilidade e Especificidade
16.
Food Chem ; 319: 126575, 2020 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-32172051

RESUMO

A core-shell molecular imprinting fluorescence nanosensor was developed for the ratiometric fluorescence and visual detection of folic acid (FA). The nanosensor was prepared by anchoring imprinting shell on the silica nanoparticles, and embedding the CdTe quantum dots in imprinted shell to provide FA-dependent fluorescence signals. Under the optimum conditions, a favorable linearity relationship between the fluorescence intensities ratio (I449/I619) and the FA concentration over 0.23-113 µM was offered with a detection limit (LOD) of 48 nM. The visual detection for FA was realized by evaluating profuse fluorescence color change from red to pink to purple to final blue. The proposed sensor possessed excellent sensing performances of rapid response, high precision, super sensitivity and selective recognition. Furthermore, endogenous FA was detected in real samples ranging from 37.4 to 265.8 µg/100 g; satisfactory spiked recoveries were obtained within 94.8-104.2%, which conformed to the measurement results by HPLC-UV.


Assuntos
Ácido Fólico/análise , Análise de Alimentos/instrumentação , Análise de Alimentos/métodos , Impressão Molecular/métodos , Compostos de Cádmio/química , Cor , Ácido Fólico/química , Limite de Detecção , Nanopartículas/química , Propilaminas/química , Pontos Quânticos/química , Sensibilidade e Especificidade , Silanos/química , Dióxido de Silício/química , Espectrometria de Fluorescência/instrumentação , Espectrometria de Fluorescência/métodos , Telúrio/química
17.
Food Chem ; 318: 126471, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32120138

RESUMO

A portable near infrared spectroscopy (NIRS) instrument was evaluated for the discrimination of individual Iberian pig carcasses into the four official quality categories (defined by a combination of genotype and feeding regime). Spectra were obtained scanning four anatomical locations (live animal skin, carcass surface, fresh meat and subcutaneous fat samples) at a commercial abattoir, using a handheld micro electro mechanical system instrument. The best assignments into official quality categories with the NIRS measurements in the carcass surface and subcutaneous fat were able to correctly classify 75.9% and 73.8% of the carcasses, respectively. Moreover, 93.2% and 93.4% of carcasses were correctly classified according to feeding regimes by using the spectra from fresh meat and subcutaneous fat samples. The results suggest that, using subcutaneous fat samples, a portable NIRS could be used in commercial abattoirs as a tool to support the control of official quality category assignment in Iberian pig carcasses.


Assuntos
Análise de Alimentos/instrumentação , Carne de Porco/análise , Espectroscopia de Luz Próxima ao Infravermelho/instrumentação , Ração Animal , Animais , Análise de Alimentos/métodos , Qualidade dos Alimentos , Pele , Espanha , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Gordura Subcutânea/química , Suínos/genética
18.
Food Chem ; 318: 126461, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32143129

RESUMO

A sensor consisting of an optical fibre with the exposed tip coated with the polyoxometalate salt [(C4H9)4N]4H[PMo10V2O40], specially designed to be insoluble in water, which UV-Vis spectrum changed in contact with formaldehyde, is presented. The sensor limit of detection for formaldehyde was 0.2 mg L-1, and the limit of quantification was 0.6 mg L-1, which were close to the conventional spectrophotometric method values of 0.2 mg L-1 and 0.5 mg L-1, respectively, and lower than the tolerable limit for ingested food. The sensor was tested for formaldehyde quantification in milk, as its deliberate addition is a matter of concern. The results obtained analysing formaldehyde in milk samples by the optical sensor and by the conventional method were not statistically different (α = 0.05).


Assuntos
Análise de Alimentos/instrumentação , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Formaldeído/análise , Leite/química , Fibras Ópticas , Animais , Limite de Detecção , Óptica e Fotônica/instrumentação , Óptica e Fotônica/métodos , Compostos de Tungstênio/química , Água/química
19.
Food Chem ; 317: 126455, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32109659

RESUMO

This study presents an experimental approach to study the kinetics and fast release of volatile organic compounds (VOCs) upon reconstitution of instant coffee products. A sampling setup coupled to PTR-ToF-MS (Proton Transfer Reaction Time-of-Flight Mass Spectrometry) for the automated and reproducible reconstitution of instant coffee products was developed to monitor the dynamic release of VOCs. A rapid release of aroma compounds was observed in the first seconds upon hot water addition ("aroma burst"), followed by subsequent decrease in headspace (HS) intensities over the course of analysis. Differences in time-intensity release profiles of individual VOCs were correlated to their Henry's Law constant, vapor pressure and water solubility. The setup and approach proposed here have shown to be sensitive and to respond to fast dynamic changes in aroma release. It allows studying VOCs release upon reconstitution and supports the development of novel technologies and formulations for instant products with improved aroma release properties.


Assuntos
Café/química , Análise de Alimentos/métodos , Odorantes/análise , Compostos Orgânicos Voláteis/análise , Análise de Alimentos/instrumentação , Cinética , Espectrometria de Massas/instrumentação , Espectrometria de Massas/métodos , Prótons , Solubilidade , Água
20.
Food Chem ; 317: 126456, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32109661

RESUMO

In recent years, gold nanoclusters (AuNCs) have received considerable attention as optical transducers in chemo/biosensors. Herein, a facile and efficient assay for NO2- has been successfully developed based on the fluorescence quenching of AuNCs co-modified by bovine serum albumin and 3-mercaptopropionic acid (BSA/MPA-AuNCs). In the presence of NO2- under acidic conditions, Fe2+ can be readily oxidized and transformed to Fe3+, which can significantly suppress the fluorescence of BSA/MPA-AuNCs via non-radiative electron-transfer mechanism. The linear range and detection limit for this system were found to be 5-30 µM (r = 0.9975) and 0.7 µM, respectively. Other common anions and cations showed only very minor interference with the NO2- detection. Furthermore, the effectiveness of the proposed sensing strategy was validated by the demonstration of good performance in the determination of the amount of NO2- in ham samples, rendering it a powerful tool for the assessment of food security and water quality.


Assuntos
Análise de Alimentos/métodos , Ferro/química , Nanoestruturas/química , Nitritos/análise , Ácido 3-Mercaptopropiônico/química , Técnicas Biossensoriais , Fluorescência , Corantes Fluorescentes/química , Análise de Alimentos/instrumentação , Ouro/química , Limite de Detecção , Nitritos/química , Oxirredução , Carne de Porco/análise , Sensibilidade e Especificidade , Soroalbumina Bovina/química , Espectrometria de Fluorescência
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