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1.
Food Chem ; 332: 127419, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32622190

RESUMO

Aflatoxins (AFs) are potent carcinogens present in numerous crops. Access to accurate methods for evaluating contamination is a critical factor in aflatoxin risk assessment. Versicolorin A (Ver A), a precursor of aflatoxin B1 (AFB1), can be used as an indicator for the presence of AFB1, even when the AF is not yet detectable. Currently employed Ver A detection methods are expensive, time consuming, and difficult to apply to numerous samples. Herein, Ver A was detected via near-infrared spectroscopy. Both quantitative and two-grade sorting methods were set-up using the extreme gradient boosting algorithm coupled with a support vector machine. This two-tiered method obtained a root-mean-square error of prediction value of 3.57 µg/kg for the quantitative model, and an accuracy rate of 90.32% for the sorting approach. This novel method is rapid, accurate, solvent free, requires no sample pretreatment, and detects Ver A in maize, making it convenient for practical use.


Assuntos
Aflatoxina B1/análise , Antraquinonas/análise , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Zea mays/química , Contaminação de Alimentos/análise , Humanos
2.
PLoS One ; 15(7): e0236634, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32706842

RESUMO

Potassium (K) input is essential for the improvement of soil fertility in agricultural systems. However, organic amendment may differ from mineral K fertilization with respect to modifying the soil K transformation among different fractions, affecting soil K availability. We conducted a 60-day lab incubation experiment to evaluate the response of soil K dynamics and availability in various fractions with a view to simulating crop residue return and chemical K fertilization in an Anthrosol of northwest China. The tested soil was divided into two main groups, no K fertilization (K0) and K fertilization (K1), each of which was subjected to four straw addition regimes: no straw addition (Control), wheat straw addition (WS), maize straw addition (MS), and both wheat straw and maize straw addition (WS+MS). Soil K levels in the available (AK) and non-exchangeable (NEK) fractions were both significantly increased after K addition, following the order of K>WS>MS. Fertilizer K was the most efficient K source, demonstrating a 72.9% efficiency in increasing soil AK, while wheat and maize straw exhibited efficiencies of 47.1% and 39.3%, respectively. Furthermore, K fertilization and wheat and maize straw addition increased the soil AK in a cumulative manner when used in combination. The mobility factor (MF) and reduced partition index (IR) of soil K were used to quantitate the comprehensive soil K mobility and stability, respectively. Positive relationships were observed between the MF and all relatively available fractions of soil K, whereas the IR value of soil K correlated negatively with both MF and all available fractions of soil K. In conclusion, straw amendment could be inferior to mineral K fertilization in improving soil K availability when they were almost equal in the net K input. Crop straw return coupled with K fertilization can be a promising strategy for improving both soil K availability and cycling in soil-plant systems.


Assuntos
Agricultura , Potássio/química , Solo/química , Triticum/metabolismo , Zea mays/metabolismo , China , Fertilizantes/análise , Potássio/metabolismo , Análise de Componente Principal , Triticum/química , Zea mays/química
3.
Food Chem ; 331: 127314, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32590264

RESUMO

The formation of short-lived and stable radicals was investigated using electron paramagnetic resonance (EPR) spectroscopy and compared with hydroperoxides and hexanal in complex starch-protein-lipid model systems, as well as in corn extrudates. Stable radicals were detected directly in ground samples. Short-lived lipid radicals were measured ex situ in ethyl acetate extracts of model systems and extrudates by the use of the spin trap PBN. Significant adduct formation was found after 30 min at 50 °C. During storage, lipid radicals (PBN adducts) increased in model systems. Simulation of EPR spectra from bulk oil demonstrated that mainly alkoxyl radical adducts were detected, to which rapidly decomposing peroxyl radical adducts also contributed. Stable radicals in extrudates were attributed to protein radicals based on g-value of 2.00467 compared with 2.00474 found in model system prepared with zein. The signal intensity of the stable radical remained constant during storage, but increased during extrusion.


Assuntos
Espectroscopia de Ressonância de Spin Eletrônica , Radicais Livres/química , Lipídeos/química , Proteínas de Plantas/química , Amido/química , Zea mays/química
4.
Food Chem ; 330: 127242, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32540530

RESUMO

The aim of this paper was to evaluate the effect of thermal treatment and UV irradiation on structural and physicochemical properties of octenyl succinate (OS) maize starches differing in content of OS groups (0.76%-2.38%). X-ray diffraction (XRD), gel permeation chromatography (GPC), and electron paramagnetic resonance (EPR) spectroscopy were used to estimate structural characteristics of octenyl succinate starches and their physically treated counterparts. Starch functional properties were also determined. XRD spectra and hydrodynamic volume distribution revealed that growth of octenyl succinate groups' content resulted in stabilization of starch structure, which was confirmed by processes of radical formation, stimulated by thermal and UV treatments. It was found, on the basis of measurements of water binding capacity, water solubility and intrinsic viscosity, that OSA addition changed physicochemical properties of starch and influenced the course of physical modifications. It was established that temperature affected starch properties to a greater extent than UV.


Assuntos
Amido/química , Succinatos/química , Zea mays/química , Solubilidade , Temperatura , Viscosidade , Difração de Raios X
5.
Food Chem ; 328: 127121, 2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-32474241

RESUMO

Chlorine dioxide (ClO2) gas was utilized for detoxifying aflatoxin B1 (AFB1) in corn for the first time. Four degradation compounds were identified by LC-MS as C17H13O8, C17H15O10, C16H15O10, and C15H11O8. Structurally, the biological activity of ClO2-treated AFB1 was removed due to the disappearance of C8-C9 double bond in the furan ring and the modification of cyclopentanone and methoxy after ClO2 treatment. The cell viability assay on human embryo hepatocytes confirmed little toxicity of the degradation products. The degradation efficiency of AFB1 on corn peaked near 90.0% under the optimized conditions and reached 79.6% for low initial contamination of AFB1 at 5-20 µg/kg. Accordingly, ClO2 has the potential to be developed into an effective, efficient, and economic approach to detoxify AFB1 in grains.


Assuntos
Aflatoxina B1/química , Compostos Clorados/química , Cloro/química , Óxidos/química , Zea mays/química , Cromatografia Líquida de Alta Pressão , Espectrometria de Massas
6.
Food Chem ; 331: 127190, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32562982

RESUMO

Monitoring neonicotinoid residues in grains is of significant interest for the proper assessment of pesticide exposure to human. The quick, easy, cheap, effective, rugged, and safe extraction method combined with dispersive liquid-liquid micro-extraction (QuEChERS-DLLME) was developed for extracting, purifying, and concentrating seven common neonicotinoid pesticides from the grains (rice, millet, and maize). Water and acetonitrile were used in tandem as extractants in QuEChERS, while water, acetonitrile, and trichloromethane in DLLME acted as the external phase, dispersant, and extractant, respectively. Comprehensive consideration of the single factor test and response surface method to optimize parameters including type and volume of extractants and dispersant. The evaluation showed that the QuEChERS-DLLME method held excellent linearity (R2 > 0.99). The limits of quantitation ranged from 0.003 to 0.08 µg kg-1 for the seven insecticides. The recoveries were in the range of 62-118%, and good reproducibility was obtained with a relative standard deviation below 15%.


Assuntos
Grão Comestível/química , Contaminação de Alimentos/análise , Microextração em Fase Líquida/métodos , Neonicotinoides/análise , Resíduos de Praguicidas/análise , Espectrometria de Massas em Tandem/métodos , Acetonitrilos/química , Cromatografia Líquida/métodos , Inseticidas/análise , Limite de Detecção , Oryza/química , Reprodutibilidade dos Testes , Zea mays/química
7.
Food Chem ; 326: 126972, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32422510

RESUMO

Different bread formulations, which provide different dough structures, were studied in order to better understand the effect of wheat flour substitution, flour type and concentration on dough development during baking, and their relationship with physical properties of the final product. Breads were produced with partial substitution of wheat flour by corn (CF), green banana (GF) and rice flour (RF), at different concentrations, and then baked at different times. Wheat flour substitution by CF, GF and RF in bread reduces heat transfer to the dough center by about 21%, 35% and 20%, respectively; and the water loss by about 5%, 15% and 0%, respectively. Those reductions were more influenced by flour type, than flour concentration. When wheat flour is substituted, the mechanisms of water migration are modified, once the pore system of bread dough is more discrete and stiffens later. Calculated thermal conductivity and diffusivity of the different flours used, and its correlations with average composite-bread heating rates (0.93) and water loss (0.85), respectively, indicates that thermal properties of composite bread dough could represent an important issue to be explored in dough systems with reduced gluten concentration.


Assuntos
Pão , Farinha , Musa , Oryza , Zea mays , Glutens/análise , Musa/química , Oryza/química , Temperatura , Triticum/química , Água , Zea mays/química
8.
Nat Struct Mol Biol ; 27(5): 480-488, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32398825

RESUMO

Cryptochromes (CRYs) are a group of evolutionarily conserved flavoproteins found in many organisms. In plants, the well-studied CRY photoreceptor, activated by blue light, plays essential roles in plant growth and development. However, the mechanism of activation remains largely unknown. Here, we determined the oligomeric structures of the blue-light-perceiving PHR domain of Zea mays CRY1 and an Arabidopsis CRY2 constitutively active mutant. The structures form dimers and tetramers whose functional importance is examined in vitro and in vivo with Arabidopsis CRY2. Structure-based analysis suggests that blue light may be perceived by CRY to cause conformational changes, whose precise nature remains to be determined, leading to oligomerization that is essential for downstream signaling. This photoactivation mechanism may be widely used by plant CRYs. Our study reveals a molecular mechanism of plant CRY activation and also paves the way for design of CRY as a more efficient optical switch.


Assuntos
Proteínas de Arabidopsis/química , Arabidopsis/química , Criptocromos/química , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Microscopia Crioeletrônica , Criptocromos/genética , Criptocromos/metabolismo , Cristalografia por Raios X , Modelos Moleculares , Plantas Geneticamente Modificadas , Mutação Puntual , Conformação Proteica , Domínios Proteicos , Multimerização Proteica , Zea mays/química
9.
Artigo em Inglês | MEDLINE | ID: mdl-32460612

RESUMO

The methane production and the microbial community dynamics of thermophilic anaerobic co-digestion (AD) of corn stover, swine manure and effluent were conducted at total solid (TS) content of 5%, 10% and 15%, the carbon to nitrogen ratio (C/N) of 20, 30 and 40 and the effluent volumetric percentage (EVP) of 20%, 40% and 60%. For batches with 5% TS, the highest methane yield of 238.5-283.1 mL g-1 volatile solid (VS) and the specific methane productivity of 138.5-152.2 mL g-1 initial VS were obtained at the C/N ratios of 20 and 30. For the mixtures with 10% and 15% TS, the highest methane yield was 341.9 mL g-1 VS and 351.2 mL g-1 VS, respectively, when the C/N ratio of 20% and 60% EVP conditions were maintained. Co-digestion of swine manure with corn stover caused an obvious shift in microbial population, in which the archaeal population changed from 0.3% to 2.8% and the bacterial community changed from 97.2% to 99.7%. The experimental batches with the highest relative abundance of the archaeal population (2.00% of total microbial population for 5% TS, 1.74% for 10% TS and 2.76% for 15% TS) had the highest rate of methanogenesis subsequently enhancing methane production (283.08 mL g-1 VS for 5% TS, 341.91 mL g-1 VS for 10% TS and 351.23 mL g-1 VS for 15% TS). The results of microbiome analysis enabled understanding the key populations in biomethane generation.


Assuntos
Reatores Biológicos/microbiologia , Esterco/análise , Metano/biossíntese , Microbiota , Resíduos Sólidos/análise , Zea mays/química , Anaerobiose , Animais , Archaea/crescimento & desenvolvimento , Bactérias Anaeróbias/crescimento & desenvolvimento , Biocombustíveis/análise , Carbono/análise , Modelos Teóricos , Nitrogênio/análise , Suínos
10.
Food Chem ; 327: 127058, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32464462

RESUMO

A "turn-on" fluorescence sensor was developed for total detection of fumonisin B1, B2 and B3 (FB1, FB2 and FB3) in maize samples. Rhodamine B isothiocyanate (RBITC) and gold nanoparticles (AuNPs) were employed as the energy donor-acceptor pairs. The intensity of restored fluorescence was inversely proportional to the concentration of the FBs. The limit of detection (LOD) of the sensor for FB1 was 23.80 pg/mL. The coefficient of variation (CV) was both less than 7% for intra- and inter-assay. The linear range was from 51.39 to 2125.92 pg/mL. The average recoveries of FBs from maize samples were ranged from 88.7% to 107.2%. The correlation coefficient of the results between the developed sensor and LC-MS/MS was 0.9970. To fulfill the procedure of the assay, only 46 min was needed. These results suggest that the fluorescence "turn-on" sensor has great potential applications in the analysis of FBs in maize samples.


Assuntos
Cisteamina/química , Fumonisinas/análise , Espectrometria de Fluorescência/métodos , Contaminação de Alimentos/análise , Ouro/química , Limite de Detecção , Nanopartículas Metálicas/química , Rodaminas/química , Zea mays/química , Zea mays/metabolismo
11.
J Vis Exp ; (159)2020 05 10.
Artigo em Inglês | MEDLINE | ID: mdl-32449746

RESUMO

Many nitrogen fertilizer studies evaluate the overall effect of a treatment on end-of-season measurements such as grain yield or cumulative N losses. A stable isotope approach is necessary to follow and quantify the fate of fertilizer derived N (FDN) through the soil-crop system. The purpose of this paper is to describe a small-plot research design utilizing non-confined 15N enriched microplots for multiple soil and plant sampling events over two growing seasons and provide sample collection, handling, and processing protocols for total 15N analysis. The methods were demonstrated using a replicated study from south-central Minnesota planted to corn (Zea mays L.). Each treatment consisted of six corn rows (76 cm row-spacing) 15.2 m long with a microplot (2.4 m by 3.8 m) embedded at one end. Fertilizer-grade urea was applied at 135 kg N∙ha-1 at planting, while the microplot received urea enriched to 5 atom % 15N. Soil and plant samples were taken several times throughout the growing season, taking care to minimize cross-contamination by using separate tools and physically separating unenriched and enriched samples during all procedures. Soil and plant samples were dried, ground to pass through a 2 mm screen, and then ground to a flour-like consistency using a roller jar mill. Tracer studies require additional planning, sample processing time and manual labor, and incur higher costs for 15N enriched materials and sample analysis than traditional N studies. However, using the mass balance approach, tracer studies with multiple in-season sampling events allow the researcher to estimate FDN distribution through the soil-crop system and estimate unaccounted-for FDN from the system.


Assuntos
Marcação por Isótopo/métodos , Isótopos de Nitrogênio/análise , Solo/química , Zea mays/química , Biomassa , Fertilizantes/análise
12.
J Biosci Bioeng ; 130(2): 195-199, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32370929

RESUMO

Ectoine production using inexpensive and renewable biomass resources has attracted great interest among the researchers due to the low yields of ectoine in current fermentation approaches that complicate the large-scale production of ectoine. In this study, ectoine was produced from corn steep liquor (CSL) and soybean hydrolysate (SH) in replacement to yeast extract as the nitrogen sources for the fermentation process. To enhance the bacterial growth and ectoine production, biotin was added to the Halomonas salina fermentation media. In addition, the effects addition of surfactants such as Tween 80 and saponin on the ectoine production were also investigated. Results showed that both the CSL and SH can be used as the nitrogen source substitutes in the fermentation media. Higher amount of ectoine (1781.9 mg L-1) was produced in shake flask culture with SH-containing media as compared to CSL-containing media. A total of 2537.0 mg L-1 of ectoine was produced at pH 7 when SH-containing media was applied in the 2 L batch fermentation. Moreover, highest amount of ectoine (1802.0 mg L-1) was recorded in the SH-containing shake flask culture with addition of 0.2 µm mL-1 biotin. This study demonstrated the efficacy of industrial waste as the nutrient supplement for the fermentation of ectoine production.


Assuntos
Diamino Aminoácidos/metabolismo , Fermentação , Halomonas/metabolismo , Microbiologia Industrial/métodos , Técnicas de Cultura Celular por Lotes , Biomassa , Biotina/metabolismo , Meios de Cultura/química , Meios de Cultura/metabolismo , Resíduos Industriais , Nitrogênio/metabolismo , Soja/química , Zea mays/química
13.
PLoS One ; 15(5): e0233094, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32392267

RESUMO

Sweet corn juice is becoming increasingly popular in China. In order to provide valuable health-related information to consumers, the nutritional and physicochemical characteristics of raw and boiled purple sweet corn juices were herein investigated. Sugars, antinutrients, total free phenols, anthocyanins, and antioxidant activity were analyzed by conventional chemical methods. The viscosity and stability of juices were determined by Ubbelohde viscosity meter and centrifugation, respectively. Boiling process could elevate viscosity, stability and sugar content, and reduce antinutrients, total free phenols, anthocyanins, and antioxidant activity in corn juice. In addition, short time boiling efficiently reduced the degradation of anthocyanins during subsequent refrigeration. The content of amino acids, vitamin B1/B2 and E were detected by High Performance Liquid Chromatography. Gas Chromatography Mass Spectrometry was used for the analysis of fatty acids and aroma compounds. Several aroma compounds not previously reported in corn were identified, including 1-heptanol, 2-methyl-2-butenal, (Z)-3-nonen-1-ol, 3-ethyl-2-methyl-1,3-hexadiene, and 2,4-bis(1,1-dimethylethyl)phenol. Interestingly, the boiling process had no apparent effect on the amino acids profile, but it caused a 45.8% loss of fatty acids in the juice by promoting the retention of fatty acids in the corn residue. These results provide detailed information that could be used for increasing consumers' knowledge of sweet corn juice, further development of sweet corn juice by food producers, and maize breeding programs.


Assuntos
Zea mays/química , Aldeídos/análise , Aminoácidos/análise , Antocianinas/análise , Antioxidantes/análise , Cromatografia Líquida de Alta Pressão , Cromatografia Gasosa-Espectrometria de Massas , Heptanol/análise , Fenóis/análise , Extratos Vegetais/análise , Riboflavina/análise , Tiamina/análise
14.
Food Chem ; 321: 126712, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32247179

RESUMO

Zein, a class of prolamine proteins extracted from maize, is extensively used in the food and pharmaceutical industries. Characterization of its components is essential for quality control and safety evaluation. We performed in silico digestion of zein proteins using tandem combinations of different proteinases, to improve protein sequence coverage and subsequent identification by nano-LC-MS/MS analysis. Trypsin/chymotrypsin yielded the highest protein sequence coverage of up to 79.5% and increased the number of proteins from 11 to 35 compared to trypsin/Lys-C. Besides, SDS-PAGE analysis revealed 37 proteins in the zein extract, as well as the possibility of protein polymers. Also, 420 peptides originating from 71 proteins were identified, of which 116 were predicted as bioactive by in silico approach. In conclusion, in silico prediction coupled with multi-enzyme digestion can significantly improve the coverage of complex zein protein proteome, and the potential function of zein proteins and peptides need be further investigated.


Assuntos
Excipientes/química , Peptídeos/química , Zea mays/química , Zeína/química , Sequência de Aminoácidos , Cromatografia Líquida de Alta Pressão , Excipientes/metabolismo , Peptídeos/metabolismo , Proteoma/química , Proteoma/metabolismo , Espectrometria de Massas em Tandem , Zea mays/metabolismo , Zeína/metabolismo
15.
PLoS One ; 15(4): e0230583, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32267871

RESUMO

Folic acid content was evaluated in food preparations containing wheat and corn flour submitted to baking, deep-frying, and steaming. Commercially fortified flours showed the absence of folic acid. Flours with laboratory folic acid fortification showed 487 and 474 µg of folic acid in 100 g of wheat and corn flours, respectively. In the corn flour preparations, the cake had the highest retention (99%) when compared to couscous (97%). Besides, the cake showed higher retention when compared to the wheat flour preparations due to the interactions of the folic acid with the hydrophobic amino acids of the Zein, a protein found in corn. In wheat flour preparations, vitamin retention was 87%, 80% and 57% in bread, cake, and White sauce respectively. These findings relate to the change of the physicochemical properties of food components that occurs during mixing and cooking of the ingredients.


Assuntos
Culinária/métodos , Farinha/análise , Ácido Fólico/análise , Triticum/química , Zea mays/química , Cromatografia Líquida de Alta Pressão
16.
PLoS One ; 15(4): e0230952, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32267852

RESUMO

Native Americans developed agronomic practices throughout the Western Hemisphere adapted to regional climate, edaphic conditions, and the extent of dependence on agriculture for subsistence. These included the mounding or "corn hill" system in northeastern North America. Iroquoian language speakers of present-day New York, USA, and Ontario and Québec, Canada were among those who used this system. While well-known, there has been little archaeological documentation of the system. As a result, there is scant archaeological evidence on how Iroquoian farmers maintained soil fertility in their often-extensive agricultural fields. Using δ15N values obtained on fifteenth- and sixteenth-century AD maize kernels from archaeological sites in New York and Ontario, adjusted to take into account changes that result from charring as determined through experiments, we demonstrate that Iroquoian farmers were successful at maintaining nitrogen in their agricultural fields. These results add to our archaeological knowledge of Iroquoian agronomic practices. Our results also indicate the potential value of obtaining δ15N values on archaeological maize in the investigation of Native American agronomic practices.


Assuntos
Agricultura/história , Isótopos de Nitrogênio/química , Solo/química , Zea mays/química , Agricultura/métodos , Arqueologia/métodos , Isótopos de Carbono/química , Clima , Fazendeiros/história , História do Século XV , História do Século XVI , Idioma , New York , Nitrogênio/química , Ontário , Quebeque
17.
J Food Sci ; 85(4): 862-869, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32237090

RESUMO

The increase in the use of bioactive compounds from purple corn in the food and pharmaceutical industries has led to the investigation of nonconventional extraction technologies that allow one to obtain more of these compounds. In this context, nonconventional techniques, known as emerging technologies, use more efficient processes that are safe for the environment, in addition to obtaining products with better functional characteristics as compared to those obtained by conventional technologies. This review aims to provide information on different nonconventional techniques used in the extraction of bioactive compounds from purple corn.


Assuntos
Tecnologia de Alimentos/métodos , Extratos Vegetais/isolamento & purificação , Zea mays/química , Extratos Vegetais/química , Sementes/química
18.
Chemosphere ; 250: 126296, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32135437

RESUMO

In some environments, a number of crops, notably maize and nuts can be contaminated by aflatoxin B1 and related compounds resulting from the growth of aflatoxin-producing Aspergilli. Fungal peroxidases have been shown to degrade a number of mycotoxins, including aflatoxin B1 (AFB1). Therefore, the purpose of this study was to investigate the in vitro enzymatic degradation AFB1 by a recombinant type B dye decolorizing peroxidase (Rh_DypB). Analysis of the reaction products by HPLC-MS analysis showed that under optimized conditions AFB1 was efficiently transformed by Rh_DypB, reaching a maximum of 96% conversion after 4 days of reaction at 25 °C. Based on high resolution mass spectrometry analysis, AFB1 was demonstrated to be quantitatively converted to AFQ1, a compound with a significantly lower toxicity. A number of low molecular mass compounds were also present in the final reaction mixture in small quantities. The results presented in this study are promising for a possible application of the enzyme Rh_DypB for aflatoxin reduction in feed.


Assuntos
Aflatoxina B1/metabolismo , Peroxidase/metabolismo , Aflatoxinas , Corantes , Modelos Químicos , Micotoxinas , Peroxidases , Zea mays/química
19.
Food Chem ; 319: 126546, 2020 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-32179370

RESUMO

A rapid and sensitive immunochromatographic strip (ICS) based on a single-chain variable fragment (scFv) was developed for detecting fumonisin B1 (FB1). The ICS was based on a competitive reaction for colloidal gold-labeled scFv between FB1 and FB1-BSA, which was used along with sheep anti-mouse IgG as capture reagents immobilized at test and control lines, respectively, on a nitrocellulose membrane of the strip. The limit of detection of the ICS was 2.5 ng/mL (25 µg/kg) FB1 in buffer, and the sensitivity was eight times higher than that of monoclonal antibodies for the preparation of the scFv. The cross-reactivity of the scFv with common mycotoxins was determined by ICS, the results showed that the scFv were not against other mycotoxins. Eight naturally contaminated maize samples were analyzed with the scFv-based ICS and by LC-MS/MS. The results of analysis obtained with the strip assay showed good agreement with those obtained by LC-MS/MS.


Assuntos
Fumonisinas/análise , Anticorpos de Cadeia Única/imunologia , Zea mays/química , Animais , Anticorpos Monoclonais/imunologia , Cromatografia de Afinidade , Cromatografia Líquida , Reações Cruzadas , Fumonisinas/imunologia , Coloide de Ouro/química , Ovinos , Espectrometria de Massas em Tandem
20.
J Chromatogr A ; 1620: 461026, 2020 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-32178860

RESUMO

Sensitive and specific analysis of zearalenone (ZEN) mycotoxin in cereals for ensuring food safety is critical and remains challenging. Herein, a new gold nanoparticles @aptamer-functionalized hybrid affinity monolithic column was proposed and employed for online specific recognition of ZEN by HPLC. Characterization on the morphology, Brunauer-Emmett-Teller (BET) surface area mechanical stability and specific performance of the obtained affinity monolith were investigated. A super-high aptamer coverage density could reach 3636 pmol/µL, which is preferable to gain an effective analysis of ZEN with high specificity and a low interference of co-existed substances including typical α-Zearalenol (α-ZOL) and Aflatoxin B1 (AFB1). The sensitive recognition of trace ZEN was obtained with the limit of detection (LOD) as low as 0.05 ng/mL. Applied to real cereal samples, satisfactory recoveries were obtained in the range of 91.6 ± 1.4%-97.8 ± 2.6% (n = 3) in corn, 93.8 ± 3.1%-95.0 ± 3.6% (n = 3) in wheat, and 90.9 ± 4.7%-94.7 ± 3.8% (n = 3) in rice, respectively. The results on quantitative analysis were similar to that of LC-MS and better than that obtained by using immunoaffinity column (IAC) or molecularly imprinted polymer (MIP). This protocol provided an efficient access to high-efficient online specific recognition of ZEN in cereals by using such an aptamer-affinity capillary monolithic column.


Assuntos
Aptâmeros de Nucleotídeos/química , Ouro/química , Nanopartículas Metálicas/química , Sistemas On-Line , Zearalenona/análise , Calibragem , Cromatografia Líquida de Alta Pressão , Grão Comestível/química , Contaminação de Alimentos/análise , Limite de Detecção , Nanopartículas Metálicas/ultraestrutura , Permeabilidade , Reprodutibilidade dos Testes , Triticum/química , Zea mays/química
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