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1.
Chemosphere ; 239: 124765, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31520981

RESUMO

In this study, palm shell activated carbon powder (PSAC) and magnesium silicate (MgSiO3) modified PSAC (MPSAC) were thoroughly investigated for fluoride (F-) adsorption. F- adsorption isotherms showed that PSAC and MPSAC over-performed some other reported F- adsorbents with adsorption capacities of 116 mg g-1 and 150 mg g-1, respectively. Interestingly, the MgSiO3 impregnated layer changed the adsorption behavior of F- from monolayer to heterogeneous multilayer based on the Langmuir and Freundlich isotherm models verified by chi-square test (X2). Thermodynamic parameters indicated that the F- adsorption on PSAC and MPSAC was spontaneous and exothermic. PSAC and MPSAC were characterized using FESEM-EDX, XRD, FTIR and XPS to investigate the F- adsorption mechanism. Based on the regeneration tests using NaOH (0.01 M), PSAC exhibited poor regeneration (<20%) while MPSAC had steady adsorption efficiencies (∼70%) even after 5 regeneration cycles. This is due to highly polarized C-F bond was found on PSAC while Mg-F bond was distinguished on MPSAC, evidently denoting that the F- adsorption is mainly resulted from the exchange of hydroxyl (-OH) group. It was concluded that PSAC would be a potential adsorbent for in-situ F- groundwater remediation due to its capability to retain F- without leaching out in a wide range pH. MPSAC would be an alternative adsorbent for ex-situ F- water remediation because it can easily regenerate with NaOH solution. With the excellent F- adsorption properties, both PSAC and MPSAC offer as promising adsorbents for F- remediation in the aqueous phase.


Assuntos
Carvão Vegetal/química , Fluoretos/isolamento & purificação , Silicatos de Magnésio/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Fluoretos/química , Concentração de Íons de Hidrogênio , Cinética , Microscopia Eletrônica de Varredura , Phoeniceae , Espectroscopia Fotoeletrônica , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica , Resíduos , Poluentes Químicos da Água/química , Purificação da Água/métodos , Difração de Raios X
2.
Chemosphere ; 240: 124772, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31542584

RESUMO

A new chitosan based imprinted polymer was prepared by copolymerization of 4-Vinylpyridine (VP) as a functional monomer and N,N'-Methylenebisacrylamide (MBA) as a crosslinker in the presence of Potassium peroxodisulfate (KPS) as an initiator to eliminate Pb(II) from aqueous solutions. The template ions were removed from ion imprinted polymer (IIPs) particles by leaching with 0.1 M nitric acid (HNO3) that leaves cavities in the particles with the capability of selective extraction of the Pb(II) ions. Some properties of the bioadsorbent were further identified using Field Emission Scanning Electron Microscopy (FE-SEM), Fourier Transform Infrared Spectroscopy (FT-IR) and Thermal Gravimetric Analysis (TGA). In addition, the equilibrium adsorption data were examined through Langmuir and Freundlich isotherm models and it was found that adsorption data fit well with the Freundlich isotherm. The competitive adsorption studies clearly showed that the Pb(II)-IP has a much higher adsorption capacity for Pb(II) than the non-imprinted polymer (NIP) with the same chemical composition; furthermore, it has excellent selectivity for the targeted ion. In addition, the studies regarding the regeneration and reuse studies revealed that the Pb(II)-IP beads showed no significant decrease in their adsorption capacities.


Assuntos
Quitosana/química , Chumbo/química , Polímeros/química , Poluentes Químicos da Água/química , Adsorção , Íons , Cinética , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de Fourier , Água
3.
Biophys Chem ; 256: 106282, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31756664

RESUMO

Structural investigations, based on density functional theory (DFT) calculations, are performed on tea catechins, including 4-aminobutyric acid (GABA), L-theanine (Thea), caffeine (CAF), theobromine (TB), theophylline (TP), catechin (C), epicatechin (EC), gallocatechin (GC), epigallocatechin (EGC), catechin gallate (CG), epicatechin gallate (ECG), gallocatechin gallate (GCG) and epigallocatechin gallate (EGCG). With an identified lowest energy conformer of investigated molecules, FTIR and FT-Raman spectra have been assigned according to DFT calculations in the way of B3LYP/6-31 + G (d, p). Normal spectra of these catechin powders are also measured by Raman spectrometers. There is a kind of everlasting correlation between experimental results and theoretical data. And our research has also obtained a clear evidence for reliable assignments of vibrational bands, bringing great feasibility to the rapid tea catechin detection.


Assuntos
Catequina/química , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , Chá/química , Catequina/análogos & derivados , Chá/metabolismo
4.
Chemosphere ; 238: 124593, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31446275

RESUMO

This paper presents the abundance, concentration and variability of microplastics (MP) in an urban wastewater treatment plant (WWTP), according to different water parameters and environmental factors, their possible sources and removal efficiency. A total of 352.6 L of wastewater from four stages of the treatment process were processed following a standardized extraction protocol by density separation, trinocular microscopic identification and polymeric analysis by Fourier transform infrared spectroscopy. MP comprised a 46.6% of total microlitter, with a statistically significant removal of 90.3% in the final effluent of the WWTP. Five different shapes were isolated; i.e. fragment, film, bead, fiber, and foam. The most prominent MP forms in the final effluent were fragments and fibers, with the most common size class being 400-600 µm. Seventeen different polymer families were identified, with low-density polyethylene being the most prevalent one (52.4%) in a film form (27.7%), mostly from agriculture greenhouses near the sewage plant and single plastic bags (it is noted that only a year ago consumers are charged for them in Spain). Influent wastewater with high concentrations of suspended solids proved to have a low MP burden with a larger MP size, possibly due to a hetero-aggregation with particulate matter. Agglomeration of polystyrene and polyethylene terephthalate with organic material is also suggested, both with surface energies higher than 25 mN m-1 enough for a high biofouling rate. The sewage plant cushions sharp-point microplastic concentrations during the warm season, allowing a stable performance of the WWTP.


Assuntos
Monitoramento Ambiental/métodos , Esgotos/química , Poluentes Químicos da Água/análise , Purificação da Água , Incrustação Biológica , Polietilenotereftalatos/análise , Poliestirenos/análise , Espanha , Espectroscopia de Infravermelho com Transformada de Fourier
5.
Chemosphere ; 238: 124564, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31472348

RESUMO

Microplastics pose a worldwide risk for the environment. Microplastic fibers, which are released during the household washing of synthetic fabrics, are a substantial percentage of microplastics in rivers and in oceans. A novel quantification and simultaneous identification of fiber polymers via Micro-FTIR (Fourier Transform Infrared Spectroscopy) was developed. Washing simulations with commercially available household products were performed and effluents were filtered either on GF/F filters (0.7 µm) or on Anodisc filter (0.2 µm), to gather even the smallest fibers. Furthermore, a novel purification procedure of effluents was developed. Subsequently, filters were analyzed also with the scanning electronic microscope (SEM) to confirm the width and length of fibers. This novel method is robust and replicable and it allows better quantification of fibers released and identification of fiber polymers with optimal matches (averagely 80%).


Assuntos
Monitoramento Ambiental/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Poluentes Químicos da Água/análise , Filtração , Produtos Domésticos/análise , Microscopia , Têxteis/análise
6.
Chemosphere ; 238: 124688, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31524623

RESUMO

Microplastic pollution has received increased attention recently due to potential threat to marine biota and human health. This study reports microplastic (MP) content in brown shrimp (Metapenaeus monocerous) and tiger shrimp (Penaeus monodon) inhabiting in the shallow and offshore waters of the Northern Bay of Bengal, Bangladesh. Gastrointestinal tract (GT) of shrimps (n = 150) were examined for MPs following alkali digestion, microscopic observation and chemical analysis by micro-Fourier Transformed Infrared Spectroscope (µFTIR). A total of 33 and 39 MP items were found in P. monodon and M. monocerous, averaging 3.40 ±â€¯1.23 and 3.87 ±â€¯1.05 items/g GT, respectively. Among various shapes, types and colours of MP, filament (57-58%), fiber (32-57%) and black (48-51%) were dominant amongst the various particles identified. Tiger shrimp had high numbers (23 items) of larger size fractions of MPs (1-5 mm) but brown shrimp had high numbers (15 items) of smaller MPs (250-500 µm), and µ-FTIR data confirmed 13 particles of polyamide-6 and 6 particles of rayon polymers. These results provide a baseline of MP contamination in seafood from Bangladesh that should be useful for future monitoring efforts.


Assuntos
Caprolactama/análogos & derivados , Celulose/análise , Monitoramento Ambiental/métodos , Penaeidae/química , Polímeros/análise , Poluentes Químicos da Água/análise , Poluição Química da Água/análise , Animais , Bangladesh , Baías/química , Caprolactama/análise , Trato Gastrointestinal/química , Alimentos Marinhos/análise , Espectroscopia de Infravermelho com Transformada de Fourier
7.
Chemosphere ; 238: 124693, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31524627

RESUMO

In this work, self-assembled gels were prepared with exfoliated montmorillonite and chitosan (EMCG) as the adsorbent for removing methyl orange (MO) from water in absence and presence of methylene blue (MB). Several techniques including scanning electron microscope (SEM), zeta potential, fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used for the characterization of the EMCG before and after removal of MO. The EMCG performed well in the removal of MO attributing to the electrostatic attraction, cation exchange and hydrogen bond. The adsorption behaviors were followed pseudo-second-order and Langmuir isotherm. More surprisingly, the maximum adsorption capacity of MO was obviously enhanced in the presence of MB that it increased from 545 mg g-1 (absence of MB) to 1060 mg g-1 with the shielding effect of MB on EMCG which allowed MO and MB to alternately arrange at the adsorption sites. This finding of the synergistic effect between the two dyes on the proposed composite opens up new vistas to imagine the enhanced purification of the wastewater with multiple dyes co-existed using the multifunctional adsorbents.


Assuntos
Compostos Azo/análise , Bentonita/química , Quitosana/química , Azul de Metileno/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Compostos Azo/química , Corantes/química , Géis , Espectroscopia Fotoeletrônica , Espectroscopia de Infravermelho com Transformada de Fourier , Águas Residuárias/química , Poluentes Químicos da Água/química
8.
Sci Total Environ ; 700: 134414, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31698277

RESUMO

This study synthesized magnetic greigite/biochar composites (MGBs) by a solvothermal method and tested their ability to remove Cr(VI) from heavy metal-polluted wastewater. X-ray diffraction (XRD), Fourier transformed infrared spectrometry (FT-IR) and scanning electron microscopy (SEM) revealed that magnetic greigite (Fe3S4) flakes were aggregated and anchored to the biochar surface, resulting in more active sites than pristine biochar. Maximum Cr removal efficiency and capacity of MGB-30 (greigite/biochar = 30%) at an initial Cr(VI) concentration of 20 mg/L were 93% and 23.25 mg/g, respectively. A pseudo-first-order kinetic model was determined for the Cr(VI) removal process and the Cr(VI) removal rate constants were highly dependent on the mass ratios of Fe3S4 loaded on biochar, initial MGB and Cr(VI) concentrations and solution pH. X-ray photoelectron spectroscopy (XPS) and flame atomic absorption spectrometric (FAAS) analysis demonstrated that Cr(VI) was preferentially adsorbed on MGBs and subsequently reduced to Cr(III) by MGBs. Electron paramagnetic resonance (EPR) spectroscopy and iron redox transformations revealed that the Cr(VI) removal enhancement was attributed to efficient surface Fe(III)/Fe(II) cycling via electron transfer with the persistent free radicals (PFRs) of biochar. These novel findings provide new insights into the Fe(III)/Fe(II) cycle induced by biochar and the prospects of using magnetic greigite/biochar composites for remediation of Cr(VI)-rich wastewaters.


Assuntos
Cromo/química , Ferro/química , Sulfetos/química , Poluentes Químicos da Água/química , Adsorção , Carvão Vegetal , Cromo/análise , Compostos Férricos/química , Fenômenos Magnéticos , Magnetismo , Espectroscopia de Infravermelho com Transformada de Fourier , Eliminação de Resíduos Líquidos , Águas Residuárias , Poluentes Químicos da Água/análise
9.
Chemosphere ; 239: 124745, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31521939

RESUMO

A novel three dimensional MnO2 modified biochar-based porous hydrogel (MBCG) was fabricated to overcome the low sorption capacity and difficulty in solid-liquid separation of biochar (BC) for Cd(II) and Pb(II) removal. BC was initially modified by a rapid redox reaction between KMnO4 and Mn(II) acetate, and then incorporated into a polyacrylamide gel network via a rapid and facile free-radical polymerization. A foaming method was deliberately introduced during the fabrication to establish interpenetrated porous structure inside the network. Various characterizations were employed to examine the morphology, porous structures, chemical compositions, and mechanical properties of the samples. Adsorption performance of MBCG on Cd(II) and Pb(II) (isotherms and kinetics) as well as its desorption and reusability were also investigated. The results indicated that MnO2 modified biochars (MBC) were successfully introduced and homogeneously distributed in the porous bulk hydrogel, endowing MBCG with more uniform pore structure, excellent thermostability, remarkable mechanic strength, and superior adsorption performance. The maximum Langmuir adsorption capacity on Cd(II) and Pb(II) is 84.76 and 70.90 mg g-1, respectively, which is comparable or even larger than that of MBC. More importantly, MBCG can be rapidly separated and easily regenerated with an excellent reusability, which could retain 92.1% and 80.5% of the initial adsorption capacities of Cd(II) and Pb(II) after five cycles. These new insights make MBCG an ideal candidate in practical applications in water treatment and soil remediation contaminated with various heavy metals.


Assuntos
Cádmio/isolamento & purificação , Carvão Vegetal/química , Hidrogéis/química , Chumbo/isolamento & purificação , Compostos de Manganês/química , Óxidos/química , Resinas Acrílicas/química , Adsorção , Cádmio/química , Poluentes Ambientais/química , Poluentes Ambientais/isolamento & purificação , Chumbo/química , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Polimerização , Porosidade , Impressão Tridimensional , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria
10.
Food Chem ; 305: 125512, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31610422

RESUMO

This study represents the first attempt to combine mid infrared (MIR) spectroscopy and multivariate data processing for prediction of alcohol degree, sugars content and total acidity in straw wine. 302 Italian samples, representing different vintages, production regions and grape varieties, were analysed using FT-MIR spectroscopy and reference methods. New regression functions based on a combination of Orthogonal Signal Correction and Partial Least Squares regression are proposed for prediction of quality parameters: this approach allows overcoming the issue of matrix complexity, reducing spectral interferences and enhancing the information embodied in fingerprinting data. The models proposed are characterised by an excellent reliability, with low error in prediction (alcohol: 0.28%; sugars: 9.9 g/L; acidity: 0.29 g/L) comparable both to reference methods and table wine models. Results demonstrate that vibrational spectroscopy, combined with a proper multivariate data strategy, represents a suitable strategy for the quick and non-destructive assessment of quality parameters of straw wine.


Assuntos
Qualidade dos Alimentos , Informática/métodos , Espectroscopia de Infravermelho com Transformada de Fourier , Vinho/análise , Análise dos Mínimos Quadrados , Análise Multivariada , Reprodutibilidade dos Testes , Vitis/química
11.
Bioresour Technol ; 296: 122315, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31706890

RESUMO

The present study is designed to evaluate the potential of deoiled algal biomass (DAB) residue as an alternative resource for the production of bioethanol and biopolymers in a biorefinery approach. Hybrid pretreatment method resulted in higher sugar solubilization (0.590 g/g DAB) than the corresponding individual physicochemical (0.481 g/g DAB) and enzymatic methods (0.484 g/g DAB). Subsequent utilization of sugars from hybrid pretreatment for bioethanol using Saccharomyces cerevisiaeresulted in maximum bioethanol production at pH 5.5 (0.145 ±â€¯0.008 g/g DAB) followed by pH 5.0 (0.122 ±â€¯0.004 g/g DAB) and pH 6.0 (0.102 ±â€¯0.002 g/g DAB). The experiments for biopolymer (PHB: polyhydroxybutyrate) production resulted in 0.43 ±â€¯0.20 g PHB/g DCW. Extracted polymer on NMR and FT-IR analysis showed the presence of PHB. Exploration of DAB as an alternative renewable resource for multiple biobased products supports sustainability and also enables entirety use of DAB by addressing the DAB-residue allied disposal issues.


Assuntos
Açúcares , Biomassa , Biopolímeros , Fermentação , Espectroscopia de Infravermelho com Transformada de Fourier
12.
J Environ Manage ; 254: 109812, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31733482

RESUMO

Antibiotics, one of the most abundant contaminants in the natural water systems possess various difficulties to remediate through conventional water treatment methods. Tetracycline (TC) remains one of the most widely used antibiotics for human and veterinary applications because of its broad-spectrum antibacterial activity. In the current study, we have employed nano zero-valent technology-based antibiotic remediation. In a first of its kind work, we applied bimetallic nZVI-Cu nanoparticles synthesized using pomegranate rind extract for remediation. TC removal of 72 ±â€¯0.5% (initial TC concentration 10 mg/L) was obtained with the nZVI-Cu concentration of 750 mg/L at pH 7. To overcome the colloidal instability and enhance TC removal further, the bimetallic nanoparticles were formed in-situ over bentonite. The bentonite supported composite (B/nZVI-Cu) was used to treat TC an initial concentration of 10 mg/L and the results confirmed significant enhancement in removal with a substantially decreased nanoparticle loading. Using only 150 mg/L of B/nZVI-Cu at pH 7, 95 ±â€¯0.05% of TC could be removed. The nanoparticles and the composites were characterized by SEM, FT-IR, and XRD analyses. The removal process was followed by UV-Visible analyses in conjunction with TOC, ORP and LCMS measurements. For treatment using B/nZVI-Cu, the reusability of the composite was established up to three cycles of operation, and the process was validated in the real water systems. Substantially decreased residual toxicity of the composite treated TC solution lends credence to the environmental sustainability of the process.


Assuntos
Nanopartículas Metálicas , Nanocompostos , Poluentes Químicos da Água , Antibacterianos , Bentonita , Ferro , Espectroscopia de Infravermelho com Transformada de Fourier
13.
Bioelectrochemistry ; 131: 107393, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31698180

RESUMO

A tryptophan (Trp) molecularly imprinted electrochemical sensor was fabricated by drop-coating an imprinted chitosan film on the surface of a glassy carbon electrode modified with multi-walled carbon nanotubes (MIP-MWCNTs/GCE). The surface morphology and electrochemical properties of the MIP-MWCNTs/GCE were characterized by scanning electron microscopy (SEM) and cyclic voltammetry (CV), respectively. The formation of hydrogen bonds between the functional polymer and the template molecule was confirmed by infrared spectroscopy. The electrochemical performance of the MIP-MWCNTs/GCE with Trp showed that the signal of the oxidation current of Trp obtained with MIP-MWCNTs/GCE was significantly enhanced relative to that of the uncovered GCE, indicating that the modified electrode can accelerate electron transfer and has strong selectivity for Trp. The experimental conditions were optimized in parallel, and under the optimal conditions, the MIP-MWCNTs/GCE showed a good linear relationship between the Trp oxidation peak current and Trp concentrations in the ranges of 2.0 nM-0.2 µM, 0.2 µM-10 µM and 10 µM-100 µM The limit of detection (LOD) was 1.0 nM (S/N = 3), and the modified electrode had good reproducibility and stability. Finally, the MIP-MWCNTs/GCE was successfully applied to the determination of Trp in the human serum samples.


Assuntos
Carbono/química , Eletrodos , Impressão Molecular , Nanotubos de Carbono/química , Triptofano/análise , Técnicas Eletroquímicas/métodos , Reprodutibilidade dos Testes , Espectroscopia de Infravermelho com Transformada de Fourier
14.
Food Chem ; 305: 125459, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31520919

RESUMO

In this study the elemental compositions of melanoidin formed at 160 °C from d-glucose (Glc) and l-alanine (Ala) as well as from fructosylalanine - the corresponding Amadori rearrangement product - were compared. Specific chemical bonds were probed by FTIR spectroscopy. This approach tackles the different chemical pathways for melanoidin formation via the Amadori rearrangement in contrast to the reaction from Glc/Ala. Melanoidins formed from fructosylalanine contain about twice as much nitrogen and therefore amino acid as compared to melanoidin from Glc/Ala and exhibit higher absorption in the UV/Vis. Consequently, melanoidins formed from Glc/Ala contain more sugar degradation products with lower absorption due to a smaller size of the conjugated double bond network.


Assuntos
Alanina/química , Frutose/química , Glucose/química , Polímeros/química , Frutose/análogos & derivados , Frutose/síntese química , Espectroscopia de Ressonância Magnética , Reação de Maillard , Polímeros/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman
15.
Food Chem ; 305: 125480, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31522125

RESUMO

Milk samples from 1264 cows in 85 farms were authenticated for different farming-systems using a 10-fold cross-validated linear-discriminant-analysis using Fourier-transform infrared spectra (FTIRS) and gas-chromatographic fatty-acid (FA) profiles. FTIRS gave correct classification greater than FAs (97.4% vs. 81.1%) during calibration, but slightly worse in validation (73.5% vs 77.3%) and their combination improved the results. All milk samples were processed into ripened model-cheeses, and analyzed by near-infrared-spectrometry (NIRS), by proton-transfer-reaction time-of-flight mass-spectrometry for their volatile organic compound (VOCs) fingerprint and by panel sensory profiling (SENS). Farming-system authentication on cheese samples was less efficient than on milk, but still possible. The instrumental methods yielded similar validation results, better than SENS, and their combination improved the correct classification rate. The efficiency of the different technics was affected by specific farming systems. In conclusion, dairy products could be discriminated for farming-systems with acceptable accuracy, but the methods tested differ in sampling procedure, rapidity and costs.


Assuntos
Queijo/análise , Ácidos Graxos/química , Aromatizantes/análise , Leite/química , Animais , Bovinos , Cromatografia Gasosa , Análise Discriminante , Ácidos Graxos/análise , Feminino , Análise de Alimentos , Espectrometria de Massas , Espectroscopia de Infravermelho com Transformada de Fourier , Compostos Orgânicos Voláteis/análise
16.
Food Chem ; 306: 125589, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31606629

RESUMO

The combined effects of plasma-activated water (PAW) and heat-moisture treatments (HMT) on the structure, physicochemical properties and in vitro digestibility of waxy (WMS) and normal maize starches (NMS) were investigated. X-ray diffraction results revealed that the relative crystallinity of starches treated with PAW-HMT increased without crystalline type transition compared to DW-HMT. Through the Fourier transform infrared spectroscopy and Raman spectroscopy, the short-range order of starches treated with PAW-HMT was improved. Differential scanning calorimetry analysis shown that PAW-HMT increased gelatinization temperatures for NMS while decreasing gelatinization temperatures for WMS. The solubility of starches treated with PAW-HMT was higher than that of DW-HMT while the swelling power decreased. Importantly, the resistant starch (RS) content of starches treated by PAW-HMT increased compared to the starches treated by DW-HMT or native starch. This study provides a novel green method to modify the structure, lower starch digestibility and improve the RS content of starch.


Assuntos
Amido/química , Ceras/química , Zea mays/química , Varredura Diferencial de Calorimetria , Temperatura Alta , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier , Água/química , Difração de Raios X
17.
Food Chem ; 306: 125615, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31622833

RESUMO

Phycocyanin (PC), a plant-based protein with interesting biological activity, is rarely directly applied in the food industry because it has structural and functional limitations. This study combined ultra-high-pressure (UHP) treatment with glycation to improve PC functionality and explored resulting structural changes using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, scanning electron microscopy, Fourier-transform infrared spectroscopy, circular dichroism, and UV-visible spectroscopy. The UHP treatment obviously improved the speed and degree of glycation and the composite-modified PC (CM-PC) showed high solubility and good emulsifying and foaming performance. Scanning electron microscopy images showed the CM-PC surface was loose and fluffy. Gel electrophoresis, Fourier-transform infrared spectroscopy, and circular dichroism results demonstrated that the content of α-helix decreased from 78.1% in PC to 26.6% in CM-PC, and hydroxyl groups were introduced. UV-visible spectroscopy showed that the mechanism of composite modification involved stretching of the PC and promotion of binding with sugars.


Assuntos
Ficocianina/química , Spirulina/química , Dicroísmo Circular , Eletroforese em Gel de Poliacrilamida , Emulsões/metabolismo , Glicosilação , Pressão , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier
18.
Equine Vet J ; 52(1): 46-51, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30900769

RESUMO

BACKGROUND: Reliable and validated biomarkers for osteoarthritis (OA) are currently lacking. OBJECTIVES: To develop an accurate and minimally invasive method to assess OA-affected horses and provide potential spectral markers indicative of disease. STUDY DESIGN: Observational, cross-sectional study. METHODS: Our cohort consisted of 15 horses with OA and 48 without clinical signs of the disease, which were used as controls. Attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy was used to investigate serum samples (50 µL) collected from these horses. Spectral processing and multivariate analysis revealed differences and similarities, allowing for detection of spectral biomarkers that discriminated between the two cohorts. A supervised classification algorithm, namely principal component analysis coupled with quadratic discriminant analysis (PCA-QDA), was applied to evaluate the diagnostic accuracy. RESULTS: Segregation between the two different cohorts, OA-affected and controls, was achieved with 100% sensitivity and specificity. The six most discriminatory peaks were attributed to proteins and lipids. Four of the spectral peaks were elevated in OA horses, which could be potentially due to an increase in lipids, protein expression levels and collagen, all of which have been previously reported in OA. Two peaks were found decreased and were tentatively assigned to the reduction of proteoglycan content that is observed during OA. MAIN LIMITATIONS: The control group had a wide range of ages and breeds. Presymptomatic OA cases were not included. Therefore, it remains unknown whether this test could also be used as an early diagnostic tool. CONCLUSIONS: This spectrochemical approach could provide an accurate and cost-effective blood test, facilitating point-of-care diagnosis of equine OA.


Assuntos
Doenças dos Cavalos/diagnóstico , Osteoartrite/veterinária , Espectroscopia de Infravermelho com Transformada de Fourier/veterinária , Animais , Estudos Transversais , Doenças dos Cavalos/sangue , Cavalos , Osteoartrite/sangue , Osteoartrite/diagnóstico , Espectroscopia de Infravermelho com Transformada de Fourier/métodos
19.
J Sci Food Agric ; 100(2): 855-862, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31646648

RESUMO

BACKGROUND: The starting point of this work is to propose a qualitative approach for authenticity confirmation of the composition of liquid egg products. To this end, it was aimed to detect the liquid egg authenticity and adulteration (with water) by using attenuated total reflectance Fourier-transform infrared (ATR-FTIR), near infrared (NIR) spectroscopy and chemometrics. RESULTS: Liquid (n = 50) and dry (n = 50) samples of whole egg, egg yolk, egg white, and whole egg containing extra egg white (BXEW) and water (BXW) were prepared. Principal component analysis (PCA) models were formed using the data obtained from ATR-FTIR and NIR measurements of liquid and dry samples. A better classification was achieved with PCA model of ATR-FTIR measurements formed by using dry samples (100%) instead of liquid ones (80%). The best separation was obtained between dry sample groups of BXEW and BXW (adulterated). The presence of water content in liquid samples showed a negative effect on classification of the samples, while a good classification (100%) was obtained for NIR measurements of both liquid and dry sample groups. The developed PCA models achieved classification regardless of the form of egg samples (liquid or dry). CONCLUSION: The results of the study revealed that adulterated egg samples (with water) could be qualitatively detected using ATR-FTIR and NIR spectroscopy techniques in combination with PCA. © 2019 Society of Chemical Industry.


Assuntos
Ovos/análise , Contaminação de Alimentos/análise , Análise de Componente Principal/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Animais , Galinhas , Água/análise
20.
Food Chem ; 308: 125676, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-31655476

RESUMO

In this study, the improving effects of green tea powder, soluble tea, and tea polyphenols on the mixing and tensile qualities of dough and texture of tea-enriched noodles, as well as the physico-chemical and structural properties of gluten proteins were progressively investigated. Dough strength and noodle texture were significantly increased by all the three tea products. Tea polyphenols in particular presented the most effective improvement with highest dough stability, resistance, and noodle chewiness. SEM indicated that tea products all induced a more developed gluten network, and polyphenol noodle showed the most continuous and ordered structure. FT-IR and fluorescence spectrum indicated that tea polyphenols promoted an enhancement in α-helix structure and the hydrophobic interactions. Tea polyphenols induced the SH/SS interchange during processing and cooking, and enhanced the water-solids interaction in noodles. AFM results showed that polyphenols induced the polymerization of gluten protein molecular chains, with increased chain height and width.


Assuntos
Polifenóis/química , Chá/química , Triticum/química , Fenômenos Químicos , Culinária , Glutens/química , Espectroscopia de Infravermelho com Transformada de Fourier
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