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1.
Plant J ; 106(2): 314-325, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33506558

RESUMO

Volatile organic compounds (VOCs) released by plants serve as information and defense chemicals in mutualistic and antagonistic interactions and mitigate effects of abiotic stress. Passive and dynamic sampling techniques combined with gas chromatography-mass spectrometry analysis have become routine tools to measure emissions of VOCs and determine their various functions. More recently, knowledge of the roles of plant VOCs in the aboveground environment has led to the exploration of similar functions in the soil and rhizosphere. Moreover, VOC patterns have been recognized as sensitive and time-dependent markers of biotic and abiotic stress. This focused review addresses these developments by presenting recent progress in VOC sampling and analysis. We show advances in the use of small, inexpensive sampling devices and describe methods to monitor plant VOC emissions in the belowground environment. We further address latest trends in real-time measurements of volatilomes in plant phenotyping and most recent developments of small portable devices and VOC sensors for non-invasive VOC fingerprinting of plant disease. These technologies allow for innovative approaches to study plant VOC biology and application in agriculture.


Assuntos
Plantas/química , Compostos Orgânicos Voláteis/análise , Componentes Aéreos da Planta/química , Doenças das Plantas , Raízes de Plantas/química , Plantas/metabolismo , Solo
2.
Molecules ; 27(18)2022 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-36144763

RESUMO

The present study is aimed at determining whether leaf volatile organic compounds (VOCs) are good markers of the grapevine response to defence elicitors in the field. It was carried out in two distinct French vineyards (Burgundy and Bordeaux) over 3 years. The commercial elicitor Bastid® (Syngenta, Saint-Sauveur, France) (COS-OGA) was first used to optimise the VOCs' capture in the field; by bagging stems together with a stir bar sorptive extraction (SBSE) sensor. Three elicitors (Bastid®, copper sulphate and methyl jasmonate) were assessed at three phenological stages of the grapevines by monitoring stilbene phytoalexins and VOCs. Stilbene production was low and variable between treatments and phenological stages. VOCs-particularly terpenes-were induced by all elicitors. However, the response profiles depended on the type of elicitor, the phenological stage and the vineyard, and no sole common VOC was found. The levels of VOC emissions discriminated between weak (Bastid® and copper sulphate) and strong (methyl jasmonate) inducers. Ocimene isomers were constitutively present in the overall blends of the vineyards and increased by the elicitors' treatments, whilst other VOCs were newly released throughout the growing seasons. Nonetheless, the plant development and climate factors undoubtedly influenced the release and profiles of the leaf VOCs.


Assuntos
Estilbenos , Compostos Orgânicos Voláteis , Acetatos , Sulfato de Cobre , Ciclopentanos , Fazendas , Oxilipinas , Folhas de Planta , Terpenos
3.
Molecules ; 27(19)2022 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-36235239

RESUMO

The volatile composition and odor of meat and meat products is based on the precursors present in the raw meat. These are influenced by various pre-slaughter factors (species, breed, sex, age, feed, muscle type). Furthermore, post-mortem conditions (chiller aging, cooking conditions, curing, fermentation, etc.) determine the development of meat volatile organic compounds (VOCs). In this review, the main reactions leading to the development of meat VOCs such as the Maillard reaction; Strecker degradation; lipid oxidation; and thiamine, carbohydrate, and nucleotide degradation are described. The important pre-slaughter factors and post-mortem conditions influencing meat VOCs are discussed. Finally, the pros, cons, and future perspectives of the most commonly used sample preparation techniques (solid-phase microextraction, stir bar sorptive extraction, dynamic headspace extraction) and analytical methods (gas chromatography mass spectrometry and olfactometry, as well as electronic noses) for the analysis of meat VOCs are discussed, and the continued importance of sensorial analysis is pinpointed.


Assuntos
Odorantes , Compostos Orgânicos Voláteis , Carboidratos , Lipídeos , Carne/análise , Nucleotídeos , Odorantes/análise , Microextração em Fase Sólida/métodos , Tiamina/análise , Compostos Orgânicos Voláteis/análise
4.
Anal Bioanal Chem ; 413(1): 159-169, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33037908

RESUMO

Nitroaromatic compounds were massively used in the formulation of explosives during both world wars. Even several decades after the end of these wars, their residues are suspected to be widely present in the environment. Their occurrence and effect on ecosystems and human health are still not fully determined. This paper describes the development of a method for the determination of 28 nitroaromatic compounds in water, including isomers of nitrotoluene (NT), dinitrotoluene (DNT), trinitrotoluene (TNT), nitrobenzene (NB), dinitrobenzene (DNB), chloronitrobenzene (ClNB), chlorodinitrobenzene (DNCB), nitronaphthalene (NN), dinitronaphthalene (DNN), nitroaniline (NA), dinitroanisole (DNAN), diphenylamine (DPA), and nitrodiphenylamine (nitro-DPA). In order to separate and individually quantify all the analytes with the best possible sensitivity, stir bar sorptive extraction (SBSE) was chosen as the extraction and pre-concentration step prior to gas chromatography (GC) separation and tandem mass spectrometry detection (MS/MS). Our SBSE optimization efforts focused on parameters such as the type of stir bar, ionic strength, addition of organic solvent, and extraction and desorption times. After these optimizations, the analytical method enabled us to reach limits of quantification (LOQs) between 1 and 50 ng/L in tap water, groundwater, and surface water. The method was applied to the determination of targeted nitroaromatic explosive residues in spring and groundwater samples collected in an area where mine warfare had raged during World War I. Up to 16 different nitroaromatic compounds were detected in the same sample. The highest concentrations were recorded for 2,4-DNT and 1,3-DNB (1700 and 2690 ng/L respectively).

5.
Molecules ; 26(18)2021 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-34577084

RESUMO

Smoke-derived taint has become a significant concern for the U.S. wine industry, particularly on the west coast, and climate change is anticipated to aggravate it. High volatile phenols such as guaiacol, 4-methylguaiacol, 4-ethylguaiacol, 4-ethylphenol, and o-, p-, m-cresols have been suggested to be related to smoke-exposed grape and wine. This paper describes an analytical approach based on ethylene glycol/polydimethylsiloxane (EG/PDMS)-stir bar sorptive extraction-gas chromatography-mass spectrometry (SBSE-GC-MS) to quantify or estimate the concentrations of some smoke-related volatile phenols in wines. Correlation coefficients with R2 ≥ 0.990 were obtained. This method can quantify most smoked-related volatile phenols down to 0.5 µg/L in wine in selective ion monitoring mode. Recovery for the targeted volatile phenols ranged from 72.2% to 142.4% in the smoke-tainted wine matrix, except for 4-vinylguaiacol. The standard deviations of the volatile phenols were from 0 to 23% in smoke-tainted wine. The approach provides another tool to evaluate wine smoke exposure and potential smoke taint.


Assuntos
Fracionamento Químico/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Fenóis/análise , Fenóis/química , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/química , Vinho/análise , Adsorção , Calibragem , Dimetilpolisiloxanos/química , Etilenoglicol/química , Padrões de Referência , Reprodutibilidade dos Testes , Fumaça , Vitis/química , Vitis/crescimento & desenvolvimento
6.
Molecules ; 26(7)2021 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-33916526

RESUMO

At present, the development of new agri-food products, including flavored meat products presented in ready-to-eat vacuum packs, is encouraged. The addition of ingredients used as flavoring agents creates the need to be able to determine the volatile compounds responsible for their characteristic aroma. The aim of this study is to propose, develop, and validate a new method that uses headspace-stir bar sorptive extraction-gas chromatography/mass spectrometry (HS-SBSE-GC/MS) to determine the saffron aroma in cured ham flavored with this spice. Results showed that safranal was the main volatile compound that could be identified and quantified in cured ham flavored with saffron. This analytical method was adequate in terms of linearity, selectivity, sensitivity, and accuracy. To our knowledge, this is the first time that an HS-SBSE-GC/MS method for determining the saffron aroma of flavored cured ham has been developed and validated, and it is of interest to agri-food industries.


Assuntos
Crocus/química , Cicloexenos/análise , Aromatizantes/análise , Odorantes/análise , Carne de Porco/análise , Terpenos/análise , Animais , Tecnologia de Alimentos/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Cromatografia Gasosa-Espectrometria de Massas/normas , Humanos , Suínos , Paladar/fisiologia
7.
Molecules ; 26(14)2021 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-34299533

RESUMO

Grapevine is susceptible to fungal diseases generally controlled by numerous chemical fungicides. Elicitors of plant defence are a way of reducing the use of these chemicals, but still provide inconsistent efficiency. Easy-to-analyse markers of grapevine responses to elicitors are needed to determine the best conditions for their efficiency and position them in protection strategies. We previously reported that the elicitor sulphated laminarin induced the emission of volatile organic compounds (VOCs) by grapevine leaves. The present study was conducted to characterise and compare VOC emissions in response to other elicitors. Bastid® was first used to test the conditions of VOC collection and analysis. Using SBSE-GC-MS, we detected several VOCs, including the sesquiterpene α-farnesene, in a time-dependent manner. This was correlated with the induction of farnesene synthase gene expression, in parallel with stilbene synthesis (another defence response), and associated to resistance against downy mildew. The other elicitors (Redeli®, Romeo®, Bion®, chitosan, and an oligogalacturonide) induced VOC emission, but with qualitative and quantitative differences. VOC emission thus constitutes a response of grapevine to elicitors of various chemical structures. Therefore, VOC analysis is relevant for studying the impact of environmental factors on grapevine defence responses and optimising the performance of elicitors in vineyards.


Assuntos
Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Vitis/microbiologia , Compostos Orgânicos Voláteis/análise , Fungicidas Industriais/análise , Cromatografia Gasosa-Espectrometria de Massas , Folhas de Planta/química , Sesquiterpenos/análise , Vitis/química
8.
Anal Bioanal Chem ; 412(21): 5169-5178, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32173792

RESUMO

The aim of this work is the highly sensitive determination of 117 contaminants in surface waters at very low concentrations. Gas chromatography-amenable priority compounds from the European Water Framework Directive (EWFD, 45 priority substances) and substances from the Turkish Regulation on the Management of Surface Water Quality (TRMSWQ, 250 substances) were analyzed. Almost a third to one half of the compounds in the TRMSWQ list were successfully detected in a single gas chromatography-tandem mass spectrometry (GC-MS/MS) injection. Analyzing these pollutants in water samples is difficult with conventional extraction methods. An efficient, easy and fast method for both extraction and analysis is thus important. Here, the stir bar sorptive extraction (SBSE) approach employing Twister® was used for analyte enrichment from 100 mL water samples. The Twister apparatus was used for thermal desorption. Compounds were separated via gas chromatography (GC) and detected by tandem mass spectrometry (MS/MS) utilizing an Agilent 7000D MS instrument. The analysis method was comprehensively validated, and complied with the requirements of the EWFD and Turkish regulation for surface water quality for inland surface water. The method includes various endocrine disruptor compounds listed in the EWFD, such as polychlorinated biphenyls, polycyclic aromatics hydrocarbons, polybrominated diphenyl ethers, phenols, phthalates and pesticides. The method is also applicable for the analysis of similar contaminants that are not on this list. The analyzed pollutants have varying polarities based on octanol-water coefficients and are extracted by SBSE. This method may be preferred for the analysis of pollutants with an octanol-water partition coefficient (log Ko/w) higher than 2. The SBSE method, which is easy, lab-friendly and quick, taking a total of only 2 h for parameter analysis, was optimized to reduce time and chemical usage. The entire extraction and analysis was completed in virtually 3 h. The limits of quantification (LOQs) ranged from 0.12 to 50 ng/L and complied with the requirements for analytical methods to be used in the analysis of the compounds included in the directives. Several quality parameters including linearity, trueness and precision were studied, with good results, and uncertainty was also estimated. Precision (in terms of relative standard deviation [RSD]) was lower than 40%, recoveries ranged from 60 to 120%, and determination coefficients were higher than 0.990 for all analytes. Graphical abstract.


Assuntos
Disruptores Endócrinos/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Espectrometria de Massas em Tandem/métodos , Poluentes Químicos da Água/análise , Calibragem , Europa (Continente) , Água Doce/química , Limite de Detecção , Reprodutibilidade dos Testes
9.
Molecules ; 25(19)2020 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-32992447

RESUMO

In this study, the detailed volatile compositions of Chinese herbaceous aroma-type Baijiu (HAB) were characterized by comprehensive two-dimensional gas chromatography-time of flight mass spectrometry (GC×GC-TOFMS). A total of 606 compounds were tentatively identified by similarity, mass spectral data, and retention indices, among which 247 compounds were positively verified by authentic standards. Esters were present in higher numbers (179), followed by aldehydes and ketones (111), and alcohols (81). In addition, there were also many terpenes (82), sulfides (37), furans (29), nitrogenous compounds (29), lactones (17), and so on. Meanwhile, the extraction effects of volatile components from different sample pretreatment methods (headspace solid-phase microextraction (HS-SPME), solid phase extraction (SPE), and stir bar sorptive extraction (SBSE)) for HAB were also revealed. The results indicated that HS-SPME has a better extraction effect on easily volatile compounds, such as alcohols and sulfides, especially for terpenes. SPE was particularly beneficial for the analysis of nitrogen-containing compounds; SBSE showed medium extraction ability for most types of compounds and was more suitable for the target analysis of trace content substances.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas , Odorantes , Plantas/química , Microextração em Fase Sólida , Compostos Orgânicos Voláteis , Humanos , Terpenos/análise , Terpenos/isolamento & purificação , Compostos Orgânicos Voláteis/química , Compostos Orgânicos Voláteis/isolamento & purificação
10.
Molecules ; 25(9)2020 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-32392764

RESUMO

Polycyclic aromatic hydrocarbons (PAHs) comprise a group of chemical compounds consisting of two or more fused benzene rings. PAHs exhibit hydrophobicity and low water solubility, while some of their members are toxic substances resistant to degradation. Due to their low levels in environmental matrices, a preconcentration step is usually required for their determination. Nowadays, there is a wide variety of sample preparation techniques, including micro-extraction techniques (e.g., solid-phase microextraction and liquid phase microextraction) and miniaturized extraction techniques (e.g., dispersive solid-phase extraction, magnetic solid-phase extraction, stir bar sorptive extraction, fabric phase sorptive extraction etc.). Compared to the conventional sample preparation techniques, these novel techniques show some benefits, including reduced organic solvent consumption, while they are time and cost efficient. A plethora of adsorbents, such as metal-organic frameworks, carbon-based materials and molecularly imprinted polymers, have been successfully coupled with a wide variety of extraction techniques. This review focuses on the recent advances in the extraction techniques of PAHs from environmental matrices, utilizing novel sample preparation approaches and adsorbents.


Assuntos
Microextração em Fase Líquida/métodos , Hidrocarbonetos Policíclicos Aromáticos/isolamento & purificação , Microextração em Fase Sólida/métodos , Poluentes Químicos da Água/análise , Adsorção , Poluição Ambiental/análise , Nanopartículas de Magnetita/química , Estruturas Metalorgânicas/química , Polímeros Molecularmente Impressos/análise , Nanotubos de Carbono/química , Hidrocarbonetos Policíclicos Aromáticos/química , Extração em Fase Sólida/métodos , Solventes/química
11.
J Sci Food Agric ; 100(6): 2512-2521, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31960973

RESUMO

BACKGROUND: The present study investigated the volatile composition of a Pedro Ximénez sweet wine that had been aged in barrels made of different types of wood (Spanish oak, French oak, American oak and chestnut) and subjected to different degrees of toasting (medium toasting and intense toasting). The analyses were carried out using stir bar sorptive extraction gas chromatography-mass spectrometry after validation of the matrix in this case. RESULTS: Good values of linearity, precision, limits of detection and limits of quantification were obtained for the 36 compounds studied, six of which were identified for the first time in Pedro Ximénez (propyl acetate, cis-3-hexenyl acetate, benzyl acetate, guaiacol, trans-whiskeylactone and 4-ethylguaiacol). The volatile composition of the samples varied as the ageing process progressed, and higher volatile concentrations were obtained in samples aged in barrels that had been intensely toasted compared to in those with medium toasting. A multivariate statistical study allowed the samples to be correctly classified according to ageing time, wood toasting and the type of wood used for ageing. CONCLUSION: The organoleptic analysis performed on the Pedro Ximénez sweet wine samples resulted in differences between the wines aged in the different types of wood during the early weeks of ageing, and scarce differences towards the end of the study period. At the end of the process, all of the wines were better valued and wines aged in medium toasted barrels were the best rated by the panel of judges for all four woods under investigation. This fact could indicate the suitability of alternative woods for the ageing of Pedro Ximénez sweet wines. © 2020 Society of Chemical Industry.


Assuntos
Manipulação de Alimentos/métodos , Compostos Orgânicos Voláteis/análise , Vinho/análise , Madeira , Adulto , Fagaceae , Feminino , Humanos , Masculino , Sensação , Vitis
12.
Biomed Chromatogr ; 33(1): e4398, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30248719

RESUMO

Depression is the largest cause of disability worldwide, affecting 350 million people. Notwithstanding that clinical trials demonstrate antidepressants efficacy, the efficient response can vary individually concerning therapeutic dosage. Although important, plasma levels monitoring remains an analytical challenge whereas clean-up and pre-concentration represent critical steps. Therefore, this study aims to develop, optimize and validate a method for fluoxetine determination in human plasma, employing a laboratory-made device consisting of a PDMS stir bar sorptive for extraction, coupled with high-performance liquid chromatography-fluorescence detection (SBSE-HPLC-FD). Optimization involved sorption-desorption steps. For sorption, temperature and time were assessed by factorial and central composite design approaches, taking into account the desirability and the response surface results, with stirring speed also examined. For desorption kinetics and ultrasonic and magnetic stirring mode were evaluated. The proposed method after validation was robust, linear (25.00-1000.00 ng mL-1 , R2 > 0.98) and presented good intra- (RSD 4.18%) and inter-day-assay (RSD 11.60%) precision and accuracy (recovery 109.60%), allowing reliable quantitation without interference. The method was successfully applied to real samples. SBSE-HPLC-FD could represent a feasible alternative with good cost-benefit for low-volume samples and therapeutic drug monitoring, as well as contributing to correlation studies between plasma fluoxetine levels and clinical response, which is still little studied.


Assuntos
Fracionamento Químico/métodos , Cromatografia Líquida de Alta Pressão/métodos , Monitoramento de Medicamentos/métodos , Fluoxetina/sangue , Fracionamento Químico/instrumentação , Humanos , Limite de Detecção , Modelos Lineares , Reprodutibilidade dos Testes , Espectrometria de Fluorescência
13.
Molecules ; 22(7)2017 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-28672781

RESUMO

The key aroma compounds and the organoleptic quality of two Chinese Syrah wines from the Yunnan Shangri-La region and Ningxia Helan mountain region were characterized. The most important eighty aroma-active compounds were identified by Gas Chromatography-Olfactometry. In both Syrah samples, ethyl 2-methylpropanoate, ethyl 3-methylbutanoate, 3-methylbutyl acetate, 2- and 3-methyl-1-butanol, ethyl hexanoate, ethyl octanoate, 2-phenethyl acetate, methional, 3-methylbutanoic acid, hexanoic acid, octanoic acid, ß-damascenone, guaiacol, 2-phenylethanol, trans-whiskylactone, 4-ethylguaiacol, eugenol, 4-ethylphenol, and sotolon were detected to have the highest odor intensities. In the chemical analysis, 72 compounds were quantitated by Stir Bar Sorptive Extraction combined with Gas Chromatography Mass Spectrometry. Based on the Odor Activity Value (OAV), the aromas were reconstituted by combining aroma compounds in the synthetic wine, and sensory descriptive analysis was used to verify the chemical data. Fatty acid ethyl esters, acetate esters, and ß-damascenone were found with higher OAVs in the more fruity-smelling sample of Helan Mountain rather than Shangri-La.


Assuntos
Odorantes/análise , Vinho/análise , Acetatos/química , China , Ésteres/química , Ácidos Graxos/química , Cromatografia Gasosa-Espectrometria de Massas , Norisoprenoides/química , Olfatometria
14.
Artigo em Inglês | MEDLINE | ID: mdl-28758837

RESUMO

The main objective of this study is to propose a new sorbent phase based on a commercial epoxy resin, for use as an alternative sorbent in the stir bar sorptive extraction (SBSE) technique. The analytes triclosan (TCS) and methyl-triclosan (MTCS) were selected in order to demonstrate the application of the bars, using some water samples as matrices. The extraction conditions of sample volume, stirring time, pH, temperature and ionic strength were evaluated, and for the back extraction, the bars were sonicated using 1.00 mL of acetonitrile for 10 min. The technique of liquid chromatography using a diode array detector was employed for the quantitation. Analytical curves of between 2.50 and 50.0 µg L-1 with r2 of 0.9894 (TCS) and 0.9933 (MTCS), and limit of detection (LOD) values of 0.6 µg L-1 (TCS) and 2.0 µg L-1 (MTCS) were observed. Recovery values between 100.4% and 121.6% were verified for ultrapure water and between 50.3% and 93.8% for wastewater samples, thereby suggesting the possibility of employing the bars for quantitation of TCS and MTCS in aqueous samples. This is the first time that this resin has been applied without the need for the adhesion of any additional sorbent phase, thereby providing a simple and low-cost method. Another feature is that only eight bars were employed in the entire work, and each bar was used approximately 40 times with the same performance without memory effects.


Assuntos
Resinas Epóxi/química , Triclosan/análogos & derivados , Águas Residuárias/química , Poluentes Químicos da Água/análise , Adsorção , Cromatografia Líquida de Alta Pressão , Limite de Detecção , Concentração Osmolar , Reprodutibilidade dos Testes , Triclosan/análise
15.
J Sci Food Agric ; 95(7): 1507-13, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25092116

RESUMO

BACKGROUND: The use of aromatic plant extracts as ingredients may be compromised owing to low transference and activity lack in food matrixes compared with in vitro trials. Rosemary essential oil (REO) was added to sheep milk to study the transference of its compounds during the cheese-making process and to determine how cheese antimicrobial activity is modified. RESULTS: The volatile characterization of dairy samples was performed using headspace stir bar sorptive extraction coupled to gas chromatography/mass spectrometry (HS-SBSE/GC/MS) so that fat matrix interferences were reduced. This method detected a decrease in volatile recovery concentration of 19.33% when REO was added to milk. A total recovery volatile yield of 62.51% was measured from the initial quantification of milk to cheese, with hydrocarbon volatiles being transferred in a higher ratio (64.88%) than oxygenated ones (58.74%). No effects were observed for REO in fortified cheese on the counts of native flora necessary for ripening processes, but the total inhibition of Clostridium spp. was provoked CONCLUSION: The study of active compound transference during cheese elaboration was achieved. The antimicrobial results in fortified cheeses with REO showed a preventive effect in the case of clostridial species, which are responsible for late cheese blowing.


Assuntos
Queijo/análise , Gorduras na Dieta , Manipulação de Alimentos/métodos , Microbiologia de Alimentos , Leite , Óleos Voláteis , Rosmarinus/química , Animais , Queijo/microbiologia , Clostridium , Humanos , Leite/microbiologia , Ovinos , Volatilização
16.
Food Chem ; 443: 138578, 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38301554

RESUMO

Optimization of seven parameters of stir bar sorptive extraction (SBSE) on mulberry volatile components for the first time. A total of 347 volatile components were identified and quantified in 14 mulberry varieties, predominantly encompassing esters, aldehydes, terpenoids, hydrocarbons, ketones, alcohols, heterocyclics, acids, and phenols. Hexanal and (E)-2-hexenal were the dominant volatiles. Furthermore, 79 volatile compounds characterized by odor activity values (OAVs) > 1 were identified, making a significant contribution to the distinctive mulberry flavor. "Green" notes were the most intense, followed by "fatty" and "fruity". Utilizing odor ring charts, the volatile flavor characteristics of the 14 mulberry varieties could be intuitively distinguished. This study not only established a viable methodology for differentiating mulberry varieties but also laid a theoretical foundation for the quality evaluation and variety breeding of mulberry flavor.


Assuntos
Aldeídos , Morus , Compostos Orgânicos Voláteis , Compostos Orgânicos Voláteis/análise , Melhoramento Vegetal , Cromatografia Gasosa-Espectrometria de Massas/métodos , Frutas/química , Odorantes/análise
17.
Small Methods ; 8(8): e2301377, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38152986

RESUMO

Developing cost-effective and high-performance thermoelectric (TE) materials to assemble efficient TE devices presents a multitude of challenges and opportunities. Cu3SbSe4 is a promising p-type TE material based on relatively earth abundant elements. However, the challenge lies in its poor electrical conductivity. Herein, an efficient and scalable solution-based approach is developed to synthesize high-quality Cu3SbSe4 nanocrystals doped with Pb at the Sb site. After ligand displacement and annealing treatments, the dried powders are consolidated into dense pellets, and their TE properties are investigated. Pb doping effectively increases the charge carrier concentration, resulting in a significant increase in electrical conductivity, while the Seebeck coefficients remain consistently high. The calculated band structure shows that Pb doping induces band convergence, thereby increasing the effective mass. Furthermore, the large ionic radius of Pb2+ results in the generation of additional point and plane defects and interphases, dramatically enhancing phonon scattering, which significantly decreases the lattice thermal conductivity at high temperatures. Overall, a maximum figure of merit (zTmax) ≈ 0.85 at 653 K is obtained in Cu3Sb0.97Pb0.03Se4. This represents a 1.6-fold increase compared to the undoped sample and exceeds most doped Cu3SbSe4-based materials produced by solid-state, demonstrating advantages of versatility and cost-effectiveness using a solution-based technology.

18.
Foods ; 13(16)2024 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-39200451

RESUMO

This study investigated the changes in the aroma of jasmine tea during storage. Solid-phase micro-extraction (SPME)-gas chromatography (GC)-mass spectrometry (MS) and stir bar sorptive extraction (SBSE)-GC-MS were combined to detect all volatile compounds. GC-olfactometry (GC-O), odor activity value (OAV), and p-value were employed to analyze and identify the key aroma compounds in six jasmine tea samples stored for different durations. Nine key aroma compounds were discovered, namely (Z)-3-hexen-1-yl acetate, methyl anthranilate, methyl salicylate, trans-ß-ionone, linalool, geraniol, (Z)-4-heptenal, benzoic acid methyl ester, and benzoic acid ethyl ester. The importance of these compounds was confirmed through the aroma addition experiment. Correlation analysis showed that (Z)-4-heptenal might be the main reason for the increase in the stale aroma of jasmine tea. Through sensory evaluation and specific experimental analysis, it can be concluded that jasmine tea had the best aroma after 3 years of storage, and too long a storage time may cause the overall aroma of the tea to weaken and produce an undesirable odor. The findings can provide a reference for the change in aroma during the storage of jasmine tea and provide the best storage time (3 years) in terms of jasmine tea aroma.

19.
J Chromatogr A ; 1713: 464501, 2024 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-37979511

RESUMO

A quantitative analytical method capable of determining the concentrations of 81 aroma-relevant wine volatiles covering nine orders of magnitude was developed and validated in this study. The method is based on stir bar sorptive extraction (SBSE) of 200 µL of wine diluted with 1.8 mL NaCl brine with pH 3.5. Volatiles thermally desorbed from the stir bars were separated in two runs in a heart-cut multidimensional gas chromatographic system and quantified using either a flame ionization detector (FID) in the first dimension (27 aroma compounds) or a mass spectrometer in the second dimension (54 aroma compounds, transferred to 22 cuts). Typical limits of compound detection lay around 0.02 mg/L by FID or ranged from 0.001 to 0.30 µg/L by mass spectrometry detector, liying below the corresponding odor thresholds in all cases. Linearity, reproducibility, and recovery were considered satisfactory for most compounds, with typical R2 values of 0.989-0.999, relative standard deviation below 10 % for 37 compounds and between 10 and 20 % for 44 compounds, and recovery rates of approximately 100 % (85-109 %) for all but acetaldehyde. An analysis of 20 wine samples completed our validation of the method, showing that a single-sample preparation procedure combined with heart-cut multidimensional two-detector gas chromatography can determine wine volatile concentrations ranging from 350 mg/L of isoamyl alcohol to 3.8 ng/L of 3-isobutyl-2-methoxypyrazine.


Assuntos
Vinho , Vinho/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Odorantes/análise , Ionização de Chama , Reprodutibilidade dos Testes , Espectrometria de Massas
20.
ACS Appl Mater Interfaces ; 16(11): 14055-14063, 2024 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-38457210

RESUMO

Fabrication of large-sized inorganic nanosheets is an efficient strategy to promote carrier transportation in flexible thermoelectric (TE) films. Herein, we report the self-assembly of large-sized Cu3SbSe4 nanosheets by using a Se nanowire template via wet chemical synthesis and then vacuum-assisted filter these plate-like microcrystals on nylon to prepare Cu3SbSe4 flexible thermoelectric (TE) hybrid films. SEM reveals that the as-synthesized Cu3SbSe4 powders by using Se nanowires as selenium sources presented 2D plate-like micron structures uniformly and tightly self-assembled by acute triangle-like nanoparticles. Furthermore, XPS evidences that extra Sb vacancies are generated in the unit cell of Cu3SbSe4 crystals synthesized by using the Se NW template, resulting in the shrinkage of the unit cell and the narrowing interplanar spacing, which are characterized by XRD and TEM. As a result, both carrier concentration and carrier mobility have been significantly improved. The high carrier concentration is proved to originate from the extra carriers induced by Sb vacancies, and the high carrier mobility of the film is mainly ascribed to its continuous grain boundaries in the plate-like microcrystal morphology. The large-sized nanosheet Cu3SbSe4/nylon hybrid film (CSS MPs) exhibits a high power factor (PF) of 235.45 µW m-1 K-2 at 400 K, which is 4.23 times higher than that of the Cu3SbSe4/nylon hybrid film (CSS NPs) where Cu3SbSe4 crystals are synthesized by using raw Se particles. This work reveals a novel approach to prepare plate-like Se-based semiconductors, which requires both high carrier concentration and high carrier mobility.

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