RESUMEN
The influence of different combinations of Syrah grape maturation degree (19, 21 and 23⯰Brix) and maceration times (10, 20 and 30â¯days) on the volatile profile and aroma potential was evaluated for the first time through different chromatographic platforms (GCâ¯×â¯GC/TOFMS, GC-O-OSME, GC-FID and GC/MS). GCâ¯×â¯GC/TOFMS analyses resulted in 145 identified compounds and among these 29 were determined to be the most important for wine differentiation. The aroma compounds allowed the discrimination of Syrah wines made with grapes macerated for a shorter time (ten days) due to the higher levels of volatile compounds. The evaluation of these wines through GC-O-OSME together with GC-FID, MS resulted in the designation of 19⯰Brix as the most appropriate grape maturation degree to obtain a greater number of volatiles with pleasant odor and higher intensity and persistence. GCâ¯×â¯GC/TOFMS allowed five and six co-elutions to be resolved, involving, respectively, ten and twelve important wine compounds.
Asunto(s)
Odorantes/análisis , Vitis/química , Vino/análisis , Cromatografía de Gases y Espectrometría de Masas/métodos , Olfatometría , Compuestos Orgánicos Volátiles/análisisRESUMEN
Urinary metabolomics offers a non-invasive means of obtaining information about the system-wide biological health of a patient. Untargeted metabolomics approaches using one-dimensional gas chromatography (GC) are limited due to the chemical complexity of urine, which poorly detects co-eluting low-abundance analytes. Metabolite detection and identification can be improved by applying comprehensive two-dimensional GC, allowing for the discovery of additional viable biomarkers of disease. In this work, we applied comprehensive two-dimensional GC coupled with time-of-flight mass spectrometry (GCâ¯×â¯GC-TOFMS) to the analysis of urine samples collected daily across 28-days from 10 healthy female subjects for a personalized approach to female reproductive health monitoring. Through this analysis, we identified 935 unique volatile metabolites. Two statistical methods, a modified T-statistic and Wilcoxon Rank Sum, were applied to analyze differences in metabolome abundance on ovulation days as compared to non-ovulation days. Four metabolites (2-pentanone, 3-penten-2-one, carbon disulfide, acetone) were identified as statistically significant by the modified T-statistic but not the Rank Sum, after a false-discovery rate of 0.1 was set using a Benjamini-Hochberg correction. Subsequent analyses by boxplot indicated that the putative volatile metabolic biomarkers for fertility are expressed in increased or decreased abundance in urine on the day of ovulation. Individual analysis of metabolome expression across 28-days revealed some subject-specific features, which suggest a potential for long-term, personalized fertility monitoring using metabolomics.
Asunto(s)
Cromatografía de Gases y Espectrometría de Masas/métodos , Ciclo Menstrual/metabolismo , Metaboloma/fisiología , Metabolómica/métodos , Acetona/orina , Adolescente , Adulto , Biomarcadores/orina , Disulfuro de Carbono/orina , Femenino , Humanos , Ciclo Menstrual/orina , Ovulación/metabolismo , Pentanonas/orina , Adulto JovenRESUMEN
Keemun, Assam, Darjeeling and Ceylon black teas are honored as the world's four most famous black teas, and their excellent aroma qualities are well received by people around the world. In this study, aroma components in these four types of teas were analyzed by comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GCâ¯×â¯GC-TOFMS) and gas chromatography-olfactometry (GC-O) technologies. A total of 42 aroma-active compounds were ultimately identified, especially benzeneacetaldehyde, geraniol, (Z)-3-hexen-1-yl hexanoate, trans-ß-ionone, cis-linalool oxide (pyranoid), hotrienol, and methyl salicylate presented the strongest aroma strengths with pleasant scents in all tested teas. The quantification results indicated that 19 compounds including (Z)-3-hexenol, 1-octen-3-ol, linalool, phenylethyl alcohol, hexanal, benzeneacetaldehyde, limonene, heptanoic acid, (Z)-3-hexen-1-ol, acetate, benzyl alcohol, trans-linalool oxide (furanoid), hotrienol, 1-octen-3-one, 2-nonanone, (E)-2-octenal, nonanal, ß-myrcene, 2-pentylfuran, and methylpyrazine were identified as the key compounds with odor activity values (OAVs) higher than 1.0 in the world's four most famous black teas. Notably, the comparison of GC-O and OAV calculation results showed that methyl salicylate (Ceylon), (E)-2-octenal (Assam), benzeneacetaldehyde (Keemun) and linalool and trans-linalool oxide (furanoid) (Darjeeling) might be the most definitive odorants in the corresponding tea categories.
Asunto(s)
Odorantes/análisis , Compuestos Orgánicos/análisis , Compuestos Orgánicos/química , Té/química , Femenino , Cromatografía de Gases y Espectrometría de Masas , Humanos , MasculinoRESUMEN
The influence of grape maturity on wine volatome was investigated using HS-SPME-GCâ¯×â¯GC-TOFMS. Shiraz wines were made from grapes harvested from four different vineyards from two berry maturity levels. A total of 1276 putative compounds were detected in at least one of the wine samples and 175 showed significant trends related to grape maturity. The first two dimensions of the Principal component analysis accounted for 57% of the variation and separated the samples according to the harvest date. Wines from the first harvest date were characterised by an abundance of lipoxygenase derived compounds, norisoprenoids and sulfur-containing compounds whereas a significant increase in some acetate esters was observed in wines produced from the more mature grapes. This study demonstrated a common evolution of grape volatiles for Shiraz inside the same mesoclimate. During the late ripening stage of the grape, a direct nexus between sugar concentration and wine volatile evolution was not observed.
Asunto(s)
Cromatografía de Gases y Espectrometría de Masas , Vitis/química , Compuestos Orgánicos Volátiles/análisis , Vino/análisis , Norisoprenoides/análisis , Norisoprenoides/aislamiento & purificación , Análisis de Componente Principal , Microextracción en Fase Sólida , Terpenos/análisis , Terpenos/aislamiento & purificación , Vitis/metabolismo , Compuestos Orgánicos Volátiles/aislamiento & purificaciónRESUMEN
The formation of and dynamic changes in aroma during white tea processing have not previously been systematically investigated. In this study, advanced comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry was employed to investigate the mechanism of white tea aroma formation. A total of 172 volatiles were identified and mainly comprising endogenous volatiles, which displayed diverse change trends during the withering period. In this process, free aroma precursor amino acids and glycosidically bound volatiles (GBVs) were found to contribute to the formation of white tea aroma, with the differential expression of aroma-related key genes accounting for various accumulation of endogenous volatiles and GBVs. In addition, the drying was also shown to play an important role in the formation of white tea aroma. Our study provides the first characterization of white tea aroma formation and establishes a theoretical basis for quality control during white tea processing operations.
Asunto(s)
Camellia sinensis/genética , Odorantes/análisis , Té/química , Compuestos Orgánicos Volátiles/análisis , Aminoácidos/análisis , Camellia sinensis/química , Cromatografía de Gases y Espectrometría de Masas/métodos , Regulación de la Expresión Génica de las PlantasRESUMEN
Beer volatile terpenic compounds arise from a network of variables, namely from plant raw-materials metabolism, yeast metabolism, among others, and may suffer modifications during brewing. In order to increase the molecular understanding of beer volatile terpenic compounds, this work intends to perform a comprehensive characterization of these molecules on lager beer, using an advanced multidimensional chromatographic methodology. This research comprises the most detailed screening of lager beer terpenic compounds through the putative identification of 94 mono and sesquiterpenic compounds, distributed over 6 chemical families: alcohols, aldehydes, esters, ketones, hydrocarbons, and oxides. The terpenic profiles allowed the beer terpen-typing according to samples' category clustering: macro and micro-brewer beers. This study adds further insight to the lager beer terpenic volatile composition, and could be applied in large-scale studies in different contexts, namely for understanding the distinctive beer styles or for beer typing.
Asunto(s)
Cerveza/análisis , Cerveza/clasificación , Terpenos/análisis , Compuestos Orgánicos Volátiles/análisis , Análisis por Conglomerados , Cromatografía de Gases y Espectrometría de Masas , Microextracción en Fase Sólida , Terpenos/química , Compuestos Orgánicos Volátiles/químicaRESUMEN
Volatile organic compounds (VOCs) emanating from the surfaces of human skin are of great interest to researchers in medical and forensic fields, as well as to biologists studying the ecology of blood-feeding insect vectors of human disease. Research involving the comparison of relative abundances of VOCs emanating from human skin is currently limited by the methodology used for sample collection and pre-concentration. The use of in-house developed silicone rubber (polydimethylsiloxane (PDMS)) passive sampling devices constructed in the form of bracelets and anklets was explored to address this need. The easy-to-use samplers were employed as non-invasive passive sampling devices for the non-targeted collection and concentration of volatile human skin emissions prior to thermal desorption thereof coupled with comprehensive gas chromatographic time-of-flight mass spectrometric (GCâ¯×â¯GC-TOFMS) analysis. Compounds collected were from a wide range of compound classes. Several compounds, notably cyclic ketones, identified have not been previously reported in skin volatile literature. Comparison of normalized unique mass peak area signals has revealed relative quantitative differences and similarities between the samples collected from two individuals' wrists and as well as between an individual's wrist and ankle. The sampling method was evaluated based on its ability to provide many candidate compounds for potential biomarker discovery. The results show the ability of the new sampling method for augmenting the current knowledge on human skin volatile emissions. The samplers are both easy to use and economical. Applications explored include the study of the complex relationships between the human skin microbiome and the attractiveness of individuals to anthropophilic blood host seeking mosquitoes.
Asunto(s)
Cromatografía de Gases y Espectrometría de Masas/métodos , Microbiota/fisiología , Mosquitos Vectores/fisiología , Fenómenos Fisiológicos de la Piel , Piel/química , Compuestos Orgánicos Volátiles/análisis , Adulto , Humanos , Masculino , Adulto JovenRESUMEN
A chestnut-like aroma is widely considered an important indicator of an excellent-quality green tea; however, the key odorants responsible for chestnut-like aroma have never been systematically studied and remain unknown. In this study, the aroma components of green teas and Chinese chestnuts were analyzed using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GCâ¯×â¯GC-TOFMS), and 58 compounds were identified as common aroma components among green teas, boiled Chinese chestnuts, roasted Chinese chestnuts and raw Chinese chestnuts. Subsequently, 17 volatiles, including 3-methylbutanal, (E)-3-penten-2-one, ethylbenzene, heptanal, benzaldehyde, 2-pentylfuran, octanal, benzeneacetaldehyde, (E)-2-octenal, (E,E)-3,5-octadien-2-one, linalool, nonanal, (E)-2-nonenal, decanal, (Z)-hex-3-en-1-yl hexanoate, trans-ß-ionone and (E)-nerolidol, were identified as the key odorants responsible for chestnut-like aroma based on the odor activity value (OAV) calculation method. Besides, the comparison of OAVs of key odorants between fresh tea leaves and finished teas indicated that all key odorants were present in fresh tea leaves and that their contents increased or decreased during tea processing. Moreover, the comparison between results of OAV and gas chromatography-olfactometry (GC-O) methods showed that ethylbenzene, heptanal, benzaldehyde, 2-pentylfuran, (E,E)-3,5-octadien-2-one, linalool, (Z)-hex-3-en-1-yl hexanoate and trans-ß-ionone were the common identified compounds between the two methods. The identification of chestnut-like aroma in green teas will provide a theoretical basis for further research on the directional adjustment and control of tea aroma quality.
Asunto(s)
Camellia sinensis/química , Odorantes/análisis , Olfato , Té/química , Compuestos Orgánicos Volátiles/análisis , Femenino , Análisis de los Alimentos/métodos , Cromatografía de Gases y Espectrometría de Masas , Humanos , Juicio , Masculino , Olfatometría , Percepción Olfatoria , Hojas de la Planta/químicaRESUMEN
The complementary information provided by tandem ionization time-of-flight mass spectrometry (TI-TOFMS) is investigated for comparative discovery-based analysis, when coupled with comprehensive two-dimensional gas chromatography (GCâ¯×â¯GC). The TI conditions implemented were a hard ionization energy (70â¯eV) concurrently collected with a soft ionization energy (14â¯eV). Tile-based Fisher ratio (F-ratio) analysis is used to analyze diesel fuel spiked with twelve analytes at a nominal concentration of 50â¯ppm. F-ratio analysis is a supervised discovery-based technique that compares two different sample classes, in this case spiked and unspiked diesel, to reduce the complex GCâ¯×â¯GC-TI-TOFMS data into a hit list of class distinguishing analyte features. Hit lists of the 70â¯eV and 14â¯eV data sets, and the single hit list produced when the two data sets are fused together, are all investigated. For the 70â¯eV hit list, eleven of the twelve analytes were found in the top thirteen hits. For the 14â¯eV hit list, nine of the twelve analytes were found in the top nine hits, with the other three analytes either not found or well down the hit list. As expected, the F-ratios per m/z used to calculate each average F-ratio per hit were generally smaller fragment ions for the 70â¯eV data set, while the larger fragment ions were emphasized in the 14â¯eV data set, supporting the notion that complementary information was provided. The discovery rate was improved when F-ratio analysis was performed on the fused data sets resulted in eleven of the twelve analytes being at the top of the single hit list. Using PARAFAC, analytes that were "discovered" were deconvoluted in order to obtain their identification via match values (MV). Location of the analytes and the "F-ratio spectra" obtained from F-ratio analysis were used to guide the deconvolution. Eight of the twelve analytes where successfully deconvoluted and identified using the in-house library for the 70â¯eV data set. PARAFAC deconvolution of the two separate data sets provided increased confidence in identification of "discovered" analytes. Herein, we explore the limit of analyte discovery and limit of analyte identification, and demonstrate a general workflow for the investigation of key chemical features in complex samples.