1,721,009 research outputs found
Vacuum-assisted and multi-cumulative trapping in headspace solid-phase microextraction combined with comprehensive multidimensional chromatography-mass spectrometry for profiling virgin olive oil aroma
No full textIn the present work vacuum (Vac) and multiple cumulative trapping (MCT) headspace solid phase microextraction (HS-SPME) were evaluated as alternative or combined techniques for the volatile profiling. A higher extraction performance for semi-volatiles was shown by all three techniques. Synergic combination of Vac and MCT showed up to 5-times extraction power for less volatile compounds. The hyphenation of said techniques with comprehensive two-dimensional gas chromatography (GC × GC) enabled a comprehensive analysis of the volatilome. Firstly, 18 targeted quality markers, previously defined by means of classical HS-SPME, were explored for their ability to classify commercial categories. The applicability of such markers proved to be limited with the alternative sampling techniques. An untargeted approach enables the selection of specific features for each technique showing a better classification capacity of the commercial categories. No misclassifications were observed, except for one extra virgin olive oil classified as virgin olive oil in 3 × 10 min Vac-MCT-HS-SPME
Multi-Cumulative Trapping HS-SPME-GC-MS in combination of with a novel data handling software for quality and geographical origin classification of virgin olive oil
No full textClassification of olive oil and geographical origin by using a multi-cumulative trapping HS-SPME-GC-MS follow by a novel data handling software
No full textThe sensory attributes of extra virgin olive oil, and in particular specific aroma defects, are officially responsible for oil classification (or declassification) into extra virgin, virgin or lampante olive oil. Undoubtedly, volatile compounds play a crucial role in defining olive oil sensory quality and research efforts have been dedicated to unravel the composition of this informative fraction, to better understand correlations with quality attributes. The relative distribution of volatiles depends on several parameters (i.e., cultivar, geographical origin, fruit ripeness, processing practices, and storage) meaning the identification of an unequivocal fingerprint correlated to quality and authenticity is a difficult task. Most of these variables contribute towards the intensity and quality of the green and fruity perception, while the presence of defects is mainly due to inappropriate manufacturing practices. Multiple-cumulative trapping headspace-solid-phase microextraction (named MC-SPME) is a powerful technique proven to enhance the level of information on the volatile profile. Shorter cumulative extraction times, using a low volume of sample to avoid headspace saturation proved effective for discriminating between different qualities of olive oil (i.e. extra-virgin, virgin and lampante oil) as well as the different geographical origins among the extra virgin oils. The use of a novel data mining and chemometrics software enabled automatic alignment of chromatograms and extraction of useful information in a simple and straightforward way, supporting the routine application of this approach to corroborate sensory panel analysis
Comprehensive analysis of floral scent and fatty acids in nectar of Silene nutans through modern analytical gas chromatography techniques
Full text linkpeer reviewedSilene is one of the largest genera of the world¿s flora, including around 700 species. Among them, the nocturnal moth-pollinated Silene nutans appeared to be a species complex comprising at least seven genetically differentiated lineages. In the present study floral scent and fatty acid composition of nectar of four reproductively isolated genetic lineages of S. nutans from different regions of Western Europe were evaluated to highlight differences among them. Comprehensive bidimensional gas chromatography (GC×GC) was used to allow enhanced separation of these complex samples. Floral scents were collected by trapping volatile organic compounds (VOCs) from flowering plants grown in a controlled chamber, onto sorbent-packed thermal desorption (TD) tubes placed near flowers prior separation through GC×GC and detection by mass spectrometry (MS). This analytical workflow provided a comprehensive chemical fingerprint in a single analytical run. The differences among lineages were revealed by a novel data mining and chemometrics software that enabled the extraction of useful information through powerful multivariate statistical analysis. Fatty acid (FA) profile of nectar, a very poorly investigated topic, was also evaluated. FAs, from crude nectar collected with microcapillary tubes from flowers grown under controlled conditions, were extracted and derivatised into methyl esters (FAMEs) before analysis by GC×GC and Flame Ionisation Detector. Statistical analysis was performed on FAMEs profiles to underline differences between lineages
A high throughput method for fatty acid profiling using simultaneous microwave-assisted extraction and derivatization followed by reversed fill/flush flow modulation comprehensive multidimensional gas chromatography
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EXPLORING THE SCENT OF SILENE BY TD-GC×GC-MS
No full textpeer reviewedSilene is one of the largest genera of the world’s flora, including about 700 species. Amongst them, the nocturnal moth-pollinated Silene nutans appeared to be a species complex comprising at least seven genetically differentiated lineages. Flower scent is known to be involved in the attraction of specific pollinators. We characterized the scent of four reproductively isolated genetic lineages of S. nutans from different regions of Western Europe. The volatiles were trapped in controlled chamber conditions using thermal desorption tubes placed at flower proximity among flowering plants. Thermal desorption (TD) enables rapid and robust in-situ sampling of VOCs onto sorbent tubes, which can be capped and safely transported back to the laboratory for analysis. High sensitivity is achieved through pre-concentration of VOCs on a focusing trap prior to GC analysis. Here, we used comprehensive two-dimensional gas chromatography coupled with mass spectrometry (GC×GC–MS) to provide enhanced separation of these complex samples. The pre-concentration effect of TD, combined with improved separation and highly-sensitive detection by GC×GC- MS provided a comprehensive chemical fingerprint in a single analytical run. The differences among lineages and regions were investigated at a first stage using a novel data mining and chemometrics software, which enabled automatic alignment of chromatograms and extraction of useful information in a simple and straightforward way using powerful multivariate statistical analysis, with the attempt to identify characteristic markers
A comprehensive study on the effect of vacuum of targeted volatile compounds on HSSPME in a complex matrix: A softer efficient method to profile olive oil aromas
No full textpeer reviewedHeadspace Solid-phase microextraction (HSSPME) is an easy, effective and selective technique for the analysis of volatiles and semi-volatiles compounds. Nevertheless, frequently a long time is requested to reach the equilibrium condition to maximize the extraction efficiency, thus pre equilibrium conditions are preferred as a compromise in term of throughput and sensitivity. Sampling under vacuum demonstrated an increasing extraction kinetics of analytes with a low affinity for the headspace without amplifying the temperature and thus preserving sensitive compounds.
In this work Vacuum-SPME has been investigated for the first time for the analysis of a fat matrix, namely olive oil and deodorized oil with added standards, for understanding behavior of volatiles under vacuum.
Gas chromatography coupled to a single quadrupole mass spectrometry was used for the final determination. A three variables (k= 3; temperature, extraction time and sample mass) inscribed rotatable central composite experimental design was used to optimize the sampling conditions. First analyses shown confirming effect of vacuum. Then, the work was oriented on lower temperature and extraction times conditions in order to highlight the gain of extraction rates in softer conditions, especially for semi- and lower volatiles.
A series of compounds, covering the entire range of volatility and a wide chemical structure, were selected from olive oil to compare atmospheric and under vacuum conditions while another series were chosen in the same way to be added in deodorized oil.
Advance analyses results made it possible to highlight patterns and thus to give explanation different observe phenomena concordant with theory
Coupling vacuum assisted headspace and multi cumulative trapping SPME with GC × GC MS to enhance the chromatographic profiling
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Bursting the chromatographic fingerprint by combining vacuum assisted headspace, multi cumulative trapping SPME, and GC × GC
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