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See detailClassification of olive oil and geographical origin by using a multi-cumulative trapping HS-SPME-GC-MS follow by a novel data handling software
Spadafora, Natasha; Mascrez, Steven ULiege; McGregor, Laura et al

Poster (2021, June)

The 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 ... [more ▼]

The 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. [less ▲]

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See detailExploring the capability of the HiSorb probe for characterization of volatile and semi-volatile compounds in brewed coffee by GCxGC-qMS
Mascrez, Steven ULiege; Eggermont, Damien; Purcaro, Giorgia ULiege

Poster (2021, June)

Volatile and semi-volatile components are highly relevant to characterize different samples, among which food. These compounds contribute to the peculiar aroma profile of foods and are widely used to ... [more ▼]

Volatile and semi-volatile components are highly relevant to characterize different samples, among which food. These compounds contribute to the peculiar aroma profile of foods and are widely used to assess quality and authenticity. The analysis of volatile and semi-volatile compounds requires the sampling of the headspace (HS) above the sample, which, now a day is mainly performed using high-concentration-capacity HS (HCC-HS) approaches, such as solid-phase microextraction (SPME), stir-bar sorptive extraction (SBSE). More recently, HiSorb has been introduced to fill the gap between SPME and SBSE. In fact, it can be easily automated (as for SPME) but present a significantly higher sorbent volume which allows a much higher trapping capacity. The aim of this work was to exploit the potentiality of HiSorb for the analysis of volatile and semi-volatile from brew coffee and compared to the traditional triphasic SPME fiber more widely applied. Time and temperature conditions were carefully optimized, and the possibility of performing multiple cumulative trapping was investigated as well. The analyses were performed on a multidimensional comprehensive gas chromatographic system coupled with a quadrupole mass spectrometer (GC×GC-qMS) and equipped with a Flow modulator. The fingerprinting obtained from a series of different coffee was investigated for quality and authentication purposes. [less ▲]

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See detailEnhancing the volatile profile at sub-ambient temperature by using vacuum-assisted HS-SPME. Case study on fish spoilage
Mascrez, Steven ULiege; Psillakis, Elefteria; Purcaro, Giorgia ULiege

Poster (2021, June)

Headspace solid-phase microextraction (HS-SPME) is an easy, effective and selective technique for the analysis of volatiles and semi-volatiles compounds. However, long equilibration time is requested to ... [more ▼]

Headspace solid-phase microextraction (HS-SPME) is an easy, effective and selective technique for the analysis of volatiles and semi-volatiles compounds. However, long equilibration time is requested to reach optimized extraction conditions. Equilibrium is reached faster in agitating or heating the sample. Heating sample increases the extraction kinetics. However, artefact production can be a limitation, especially for matrices sensible to temperature. Beside other strategies to improve extraction kinetics, the use of vacuum has been recently and successfully proposed to speed up the extraction without increasing the temperature. The aim of this work was to investigate and compare the use of Vac-HS-SPME to regular HS-SPME sampling from complex solid food like fish. The performances of Vac-HS-SPME were investigated at different sampling temperatures and times. In the present work, the effects of extraction temperature, sampling time and SPME phase were investigated using traditional one variable at a time approach. A series of compounds, markers of fish spoilage and covering the entire chromatogram, were selected for the comparison. Gas chromatography coupled to a single quadrupole mass spectrometry was used for the final determination. Comparable results were obtained between sampling at 5 °C under vacuum condition and at 40 °C at atmospheric pressure. This work showed that the use of vacuum can be a powerful approach for volatiles sampling in refrigerated foods. [less ▲]

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See detailA rapid and efficient method for dialkyl ketones and sterols determination in fat
Mascrez, Steven ULiege; Danthine, Sabine ULiege; Purcaro, Giorgia ULiege

Poster (2021, May)

The present work deals with the optimization of a fast method for the determination of dialkyl ketones (DAKs) in interesterified fats. Microwave-assisted saponification was optimized, followed by ... [more ▼]

The present work deals with the optimization of a fast method for the determination of dialkyl ketones (DAKs) in interesterified fats. Microwave-assisted saponification was optimized, followed by purification on a lab-packed silica solid-phase extraction (SPE) cartridge. The method proposed may be used for the determination of DAKs or both DAKs and sterols by simply eluting an additional fraction from the SPE cartridge. The final determination was performed by gas chromatography- flame ionization detector (GC-FID) for quantification and gas chromatography-mass spectrometry (GC-MS) for confirmation purposes. The proposed method showed good recoveries (>80%) and limit of quantification (0.04-0.07 μg/g for the 4 standard DAKs and of 0.07 μg/g for α-cholestanol). Repeatabilities (n=3) were below 15% for DAKs and generally lower than 6% for sterols. Accuracy on the entire sterol profile was confirmed in comparison to the International Olive Council reference method. The method was finally applied to real-world samples before and after chemical interesterification. [less ▲]

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See detailMulti-Cumulative Trapping HS-SPME to enhance the volatile profile of extra-virgin olive oil
Mascrez, Steven ULiege; Purcaro, Giorgia ULiege

Poster (2021, May)

This work explores the capability of multiple-cumulative trapping (MC) SPME on the characterization of the aroma profiling of olive oils, exploiting the automation capability of a novel headspace ... [more ▼]

This work explores the capability of multiple-cumulative trapping (MC) SPME on the characterization of the aroma profiling of olive oils, exploiting the automation capability of a novel headspace autosampler. The theory that underlays this extraction technique is based on the equilibrium among a three-phase system, i.e., sample-headspace-fiber. A compromise between sensitivity and extraction time is usually needed to optimize the sample throughput, mainly when a large number of samples are analyzed, as usually the case in cross-samples studies. Moreover, contrary to what is usually applied, the selection of the sample volume which does not saturate the headspace (i.e. even 10 times lower than the commonly used quantity), is of high relevance in order to maximize the information extractable. In this work, the fingerprinting of olive oil is explored to discriminate among extra virgin, virgin, and lampante oil, a challenging task of interest for quality and authenticity assessment. The different conditions were compared, considering the general information as pattern analysis, rather than intensity-wise. [less ▲]

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See detailShelf-Life Evolution of the Fatty Acid Fingerprint in High-Quality Hazelnuts (Corylus avellana L.) Harvested in Different Geographical Regions
Ciale Rosso, Marta; Stilo, Federico; Mascrez, Steven ULiege et al

in Foods (2021), 10(3), 685

Hazelnuts are characterized by a relatively high abundance of oleic acid and poly-unsaturated fatty acids, which give this fruit a high nutritional value. As a counterbalance, such a lipid profile is more ... [more ▼]

Hazelnuts are characterized by a relatively high abundance of oleic acid and poly-unsaturated fatty acids, which give this fruit a high nutritional value. As a counterbalance, such a lipid profile is more susceptible to autoxidation and/or degradation reactions under enzymatic catalysis. Lipid oxidation occurs on fatty acids (FAs), both esterified on triacylglycerols and in free form (after lipolysis), but with favorable kinetics on the latter. In this study, the quali-quantitative changes in FA profiles (both free and esterified) were monitored during the shelf life (time 0, 6, and 12 months) as a function of different drying and storage conditions and different cultivars and geographical areas. A derivatization/extraction procedure was performed to quantify the profile of free and esterified fatty acids accurately. The overall profile of the free and esterified fatty acids concurred to create a biological signature characteristic of the cultivar and of the harvest region. The free and esterified forms’ characterization enabled the efficient monitoring of the effects of both the hydrolytic activity (increment in overall free fatty acids) and the oxidative process (decrease in unsaturated free fatty acids versus esterified fatty acids) over the 12 months of storage. [less ▲]

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See detailVacuum-assisted headspace SPME: A powerful tool for extra virgin olive oil profiling enhancement
Mascrez, Steven ULiege; Psillakis, Elefteria; Purcaro, Giorgia ULiege

Poster (2021, March)

Vacuum is a new experimental parameter to control and exploit during headspace microextraction (HS-SPME) method optimization and has been proved to be a powerful alternative to accelerate the extraction ... [more ▼]

Vacuum is a new experimental parameter to control and exploit during headspace microextraction (HS-SPME) method optimization and has been proved to be a powerful alternative to accelerate the extraction kinetics of analytes with a low affinity for the headspace. The effect of this additional parameter was explored for the first time on a fatty matrix, namely olive oil. Extra virgin olive oil has a complex volatile aroma profile, which depends on several parameters (e.g., cultivar, geographical origin, processing practices, storage). Past and current research efforts focus on unravelling the composition of this informative volatile fraction, so as to understand correlations with quality attributes. In the present work, the effects of extraction temperature and sampling time were investigated using traditional one variable at a time approach. The results showed a great improvement in the extraction of semi-volatile compounds using Vac-HS-SPME leading to an enhancement in the information gained by the olive oil aroma fingerprint. [less ▲]

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See detailMicrowave-assisted saponification and SPE for the simultaneous or alternative analysis of dialkyl ketones and sterols in fats
Mascrez, Steven ULiege; Danthine, Sabine ULiege; Purcaro, Giorgia ULiege

Poster (2021, March)

Sterols and, in particular, phytosterols play an important role in the human diet and in verifying the authenticity of the oil products (e.g., to discriminate olive oil from seed oil). The traditional ... [more ▼]

Sterols and, in particular, phytosterols play an important role in the human diet and in verifying the authenticity of the oil products (e.g., to discriminate olive oil from seed oil). The traditional determination of sterols usually involved a first saponification step, followed by liquid-liquid extraction of the unsaponifiable fraction, TLC for isolation of the sterol and final instrumental determination, most often in gas chromatography (GC) after derivatization. Interesterification is an industrial process used to redistribute the fatty acids among triglycerides changing the physicochemical characteristics of fat (e.g. changing crystallization behaviour and the melting point, improving plasticity). Different from the enzymatic process, the chemical one leads to the formation of dialkyl ketones (DAKs) as by-products. So far, only two papers have dealt with DAKs determination in food [1,2]. Microwave-assisted saponification followed by a lab-made solid-phase extraction (SPE) was optimized for the characterization of either DAK or sterols or both simultaneously. The final instrumental determination was performed by GC-FID for quantification and GC-MS for confirmation purposes [less ▲]

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See detailMulti-Cumulative Trapping HSSPME to enhance the volatile profile of extra virgin olive oil
Mascrez, Steven ULiege; Purcaro, Giorgia ULiege

Poster (2021, March)

Multiple-cumulative (MC) HS-SPME is a very powerful technique to enhance the level of information on the volatile profile of foods. A fully automated multi-mode sample preparation system, containing a ... [more ▼]

Multiple-cumulative (MC) HS-SPME is a very powerful technique to enhance the level of information on the volatile profile of foods. A fully automated multi-mode sample preparation system, containing a sorbent based focussing trap to retain and preconcentrate analytes, was used. The novel approach was investigated for the analysis of olive oil aroma profile using a pattern recognition approach. Different extraction parameters were investigated, e.g. extraction time, numbers of cumulative extraction, and, last but not least, the sample volume. Shorter cumulative extraction times proved to be more effective than a single longer extraction to provide more comprehensive profile of volatiles and semivolatiles. Fundamental was the choice of a proper sample volume avoiding headspace saturation in order to maximize the exctraction of the semi-volatile compounds. This technique was successfully applied for the distinction of extra virgin olive oil, from the less expensive virgin olive oil and lampante oil [1,2]. Finally, the coupling of MC-SPME with GCxGC-MS provided a powerful platform for the detailed characterization of the extra-virgin olive oil aroma profile. [less ▲]

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See detailVacuum-assisted headspace SPME under sub-ambient temperature for the analysis of fish samples
Mascrez, Steven ULiege; Psillakis, Elefteria; Purcaro, Giorgia ULiege

Poster (2021, March)

Vacuum-assisted headspace solid-phase microextraction (Vac-HS-SPME) has been proposed as a valid technique to increase the performance of conventional HS-SPME in particular in terms of kinetics for the ... [more ▼]

Vacuum-assisted headspace solid-phase microextraction (Vac-HS-SPME) has been proposed as a valid technique to increase the performance of conventional HS-SPME in particular in terms of kinetics for the semi-volatiles compounds. Although the total amount extracted at the equilibrium does not change when reduced pressure conditions are applied, the overall result from an applicative viewpoint is an increase of extraction yield at shorter extraction time and milder extraction temperature compared to conventional applications, thanks to the improved kinetics. This is particularly beneficial for analysis of food volatiles for a more comprehensive evaluation of the aroma profile and when heating the sample can easily cause artefact formation. The advantages of using Vac-HS-SPME in food samples have been explored at sub-ambient temperature (i.e., refrigerated temperature) for the analysis of particularly perishable foods, such as raw fish. The use of reduced pressure conditions allowed to efficiently sampling at refrigerated temperature, obtaining results comparable to regular HS-SPME at room temperature. [less ▲]

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See detailEnhanced fingerprinting of extra virgin olive oil by multiple-cumulative SPME and GCxGC
Mascrez, Steven ULiege; Purcaro, Giorgia ULiege

Poster (2021, February)

The use of multiple-cumulative headspace-solid-phase microextraction (named MC-SPME) was explored to enhance the volatile profiling of extra-virgin olive oil (EVO). The SPME extraction was performed using ... [more ▼]

The use of multiple-cumulative headspace-solid-phase microextraction (named MC-SPME) was explored to enhance the volatile profiling of extra-virgin olive oil (EVO). The SPME extraction was performed using an automated multimode sample preparation system containing a sorbent based focussing trap to retain and preconcentrate analytes. The novel approach was investigated for the analysis of olive oil aroma profile using a pattern recognition approach. Different extraction parameters were investigated, e.g. extraction time, numbers of cumulative extraction and sample volume to maximize the sensitivity and the sample throughput, important factor in large cross-sample studies. This technique has been successfully applied for the distinction of extra virgin olive oil (EVO), from the less expensive virgin olive oil (VO) and lampante oil (LO). The coupling of MC-SPME with GCxGC-MS generates a powerful platform for the detailed characterization of the extra-virgin olive oil aroma profile, with high potential to be extended towards different fields of applications. [less ▲]

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See detailMicrowave-Assisted Saponification Method Followed by Solid-Phase Extraction for the Characterization of Sterols and Dialkyl Ketones in Fats
Mascrez, Steven ULiege; Danthine, Sabine ULiege; Purcaro, Giorgia ULiege

in Foods (2021), 10

Unlike other fields, the methods routinely applied for fats and oils are still tied to traditional, time- and solvent-consuming procedures, such as saponification, column chromatography and thin-layer ... [more ▼]

Unlike other fields, the methods routinely applied for fats and oils are still tied to traditional, time- and solvent-consuming procedures, such as saponification, column chromatography and thin-layer chromatography. In this paper, microwave-assisted saponification followed by a labmade solid-phase extraction was optimized for the characterization of either dialkyl ketones (DAK)or sterols or both simultaneously. The instrumental determination was performed by gas chromatography-flame ionization detector (GC-FID) for quantification and gas chromatography-mass spectrometry (GC-MS) for confirmation purposes. The proposed method showed good recoveries (>80%) and limit of quantification (0.04–0.07 μg/g for the 4 DAK and of 0.07 μg/g for α-cholestanol). Repeatabilities (n = 3) were below 15% for DAKs and generally lower than 6% for sterols. Accuracy on the entire sterol profile was confirmed in comparison to the International Olive Council reference method. The method was finally applied to real-world samples before and after chemical interesterification. [less ▲]

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See detailExploring multiple-cumulative trapping solid-phase microextraction for olive oil aroma profiling
Mascrez, Steven ULiege; Purcaro, Giorgia ULiege

in Journal of Separation Science (2020), 43

Headspace solid-phasemicroextraction is a solvent-free sample preparation technique that is based on the equilibrium among a three-phase system, i.e., sample-headspacefiber. A compromise between ... [more ▼]

Headspace solid-phasemicroextraction is a solvent-free sample preparation technique that is based on the equilibrium among a three-phase system, i.e., sample-headspacefiber. A compromise between sensitivity and extraction time is usually needed to optimize the sample throughput, especially when a large number of samples are analyzed, as usually the case in cross-samples studies. This work explores the capability of multiple-cumulative trapping solid-phase microextraction on the characterization of the aroma profiling of olive oils, exploiting the automation capability of a novel headspace autosampler. It was shown that multiple-cumulative solid-phase microextraction has the potential to improve the overall sensitivity and burst the level of information for cross-sample studies by using cumulative shorter extraction times. [less ▲]

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See detailVacuum Assisted Headspace Solid-Phase Microextraction: A Powerful Tool for Olive Oil Analysis
Mascrez, Steven ULiege; Purcaro, Giorgia ULiege

in Chromatography Today (2020)

The performance of vacuum-assisted headspace solid-phase microextraction (Vac-HS-SPME) was compared to regular headspace solid-phase microextraction (HS-SPME) for the analysis of extra-virgin olive oil ... [more ▼]

The performance of vacuum-assisted headspace solid-phase microextraction (Vac-HS-SPME) was compared to regular headspace solid-phase microextraction (HS-SPME) for the analysis of extra-virgin olive oil. Vac-HS-SPME proved beneficial in particular for semi-volatile compounds, significantly improving the kinetics of extraction. Moreover, for viscous oil samples combining the effects of heating the sample and vacuum was proven beneficial since it reduced the viscosity of the sample, increased the diffusivity of compounds in the liquid phase and improved volatilisation of less volatile compounds. [less ▲]

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See detailEnhancement of volatile profiling using multiple-cumulative trapping solid-phase microextraction. consideration on sample volume
Mascrez, Steven ULiege; Purcaro, Giorgia ULiege

in Analytica Chimica Acta (2020), 1122

In the present work, the performance of the multiple-cumulative trapping headspace solid-phase microextraction technique used in the headspace linearity range and saturated headspace was investigated and ... [more ▼]

In the present work, the performance of the multiple-cumulative trapping headspace solid-phase microextraction technique used in the headspace linearity range and saturated headspace was investigated and compared, with the ultimate goal of maximizing the fingerprinting information extractable using a cross-sample comparison algorithm for olive oil quality assessment. It was highlighted as the use of 0.1 g of olive oil provides comparable or even better profiling than 1.5 g at a little expense of sensitivity. However, the use of multiple-cumulative-solid-phase microextraction, along with the correct sample volume, improved not only the overall sensitivity but significantly burst the level of information for cross-sample studies. [less ▲]

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See detailA Multifaceted investigation of the effect of reduced pressure condition on the headspace-solid phase microextraction of extra-virgin olive oil
Mascrez, Steven ULiege; Psillakis, Elefteria; Purcaro, Giorgia ULiege

in Analytica Chimica Acta (2020), 1103

Headspace solid-phase microextraction (HS-SPME) is an easy, effective, and selective technique for the extraction of volatiles and semi-volatiles compounds. For the latter, longer equilibration times are ... [more ▼]

Headspace solid-phase microextraction (HS-SPME) is an easy, effective, and selective technique for the extraction of volatiles and semi-volatiles compounds. For the latter, longer equilibration times are needed, which are typically shortened by applying agitation or heating the sample. A less explored way to improve the extraction kinetics of analytes with a low-affinity for the headspace is to sample under vacuum conditions. The methodology that evolved from this approach was termed “vacuum-assisted HSSPME” (VaceHSeSPME) and was mainly used for water- and solid-based samples. The aim of this work was to investigate the effect of vacuum when dealing with non-aqueous liquid samples. For this purpose, the volatile profile of extra virgin olive oil was analyzed using a divinylbenzene/ carboxen/polydimethylsiloxane fiber followed by gas chromatography-mass spectrometry. The effects of extraction temperature and sampling time were investigated using traditional one-variable at a time approach and a two-variable central component design for both VaceHSeSPME and regular HSSPME. The results showed an important enhancement in the extraction of semi-volatile compounds when using VaceHSeSPME, and improved the information gained for the olive oil aroma fingerprint. A theoretical formulation of the underlying process was proposed, providing new insights into the SPME extraction theory. Lowering the sampling pressure effectively reduced gas-sided limitations and accelerated extraction kinetics. However, for viscous samples such as olive oils, the liquid-phase resistance played an important role and delayed extraction. Overall, applying heating (i.e. reducing the viscosity of the oily sample and increasing headspace concentrations) next to reducing the total pressure in the headspace is the best analytical HS-SPME strategy for obtaining fast a rich volatile profile from the oily samples. [less ▲]

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See detailVacuum-Assisted HSSPME, An Innovative Sampling Approach, For Food Applications
Mascrez, Steven ULiege; Psikallis, Elia; Purcaro, Giorgia ULiege

Poster (2020)

Vacuum assisted headspace solid-phase microextraction (Vac-HSSPME) has been proposed as a valid technique to increase the performance of conventional HSSPME. Although the total amount extracted at the ... [more ▼]

Vacuum assisted headspace solid-phase microextraction (Vac-HSSPME) has been proposed as a valid technique to increase the performance of conventional HSSPME. Although the total amount extracted at the equilibrium does not change when reduced pressure conditions are applied, an improvement of extraction yield is observable at shorter extraction time and milder extraction temperature compared to conventional applications. This is particular beneficial for analytes with a low affinity for the headspace (semi-volatiles). The use of Vac-HSSPME is of particular interest for the analysis of food volatiles, allowing to obtain a more comprehensive evaluation of the aroma profile, especially when heating the sample can easily cause artifacts formation. The effect of reduced pressure conditions on a completely fatty sample, i.e. extra-virgin olive oil, has been investigated for the first time and new insight into the SPME mechanism have been obtained. In the present work, the effects of extraction temperature and sampling time were investigated using both traditional one variable at a time approach and a two-variable central component design (CCD). Moreover, Vac-HSSPME has been used to sampling the volatile compounds of raw fish at efrigerated temperature obtaining results comparable to regular SPME at room temperature. [less ▲]

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