Changes in the fatty acid profiles and health indexes of bovine colostrum during the first days of lactation and their impact on human health.

Our objective was to analyze the changes in fatty acid (FA) profiles of bovine colostrum and immature milk during the first four days of lactation and assess their potential impact on human health. Colostrum and immature milk samples were collected from Czech Fleckvieh cows during their first to third lactation and the FA profiles were analyzed using multidimensional gas chromatography with a vacuum ultraviolet detector (GC×GC-VUV). The colostrum of primiparous cows contained lower levels of medium-chain and saturated fatty acids, and higher levels of mono- and unsaturated fatty acids compared to that of multiparous cows. The atherogenic and thrombogenicity indexes, as well as the hypocholesterolemic-to-hypercholesterolemic fatty acid ratio, were more favourable in primiparous cows. This makes colostrum fat an attractive product for human nutrition. To obtain the maximum health benefits, we recommend collecting and processing the colostrum of primiparous cows and immature milk at the end of the milk transition separately.

Vacuum-assisted and multi-cumulative trapping in headspace solid-phase microextraction combined with comprehensive multidimensional chromatography-mass spectrometry for profiling virgin olive oil aroma.

In 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.

Solid-phase microextraction coupled to comprehensive multidimensional gas chromatography for food analysis.

Solid-phase microextraction and comprehensive multidimensional gas chromatography represent two milestone innovations that occurred in the field of separation science in the 1990s. They have a common root in their introduction and have found a perfect coupling in their evolution and applications. This review will focus on food analysis, where the paradigm has changed significantly over time, moving from a targeted analysis, focusing on a limited number of analytes at the time, to a more holistic approach for assessing quality in a larger sense. Indeed, not only some major markers or contaminants are considered, but a large variety of compounds and their possible interaction, giving rise to the field of foodomics. In order to obtain such detailed information and to answer more sophisticated questions related to food quality and authenticity, the use of SPME-GC × GC-MS has become essential for the comprehensive analysis of volatile and semi-volatile analytes. This article provides a critical review of the various applications of SPME-GC × GC in food analysis, emphasizing the crucial role this coupling plays in this field. Additionally, this review dwells on the importance of appropriate data treatment to fully harness the results obtained to draw accurate and meaningful conclusions.

Comprehensive two-dimensional gas chromatographic platforms comparison for exhaled breath metabolites analysis.

The high potential of exhaled breath for disease diagnosis has been highlighted in numerous studies. However, exhaled breath analysis is suffering from a lack of standardized sampling and analysis procedures, impacting the robustness of inter-laboratory results, and thus hampering proper external validation. The aim of this work was to verify compliance and validate the performance of two different comprehensive two-dimensional gas chromatography coupled to mass spectrometry platforms in different laboratories by monitoring probe metabolites in exhaled breath following the Peppermint Initiative guidelines. An initial assessment of the exhaled breath sampling conditions was performed, selecting the most suitable sampling bag material and volume. Then, a single sampling was performed using Tedlar bags, followed by the trapping of the volatile organic compounds into thermal desorption tubes for the subsequent analysis using two different analytical platforms. The thermal desorption tubes were first analyzed by a (cryogenically modulated) comprehensive two-dimensional gas chromatography system coupled to high-resolution time-of-flight mass spectrometry. The desorption was performed in split mode and the split part was recollected in the same tube and further analyzed by a different (flow modulated) comprehensive two-dimensional gas chromatography system with a parallel detection, specifically using a quadrupole mass spectrometer and a vacuum ultraviolet detector. Both the comprehensive two-dimensional gas chromatography platforms enabled the longitudinal tracking of the peppermint oil metabolites in exhaled breath. The increased sensitivity of comprehensive two-dimensional gas chromatography enabled to successfully monitor over a 6.5 h period a total of 10 target compounds, namely α-pinene, camphene, ß-pinene, limonene, cymene, eucalyptol, menthofuran, menthone, isomenthone, and neomenthol.

Exploring multiple-cumulative trapping solid-phase microextraction coupled to gas chromatography-mass spectrometry for quality and authenticity assessment of olive oil.

This study explores the potential of an innovative multi-cumulative trapping headspace solid-phase microextraction approach coupled with untargeted data analysis to enhance the information provided by aroma profiling of virgin olive oil. Sixty-nine samples of different olive oil commercial categories (extra-virgin, virgin and lampante oil) and different geographical origins were analysed using this novel workflow. The results from each sample were aligned and compared using for the first time a tile-based approach to enable the mining of all of the raw data within the chemometrics platform without any pre-processing methods. The data matrix obtained allowed the extraction of multiple-level information from the volatile profile of the samples. Not only was it possible to classify the samples within the commercial category that they belonged to, but the same data also provided interesting information regarding the geographical origin of the extra-virgin olive oil.

Sub-ambient temperature sampling of fish volatiles using vacuum-assisted headspace solid phase microextraction: Theoretical considerations and proof of concept.

The extraction of volatiles from perishable food at a sub-ambient temperature using headspace solid-phase microextraction (HS-SPME) has not been considered in the past due to the corresponding loss in sensitivity. We propose HS-SPME sampling under vacuum (Vac-HS-SPME) to compensate problems of sensitivity loss and achieve substantial improvement in extraction efficiencies whilst sampling at temperatures as low as 5 °C. The approach was applied to fish samples, representing a highly vulnerable perishable food sample. The theoretical considerations explaining the performance of Vac-HS-SPME at sub-ambient temperatures are discussed and related to the increase in gas diffusivities when sampling under vacuum. A comparative study between Vac- and regular HS-SPME for the extraction of 18 compounds from salmon was carried out at different temperatures (5, 30 and 40 °C) and sampling times (10-60 min). For the majority of the compounds, Vac-HS-SPME at 5 °C yielded similar or superior extraction efficiencies than regular HS-SPME even when sampling at 40 °C. However, four compounds were better extracted at 1 atm presumably due to the intensification of competitive adsorption of analytes on the SPME fiber under vacuum or the partial losses of more volatile analytes during air-evacuation in the presence of the frozen samples. Sub-ambient temperature sampling (5 °C) combined with Vac-HS-SPME was also applied to monitor the changes in the 18 compounds present in salmon, redfish, and cod refrigerated for up to five days. The results were compared to those obtained with regular HS-SPME at 40 °C. Overall, Vac-HS-SPME sampling at 5 °C represents a new and powerful approach for the analysis of volatiles in refrigerated foods, and has a great potential for future studies in quality control and freshness assessment.

Shelf-Life Evolution of the Fatty Acid Fingerprint in High-Quality Hazelnuts (Corylus avellana L.) Harvested in Different Geographical Regions.

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.

Microwave-Assisted Saponification Method Followed by Solid-Phase Extraction for the Characterization of Sterols and Dialkyl Ketones in Fats.

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 lab-made 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.

Enhancement of volatile profiling using multiple-cumulative trapping solid-phase microextraction. Consideration on sample volume.

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.

Exploring multiple-cumulative trapping solid-phase microextraction for olive oil aroma profiling.

Headspace solid-phase microextraction is a solvent-free sample preparation technique that 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, 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.

A multifaceted investigation on the effect of vacuum on the headspace solid-phase microextraction of extra-virgin olive oil.

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 HS-SPME" (Vac-HS-SPME) 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 Vac-HS-SPME and regular HS-SPME. The results showed an important enhancement in the extraction of semi-volatile compounds when using Vac-HS-SPME, 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.