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.

Unraveling the impact of the capsule material on the aroma of brewed coffee by headspace analysis using a HiSorb probe followed by reverse fill/flush flow modulation GC×GC-MS.

The present paper discusses the use of a high-concentration-capacity tool, HiSorb, to investigate the impact of capsule material on the aroma profile of espresso-brewed coffee. The specific high-concentration-capacity probe used is characterized by a sorbent volume (63 µL) intermediate between the solid-phase microextraction (SPME) fiber (0.6 µL) and the stir-bar sorptive extraction rod (126 µL). The extraction performance of the HiSorb was compared, in terms of both absolute signal and compound coverage, with both an equivalent sorbent (polydimethylsiloxane) and a divinylbenzene/carboxen/polydimethylsiloxane SPME fiber using both targeted and untargeted approaches. The HiSorb showed superior extraction compared with the SPME fibers. The HiSorb was then optimized in terms of extraction time and temperature and used to investigate the volatile profile of 23 espresso-brewed coffees prepared with capsules made of different materials-aluminum, compostable, and aluminum multilayer pack-prepared using a refillable capsule. Comprehensive two-dimensional gas chromatography equipped with a reverse fill/flush flow modulator and coupled to mass spectrometry was used to obtain a chromatographic fingerprint of the volatile profile of the brewed coffee. The data were aligned and compared using a tile-based approach, and the results were obtained by performing raw data mining within the same software platform. The data mining enabled the extraction of informative features responsible for the differentiation between the different capsule materials, showing a significant depletion in aroma intensity in the compostable capsule.

Exploring different high-capacity tools and extraction modes to characterize the aroma of brewed coffee.

In the present work, the potential benefit of using multi-cumulative trapping headspace extraction was explored by comparing the results using solid-phase microextraction (SPME) coated with divinylbenzene/carboxen/polydimethylsiloxane and a probe-like tool coated with polydimethylsiloxane. The efficiency of a single 30-min extraction, already explored in previous work, was compared with that of multiple shorter extractions. We evaluated three different conditions, i.e., three repeated extractions for 10 min each from different sample vials (for both the probe-like tool and SPME) or from the same vial (for SPME) containing brewed coffee. The entire study was performed using comprehensive two-dimensional gas chromatography coupled with mass spectrometry. The two-dimensional plots were aligned and integrated using a tile-sum approach before any statistical analysis. A detailed comparison of all the tested conditions was performed on a set of 25 targeted compounds. Although a single 30-min extraction using the probe-like tool provided a significantly higher compound intensity than SPME single extraction, the use of multiple shorter extractions with SPME showed similar results. However, multiple extractions with the probe-like tool showed a greater increase in the number of extracted compounds. Furthermore, an untargeted cross-sample comparison was performed to evaluate the ability of the two tested tools and the different extraction procedures in differentiating between espresso-brewed coffee samples obtained from capsules made of different packaging materials (i.e., compostable capsules, aluminum capsules, aluminum multilayer pack). The highest explained variance was obtained using the probe-like tool and multiple extractions (91.6% compared to 83.9% of the single extraction); nevertheless, SPME multiple extractions showed similar results with 88.3% of variance explained.

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.

Comprehensive analysis of floral scent and fatty acids in nectar of Silene nutans through modern analytical gas chromatography techniques.

The aim of this work was to show the potential of multidimensional gas chromatography combined with mass spectrometry and suitable chemometrics means based on untargeted and profiling data analysis to strengthen the information provided by floral scent and nectar fatty acids of four genetically differentiated lineages (E1, W1, W2, and W3) of the nocturnal moth-pollinated herb Silene nutans. Volatile organic compounds emitted by flowers were trapped for a total of 42 samples by in-vivo sampling dynamic head space for analysing floral scent by untargeted approach, while 37 samples of nectar were collected for analysing fatty acids through profiling analysis. The resulting data from floral scent analysis were aligned and compared using a tile-based methodology followed by data mining to access high-level information. Based on floral scent and nectar fatty acid results, it was possible to distinguish E1 from the W lineages, and W3 from W1 and W2. This work puts the bases for a larger study aiming to clarify the existence of prezygotic barriers involved in speciation among lineages of S. nutans, and thus the possible implication of different flower scents and nectar compositions in this phenomenon.