Search Results (100)

The aroma of wine is a defining quality attribute, determined mainly by volatile organic compounds (VOCs) originating from grape metabolism, fermentation, and maturation. This study aimed to characterize the VOC composition of young monovarietal red wines from the Alentejo region (Portugal), produced from Alicante Bouschet, Touriga Nacional, and Trincadeira across five consecutive vintages (2020–2024). Headspace solid-phase microextraction (HS-SPME) coupled with comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC×GC-ToFMS) was applied for VOC profiling, followed by multivariate statistical analyses. A strict identification and reproducibility criterion was applied to ensure longitudinal consistency over the five vintages. MANOVA analysis revealed significant effects (p < 0.001) of both grape variety and vintage on VOC distribution. Esters were the most abundant and discriminant group, while aldehydes and terpenes contributed markedly to varietal differentiation. Alicante Bouschet wines were associated with fruity ethyl esters, Touriga Nacional with monoterpenes (citronellol, terpinolene, α-farnesene) and aromatic alcohols, and Trincadeira with aldehydes and sesquiterpenes. Canonical discriminant analysis (CDA) achieved clear separation among varieties and vintages, with the first two canonical functions accounting for over 70% of the total variance. Heatmap analysis highlighted distinctive terpene and C13-norisoprenoid profiles across samples. These findings demonstrate the pivotal role of VOCs in defining Alentejo wine typicity and support their use as chemical markers for authenticity and PDO valorization. Full article

To characterize the key odorants and elucidate the flavor profiles of compound fermented beverages after fermentation, single-compound fermented beverages (GW, AW) and a compound fermented beverage (CW) were prepared using Italian Riesling grapes and SirPrize apples as raw materials. The flavor and metabolite profiles were systematically analyzed by integrating flavoromics (comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry, GC × GC–TOF MS) and metabolomics (LC–MS/MS). The results demonstrated that CW exhibited the most favorable acid/reducing sugars (2.18), imparting a drier taste and superior stability. Compounds with relative odor activity values (rOAV) greater than 1—including 3-methyl-1-butyl acetate, ethyl hexanoate, ethyl butanoate, and ethyl octanoate—collectively contributed prominent fruity, floral, and sweet aromas to all three wine types. Ethyl decanoate provided an additional distinctive traditional fruity note specifically to AW, while 1-octen-3-ol contributed a mushroom-like aroma to both GW and CW. Moreover, 3-methylbutanal, 4-ethyl-2-methoxyphenol, and ethyl 3-methylbutanoate added additional significant aroma contributions to CW, imparting floral, clove-like, and fruity notes, respectively. Notably, ethyl hexanoate (fruity aroma) exhibited a remarkably high rOAV of 27.43 in CW, significantly surpassing its levels in the single-substrate fermentations. Lipid metabolism and the phenylpropanoid pathway were significantly activated in CW, facilitating the coordinated synthesis of esters and phenolic compounds. Sensory attribute network analysis further confirmed that CW possessed more pronounced “sweet”, “fruity”, and “floral” characteristics. Correlation analysis revealed significant relationships between volatile organic compounds (VOCs) and total soluble solids (TS), titratable acidity (TA), the TA/TS ratio, and metabolite levels, underscoring the close connections among physicochemical properties, precursor/intermediate metabolites, and flavor formation. Comprehensive analysis of non-volatile metabolites and flavor-associated VOCs revealed variety-specific characteristics and compounding effects, providing valuable insights for enhancing the quality of compound fermented beverages. Full article

This study investigated the effects of three cooking methods—fragmenting process (FP), boiling treatment (BT), and high-pressure steam (HPS) treatment—on the structure and volatile compounds (VOCs) of fresh Lyophyllum decastes. The surface morphology and functional groups of L. decastes were analyzed by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The VOCs in L. decastes were analyzed by comprehensive two-dimensional gas chromatography–mass spectrometry (GC×GC-MS) and gas chromatography–ion mobility spectrometry (GC-IMS). SEM results showed that HPS resulted in the most pronounced structural disruption, forming a honeycomb-like porous surface, whereas FP yielded smaller fragments with smoother surfaces. FTIR spectra indicated that none of the treatments significantly altered the characteristic functional groups. A total of 73 VOCs were identified by GC×GC-MS, including 23 hydrocarbons, 14 alcohols, 10 ketones, seven aldehydes, six ethers, three esters, two terpenes, and eight other compounds. Additionally, 22 VOCs were identified by GC-IMS, including seven alcohols, six aldehydes, five esters, three ketones, and one other compound. The four compounds benzaldehyde, benzeneacetaldehyde, (E)-2-hexen-1-ol, and 1-hexanal were detected by both methods. Among the three methods, FP induced the least structural damage and better preserved the VOCs. These results offer theoretical insights and technical support for the flavor-oriented deep processing of L. decastes. Full article

Dietary intake is the major route of human exposure to fat-soluble and persistent chlorinated paraffins (CPs), which tend to accumulate in lipid-rich foods such as edible vegetable oils. This study investigated the levels of short-chain (SCCPs) and medium-chain chlorinated paraffins (MCCPs) in commercially available vegetable oils and assessed their potential health risks. The concentrations of SCCPs and MCCPs in 29 commercial edible vegetable oils were analyzed using comprehensive two-dimensional gas chromatography coupled with electron capture negative ionization mass spectrometry (GC × GC-ECNI-MS). Dietary exposure levels were estimated through probabilistic assessment integrating analytical results with dietary consumption data from the Chinese Total Diet Study (2017–2020). The margin of exposure (MOE) approach was employed for risk characterization. The average concentrations of SCCPs and MCCPs were 112 ng/g and 139 ng/g, respectively. The highest SCCP and MCCP concentration were found in sesame oil and peanut oil, respectively. Overall, MCCPs levels were generally higher than SCCPs. The estimated daily intakes (EDIs) of SCCPs and MCCPs were 56.06 and 73.63 ng/kg bw/d on average, with high consumers (P95) exposed to 180.91 and 230.49 ng/kg bw/d, respectively. Corresponding MOE at P95 were 1.27 × 10⁴ for SCCPs and 1.56 × 10⁵ for MCCPs. The current SCCPs and MCCPs dietary intake originated from edible vegetable oils did not pose a significant health risk. This study provides the first probabilistic exposure assessment of CPs in Chinese edible vegetable oils, offering current contamination profiles. Full article

This study examines the swelling behaviour of nitrile-butadiene rubber (NBR) when interacting with tyre pyrolysis oils (TPO), with a focus on the chemical composition of TPO and their interaction with rubber matrices. Initially, a comparative analysis with conventional diesel fuel (DF) was performed using advanced analytical techniques, including two-dimensional gas chromatography coupled to mass spectrometry (2D-GC/MS), infrared (IR) spectroscopy, and nuclear magnetic resonance (¹H-NMR) spectroscopy. The analysis revealed that TPO contains a significantly higher proportion of aromatic hydrocarbons than DF, along with unsaturated and oxygen-containing compounds not present in DF. Based on these compositional differences, blends of TPO and DF were formulated and evaluated for their suitability as liquid energy carriers according to the specifications of DF. In principle, blends with an addition of up to 5 vol% TPO in DF are technically suitable for use as fuel. Subsequently, the sorption behaviour of TPO, DF, and their blends in NBR was investigated. The swelling potential was determined based on mass, density, and volume, and the changes in the hardness and tensile strength of NBR were recorded. The results demonstrate that TPO induces pronounced swelling in NBR, as evidenced by a marked increase in mass uptake and volume expansion. A linear increase was observed between the degree of swelling and the increasing TPO content in the blends. Mechanical property assessments revealed a corresponding decrease in the hardness and tensile strength of NBR upon exposure to TPO, with the most severe effects associated with neat TPO. This work provides a comprehensive assessment of TPO as a potential blend component for DF. It highlights the need for careful consideration of material compatibility in practical applications. Full article

With the increasing consumption of mulberry fruits in commercial markets, flavor profiles have emerged as critical determinants of consumer preference and market acceptance. This investigation utilized four Morus laevigata (Morus L.) accessions exhibiting pronounced variations in fruit pigmentation and flavor characteristics as experimental materials. Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOF MS) was employed to identify key volatile aromatic compounds, while integrated untargeted metabolomics and transcriptomics approaches were applied to elucidate the underlying mechanisms of flavor biosynthesis. Analysis revealed that aldehydes, ketones, lactones, and heterocyclic compounds constitute the primary volatile organic compounds responsible for M. laevigata flavor complexity. The biosynthesis of these volatile aromatic compounds exhibits a direct correlation with lipid metabolite oxidation pathways. Concurrently, oxidative processes are modulated by M. laevigata flavonoid metabolites with antioxidant properties, which subsequently regulate both the compositional profile and quantitative distribution of volatile aromatic compounds. These findings offer novel insights into the metabolite–volatile compound interactions within mulberry systems, establishing a foundational framework for advancing fruit flavor research and cultivar development programs. Full article

Sichuan Paocai is a representative traditional fermented vegetable in China, which is deeply embedded in local geographical and cultural heritage. However, regional differences in product characteristics remain poorly understood. In this study, the physicochemical properties, volatile compounds, and microbial communities of Paocai from seven production regions in Sichuan (named FB, AB, BZ, CD, DZ, MY, and YS) were systematically investigated. Parameters including pH, salinity, nitrite, organic acids, and color were determined, while volatile profiles were analyzed using an electronic nose and comprehensive two-dimensional gas chromatography–mass spectrometry. A total of 294 volatile compounds were identified, with alcohols, esters, and isothiocyanates emerging as the major contributors to flavor differentiation. UMAP and OPLS-DA analyses revealed distinct regional clustering, which was consistent with electronic nose profiling, and 111 volatile compounds were identified as key aroma markers. Microbial diversity was assessed using 16S rRNA gene sequencing, demonstrating that Lactobacillus, Lentilactobacillus, Pediococcus, and Weissella were the dominant taxa, although the richness varied significantly across regions. An LEfSe analysis further identified region-specific biomarkers, including Pediococcus, Lactococcus, and Leuconostoc in FB; Lactobacillus in AB; Pediococcus ethanolidurans in BZ; Levilactobacillus in DZ; Lentilactobacillus in MY; and a more diverse microbiota in MS. A correlation analysis highlighted the pivotal roles of distinct microbial groups in shaping and transforming flavor compounds across different regions. Overall, these findings provide scientific guidance for the development of high-quality, region-specific products and contribute to the protection, branding, and market competitiveness of geographically indicated foods. Full article

The present study provided an exhaustive examination of VOC emissions originating from 13 different raw materials susceptible to being used in the sampling of the human volatilome and encompassing both polymeric and non-polymeric compositions. To achieve this aim, thermodesorption coupled with comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (TD-GC×GC/ToFMS) was employed. For each material, we report the total number of detected peaks, total volatile organic compound (TVOC) concentration, distribution of VOC emissions across different chemical families, minimum and maximum individual concentrations, as well as hypotheses regarding the origins of some specific VOCs depending on the material considered. The findings from this investigation revealed that materials, such as silicone and polyurethane, could emit an extensive array of VOCs, with up to 2000 chromatographic peaks detected, and emissions of total volatile organic compounds (TVOCs) reaching levels of 5.4 µg·g⁻¹ and 9.8 µg·g⁻¹, respectively. In the case of polyamide, some VOCs could be related to potential reagents involved in its synthesis. While highlighting materials that should be used with caution depending on the topic and target analytes, this study identified materials that exhibited minimal VOC emissions, such as polytetrafluoroethylene, aluminum, and stainless steel, after an adequate conditioning step. The selected analytical technique, TD-GC×GC/ToFMS, proved its relevance to identify and characterize semi-quantitatively VOC emissions coming from those materials. Such information was essential within the frame of the development of a body odor sampling system, our primary objective. Full article

Shubat, a traditional fermented camel milk from Kazakhstan, is renowned for its unique flavor and nutritional properties, though its volatile compound profile remains poorly characterized. In this study, headspace solid-phase microextraction coupled with comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (HS-SPME-GC×GC–ToFMS) was employed to qualitatively identify and semi-quantitatively analyze volatile metabolites in seven Shubat samples collected from four regions of Kazakhstan. Of the 372 volatile organic compounds initially detected, 202 were retained after screening, predominantly comprising esters, acids, alcohols, ketones, and aldehydes. Esters, acids, and alcohol were found to be the most abundant categories. Diversity analyses (α and β) revealed substantial variation across regions, likely influenced by Shubat’s rich and region-specific microbiome. An UpSet analysis demonstrated that 75 volatile compounds were shared among all samples, accounting for over 87% of the total volatile content, indicating a chemically stable core. These findings underscore the chemical complexity of Shubat and provide novel insights into its metabolite composition, thereby establishing a foundation for future sensory, microbial, and quality-related research. Full article

Distillation, a crucial step in Baijiu production, profoundly influences its flavor. However, the aroma-active compounds of Sichuan Xiaoqu Qingxiangxing (SXQ) Baijiu during distillation remain unclear. Here, we comprehensively analyzed the volatile flavor compound (VFC) composition and alcohol content variations across three key distillation stages (i.e., head, heart, and tail) of SXQ Baijiu using headspace solid-phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography–mass spectrometry (GC×GC-MS), alongside electronic nose (E-nose) and electronic tongue (E-tongue). A total of 111 VFCs, 22 key odorants, and 11 pivotal differential VFCs were identified. Ethyl octanoate were identified as the most critical odor-active compounds, while isoamylol was recognized as a key difference marker. VFC concentrations in raw Baijiu decreased from head > heart > tail, while VFC categories increased from tail > head > heart. The flavor profiles of the head differ significantly from those of the heart and tail in Baijiu distillation. Alcohol content decreased as distillation proceeded. The E-nose and E-tongue effectively distinguished raw Baijiu samples from different distillation stages. This study enhances our understanding of volatile compounds and their aroma contributions during the distillation process of SXQ Baijiu. The findings provides bases for optimizing the distillation and quality-based classification of distillates in SXQ Baijiu production. Full article

Base Mine Lake (BML) is the first full-scale demonstration of water-capped tailing technology in a pit lake to reclaim lands impacted by surface mining in the Alberta Oil Sands Region (AOSR). Biogeochemical cycling and/or exchange near the fluid water interface (FWI) of the organic-rich fluid fine tailings (FFT) can hinder the reclamation process. To monitor this activity, sedimentary depth profiles were collected from three platforms (P1 to P3) at BML. Seventy-four chromatographically well-resolved petroleum hydrocarbon (PHC) isomers were quantified at each depth interval using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC/TOFMS). The range of total concentrations of all isomers examined across the FFT was the highest at P1 (range = 3.6 × 10⁰–5.5 × 10³ ng/g TOC), second highest at P2 (range = 3.8 × 10⁰–1.9 × 10³ ng/g TOC), and lowest at P3 (range = 5.6 × 10⁰–7.1 × 10² ng/g TOC). The elevated levels of the same isomers across platforms suggest a consistent source fingerprint. While the source fingerprint was mostly consistent across the platforms and depths, Principal Component Analysis (PCA) identified small differences between geospatial locations caused by variations in specific isomer concentrations. Hierarchical Clustering Analysis (HCA) identified the isomers responsible for the PCA separation, showing that the concentrations of low-molecular-weight n-alkanes (C11–C13) and drimane varied compared to the heavier PHCs with depth. These alkanes are the most biodegradable of the compounds identified in this study, and their variations may reflect biogeochemical cycling within the FFT. Combining these statistical tools provided deeper insight into how isomer concentrations vary with depth, helping to identify possible influences like changing inputs, biogeochemical cycling, and species exchange with the water column. Full article

Cooked-rice aroma strongly affects consumer choice, yet the chemical traits distinguishing glutinous rice from normal-amylose japonica rice remain underexplored because earlier studies targeted only a few dozen volatiles using one-dimensional gas chromatography–mass spectrometry (GC-MS). In this study, four glutinous and seven normal Japanese cultivars were cooked under identical conditions, their headspace volatiles trapped with MonoTrap and qualitatively profiled by comprehensive GC × GC-TOFMS. The two-dimensional platform resolved 1924 peaks—about ten-fold previous coverage—and, together with hierarchical clustering, PCA, heatmap visualization and volcano plots, cleanly separated the starch classes (78.3% cumulative PCA variance; Euclidean distance > 140). Volcano plots highlighted 277 compounds enriched in the glutinous cultivars and 295 in Koshihikari, including 270 compounds that were not previously documented in rice. Normal cultivars were dominated by ethers, aldehydes, amines and other nitrogenous volatiles associated with grainy, grassy and toasty notes. Glutinous cultivars showed abundant ketones, furans, carboxylic acids, thiols, steroids, nitro compounds, pyrroles and diverse hydrocarbons and aromatics, yielding sweeter, fruitier and floral accents. These results expand the volatile library for japonica rice, provide molecular markers for flavor-oriented breeding and demonstrate the power of GC × GC-TOFMS coupled with chemometrics for grain aroma research. Full article

China is the place of origin and main producer of black tea worldwide, with Dianhong (DH), Chuanhong (CH), and Keemunhong (KH) being the famous Chinese black teas. The contents of various odor components in black teas differ with their origins. However, the effects of these differences on the presentation of distinctive odor characteristics in various products remain unclear. We aimed to elucidate the odor characteristics and odor compounds of these three black teas; to this end, we performed a sensory evaluation and multivariate statistical analysis based on comprehensive two-dimensional gas chromatography–mass spectrometry (GC×GC-MS) results. The sensory evaluation revealed that the odor characteristics of DH were floral and fruity, whereas sweet and herbal-like odors were more intense in CH and QH. A total of 119 volatile compounds were detected, with alcohols, aldehydes, and esters being the main volatile compounds. Among them, 41 volatile compounds were identified with an odor activity value (OAV) of >1, and 24 of them were selected through principal component analysis, hierarchical cluster analysis, and orthogonal partial least squares discriminant analysis as marker substances to distinguish the three teas; thus, 24 volatile compounds are important odor compounds of DH, CH, and QH. Full article

Lager beer has the characteristics of a refreshing aroma, clean and less intense taste, as well as a low alcohol degree, which is suitable for daily drinking. This study aimed to clarify the relationship between important flavor compounds and flavor profiles for lager beer. Headspace solid-phase microextraction, solvent-assisted flavor evaporation combined with comprehensive two-dimensional gas chromatography–mass spectrometry, gas chromatography–mass spectrometry, and gas chromatography-olfactometry–mass spectrometry were applied for the qualitative and quantitative analysis of the trace components in lager beer. Furthermore, the recombination experiment was successfully applied to simulate the flavor profile, and the omission experiment was conducted to study the effects of flavor compounds on the flavor profile. A total of nine compounds were identified as the key flavor compounds, and their contribution to the flavor characteristics of lager beer was verified according to validation experiments. It was found that the influence of the key flavor compounds on the sensory attributes such as malty aroma, fruity aroma, sweetness, and bitterness varied with their concentration. These findings might provide ideas for the research regarding the flavor compounds and flavor profile of lager beer, and contribute to the development of different types of beer in the future. Full article

The most efficient technique for resolving the issue of plastic waste disposal is by converting the wastes into high-quality liquid oils through thermal and catalytic pyrolysis. The objective of this work was to study the composition of liquid oils obtained by thermal and catalytic degradation of plastic wastes containing polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET). The clay catalysts were characterized by N₂ adsorption–desorption isotherms (BET), Scanning Electron Microscopy (SEM) and Fourier transform Infrared Spectrometry (FTIR), Polarized Optical Microscopy (POM), Atomic Force Microscopy (AFM). The effect of temperature and clay catalyst type on the yields of the end-products resulting in thermo-catalytic degradation of PS has been evaluated. Degradation of PS showed the highest liquid oil production at 86.85% in comparison to other plastic types. The characterization of the liquid oils was performed by comprehensive two-dimensional gas chromatography coupled with single quadrupole mass spectrometry (GC × GC-qMS). In liquid oils of PS, eighteen principal compounds (of groups: linear hydrocarbons, mono-aromatics, and di-aromatics) were identified. In the liquid oils of the plastic waste mixture, twenty-four principal compounds (of groups: linear hydrocarbons, mono-aromatics, oxygen-containing aromatic, di-aromatics, and tri-aromatics) were identified. The liquid oils were investigated in order to reconvert them as styrene monomers or other chemicals in energy recovery. Full article