Search Results (986)

Based on ancient records of “Marching tea” and the flavonoid-rich properties of Lespedeza juncea, this study optimized green tea processing parameters for Lespedeza juncea tea. By adjusting leaf loading, roasting temperature, and time and employing precise methods such as gas chromatography–olfactory–mass spectrometry (GC-O-MS), liquid chromatography–mass spectrometry (LC-MS), and electronic tongues to determine key indicators, including metabolites, volatile compounds, and flavor profiles, the optimal processing conditions were determined through comprehensive analysis as 150 g, 200 °C, and 180 s. These conditions resulted in superior sensory quality (score: 90.9), the highest flavonoid content (4.11%), strong antioxidant activity (DPPH: 66.0% at 20 mg/mL; ABTS: >95% at 2.5 mg/mL), and key aroma compounds 1-octen-3-ol and β-ionone. This work revives an ancient tea tradition and provides a scientific basis for developing novel functional teas from grassland resources. Full article

To explore the characteristic volatile compounds of ‘Hujing Milu’ peaches from different growing regions, headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME-GC-MS) and headspace gas chromatography–ion mobility spectrometry (HS-GC-IMS) were employed to analyze volatile components in samples from six production areas. A total of 73 and 56 volatile compounds were identified by HS-SPME-GC-MS and HS-GC-IMS, respectively. Quantitative analysis revealed that esters, aldehydes, and alcohols were the main contributors to the aroma profile, accounting for over 70% of the total relative content. Combined with chemometric analysis (VIP > 1 and OAV/ROAV > 1), 17 potential biomarkers were identified that can distinguish ‘Hujing Milu’ peaches from different regions, including ethyl acetate, hexanol, (E)-2-nonenal, and dihydro-β-ionone. Moreover, soil properties of these regions and their correlation with volatile compounds were analyzed to elucidate the formation mechanisms of characteristic aromas. The results showed that ethyl acetate exhibited a significant positive correlation with soil pH (r = 0.530, p < 0.05), whereas dihydro-β-ionone showed a significant positive correlation with soil organic matter (r = 0.587, p < 0.05) and available potassium (r = 0.830, p < 0.05). This study identified characteristic volatile compounds of ‘Hujing Milu’ peaches from different regions, providing a reliable technical basis for origin traceability and the enhancement of aroma quality in ‘Hujing Milu’ peaches. Full article

Ripened Pu-erh tea (RPT) experiences notable aroma transformations during industrial pile fermentation, yet the stage-dependent evolution of key aroma compounds remains poorly understood. This study analyzed two independent industrial batches of RPT across three fermentation stages: raw material (RM), intermediate fermentation (IF), and final fermentation (FF). Using HS-SPME/GC-MS coupled with multivariate statistical analysis and relative odor activity values (rOAVs), 134 volatile organic compounds (VOCs) were identified, with hydrocarbons, alcohols, and esters as predominant classes. In total, 13 key aroma-active compounds (rOAVs > 1) were found to be major contributors to RPT’s characteristic aroma. During early fermentation, relative levels of VOCs responsible for fresh and green aromas (e.g., linalool, D-limonene) diminished, while those for woody and minty aromas (e.g., isophorone, methyl salicylate) increased. A flavor wheel was developed to illustrate the dynamic shifts in aroma profiles. This stage-resolved analysis offers new mechanistic insights into aroma formation, aiding in the optimization of aroma quality control and process standardization for RPT production. Full article

This study examined the evolution of volatile and non-volatile compounds of a Cypriot monovarietal cultivar Maratheftiko red wine over a span of six years (2019–2024). Several physicochemical properties of the wines were evaluated. Alcohol content and volatile acidity remained stable; acidity and malic acid are the main differentiating factors among vintages. In addition, bioactive molecules in the wines showed a distinct vintage effect, with the 2024 vintage exhibiting significantly higher concentrations. For instance, the high concentration of polyphenols (3877.86 mg gallic acid equivalents per L), tannins (688.43 mg of catechin equivalents per L), flavonoids (506.90 mg of rutin equivalents per L), and anthocyanins (413.74 mg of cyanidin equivalents per L) contributed to the high antioxidant capacity of the specific vintage, as FRAP and DPPH assays were measured at 44.60 and 29.91 mmol of ascorbic acid equivalents per L, respectively. Furthermore, the intense crimson color of this red wine could be attributed to the high concentration of the abundant anthocyanin malvidin-3-O-glucoside in this vintage (21.62 mg/L). On the other hand, it was observed that the latest vintage showed high polyphenol concentration but low volatile compound concentration. This pattern was ascertained through correlation analyses and could be attributed to an unsatisfactory level of the aging process. Correlation analysis (Pearson’s r) confirmed inverse relationships between polyphenol concentration and volatile compounds (r = −0.62, p < 0.05). Principal component analysis (PCA) further highlighted the 2024 as an outlier vintage, distinguished by elevated phenolic and antioxidant profiles. Full article

This study examined the effects of varying enzymatic pretreatment durations (0–80 min) of wheat gluten on flavour characteristics of high-moisture plant-based extrudates (HMPEs). Through a comprehensive analysis involving sensory evaluation, electronic tongue, free amino acid (FAA) profiling, electronic nose, and headspace solid-phase microextraction-gas chromatography-mass spectrometer (HS-SPME-GC-MS) analysis of volatile odour compounds, it was found that HMPEs with moderate enzymatic pretreatment (40 min) achieved the highest overall sensory score. Electronic tongue and FAA results confirmed a significant enhancement in umami and sweetness, while electronic nose effectively discriminated differences in odour profiles. Extending pretreatment durations gradually reduced beany off-flavours substances (hexanal reduced by up to 174.7 μg/kg) and encouraged the formation of meaty aroma compounds (furans and pyrazines). However, excessive pretreatment (>40 min) reduced acceptance due to burnt odour caused by the excessive accumulation of pyrazines, particularly 2,3-diethyl-5-methylpyrazine. Six key volatile odour compounds were identified by integrating the analysis of variable importance projection (VIP ≥ 1) and relative odour activity value (ROAV ≥ 1), offering a foundation for targeted flavour regulation in HMPEs. Full article

Slovenia preserves one autochthonous pig breed, the Krškopolje pig, whose meat has been reported to exhibit a favourable fatty acid profile compared with that of modern breeds. However, meat quality is not solely determined by genetics; the production system also influences it, as organic and conventional farming differ in feed composition, housing and outdoor access. This study aimed to compare the effects of pig breed (Krškopolje vs. modern) and production system (organic vs. conventional) on the fatty acid composition and volatile organic compound (VOC) profile of pork. Fatty acid composition was determined by GC-FID after methylation, and the VOCs profile was obtained using headspace solid-phase microextraction (HS-SPME) coupled with GC-MS. Results showed that Krškopolje meat had higher SFA and MUFA, while modern pig meat had higher PUFAs, particularly n-6, reflecting genetic and dietary influences. Modern breeds also showed greater fatty acid response to the rearing system than the Krškopolje breed. Several VOCs were unique to modern breed pigs, indicating breed-specific differences in lipid composition, amino acid metabolism, and microbial activity. Aldehydes were the dominant VOC class in both breeds, slightly higher in Krškopolje meat. OPLS-DA model revealed breed-related differences in VOCs, pinpointing compounds likely responsible for breed-specific aroma and flavour. Full article

Cheese ripening involves a series of biochemical and microbiological transformations that directly affect the texture, aroma, flavor, and quality of the final product. This study aimed to characterize the volatile organic compounds (VOCs) produced during the ripening of goat cheese to find suitable molecular markers for monitoring the maturation process. Headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME/GC–MS) was applied to samples collected at different ripening times (0, 30, 60, 90, 120, and 150 days). Overall, sixty-eight different VOCs were identified, including alcohols, esters, ketones, carboxylic acids, aldehydes, terpenes, sulfur compounds, and others. The total volatile content progressively increased up to 120 days and slightly decreased thereafter. This dynamic evolution reflected the interplay of proteolysis, lipolysis, and microbial metabolism occurring during the ripening process. Among the compounds, 2-butanone and 2-butanol appeared as promising volatile markers of the advanced ripening stages. These results offer new insights into goat cheese flavor development and support the design of a sensing approach for a first warning of the end of the cheese maturation process. Full article

While the sturgeon farming industry is renowned for its valuable caviar, sturgeon muscle tissue remains an underutilized byproduct. The present investigation evaluated the physiological profiles and meat quality attributes of hybrid sturgeon (Acipenser baerii ♀ × Acipenser schrenckii ♂) cultivated in freshwater (FW) and seawater (SW) in terms of conventional nutritional components, color, amino acid, texture, fatty acid, as well as volatile flavor substances. Results revealed that the SW group demonstrated significantly higher muscle whiteness and hardness. The SW group showed significantly higher contents of crude protein, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), n-3 polyunsaturated fatty acids (p < 0.01). Although there was no significant difference in the total hydrolyzed amino acids between the SW and FW groups (p > 0.05), the SW group exhibited significantly higher levels of umami free amino acids, such as glutamic acid and aspartic acid (p < 0.01). Flavor profiling indicated that the SW group exhibited lower levels of several off-flavor compounds, including 1-octen-3-ol, (E,E)-2,4-decadienal, and 3,5-octadien-2-one. Notably, the contents of geosmin (GSM) and 2-methylisoborneol (2-MIB), responsible for earthy off-flavors, were significantly lower in the SW group (p < 0.05). Overall, seawater-cultured hybrid sturgeons offer superior nutritional value and sensory characteristics compared to their freshwater counterparts. These findings provide important scientific insights for enhancing the value-added processing of sturgeon products and the sustainable development of the aquaculture industry. Full article

Table grapes are commonly consumed fresh, and their market value is largely determined by ripeness, grape color, mineral composition, and variety-specific aroma. This study integrated physicochemical ripening indicators (°Brix%, pH, titratable acidity, maturity index), CIELAB color parameters measured on the outer skin and inner sections, multi-element mineral profiling following microwave-assisted digestion (ICP-MS), and volatile organic compound (VOC) profile by HS-SPME/GC-MS to characterize five table grape varieties (Thompson Seedless, Isabella, Mevlana, Pepita Alfonso, and Red Globe). Significant differences in ripeness were found among the varieties (p < 0.01). Isabella had the highest soluble solids content (22.91 °Brix%), while Pepita Alfonso had the highest maturity index (79.89) and the lowest titratable acidity (0.22%). Color measurements also showed significant differences among the varieties (p < 0.01). Thompson Seedless exhibited the highest peel lightness/yellowness and chroma values, while Pepita Alfonso and Red Globe had a darker, lower chroma profile. Color index values differed between the peel and the inner cross-section depending on the variety (p < 0.01). Mineral composition was found to be variety-specific (p < 0.01). The dominant macroelements among the samples were K, P, and Mg, and statistically significant differences were also determined in trace elements (p < 0.01). A total of 42 volatile organic compounds (VOCs) were identified. Aldehydes were dominant in the volatile fraction (39.07–64.96%), nonanal contributed a significant percentage, and terpenoids (floral aroma note) were found in the highest percentage in the Isabella variety (28.87%). PCA applied to the integrated physicochemical, color, and mineral dataset enabled the clear discrimination of the five table grape cultivars. Pepita Alfonso was positioned toward positive PC2, and Red Globe occupied the opposite segment. Thompson Seedless and Isabella were separated mainly along PC1, while Mevlana showed an intermediate profile. SIMCA class-distance results confirmed the visual separation. All pairwise interclass distances were above the decision threshold (ICD > 3), ranging from 62,922 (Red Globe–Mevlana) to 806,425 (Isabella–Pepita Alfonso). Findings indicated robust cultivar-level classification for authenticity and quality control purposes. Overall, the integrated multi-domain approach is considered to provide a solid foundation for variety differentiation and quality-oriented harvesting and market management. Full article

Background/Objectives: The COVID-19 pandemic has emphasized the urgent need for non-invasive diagnostic strategies. While breath analysis has been widely investigated, sweat and sebum remain largely unexplored, despite being abundant, chemically diverse, and easily collected. This exploratory study presents a proof-of-concept workflow to evaluate their potential for infection biomarker discovery. Methods: Samples from 51 subjects were analyzed by headspace solid-phase microextraction coupled with gas chromatography and time-of-flight mass spectrometry (HS-SPME-GC/ToF-MS). Over 8000 untargeted volatile compounds were detected, reflecting the high complexity of these matrices. Results: Data refinement and chemometric modelling using principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) revealed robust separation between SARS-CoV-2-positive Patients and Controls. Classification accuracies consistently exceeded 95%, demonstrating the robust discriminative performance of the approach. Among the detected volatiles, 2-methylbenzenemethanol acetate emerged as the most informative compound, representing a potential biomarker candidate. Conclusions: This work shows that the sweat and sebum volatilome can be exploited for clinical applications. The workflow integrates non-invasive sampling, comprehensive chromatographic profiling, and advanced statistical modelling, representing a methodological contribution to analytical chemistry. Beyond COVID-19, the strategy provides a potential framework for volatile organic compound (VOC)-based diagnostics across different diseases and supports future development of sensor technologies for translation into healthcare practice. Full article

Background: Alecrim-do-campo (Baccharis dracunculifolia) is a species of agroindustrial and medicinal relevance that has attracted increasing interest in recent years due to its distinctive chemical profile rich in bioactive compounds. In this context, the present study evaluated the efficiency of different extraction conditions for volatile compounds in alecrim-do-campo, aiming to contribute to the traceability of products that use this species as a source of metabolites. Methods: A 2³ factorial design was employed to assess the best conditions for extracting volatiles by headspace solid-phase microextraction (HS-SPME), using three different semipolar fibers (PDMS/DVB, DVB/CAR/PDMS and CAR/PDMS). Regarding the effect of the variation factors to which the samples were subjected, only the extraction time (min) had a significant effect on compound extraction using the CAR/PDMS fiber. Results: In total, 79 volatile compounds were detected using the three fibers, with CAR/PDMS (43 compounds) and DVB/CAR/PDMS (44 compounds) showing the highest diversity. The nature of this study is important for the industry because it optimizes the search for quality parameters in plant-derived products. Full article

The addition of Bifidobacterium animalis subsp. lactis and prebiotics to fermented milk can enhance its flavor and sensory properties; however, research on the effects of their combined supplementation on flavor profiles remains limited. This study investigated the impact of simultaneously adding B. lactis IU100 and resistant starch type III (RS3) to fermented milk on flavor and texture. The results showed that co-supplementation shortened the fermentation time by 1 h. It also increased hardness by 28.8%, springiness by 1.14 mm, and water holding capacity by 12.45%, accompanied by the formation of a more continuous and dense gel network. Headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME-GC-MS) combined with odor activity value analysis indicated the enrichment of 115 key aromatic compounds, among which ethyl caprylate, ethyl n-butyrate, 1-octanol, and 2,3-heptanedione were identified as representative flavor compounds associated with fruity and creamy notes. KEGG pathway analysis revealed that 24 differential metabolites were predominantly enriched in purine metabolism and amino acid-related pathways. Within these pathways, coordinated enzymatic reactions convert α-keto acids and fatty acid metabolites into key flavor esters and catalyze the formation of volatile alcohols from amino acids and aromatic fatty acid precursors. Overall, this combined strategy effectively optimized fermentation efficiency, texture, and flavor through the targeted reprogramming of microbial metabolic flux. Full article

Rapeseed meal (RSM), a major agricultural byproduct, is limited in application due to high anti-nutritional factors like glucosinolates, while microbial fermentation can improve its nutritional and flavor profiles. This study combined physicochemical analyses, volatile metabolomics, and quantitative proteomics to investigate flavor evolution and protein dynamics during RSM fermentation. Results showed RSM reached optimal quality at 40 h fermentation, with increased soluble protein and peptides, decreased glucosinolates, and HS-SPME-GC-MS and electronic nose analysis identified that esters, terpenoids, ketones as dominant volatile compounds, 3(2H)-furanone, dihydro-2-methyl-, Benzenemethanethiol is a key volatile differential metabolite. Proteomics analyzed a total of 51 differentially expressed proteins (DEPs), which are mainly involved in organonitrogen compound, peptide and protein metabolic. Additionally, these DEPs were identified to have significant correlations with 13 differentially accumulated volatile metabolites. These findings provide a theoretical basis for the high-value valorization of rapeseed meal, proposing feasible pathways for its use as a condiment base or a functional ingredient in bakery products. Full article

Consumer demand is growing for traceable, high-quality Cinnamomum cassia with defined sensory attributes. However, research linking cultivar morphology to these specific flavor signatures remains scarce. This study elucidated the relationships between phenotypic traits, volatile constituents, and key aroma characteristics of three C. cassia cultivars (Xijiang [XJ], Dongxing [DX], and Qinghua [QH]) using phenotypic evaluation, headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS), and a combination of relative odor activity value and principal component analysis (rOAV-PCA). XJ exhibited an intensely spicy aroma, attributable to its high trans-cinnamaldehyde content (718.76 ± 60.08 mg/g). In contrast, DX showed the highest δ-cadinene level (44.86 ± 4.48 mg/g) and a complex spicy–woody–sweet profile, shaped by sesquiterpenes such as α-humulene, α-copaene, caryophyllene, and β-caryophyllene. QH displayed both a high volatile oil yield (2.57 ± 0.28%) and a distinct herbal–woody character, primarily contributed by δ-cadinene and α-muurolene. This study constructed an integrated phenotype–chemistry–sensory map for C. cassia cultivars, facilitating cultivar discrimination, supporting flavor quality management, and enabling marker-assisted breeding for desirable aroma profiles. Full article

Enzymatic pretreatment is a promising method for modulating essential oil isolation. This study evaluated the effects of pectinase, cellulase, xylanase, and their mixture, applied in purified water or citrate buffer before Clevenger hydrodistillation, on the yield and volatile composition of essential oils from orange, mandarin, and clementine peels. Essential oil yield increased slightly for orange and mandarin peels (up to approximately 2%) compared to non-enzymatic controls, while clementine yield was unaffected. Limonene remained the dominant compound in all oils, reaching 81.16% in orange, 77.50% in mandarin, and 75.29% in clementine. Enzyme pretreatment particularly affected the secondary components: mandarin peel showed increased sesquiterpenes (up to 60.52%) and aldehydes (up to 4.86%), while clementine oils exhibited higher oxygenated monoterpenes after buffer-based enzymatic treatments. These results indicate that enzyme-assisted pretreatment can modulate the volatile profile of citrus essential oils, although overall yield gains are modest. The inclusion of no-enzyme and no-pretreatment controls is crucial for the reliable assessment of enzymatic effects under laboratory conditions. This systematic approach provides insight into enzyme-assisted extraction, highlighting its potential to influence essential oil quality and composition rather than dramatically increase yield, and offers a foundation for further optimization research. Full article