Search Results (81)

Hawk tea (Litsea coreana Levl. var. lanuginosa), a naturally caffeine-free herbal beverage widely consumed in Southwest China, is characterized by a pronounced camphoraceous note that often deters first-time consumers. In this study, hawk tea leaves were subjected to solid-state fermentation with four microbial strains—Monascus purpureus, Aspergillus cristatus, Bacillus subtilis, and Blastobotrys adeninivorans. The volatile compounds of unfermented and fermented hawk teas were identified by ultra-fast gas chromatography electronic nose (ultra-fast GC e-nose), gas chromatography–mass spectrometry (GC-MS) and gas chromatography–ion mobility spectrometry (GC-IMS) analyses, respectively. Furthermore, the calculation of odor activity values (OAVs) and relative odor activity value (ROAV) revealed that 6 and 25 volatile chemicals, including perillaldehyde (OAV 3.692) and linalool (ROAV 100), were the main contributors to the floral, fruity, and woody aroma of fermented hawk tea. Sensory evaluation confirmed that fermentation generally enhanced woody notes while significantly reducing the characteristic camphoraceous and oil oxidation odors. Notably, the Blastobotrys adeninivorans-fermented sample exhibited the most pronounced floral and fruity nuances, accompanied by significantly elevated aroma complexity and acceptability. Consequently, Blastobotrys adeninivorans represents a promising starter culture for the improvement of hawk tea flavor. Full article

Oolong tea presents notable variations in taste profile and aroma characteristics under different cultivation conditions, particularly across altitudes. However, systematic investigations into the altitude-induced differences in key taste compounds and aroma composition remain limited. In this study, we examined six oolong tea cultivars, comparing their taste-related chemical constituents and aroma profiles under high- and low-altitude cultivation. Sensory evaluation, high-performance liquid chromatography (HPLC) and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) were employed to characterize these differences. Sensory evaluation revealed that high-altitude oolong teas exhibited enhanced umami, sweetness, and floral intensity. In most cultivars, the levels of free amino acids, polyphenols, and soluble sugar were relatively higher under high-altitude conditions. HS-SPME-GC-MS identified 55 common volatile organic compounds (VOCs), with terpenes and esters comprising the largest number of compounds. Identification by partial least squares discriminant analysis (PLS-DA) combined with relative odor activity value (rOAV) screening yielded 22 candidate differential volatile organic compounds. Floral monoterpenes, including linalool, linalool oxide II and geraniol, were consistently higher in high-altitude teas, whereas most other volatiles varied primarily with cultivar rather than altitude. These chemical patterns are consistent with the sensory finding of stronger floral intensity in high-altitude samples. This study provides theoretical insights for cultivar selection and quality improvement of oolong tea grown in high-altitude regions. 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

Sichuan-style black soybean soy sauce is a traditional fermented condiment renowned for its complex and regionally distinctive flavor profile. This study systematically investigated the physicochemical properties, flavor compounds, and microbial succession during six months of natural fermentation to elucidate the mechanisms underlying its unique flavor formation. Results showed that the amino acid nitrogen level increased to a peak of 1.37 g/100 mL before stabilizing at 1.01 g/100 mL, accompanied by a continuous rise in total acidity (0.69–2.75 g/100 mL). A total of 132 volatile compounds were identified, with esters (e.g., hexanoic acid, methyl ester, hexadecanoic acid, and methyl ester), alcohols (e.g., (E)-2-hepten-1-ol and trans-2-undecen-1-ol), and aldehydes (e.g., benzaldehyde and benzeneacetaldehyde) serving as key differentiating components. Nine taste-active (TAV ≥ 1) and 22 odor-active (ROAV ≥ 1) compounds were recognized as major flavor determinants, among which methional (ROAV = 4.77–119.05), 1-octen-3-ol (ROAV = 40.68–149.35), and 4-ethyl-2-methoxyphenol (ROAV = 4.70–36.26) were dominant contributors imparting sauce-like, mushroom-like, and smoky-clove notes, respectively. Microbial succession revealed a transition from Weissella and Aspergillus dominance in the early stage to salt-tolerant Tetragenococcus and aroma-producing yeasts (Kodamaea and Zygosaccharomyces) in later phases. Beyond organic acids and fermentation parameters (e.g., pH and salinity), microbial interactions were identified as critical drivers shaping community assembly and succession. Metabolic pathway analysis revealed a stage-dependent mechanism of flavor formation. During the initial stage (0–2 months), Aspergillus-mediated proteolysis released free amino acids as key taste precursors. In the later stages (3–6 months), Tetragenococcus and aroma-producing yeasts dominated, synthesizing characteristic esters (e.g., benzoic acid and methyl ester, correlated with Tetragenococcus; r = 0.71, p < 0.05), phenolics (e.g., 4-ethyl-2-methoxyphenol, correlated with Wickerhamomyces; r = 0.89, p < 0.05), and sulfur-containing compounds (e.g., methional, correlated with Wickerhamomyces; r = 0.83, p < 0.05). Full article

Gardenia black tea (GBT) is a prized Chinese scented tea, renowned for its pleasant aroma. However, the influence of repeated scenting rounds on its volatile profile remains poorly characterized. This study investigated the aroma profiles of GBT produced with zero, two, and three scenting rounds (T0, T1, T2) using sensory evaluation and Headspace Solid-Phase Microextraction–Gas Chromatography–Mass Spectrometry (HS-SPME-GC-MS). Sensory analysis revealed that GBTs (T1, T2) scored significantly higher in aroma and taste than the black tea base (T0). GC-MS analysis identified numerous volatile compounds, with esters, terpenoids, and ketones being predominant. Multivariate analysis identified 52 key volatiles (VIP > 2.0) that differentiated the tea samples. Among these, 28 compounds had odor activity values (OAVs) > 1, indicating significant sensory contributions. Ultimately, 11 volatiles, including (Z)-hex-3-enyl acetate, linalool, and (E)-hex-2-enal, were identified as the crucial basis for the characteristic fresh and floral scent of GBTs. The specific abundance levels of these compounds are hypothesized to underlie the superior, fresh, and elegant aroma of T1, compared to the slightly ripe and stuffy floral notes of T2. Therefore, it is advisable to prioritize two rounds of scenting during the production of gardenia black tea. These findings provide a theoretical foundation for optimizing the scenting process and enhancing the quality of GBT. Full article

Storage time significantly influences the aroma quality of peanut oil. In this study, gas chromatography–mass spectrometry (GC-MS) and gas chromatography–ion migration spectrometry (GC-IMS) were used to analyze the volatile flavor compounds of hot-pressed peanut oil baked at two temperatures (140 °C and 160 °C, denoted as OPO and RPO, respectively) during storage. The two methods detected 80 and 76 volatile flavor compounds, respectively, and principal component analysis (PCA) revealed clear distinctions between OPO and RPO during the storage period. Ten key aroma compounds were identified based on relative odor activity value (ROAV) analysis, including 3-methylbutanal, hexanal, heptanal, octanal, benzeneacetaldehyde, 3-ethyl-2,5-dimethylpyrazine,2-ethyl-6-methylpyrazine, acetylpyrazine, 2-methoxy- 4-vinylphenol, and acetic acid. During storage, the degradation and transformation of flavor compounds were more pronounced in RPO than in OPO. Physicochemical analyses showed increased acid and peroxide values, concomitant with decreased vitamin E and phytosterol content. Notably, these parameters changed more slowly in OPO than in RPO, confirming that OPO maintained superior quality over time. Correlation analysis suggested that changes in the aldehyde and pyrazine contents are key indicators of flavor and quality evolution in peanut oil during storage. This study provides insights into how baking temperature and storage time affect peanut oil aroma, elucidating the mechanisms of flavor variation and offering a theoretical basis for optimizing the flavor and quality of hot-pressed peanut oil. Full article

4-Chlorophenoxyacetic acid (4-CPA) is an auxin-type plant growth regulator widely used in fruit and vegetable production. However, its influence on the nutritional and sensory qualities of horticultural crops remains insufficiently characterized. This study investigated the influence of 4-CPA application and oscillator-mediated pollination on the metabolic composition of fully ripe fruits of Solanum lycopersicum var. cerasiforme cv. ‘Zheyingfen No. 1’. Two concentrations of 4-CPA (16 mg/L and 8 mg/L) were applied during flowering, and their effects on amino acids, soluble sugars, organic acids, and volatile compounds (VOCs) were comparatively analyzed. The results indicated that treatment with 8 mg/L 4-CPA treatment significantly increased the total amino acid content in ripe fruits compared with the control and the 16 mg/L treatment. Among the 17 amino acids identified, the contents of umami-related amino acids, including glutamic acid (Glu) and aspartic acid (Asp), were markedly enhanced. In particular, Glu content in the C8 treatment was the highest and accounted for more than 50% of the total amino acid content. The accumulation of sugars was not significantly affected by 4-CPA treatment, while the C8 treatment resulted in the lowest level of total organic acids, which are crucial for flavor development at the ripening stage. A 29.35% increase in VOCs was observed” for conciseness in 4-CPA-treated fruits compared with the control. Analysis of relative odor activity values (rOAVs) showed that although 4-CPA treatment reduced the number of aroma-active compounds, it promoted the accumulation of β-ionone, thereby shifting the tomato fruit aroma profile toward floral, woody, sweet, and fruity notes. In summary, 4-CPA treatment regulated the nutritional and flavor quality of ripe cherry tomato fruits by increasing the content of Glu and other amino acids, enhancing the diversity of VOCs, and promoting the formation of key aroma-active substances such as β-ionone. Full article

Fixation is a necessary step in bamboo leaf powder processing and plays a decisive role in determining its color, aroma, and taste. It is irreplaceable for maintaining quality, stability, and forming unique sensory characteristics. In this study, optimal conditions for steamed bamboo leaf powder (SBL), baked bamboo leaf powder (BBL), and blanched bamboo leaf powder (BCBL) were determined by measuring chlorophyll content, color parameters, and enzyme inactivation. In addition, volatile organic compounds (VOCs) in bamboo leaf powder processed with different fixation methods were analyzed using gas chromatography–mass spectrometry (GC-MS), gas chromatography–olfactometry (GC-O), and relative odor activity value (ROAV). Steaming for 120 s, baking for 60 s, and blanching for 30 s effectively preserved color, with a* values of −1.37, −1.44, and −1.62, all superior to untreated bamboo leaf powder (UBL). Among them, BCBL showed the best color stability, with the lowest color difference (ΔE = 0.66) compared with fresh bamboo leaves (FBLs). Results showed that BBL retained the highest VOC abundance (15.67% of FBLs), followed by SBL (5.73%) and BCBL (5.48%). Hexanal, nonanal, linalool, and α-ionone were identified as key aroma contributors, forming green, fresh, and floral notes. Sensory differences were evident: SBL exhibited strong seaweed-like and roasted notes, BCBL showed partial loss of characteristic aromas, while BBL preserved grass, fruity, and woody attributes. These findings highlight the significant influence of fixation methods on aroma-active compounds and color stability, providing a theoretical basis for producing bamboo leaf powder with superior sensory quality. Full article

‘Qiancha 1’ is an excellent raw material for manufacturing white tea. The effects of different drying parameters on the quality performance of ‘Qiancha 1’ white tea remain poorly understood, which restricts the precise regulation of the quality of ‘Qiancha 1’ white tea. In this research, we systematically investigated the influence of drying temperature (65 °C, 75 °C, and 90 °C) and drying duration (1 h, 2 h, and 3 h) on its non-volatile and volatile compositions, using sensory evaluation, E-tongue, and non-volatilomic and volatilomic analyses. The results showed that the tea sample dried at 65 °C for 3 h had a sweet, mellow, and fresh flavor and scored 95 points, but high-temperature drying (90 °C) could promote increased bitterness and decreased sweetness. High-temperature drying was closely related to a caramel-like and milk-like flavor, which promoted an increase in the content of terpenoids, heterocycle compounds, and esters. During drying, the flavonoid and phenolic acid content increased markedly, contributing to bitterness and astringency, while nucleotides, amino acids, and their derivatives decreased, leading to a reduced umami intensity. A total of 37 key taste-active metabolites were identified, including bitter compounds (e.g., alkaloids), sweet compounds (e.g., phenolic acids), and umami compounds (e.g., nucleotides), whose dynamic changes directly influenced the taste profile of white tea. High-temperature drying promoted an increase in the content of volatile metabolites, such as terpenoids, heterocyclics, and esters, while low-temperature and long-duration drying was beneficial for preserving volatile metabolites like heptanal. 2-Methoxy-3-(1-methylethyl)-pyrazine was determined as the volatile compound with the highest rOAV, providing a sweetness and caramel-like flavor. Overall, the metabolomic analysis revealed that the content of flavonoids and phenolic acids increased after the drying process, which was related to the bitter and astringent taste of the tea liquor. The content of nucleotides, amino acids, and their derivatives decreased after drying, which caused the umami of the tea liquor to weaken. This study provides a theoretical basis for the optimization of the ‘Qiancha 1’ white tea drying process. Full article

Summer–autumn green tea (SAGT) is a high-yield green tea often compromised by pronounced bitterness, astringency and a weak aroma, which severely limit its consumer acceptability and economic value. To enhance its quality, this study employed solid-state fermentation with Eurotium cristatum, the core probiotic fungus in Fu brick tea (FBT), to investigate its effects on the physicochemical, sensory, and volatile profiles of SAGT. The findings showed that after fermentation, the tea leaves developed a golden-yellow color, and the tea infusion turned brown. Moreover, the contents of flavonoids, tea polyphenols, soluble sugars, catechins, and free amino acids showed decreases of 3%, 33%, 38%, 41%, and 48%, respectively, when compared to SAGT. At the same time, the astringency and bitterness levels of the infusions significantly diminished (p < 0.05) post-fermentation, and the 8-day fermented tea sample was the most preferred by the sensory panel. During fermentation, E-nose, GC-MS, and GC-IMS analyses revealed a substantial transformation of the volatile profile, with a total of 104 and 129 volatile organic compounds (VOCs) were identified using GC-MS and GC-IMS techniques, respectively. The ROAV analysis highlighted 22 aroma-active compounds, particularly linalool and methyl salicylate, whose values increased significantly (p < 0.05), reaching values of 19,561.95 and 109.56, respectively, making them key contributors to the prominent floral and minty fragrance in the fermented tea. Additionally, PLS-DA analysis revealed 22 and 33 differential VOCs in the GC-MS and GC-IMS methods, respectively, with the majority stemming from the PAL and MEP metabolic pathways. This study provides theoretical insights aimed at enhancing the flavor quality of SAGT. Full article

This study deciphered the aroma differences in three Kadsura coccinea cultivars (F023, F054, F055) through integrated volatile-omics and sensory analysis. HS-SPME-GC-MS identified 49 volatiles dominated by sesquiterpenes (65.2–78.4%). ROAV prioritization revealed cultivar-specific drivers: γ-dodecalactone (ROAV = 73.0) defined F054’s fruity–floral character; humulene (ROAV = 100) and β-caryophyllene shaped F023’s woody–pungent profile; and β-pinene (ROAV = 100) characterized F055’s herbaceous freshness. Molecular docking confirmed high-affinity binding of γ-dodecalactone to OR2W1 (ΔG = −6.42 kcal/mol via ASN155 H-bonding). Sensory PCA explained 83.48% of the variance, segregating cultivars along distinct axes (F054: sweet-aromatic; F023: woody-spicy; F055: herbaceous-fresh). Joint PCA validated γ-dodecalactone–coconut milk spatial co-localization (θ < 10°) and β-caryophyllene–woody note correlations (r > 0.9), establishing γ-dodecalactone as a breeding biomarker for aroma-driven cultivar improvement. Full article

Pomegranate (Punica granatum L.), valued for its health benefits and distinctive flavor, derives its characteristic aroma from volatile organic compounds (VOCs) that vary significantly with geographical origin. In this study, VOCs in pomegranates from six Chinese geographical regions were characterized using an electronic nose (E-nose), an electronic tongue (E-tongue), headspace gas chromatography–ion mobility spectrometry (HS-GC-IMS), and headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS). To elucidate geographical variations in odor, taste, and volatile profiles, a comprehensive multivariate statistical analysis integrating principal component analysis (PCA), hierarchical cluster analysis, orthogonal partial least squares-discriminant analysis (OPLS-DA), and variable importance in projection (VIP) was employed. The results demonstrated that the E-nose and E-tongue effectively distinguished pomegranate by geographical origin, with aroma contributing more significantly than taste to regional differentiation. A total of 46 and 58 VOCs were identified using HS-GC-IMS and HS-SPME-GC-MS, respectively, with different characteristic volatile compounds in pomegranate from various origins, and alkenes, esters, and alcohols were the primary contributors to regional variations. Notably, OPLS-DA revealed that HS-GC-IMS exhibited superior discriminatory power in separating pomegranates of different geographical origins, with HY and HL displaying closely related odor profiles while the other samples showed the most pronounced odor differences, but these findings contrasted with HS-SPME-GC-MS results. Additionally, the VIP method and the relative odor activity value (ROAV) further identified six and eight key aroma compounds based on HS-GC-IMS and HS-SPME-GC-MS data; in particular, hexanal, nonanal, β-pinene, 3-hydroxybutan-2-one, and β-ocimene were identified as key aroma compounds in pomegranate as potential regional markers. These findings highlight VOC profiles as potential geographical origin markers, supporting origin traceability and quality control in the pomegranate industry. Full article

Volatile organic compounds (VOCs) are critical indicators of the metabolic status of whole-plant maize silage (WPMS). However, the impact of inoculating various strains of fermentation agents on VOC changes has not been systematically explored. This study aimed to determine how inoculation with Lactiplantibacillus plantarum and Lentilactobacillus buchneri modulates the VOC profile and odor of WPMS after 90 days. VOCs were extracted by headspace solid-phase microextraction and analyzed by gas chromatography-mass spectrometry (HS-SPME-GC-MS). Key VOCs were screened using the variable importance in projection (VIP) and substantiated by relative odor activity values (rOAV) and odor descriptions. A total of 82 compounds were identified, including 22 esters, 19 alcohols, 3 acids, 9 aldehydes, 2 ethers, 6 hydrocarbons, 4 ketones, 10 phenols, and 8 terpenoids. L. plantarum enhanced green/fruity odors while strain L. buchneri significantly reduced undesirable phenolic and aldehydic compounds. Six key VOCs influencing the odor of WPMS were selected: 4-ethyl-2-methoxyphenol and benzaldehyde, which contribute smoky, bacon, and bitter almond aromas, and (E)-3-hexen-1-ol, benzyl alcohol, (E, E)-2,4-heptadienal and methyl salicylate, which impart green, fruity, and nutty aromas. These findings highlight the effects and contributions of various strain additives on VOCs in WPMS, providing new theoretical insights for regulating the flavor profile of WPMS. Full article

This study aimed to systematically characterize the volatile organic compound (VOC) profiles of safflower (Carthamus tinctorius L.) from eight major production regions, providing a scientific basis for quality evaluation and geographical traceability. VOC profiling was conducted using gas chromatography–ion mobility spectrometry (GC–IMS), and regional differences were assessed through multivariate statistical analyses, including Principal Component Analysis (PCA), Orthogonal Partial Least Squares Discriminant Analysis (OPLS–DA), Euclidean distance, and hierarchical clustering. Key differential compounds were identified by variable importance in projection (VIP) and relative odor activity value (ROAV) analyses, with aldehydes and esters emerging as the primary contributors to the discrimination of samples across regions. VOC fingerprints of safflower were further established, and a combined VIP–ROAV strategy was proposed for the screening of characteristic compounds. These findings provide a reliable reference for safflower quality control and offer practical guidance for its geographical authentication in the food industry. Full article

Objectives: This study systematically compared the differences in egg quality between the BIAN chicken, an indigenous breed of Shanxi Province, and the Hy-Line Brown, a commercial breed, through the integration of non-targeted metabolomics and volatile flavoromics methods. Methods: A total of 675 metabolites and 84 volatile flavor compounds were identified in eggs from 300-day-old laying hens using LC-MS and GC × GC-TOF MS techniques. Results: BIAN chicken eggs exhibited notable advantages in flavor quality. The relative odor activity value (ROAV) of 1-octen-3-ol, a key flavor component, was 27.01 in BIAN compared with 13.46 in Hy-Line Brown, contributing to the characteristic mushroom aroma of BIAN eggs. Furthermore, the levels of heptaldehyde, 2-pentylfuran, and styrene in BIAN chicken eggs were significantly elevated, contributing to its characteristic flavor profile. Metabolomic analysis identified 40 breed-specific metabolites in BIAN chicken, with 21 up-regulated and 19 down-regulated. These metabolites were primarily involved in biological processes such as α-linolenic acid metabolism, cholesterol metabolism, and unsaturated fatty acid biosynthesis, highlighting the distinctive lipid metabolism regulation in BIAN chicken. Sensory evaluation based on relative odor activity values (ROAV) demonstrated that BIAN chicken eggs exhibited enhanced sweet, fruity, herbal, and citrus aromas, which correlated with the enriched lipid metabolism pathways. Conclusions: This study elucidates the molecular basis of distinctive egg quality characteristics in local chicken breeds, offering a scientific rationale for the conservation and utilization of indigenous breeds and the documentation of their unique metabolic and sensory properties. Furthermore, it furnishes a theoretical framework for understanding breed-specific flavor development and provides baseline data for future genetic selection and nutritional intervention strategies. Full article