Search Results (348)

VOCs are significant precursors for the formation of O₃ and SOA, directly impacting human health. This study employs multiple approaches to analyzing atmospheric VOCs by focusing on OVOCs including aldehydes, ketones, and phenols, with a case study in Beijing, China. We analyzed the concentration levels and compositions of VOCs and their atmospheric activities, offering a new perspective on VOCs. This analysis was conducted through offline measurements of volatile phenols and carbonyl compounds, complemented by online VOC observations during the summer period of high O₃ levels. The total atmospheric VOCs concentration was found to be 51.29 ± 10.01 ppbv, with phenols contributing the most (38.87 ± 11.57%), followed by carbonyls (34.91 ± 6.85%), and aromatics (2.70 ± 1.03%, each compound is assigned to only one category based on its primary functional group, with no double counting). Carbonyls were the largest contributors to the OFP at 59.03 ± 14.69%, followed by phenols (19.94 ± 4.27%). The contribution of phenols to the SOAFP (43.37 ± 9.53%) and the L_OH (67.74 ± 16.72%) is dominant. Among all quantified VOC species, phenol and formaldehyde exhibited the highest species-level contributions to atmospheric reactivity metrics, including L_OH, OFP and SOAFP, owing to their combination of elevated concentrations and large kinetic or MIR coefficients. Using the PMF model for source analysis, six main sources of volatile organic compounds were identified. Solvent use and organic chemicals production were found to be the primary contributors, accounting for 31.76% of the total VOCs emissions, followed by diesel vehicle exhaust (17.80%) and biogenic sources (15.51%). This study introduces important OVOCs such as phenols, re-evaluates the importance of OVOCs and their role in atmospheric chemical processes, and provides new insights into atmospheric VOCs. These findings are crucial for developing effective air pollution control strategies and improving air quality. This study emphasizes the importance of OVOCs, especially aldehydes and phenols, in the mechanism of summer O₃ generation. Full article

Comprehensive characterization of the mango peel volatilome is essential to revealing its aromatic potential and enabling its revalorization as a natural flavoring. The volatile profile of Mangifera indica L. var. Osteen peels at three ripening stages (green, ripe, overripe) was analyzed before and after thermal drying (45 °C, 18 h): an unavoidable stabilization step for valorization applications. HS–SPME/GC–MS enabled the identification of 76 volatile compounds across different key aroma-contributing families: monoterpenes, sesquiterpenes, alcohols, aldehydes, ketones, esters, furanics and norisoprenoids. The ripening stage significantly influenced the qualitative and quantitative volatilome in fresh samples but drying heavily reduced those differences. Multivariate analyses confirmed that the drying process is the dominant factor shaping the stabilized peels’ volatilome. These findings underscore the industrial relevance of this side-stream: regardless of ripening stage, mango peels can be uniformly stabilized to be upcycled into aroma-rich ingredients. It simplifies raw material sourcing and supports food waste revalorization strategies in flavor and fragrance developments. Full article

Pile fermentation is a crucial process for developing the characteristic mellow taste and aged aroma of dark tea, yet the internal quality transformation mechanism of this process is still unclear. This study employed a high-sensitivity analytical platform based on gas chromatography–mass spectrometry (GC-MS) to systematically investigate the dynamic interplay between key chemical components, enzyme activities, and volatile compounds during the pile fermentation of primary dark tea. Our findings revealed a significant decrease in ester-type catechins, crude protein, and protopectin, alongside a notable accumulation of non-ester-type catechins, gallic acid, and soluble components. The multi-enzyme system—comprising PPO/POD, pectinase/cellulase, and protease—cooperatively drove the oxidation of phenols, cell wall degradation, and the release of aromatic precursors. This was complemented by GC-MS analysis, which identified and quantified 103 volatile compounds across nine chemical classes. The total content of volatile compounds increased significantly, with alcohols, esters, and aldehydes/ketones being the dominant groups. Floral and fruity compounds such as linalool and geraniol accumulated continuously, while esters exhibited an initial increase followed by a decrease. Notably, carotenoid degradation products, including β-ionone, were significantly enriched during the later stages. This study revealed a “oxidation–hydrolysis–reconstruction” metabolic mechanism co-driven by microbial activity and a multi-enzyme system, providing a theoretical foundation for the precise regulation of pile fermentation and targeted quality improvement of primary dark tea. Full article

This study aimed to produce the hydrolysates of Xuanwei ham bone using enzymatic hydrolysis assisted by microwave and ultrasound pretreatment. A back propagation artificial neural network (BP-ANN) model was utilized to predict the optimal conditions, which involved 15 W/g bone for 15 min of ultrasound pretreatment and 5 W/g bone for 30 min of microwave pretreatment, achieving the highest degree of hydrolysis (DH). The model predicted a DH of 27.69, closely aligning with the experimentally measured actual DH of 28.33. DPPH radical scavenging and TBARS demonstrated that hydrolysates prepared by ultrasound combined microwave pretreatment (UMH) exhibited the highest antioxidant activity and significantly inhibited lipid oxidation. GC-MS analysis revealed that the UMH showed removal of bitter volatile flavor compounds, such as o-Cresol and m-Cresol, the retention of aromatic volatile compounds, such as 2-pentylfuran, formation of new aromatic volatile compounds such as 3-methylbutanal, and the reduction in certain aldehyde and ketone compounds. Pearson correlation analysis elucidated that the reduction in aldehyde and ketone compounds was positively linked to the enhanced antioxidant capacity of UMH. The results obtained hold substantial significance for enhancing the added value of Xuanwei ham within the food industry. Full article

The flavor and aroma of kiwifruit are largely influenced by the concentration of Volatile Organic Compounds (VOCs). To analyze the volatile profiles and identify characteristic aroma compounds, this study utilized Gas Chromatography-Ion Mobility Spectrometry (GC-IMS) to analyze the aromatic compounds sourced from seven major production regions in China and New Zealand, covering red-, green-, and yellow-fleshed varieties. A total of 77 VOCs were identified, with esters, aldehydes, and ketones as the dominant classes. Significant regional and varietal differences were observed: red-fleshed kiwifruits from Yunnan exhibited high levels of 2-Vinyl-5-methylfuran, Ethyl formate, and 1-Penten-3-one; green-fleshed fruits from Shaanxi were rich in Limonene and Methyl hexanoate, and those from Yunnan were rich in 1-Propanol and 1-Hexanol; and yellow-fleshed fruits from Henan were characterized by Methyl salicylate and 3-Hydroxy-2-butanone. Orthogonal partial least squares discriminant analysis (OPLS-DA) successfully classified kiwifruits by origin and variety, confirming the stability and predictive power of the model (Q2Y > 0.97). This study also elucidated the key metabolic pathways—including lipid oxidation, amino acid degradation, and terpenoid metabolism—underlying the formation of these characteristic VOCs. These findings provide a theoretical foundation for the biochemical regulation of kiwifruit flavor and support the development of origin-tracing and quality-assessment tools based on VOC fingerprints. Full article

This study aimed to characterize the physicochemical, structural, and volatile compound changes in commercially sterilized pre-cooked braised chicken (PBC) during storage at 25 °C, using analyses conducted every 30 days from 30 to 180 days. Assessed parameters included microstructure, color, texture, pH, malondialdehyde (MDA) content, Ca²⁺-ATPase activity, and volatile organic compounds (VOCs). Significant quality changes occurred during storage. Specifically, the L* value decreased, and the a* value increased, while hardness, springiness, chewiness, and Ca²⁺-ATPase activity declined. pH increased from 6.01 to 6.59, and MDA content rose from 10.16 to 23.42 nmol/g. 91 VOCs were identified by gas chromatography-ion mobility spectrometry (GC-IMS), comprising 13 alcohols, 18 aldehydes, 18 ketones, 3 acids, 9 esters, 12 hydrocarbons, 6 aromatics, and 12 others. VOC profiles shifted dynamically: key aldehydes and ketones decreased initially, then increased, whereas alcohols, esters, hydrocarbons, and sulfur-containing compounds increased, then decreased. Prolonged storage significantly deteriorated the quality and altered the flavor profile, providing insights for PBC storage. Full article

Michler’s Ketone (MK) is widely utilized as an additive in pigments, dyes, and other colorants, and has become a non-negligible environmental presence. Currently, environmental monitoring data and toxicity data for MK are extremely limited, and its specific mechanisms of neurotoxicity remain poorly characterized. A zebrafish model was employed to systematically delineate the neurotoxic mechanisms of MK through the integration of network toxicology predictions, transcriptomic profiling, and RT-qPCR validation. The results demonstrated that MK exposure was found to induce oxidative stress in zebrafish larvae, which subsequently disrupted the calcium signaling pathway and triggered apoptosis, ultimately leading to neurodevelopmental and locomotor behavioral impairments. This study provides a fundamental basis for elucidating MK’s developmental neurotoxicity mechanisms, while also holding significant value for its ecological risk assessment. Full article

This study investigated the impact of thawing methods on the roasting quality and flavor of reduced-salt marinated large yellow croaker to optimize processing protocols for frozen products. Three thawing methods, low-temperature thawing (LTT), room-temperature thawing (RTT), and flowing-water thawing (FWT), were systematically evaluated. Freshly marinated (FM) and non-thawed (WT) samples served as controls. Key parameters, including thawing efficiency, physicochemical properties, texture, color, sensory attributes, and volatile organic compounds (VOCs), were analyzed. The results showed that FWT achieved the fastest thawing (14.67 min), significantly outperforming RTT (32.57 min) and LTT (591 min) (p < 0.05). Moisture content and springiness remained stable across treatments (p > 0.05). For color parameters, lightness (L*), yellowness (b*), and browning index (BI) showed no significant variations (p > 0.05), while the total color difference (ΔE) was significantly affected by thawing methods (p < 0.05). FWT exhibited the lowest salt retention (3.49 g/100 g), a 18.8% reduction compared to WT (4.30 g/100 g). Texture analysis revealed that FWT samples maintained optimal hardness and chewiness, with sensory scores second only to WT. Volatile profiling identified distinct “thermal–oxygen–temporal” effects, referring to the respective influences of heating conditions, oxidative environments, and processing time on flavor compound formation. RTT and WT treatments significantly increased the relative 1-propanethiol and 5-methyl-2-furanmethanol (>10% increase) contents, respectively, and markedly reduced the 2-butanol levels (<0.3%) due to volatilization losses. GC-IMS and electronic nose analysis established a robust correlation network among three major VOC clusters (aldehydes/alcohols, esters/acid/sulfides, and ketones), with sensory scores showing strong positive correlations with the alkane- and aromatic-sensitive sensors (W5C/W1C) of the electronic nose (r > 0.90) and negative correlations with other sensors (r < −0.70). These findings demonstrate that FWT offers the best balance of efficiency, salt reduction, and sensory quality, making it a superior method for reduced-salt marinated large yellow croaker industrial applications. Full article

This research study investigated the potential biotechnological applications of yeast species obtained from cocoa fermentation performed in Côte d’Ivoire. A total of 279 yeast isolates were molecularly identified and then screened for their antifungal ability against various Aspergillus species and for the production of aromatic compounds and extracellular enzymes. Thirty-one yeast species belonging to nineteen genera, dominated by Pichia, Candida, Hanseniaspora, and Rhodotorula, were isolated from fermented cocoa beans. All extracellular enzymes screened were produced by most yeast species, except β-glucanase and esterase activity, whereas the most common enzyme was β-glucosidase. Yeasts of the Pichia, Saccharomyces, Candida, Clavispora, and Hanseniaspora genera produced various enzymes, including xylanase, β-glucosidase, polygalacturonase, invertase, pectinase, and chitinase. The 88 aromatic compounds produced were grouped into five main chemical families, including esters, alcohols, acids, aldehydes, and ketones. Wickerhamomyces anomalus was the highest producer of major desirable aromatic compounds, including alcohols, ketones, and esters. All yeast species showed a specific antagonistic effect against the growth of various Aspergillus species, but Candida incommunis, Saccharomyces cerevisiae, and Torulaspora delbrueckii recorded the greatest antifungal ability. These yeast species could be used to develop promising starter cultures to improve the organoleptic quality of various fermented foods and beverages. Full article

Gardenia tea is esteemed for its delicate and fragrant aroma. Background: However, there is a scarcity of studies focused on the aromatic properties of gardenia-scented white tea, particularly regarding how these aroma profiles evolve over different storage durations. Methods: This research sought to analyze the volatile compounds present in gardenia white tea through headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC-MS) alongside multivariate analysis techniques. Results: Findings indicated that the main chemical categories found in newly white tea (NWT), aged white tea (AWT), gardenia newly white tea (GNWT), and gardenia aged white tea (GAWT) included esters, terpenoids and ketones. The multivariate analysis pinpointed 11 significant volatile compounds (such as linalool, [(Z)-non-6-enyl] acetate, and (E)-non-4-enal) and an 10 additional key volatile compounds (including linalool, [(Z)-non-6-enyl] acetate, and 1-isothiocyanato-3-(methylthio)-2-Propane) that had variable importance in projection (VIP) values exceeding 2 and odor activity values (OAVs) greater than 1. These compounds effectively distinguished the aroma profiles of GNWT from NWT and GAWT from AWT. Notably, the levels of these compounds were significantly elevated in GNWT and GAWT compared to their NWT and AWT counterparts. Additionally, three volatile compounds in GNWT and six in GAWT showed a decline in concentration relative to NWT and AWT. Conclusions: These compositional differences are suggested to clarify the aromatic distinctions between gardenia-scented white tea and its white tea base. The outcomes of this study will contribute to a deeper chemical understanding of the unique aroma of gardenia white tea, providing a theoretical basis for assessing quality and developing products based on different storage periods. Full article

Raspberry ketone (RK) is the primary aromatic compound in raspberry fruit, which is widely utilized in perfume, cosmetics, and food additive industries. Currently, RK is predominantly produced chemically. RK biosynthesis through enzyme or whole cell has garnered significant attention due to the mild reaction conditions and the process being regarded as ‘natural’. This study proposed a ‘dual-microorganism, two-phase’ stepwise cascade strategy to produce RK from an economical precursor, 4-hydroxybenzaldehyde (4-HBD). An acetone-tolerant deoxyribose-phosphate aldolase DERA_Ec (S238D) mutant was obtained through a site-specific rigidification strategy for converting 4-HBD to 4-hydroxybenzylaceton (4-HBA). Then, an engineered E. coli co-expressing isocitrate dehydrogenase and raspberry ketone synthase RiRZS1 with a citrate-sodium citrate buffer to recycle nicotinamide adenine dinucleotide phosphate (NADPH) was constructed for the conversion of 4-HBA to RK. The final concentration of RK was 50.00 ± 1.92 mmol·L⁻¹ with a yield of 86.96%. This strategy provides a scalable coenzyme self-recycling and two-phase catalysis platform for high-value phenolic compounds. Full article

Using the Ministry of Environment’s fixed-site air quality monitoring network, we analyzed multiple hazardous air pollutants (HAPs)—including volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), and heavy metals—during 2021–2024 and compared their concentrations with internationally reported levels. Pronounced spatial heterogeneity was observed across stations, particularly for VOCs and heavy metals. Stations A, E, and F were dominated by alkanes, whereas stations B, C, and D exhibited higher proportions of oxygenated VOCs (mainly aldehydes and ketones). Across the network, formaldehyde (0.015 μg/m³), dichloromethane (2.60 μg/m³), toluene (2.53 μg/m³), and acetaldehyde (0.004 μg/m³) were identified as the most abundant species. Stations A and E served as VOC hotspots—formaldehyde peaked at station A and toluene at station E—likely due to nearby industrial and port activities. Concentrations of BTEX generally decreased throughout the study period, with a minor rebound at station C in 2022. Regarding heavy metals, elevated concentrations of lead (16.83 ng/m³), nickel (4.71 ng/m³), and arsenic (1.29 ng/m³) were observed at station A, again suggesting influences from industrial or port-related emissions. Overall, formaldehyde, benzene, and 1,2-dichloroethane were identified as key pollutants of concern, with station A representing the most critical hotspot in the monitoring network. Full article

Volatile organic compounds (VOCs) emitted from indoor surface coatings can significantly impact indoor air quality and health. This study compared emissions from water-based polyurethane (PUR) and acrylate–polyurethane (ACR–PUR) coatings, identifying 94 VOCs across 16 chemical classes. Time-resolved concentrations were analysed via Principal Component Analysis (PCA), which revealed distinct temporal emission patterns and chemically coherent clusters. Aromatic hydrocarbons, alcohols, esters, and isocyanates dominated the emission profiles, with ACR–PUR releasing markedly higher concentrations of symptom-relevant compounds. Acute exposure was linked to toluene, styrene, phenol, and methyl butyl ketone (MBK), which decreased sharply within 60 days, while compounds such as 1,3-dioxolane, isopropylbenzene, and ethenyl acetate exhibited persistent emissions, suggesting increased chronic risk. Although total VOC levels remained below the German UBA “excellent” threshold (<200 µg/m³), neurotoxic and carcinogenic compounds remained detectable. The combination of PCA-based temporal insights with toxicological profiling and emission transfer dynamics offers a refined framework for indoor air risk assessment. These results underscore the need to complement total VOC indices with symptom-oriented, time-resolved screening protocols to better evaluate SBS risk in indoor environments using water-based coatings. Full article

Although the aroma profile of Lentinula edodes has been extensively studied in fruiting bodies, the mycelial stage provides a distinct context for elucidating the fundamental metabolic pathways, free from the complexities of organismal development. To elucidate the mechanism underlying aroma differences between L. edodes strain 808 (the control strain) and its mutant strain ww808 (with almost no shiitake aroma), this study employed GC-IMS combined with PCA and OPLS-DA to identify key aroma biomarkers during the mycelial stage. All analyses were performed with three biological replicates. Furthermore, fatty acids composition, key enzyme activities of the LOX pathway, and their gene expression levels were systematically compared. The results indicated significant differences in the content of volatile aroma compounds in the mycelia of the two strains, primarily stemming from fundamental restructuring of gene expression and enzyme activity in the LOX pathway. The LOX gene expression and LOX activity of 808 mycelium were relatively high, facilitating the accumulation of key aroma compounds such as phenylethanal, benzaldehyde, and ethyl acetate, which constitute its distinctive aromatic profile. However, although the mycelium of ww808 possessed richer fatty acid precursor (C18:2), its lower LOX gene expression restricted the flux of this pathway. The significantly increased expression of ADH2, ADH3, and ADH5 genes and higher ADH activity enhanced the conversion capacity of aldehydes to alcohols and ketones. Given the generally higher odor thresholds of alcohols and ketones compared to aldehydes, distinct aroma profiles emerged between the two strains. Pearson correlation analysis further confirmed the significant correlations between the aroma biomarkers, fatty acids, key genes, and enzyme activities. This study revealed the formation mechanism of aroma differences in the mycelia of the two strains from the perspective of metabolic pathways, providing a theoretical foundation and candidate targets for the directed genetic improvement of L. edodes aroma quality. Full article

This study aimed to evaluate the impact of autochthonous strains (Pediococcus pentosaceus 128b, Latilactobacillus sakei S15, Lactiplantibacillus plantarum S91, L. plantarum S24 and Staphylococcus carnosus G109) used as mono and mixed starter cultures on the quality attributes of traditionally produced sucuk, a Turkish dry fermented sausage, in a local small-scale facility. At the end of ripening, samples underwent comprehensive microbiological and physicochemical analyses. The use of autochthonous starter cultures (ASC) showed no statistically significant influence on thiobarbituric acid-reactive substances and water activity value. Lower pH values were observed in groups with autochthonous lactic acid bacteria strains (ALABS) compared to the control group. However, ALABS inhibited Micrococcus/Staphylococcus growth by rapidly lowering the pH, except in the groups with S. carnosus G109. The use of ASC led to an increase in the L* values of sucuk samples, except monoculture L. plantarum S91. The correlation heat map illustrating the relationships between the starter cultures and volatile compounds revealed that all groups containing L. plantarum S91 exhibit a volatile compound profile different from other single or mixed cultures. According to the results of the principal component analysis performed to determine the relationship between the chemical groups of the starter cultures and volatile compounds, the groups containing L. plantarum S91 differed from the other groups and showed positive correlations with phenols, furans, acids, terpenes, aromatic hydrocarbons, ketones, nitrogenous compounds, esters, and aliphatic hydrocarbons. Full article