Search Results (748)

White tea quality is primarily determined by its chemical composition, which varies significantly among cultivars. This study aimed to elucidate the chemical basis underlying quality differentiation in Baimudan white tea produced from three major Fujian tea cultivars: “Zhenghe Dabaicha” (ZHDB), “Fuan Dabaicha” (FADB), and “Fuding Dahaocha” (FDDH). Headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME-GC-MS), liquid chromatography–mass spectrometry (LC-MS), and quantitative descriptive analysis (QDA) were employed to characterize volatile compounds, amino acids, and saccharides. Odor Activity Values (OAVs) and Taste Activity Values (TAVs) were calculated to identify key contributors to sensory perception. Results showed that theanine, glutamic acid, asparagine, and serine were the primary contributors to umami taste, especially in ZHDB and FADB. Sweetness differences were largely due to sucrose, serine, and asparagine. OAV analysis further identified 22 critical aroma compounds: methyl salicylate, linalool, and β-ionone predominantly imparted floral notes, while β-ocimene, benzaldehyde, and geraniol enhanced sweet and fruity aromas. In contrast, (Z)-3-hexenol, (Z)-3-hexenal, and (E)-2-hexenal contributed grassy and refreshing characteristics, together defining the unique aroma profiles of each cultivar. This study provides an integrated chemical and sensory framework for understanding white tea quality variation, offering a theoretical basis for targeted flavor modulation. Full article

The seafood industry is increasingly adopting intelligent packaging to preserve product quality and improve freshness transparency. This study developed and evaluated a pH-sensitive freshness indicator (FI) for skate sashimi (Zearaja chilensis). This product is consumed at varying stages of fermentation. The FI incorporated bromothymol blue (BTB) and bromocresol purple (BCP) in a polymer matrix. It targeted volatile basic nitrogen (VBN) compounds, with trimethylamine (TMA) as the primary marker. As freshness declined, VBN compounds accumulated in the package headspace and caused a gradual FI color change from yellow to blue through pH variation. ΔE increased from 7.72 on day 2 to 23.52 on day 3. This marked the onset of visible color change and the FI reached full blue by day 7. Headspace solid-phase microextraction (HS-SPME) and gas chromatography–flame ionization detection (GC-FID) quantified monomethylamine (MMA), dimethylamine (DMA) and TMA throughout storage. ΔE correlated strongly with total bacterial count (TBC, r = 0.978), pH (r = 0.901) and TMA (r = 0.888). These results indicate that microbial growth, alkalinity increase and amine production were closely associated with color transitions. The FI reliably tracked freshness loss in skate sashimi. It has potential to enhance consumer transparency and strengthen quality control in the seafood supply chain. Full article

This study investigates the evolution of the chemical components of kombucha aroma during refrigerated storage. Two preparation methods (MT1 and MT2) were used to produce kombucha from a 1:1 mixture of black and green tea. The bottled beverages were stored at 4 °C for three months, and changes in headspace (HS) volatiles were monitored at different time points using solid-phase microextraction (SPME) and GC-MS. A total of 68 volatile substances were identified, with alcohols, acids, and esters dominating the aroma profile. The study revealed significant changes in flavor composition during cold storage, particularly in the first two weeks, with an increase in the number of esters, acids, ketones and terpenoids, as well as the total amount of esters and alkanols. While some changes contribute to the desirable “cider-like” characteristics, others, like certain volatile acids, aliphatic aldehydes and ketones, are associated with off-flavors. These findings suggest that refrigeration alone is not sufficient to completely inhibit microbial activity in freshly prepared kombucha, highlighting the need for further research to correlate chemical changes with sensory properties to establish optimal organoleptic standards and shelf life. Full article

Food irradiation is a clean, safe and non-thermal technology applied to destroy pathogenic microorganisms, i.e., Salmonella spp., in hen eggs. Currently, in Europe only the egg white can be irradiated up to 3 kGy, so different control methods are crucial for official inspections to identify illicit treatments. In this work, an analytical method was proposed to determine the radiolytic markers, namely 2–dodecylcyclobutanone (2–DCB) and 2–tetradecylcyclobutanone (2–TCB) in hen egg samples. This method is based on headspace solid phase micro-extraction coupled with gas chromatography/mass spectrometry (HS–SPME/GC–MS). The eggs were treated by an X-ray irradiator at dose levels of 0.5, 1.0 and 3.0 kGy. The preliminary validation showed good selectivity, without matrix interferences in non-irradiated samples. Spiked samples showed linear responses in the range 2.5–25.0 µg kg⁻¹, where 2.5 µg kg⁻¹ was the limit of detection for both analytes. Irradiated samples showed a dose-dependent increase in signal intensity and a constant 2–DCB/2–TCB ratio. The minimum dose level detected was 0.5 kGy for all samples, and the 2–DCB and 2–TCB signals remained stable over one month after irradiation. Not least, white analytical chemistry was used to evaluate the HS–SPME/GC–MS method validation effectiveness, greenness power and economic efficiency, compared to the EN 1785:2003 standard method. The results of this study prove that the HS–SPME/GC–MS method is a reliable green alternative to the official method, which is suitable in food safety control programs. Full article

The detection of blood by human remains detection (HRD) canines and blood detection dogs (BDDs) is crucial to both search and rescue (SAR) and crime scene investigation. They can be used to find both missing persons and to detect otherwise undetectable blood evidence at crime scenes. An added level of difficulty with training occurs as blood volatile organic compounds (VOCs) are drastically affected by time. Previous studies have shown this, with a focus on a longer timescale (weeks/months). Little data exists on the changes in the first 48 h, the most crucial time in SAR, something this study aims to rectify. Data was collected using headspace solid-phase microextraction/gas chromatography–mass spectrometry, which was then analyzed using chemometrics and confirmed with canine trials. The results of the laboratory analysis indicated that there were multiple, distinct odor profiles between the 1 h and 2-week time windows—namely, the fresh, intermediate, and aged stages of decomposition. The noted changes in the odor profiles were validated with HRD canine trials. Canines had difficulty detecting the fresh blood (1–2 h old) and had the greatest detection rate for the aged blood (34–36 h old). Both the chemical analysis and canine behavior data displayed a clear change in the odor profile within the first 48 h. This information will assist SAR, HRD, and BBD training to ensure they train on all distinct odor profiles. Full article

This paper presents the first comprehensive analysis of the composition of volatile organic compounds (VOCs) present in the liverwort Calypogeia sphagnicola belonging to the Calypogeiaceae family. Based on DNA markers, three genetically distinct groups were examined: C. sphagnicola f. sphagnicola; C. sphagnicola f. paludosa; and C. sphagnicola LC. The volatile organic compounds were determined using headspace solid-phase microextraction (HS-SPME) and analyzed by gas chromatography combined with mass spectrometry (GC-MS). A total of 65 organic compounds were detected from the tested plant material and 42 compounds were identified. The chemical analysis revealed distinct VOC profiles corresponding to three genetically defined groups. Sesquiterpenes (49.91–64.21%) and sesquiterpenoids (4.99–11.56%) dominated the VOC profiles, followed by monoterpenes (0.95–4.73%), aromatic compounds (2.43–5.12%), and aliphatic compounds (0.74–1.55%). It is noteworthy that aliphatic compounds were absent in C. sphagnicola f. paludosa, whereas the most abundant compounds were bicyclogermacrenes (20.92–33.60%) and anastreptenes (6.75–14.95%). Marker compounds were selected to allow for the rapid identification of individual genetic groups. Full article

Bacterial diseases of Pleurotus pulmonarius, caused by diverse pathogens and associated with a range of symptoms, reduce its commercial value and lead to substantial economic losses. While most research has focused on Pseudomonas tolaasii and its non-volatile toxin tolaasin, little is known about other bacterial pathogens and their volatile metabolites. In this study, two bacterial pathogens were isolated from symptomatic P. pulmonarius fruiting bodies in Guangxi, China, and identified as Ewingella americana and Cedecea neteri. Using headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME-GC-MS), we identified 16 volatile organic compounds (VOCs) produced by these two species, seven of which exhibited toxicity-inducing sunken lesions, discoloration, and inhibition of mycelial growth. Symptom severity was quantified by colorimetric analysis. Among the toxic VOCs, 2,4-di-tert-butylphenol was the most potent, inducing sunken lesions and slight discoloration at concentrations as low as 0.5 mg/mL, and causing significant inhibition of mycelial growth at 5 μg/L. The remaining VOCs also caused varying degrees of sunken lesions, yellowing or browning, and suppression of mycelial growth. This study is the first to demonstrate the pathogenic potential of VOCs produced by bacterial pathogens in P. pulmonarius, underscoring their role as important virulence factors and providing a foundation for further investigation into their mechanisms and control strategies. Full article

Hydrolates are aromatic aqueous solutions saturated with volatile water-soluble compounds of essential oil. Despite their potential, hydrolates remain less explored than essential oils. In this work, the hydrolate of Pelargonium odoratissimum (L.) L’Hér. has been analyzed by multiple analytical techniques in order to describe its chemical composition. Headspace (HS-) and Direct Immersion-Solid Phase Microextraction-Gas Chromatography/Mass spectrometry (DI-SPME-GC/MS) and Proton Transfer Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS) were employed to reveal the VOC emission from the hydrolate. Further, a direct injection of the pure hydrolate and of the hydrolate after extraction with hexane was performed by Large-Volume Injection Gas Chromatography/Mass Spectrometry (LVI-GC/MS) and GC/MS. The results obtained by HS- and DI-SPME-GC/MS highlighted a nearly overlapping chemical profile with linalool, isomenthone, and α-terpineol as the main volatiles. On the other hand, analysis of the hydrolate by GC/MS after solvent extraction revealed a lower overall number of compounds but allowed the detection of thujone and cis-linalool oxide. In comparison, LVI-GC/MS was the technique that allowed the identification of a higher number of volatiles with citronellol, linalool, and α-terpineol as the principal compounds. Finally, PTR-ToF-MS was a fundamental approach to quantify and evaluate total terpene emissions from this complex matrix starting from low-molecular-weight compounds such as acetylene, methanol, acetaldehyde, acetone, and ethanol, which were the most abundant. Among the detected compounds, dimethyl sulfide and small amounts of dimethyl-furan and 2-butylfuran were also identified. Overall, the findings showed that the hydrolate was rich in monoterpene compounds while sesquiterpene compounds were missing. A very low intensity relating to sesquiterpenes was recorded only by PTR-ToF-MS technique. Full article

Propolis is a substance produced by bees from the collection of plant resins, with a chemical composition that varies according to the available flora and region, and it has several biological activities. Stingless bee propolis is often produced in reduced amounts, posing a challenge to the study of their volatile compounds, as traditional hydrodistillation extraction would demand more raw propolis than available. These bees collect resins from various sources, resulting in a variable composition, so a standardized reproducible method is fundamental for their analysis. Headspace solid-phase microextraction (HS-SPME), associated with gas chromatography, appears to be an efficient alternative for the analysis of these volatiles. In this study, the GC-MS results of three types of SPME fibers were compared to those of extracts obtained by hydrodistillation to evaluate their efficiency in representing the composition of essential oils from (geo)propolis of different species. The extraction time and temperature were also standardized. Among the fibers tested, PDMS/DVB extracted the volatiles in a similar manner to the essential oil obtained by hydrodistillation for all the samples tested, indicating this to be the best choice of fiber coating for propolis volatile extraction and analysis. 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

Commercial fruit juices are categorized into juice not from concentrate (JNFC) and juice from concentrate (JFC). Tomato juice is one of the most popular vegetable juices, and its aroma is an important factor in evaluating its quality. However, differences in the aroma characteristics of JNFC and JFC tomato juices have not been clearly identified. This study aimed to investigate the volatile organic compounds (VOCs) involved in distinguishing between JNFC and JFC using commercially available tomato juices. Furthermore, the effect of concentration on the VOC composition was evaluated using different procedures. Twenty-three commercial tomato juices were prepared for analysis of VOCs using headspace solid phase microextraction-gas chromatography mass spectrometry (HS-SPME-GC-MS). Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to discriminate the samples into JNFC and JFC groups. JNFC contained 43 VOCs, which was more than twice that contained in JFC, and the quantitative variation was larger in JNFC than in JFC. In particular, the JNFC group contained significantly more alcohol and phenol compounds. On the other hand, the JFC group contained more formyl pyrrole and Strecker aldehydes. Additional GC-MS/olfactometry (GC-MS/O) and odor active value analyses indicated that (Z)-3-hexenol and 3-methylbutanal were the best VOCs to distinguish between the JNFC and JFC groups. Furthermore, different concentration procedures, including heating concentration (HC), decompression concentration (DC), and freeze drying (FD), were performed, and the corresponding VOCs were compared. HC and DC reduced the levels of most of the compounds to the levels seen in commercial JFC. These results indicate that the concentration procedure is an important processing stage, in addition to the break process, that determines the quality of tomato juice. Full article

Fermented vinegars have been highlighted globally for their health benefits. The benefits can differ according to the type of vinegar; therefore, we investigated the differences of 15 grain (GV), 10 persimmon (PV), and 14 apple vinegars (AV) using integrated non-targeted and targeted metabolome analyses. We profiled non-volatile and volatile metabolites using gas chromatography time-of-flight mass spectrometry (GC-TOF-MS), ultra-high-performance liquid chromatography–orbitrap–tandem mass spectrometry, and headspace–solid-phase microextraction–GC-TOF-MS. Among the 132 identified metabolites, 73 non-volatile and 40 volatile metabolites showed significant differences across the three vinegar types. Amino acids, hydroxy fatty acids, phenolic compounds, aldehydes, pyrazines, and sulfides were abundant in GV. Some phenolic compounds, alcohols, and esters were abundant in PV, whereas carbohydrates, flavonoids, and terpenoids were abundant in AV, contributing to nutrients, tastes, and flavors. Bioactivity assays revealed that GV showed notable antioxidant activity, whereas PV and AV had the highest total phenolic and flavonoid contents, respectively. Through quantitative analysis, we revealed that acetic acid, propionic acid, butanoic acid, lactic acid, and alanine were major components in the three types of vinegar, although their composition was different in each vinegar. Our comprehensive qualitative and quantitative metabolite comparison provides insights into the differences among the three vinegar types, classified according to their raw materials. Full article

Heyang Fragrance, a traditional incense dating back to the Eastern Han Dynasty (25–220 AD), was recently inscribed on China’s national list of intangible cultural heritage. This study aimed to systematically analyze three variants of Heyang Fragrance (Aicao, Qinqiang, and Jianjia) through integrated methodologies including electronic nose analysis, headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME-GC-MS), and antimicrobial activity assays. We selected Escherichia coli, Bacillus subtilis, and Candida glabrata for the antimicrobial activity assays. Comparative analysis revealed significant compositional differences between pre- and post-combustion volatile profiles. Upon ignition, sensor response values increased by 50–100% relative to baseline measurements, with sulfides, terpenes, and short-chain alkanes emerging as dominant components. Qinqiang demonstrated the highest odor activity values (OAVs), particularly through carvacrol (OAV = 6676.60) and eugenol (OAV = 2720.84), which collectively contributed to its complex aromatic characteristics. Antimicrobial assessments revealed concentration-dependent efficacy, with Qinqiang exhibiting broad antimicrobial activity against Escherichia coli (11.33 mm inhibition zone) and Bacillus subtilis (15.00 mm), while Jianjia showed maximal effectiveness against Bacillus subtilis (17.67 mm). These findings underscore the dual significance of Heyang Fragrance in cultural conservation and its prospective applications in aroma therapeutic and antimicrobial contexts. 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

Appropriate aroma extraction methods are crucial prerequisites for accurately and objectively characterizing the authentic aroma profile of samples. Purified water and ionized water were used as brewing water, and the effects of different tea-to-water ratios, extraction temperatures, and extraction times on the aroma authenticity and component enrichment of tea infusions were compared. The conditions of a tea-to-water ratio of 1 g:10 mL, extraction at 30 °C for 30 or 45 min were identified as the optimal parameter range, which could maximize the enrichment of aroma while maintaining fidelity. The cosine value of the aroma attribute scores between the optimal parameter set and the control group (tea brewed at 1 g:10 mL ratio for 4 min) exceeded 0.979, and the correlation coefficient surpassed 0.828. Test evaluation results indicate the method had good reproducibility and effectively highlighted the differential impacts of ionic content in brewing water on tea aroma constituents. This approach effectively solved the problem of sensory distortion caused by conventional high-temperature and long-duration extraction, enabling precise analysis of how water quality authentically influences tea infusion aroma characteristics. Full article