Varietal differences in flavor, stability, and functional components analysis of fried red and green Huajiao oils

The aim of this study was to evaluate volatile compounds of dried fish floss with different sugar using electronic nose (e-nose) and headspace-solid-phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC-MS). Maillard reaction (MR) was carried out by reducing sugar (glucose, xylose, fructose, and galactose) instead of sucrose to increase the flavor of fish floss. The results showed that 64 volatile compounds were detected in fish floss. Hexanal, heptanal, nonanal, decanal, undecanal, tridecanal, pentadecanal, 4-ethyl-benzaldehyde, dodecanal, benzene acetaltaldehyde, (E, E)-2,6-nonadienal, (E, E)-2,4-decadienal, 2-undecanone, 1-octen-3-ol, (E)-2-hepten-1-ol, 1-heptanol, and 2-pentyl-furan were regarded as key volatile compounds. Furthermore, e-nose and partial least squares-discriminant analysis (PLS-DA) showed that there were significant differences in flavor among fish floss samples. The correlation analysis of browning index, fatty acids, and key volatile compounds confirmed that MR and lipid oxidation made a great contribution to the flavor formation. These results might provide guidance for the production and flavor formation of fish floss. Practical applications Dried fish floss deeply loved by the public is a traditional leisure food with unique odor and delicious taste. The attractive flavor of dried fish floss could be increased with the help of the Maillard reaction (MR). The type of sugar in MR has a great influence on the reaction process and the flavor of substances. The comprehensive information on the flavor among the dried fish floss with different sugar (sucrose, glucose, xylose, fructose, and galactose) was characterized by using HS-SPME/GC-MS, electronic nose (E-nose), and fatty acid analysis, which may provide a reference for the quality improvement of dried fish floss.

The efficacy of using human volatile organic compounds (VOCs) as a form of forensic evidence has been well demonstrated with canines for crime scene response, suspect identification, and location checking. Although the use of human scent evidence in the field is well established, the laboratory evaluation of human VOC profiles has been limited. This study used Headspace-Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry (HS-SPME-GC-MS) to analyze human hand odor samples collected from 60 individuals (30 Females and 30 Males). The human volatiles collected from the palm surfaces of each subject were interpreted for classification and prediction of gender. The volatile organic compound (VOC) signatures from subjects’ hand odor profiles were evaluated with supervised dimensional reduction techniques: Partial Least Squares-Discriminant Analysis (PLS-DA), Orthogonal-Projections to Latent Structures Discriminant Analysis (OPLS-DA), and Linear Discriminant Analysis (LDA). The PLS-DA 2D model demonstrated clustering amongst male and female subjects. The addition of a third component to the PLS-DA model revealed clustering and minimal separation of male and female subjects in the 3D PLS-DA model. The OPLS-DA model displayed discrimination and clustering amongst gender groups with leave one out cross validation (LOOCV) and 95% confidence regions surrounding clustered groups without overlap. The LDA had a 96.67% accuracy rate for female and male subjects. The culminating knowledge establishes a working model for the prediction of donor class characteristics using human scent hand odor profiles.

Identification of volatile compounds and metabolic pathway during ultrasound-assisted kombucha fermentation by HS-SPME-GC/MS combined with metabolomic analysis

In this study, headspace solid-phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC-MS) and electronic-nose (E-nose) analyses were performed to examine the comprehensive flavor profiles of robusta coffee during heat air drying. A total of 62 volatile compounds were identified by HS-SPME/GC-MS, the level of acids, aldehydes, alcohols and esters decreased during drying process, however, the relative content of hydrocarbons and acids increased. Principal component analysis of the E-nose results clearly differentiated the samples related to drying time, and it was found that samples of initial stages (0 h, 3 h, and 6 h) had strong positive with different sensors. Partial least squares-discriminant analysis (PLS-DA) indicated that alcohols, ketones, and esters were the main contributing compounds to the flavour of coffee beans. The VIP score of PLS-DA larger than one illustrated that T30/1, T70/2, PA/2, and P30/2 were positive with ketones, sulfur compounds, and esters. These results could provide theoretical evidence about the change rule in volatile compounds of coffee beans during drying process, and could be applied to other thermally sensitive tropical agricultural products.

Authenticating monofloral honeys is essential for protecting premium markets and ensuring traceability. This study applied an integrated analytical and explainable machine-learning workflow to identify volatile biomarkers for four New Zealand monofloral honeys: thyme, mānuka, kānuka, and clover. Twenty-two samples were profiled using headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME/GC-MS), yielding 122 tentative volatiles across aldehydes, alcohols, acids, esters, terpenoids, and phenolics. Data were analysed using ANOVA, hierarchical clustering, Partial Least Squares Discriminant Analysis (PLS-DA), and Random Forest classification with SHapley Additive exPlanations (SHAP). ANOVA and heatmap analysis revealed honey-specific volatile modules, while PLS-DA confirmed clear supervised separation of floral types. A rule-based SHAP framework was implemented to select biomarkers that were not only influential in the model but also directionally consistent and chemically distinctive. Thyme honey was characterised by short-chain fatty acids and oxygenated terpenoids; mānuka by methoxyacetophenones and benzofuran/methoxylated benzoates; kānuka by anisole-type aromatics and bicyclic monoterpenes; and clover by phenylpropanoid-related aldehydes, fusel alcohols, and linalool-oxide derivatives. These panels achieved non-overlapping group separation and near-perfect cross-validated performance (micro-average ROC-AUC=0.995). This combined HS-SPME/GC-MS and RF-SHAP approach provides a transparent, statistically supported route to defining interpretable volatile biomarkers, offering a scalable framework for honey authentication, quality assurance, and traceability, and helping safeguard the premium positioning of New Zealand monofloral honeys in global markets.

A combined headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) approach was employed to examine changes in volatile organic compounds (VOCs) in rice and rice bran across different degrees of milling (DOM) and to identify characteristic VOCs. A total of 43 and 63 VOCs were detected in rice samples using HS-SPME-GC-MS and HS-GC-IMS, respectively, while 73 and 63 VOCs were identified in rice bran. With increasing DOM, the VOC content in both rice and rice bran showed a fluctuating trend, initially decreasing, then increasing, and finally declining, with peak levels observed in samples R-3 and B-4, respectively. Based on odor activity value (OAV) analysis, 13 and 20 key VOCs were identified in rice and rice bran, respectively, among which 2-acetyl-1-pyrroline, (E)-2-nonene, and (E, E)-2,4-decadienal were the most influential compounds. Principal component analysis and partial least squares discriminant analysis (PLS-DA) successfully distinguished rice and rice bran with different DOM based on their changes in VOCs. PLS-DA further identified 7 VOCs with OAV > 1 as key VOCs of rice at different DOM. Similarly, 8 VOCs with OAV > 1 were identified as key VOCs for rice bran. From the perspective of aroma compound content, sample R-3 represented the optimal DOM. Moreover, B-4, corresponding to the outermost layer of R-3, played a significant role in shaping its flavor profile. PRACTICAL APPLICATIONS: The findings indicated that the DOM governed both the retention and generation of VOCs, significantly shaping the overall VOC profile and flavor characteristics of rice and rice bran. These results established a theoretical basis for understanding how milling precision affects rice flavor quality.

By employing headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS), this study displayed the compositional changes in volatile organic compounds (VOCs) in Tricholoma matsutake samples subjected to hot-air drying (HAD) and vacuum freeze-drying (VFD) processes from their fresh samples. A total of 99 VOCs were detected, including 2 acids, 10 aldehydes, 10 alcohols, 13 esters, 12 ketones, 24 alkanes, 14 olefins, 7 aromatic hydrocarbons, and 7 heterocyclic compounds. Notably, the drying process led to a decrease in most alcohols and aldehydes, but an increase in esters, ketones, acids, alkanes, olefins, aromatic, and heterocyclic compounds. Venn diagram (Venn), principal component analysis (PCA), and partial least squares-discriminant analysis (PLS-DA) analyses enabled an easy and rapid distinction between the VOC profiles of T. matsutake subjected to different drying methods. Among the identified VOCs, 30 were designated as marker VOCs indicative of the employed drying process. And the VFD method was more capable of preserving the VOCs of fresh T. matsutake samples than the HAD method. Benzaldehyde, 1-Octen-3-ol, 3-Octanol, and (E)-2-Octen-1-ol were identified as markers for FRESH T. matsutake. Conversely, (E)-3-Hexene, lavender lactone, and α-Pinene were associated with VFD T. matsutake. For HAD T. matsutake, olefins, pyrazine, and esters, particularly ocimene, 2,5-Dimethyl-pyrazine, and methyl cinnamate, significantly contributed to its particularities. The results from this present study can provide a practical guidance for the quality and flavor control of volatile organic compounds in preciously fungal fruiting bodies by using drying processes.

Volatile fraction analysis by HS-SPME/GC-MS and chemometric modeling for traceability of apples cultivated in the Northeast Italy

The volatile and semivolatile components in burley tobacco leaves were analyzed by headspace solid-phase microextraction gas chromatography/mass spectrometry (HS-SPME-GC/MS). Twenty milligrams of tobacco powder was incubated at 60 ℃ for 8 min and then extracted using 65 μm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber for 40 min. Finally, the fiber was desorbed at 250 ℃ for 3 min. One hundred twenty two kinds of volatile and semivolatile components in the burley tobacco leaves were tentatively identified by comparing with standard products and mass spectrometry databases, and these compounds were semi-quantitatively analyzed by the internal standard method. The differences between the volatile and semivolatile components for the burley tobacco leaves before and after baking were discriminated and visualized by principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA). This method has the advantages of small sample size, simple pretreatment, and high sensitivity. In combination with chemometrics, the HS-SPME-GC/MS method is suitable for discriminating changes in the chemical composition of burley tobacco before and after baking, and hence has broad prospective application in the optimization of the baking conditions used for burley tobacco.

A headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) method was developed and optimized for qualitative and semi quantitative analysis of volatile components from Schisandra propinqua, a kind of Yi Nationality herb medicine. This method was used for analysis and evaluation of volatile components from S.propinqua from four different geometrical origins (Yunnan Wuding, Yunnan Luoping, Guizhou Qingzhen and Hubei Shennongjia). 51, 53, 52， 50 compounds were identified from the above four kinds of samples respectively, in which 46 volatile components were contained in all of these four origins. The volatile components in these samples from different geographical origins were then compared by using principal component analysis, cluster analysis and other chemometrics methods. The results suggested that the analysis of volatile components can be used to distinguish the S.propinqua from four origins, and those samples from close geographical origins were more similar in volatile components. The developed method was stable, reliable, and suitable for rapid analysis of volatile components from S.propinqua, providing reference for quality control, drug development and scientific utilization of the herb.

Undesirable volatile compound analysis in infant formula based on nutritional analysis, GC-MS, and recombination/omission experiments methods

Fourier transform infrared spectroscopy (FT-IR) is widely used in the analysis of the chemical composition of biological materials and has the potential to reveal new aspects of the molecular basis of diseases, including different types of cancer. The potential of FT-IR in cancer research lies in its capability of monitoring the biochemical status of cells, which undergo malignant transformation and further examination of spectral features that differentiate normal and cancerous ones using proper mathematical approaches. Such examination can be performed with the use of chemometric tools, such as partial least squares discriminant analysis (PLS-DA) classification and partial least squares regression (PLSR), and proper application of preprocessing methods and their correct sequence is crucial for success. Here, we performed a comparison of several state-of-the-art methods commonly used in infrared biospectroscopy (denoising, baseline correction, and normalization) with the addition of methods not previously used in infrared biospectroscopy classification problems: Mie extinction extended multiplicative signal correction, Eiler’s smoothing, and probabilistic quotient normalization. We compared all of these approaches and their effect on the data structure, classification, and regression capability on experimental FT-IR spectra collected from five different prostate normal and cancerous cell lines. Additionally, we tested the influence of added spectral noise. Overall, we concluded that in the case of the data analyzed here, the biggest impact on data structure and performance of PLS-DA and PLSR was caused by the baseline correction; therefore, much attention should be given, especially to this step of data preprocessing.

Aroma plays a pivotal role in defining tea quality and distinctiveness, and tea producers have often observed that specific drought conditions are closely associated with the formation and accumulation of characteristic aroma compounds in tea leaves. However, there is still limited understanding of the differential strategies employed by various tea cultivars in response to drought stress for the accumulation of key volatile aroma compounds in fresh tea leaves, as well as the associated metabolic pathways involved in aroma formation. In this study, two widely cultivated tea cultivars in China, Fuding Dabai (FD) and Wuniuzao (WNZ), were examined to assess the impact of mild field drought stress on the composition and accumulation of key volatile aroma compounds in fresh leaves using headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) and headspace solid phase micro-extraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) technologies. Results revealed that drought stress led to a substantial increase in the diversity of volatile compounds (VOCs) in FD, while WNZ exhibited a notable rise in low-threshold VOC concentrations, amplifying sweet, floral, fruity, and earthy aroma profiles in post-drought fresh leaves. Through partial least squares discriminant analysis (PLS-DA) of HS-GC-IMS and HS-SPME-GC-MS data, integrating variable importance projection (VIP) scores and odor activity values (OAVs) above 1, 9, and 13, key odor-active compounds were identified as potential markers distinguishing the drought responses in the two cultivars. These compounds serve as crucial indicators of the aromatic profile shifts induced by drought, providing insights into the differential metabolic strategies of the cultivars. Additionally, KEGG enrichment analysis revealed 12 metabolic pathways, such as terpenoid biosynthesis, fatty acid synthesis, cutin, suberine, and wax biosynthesis, and phenylalanine metabolism, which may play crucial roles in the formation and accumulation of VOCs in tea leaves under drought stress. These findings provide a comprehensive framework for understanding the cultivar-specific mechanisms of aroma formation and accumulation in tea leaves under mild drought conditions.

To explore the volatile profiles and the contents of ten bioactive components (polyphenols and caffeine) of sun-dried Pu-erh tea leaves from ancient tea plants on Bulang Mountain, 17 samples of three tea varieties were analyzed by headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and high-performance liquid chromatography (HPLC). A total of 75 volatile components were tentatively identified. Laomaner (LME), Laobanzhang (LBZ), and other teas on Bulang Mountain (BL) contained 70, 53, and 71 volatile compounds, respectively. Among the volatile compounds, alcohols (30.2%-45.8%), hydrocarbons (13.7%-17.5%), and ketones (12.4%-23.4%) were qualitatively the most dominant volatile compounds in the different tea varieties. The average content of polyphenol was highest in LME (102.1 mg/g), followed by BL (98.7 mg/g) and LBZ (88.0 mg/g), while caffeine showed the opposite trend, 27.3 mg/g in LME, 33.5 mg/g in BL, and 38.1 mg/g in LBZ. Principal component analysis applied to both the volatile compounds and ten bioactive components showed a poor separation of samples according to varieties, while partial least squares-discriminant analysis (PLS-DA) showed satisfactory discrimination. Thirty-four volatile components and five bioactive compounds were selected as major discriminators (variable importance in projection (VIP) >1) among the tea varieties. These results suggest that chromatographic data combined with multivariate analysis could provide a useful technique to characterize and distinguish the sun-dried Pu-erh tea leaves from ancient tea varieties on Bulang Mountain.

Tea (Camellia sinensis (L.) O. Kuntze) is a popular beverage consumed worldwide. To establish fundamental scientific data, we analyzed the amino acids and volatile compounds in seven tea cultivars grown in Korea investigated phenotype also. Phenotypically, the leaf area and greenness index of young shoots and leaf blades were particularly different among the four Korean cultivars. Nine amino acids were detected from each cultivar, with the total amino acid and theanine contents being 9.08–41.42 and 2.81–24.60 mg/g, respectively. Moreover, 107 volatile compounds were identified as common components among tea cultivars using headspace solid-phase microextraction / gas chromatography–mass spectrometry (HS-SPME/GC-MS), and 38 key compounds were identified using partial least squares-discriminant analysis (PLS-DA) and hierarchical cluster analysis (HCA). The (Z)-linalool oxide (furanoid) concentrations were significantly high in Korean tea plant cultivars, and linalool concentrations were also high or low, but had high relative contents. Linalool and its various oxides are the major compounds responsible for the tea aroma. In conclusion, Korean tea cultivars have distinct characteristics, and the results of this study will form the basis for identifying Korean tea plant cultivars that can produce high-value tea products.