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Jiang‐flavor Chinese spirits are one of the four basic liquor types in China. It has thousands of years of history in China and is widely enjoyed because of its unique flavor and broad application. Although Jiang‐flavor Chinese spirits have a unique soy sauce flavor, the associated key compounds and production mechanism remain unknown. To investigate this process, soy sauce flavor‐producing strains were obtained, and their metabolites were evaluated. Using wheat as the fermentation medium, we observed changes in total acid, amino nitrogen, and reducing sugar in three strains of Bacillus cerberus with high yield of tetramethylpyrazine during the fermentation process. The results showed that total acid and amino nitrogen contents increased and reducing sugars decreased in a time‐dependent manner. Additionally, detection of volatile compounds via solid‐phase microextraction and gas chromatography–mass spectrometry that total pyrazine content reached 43.175%, 50.461%, and 45.955% in wheat fermentation medium fermented by strains Q1, Q2, and Q5, respectively, suggesting that this important flavor compound might be related to the flavor of soy sauce. Moreover, we found that fermentation time was an important factor in soy sauce flavor, as volatile compounds were detected at different times by the three strains, with pyrazines not detected before 48 hr and peaking at 50.461% after 144 hr. These results indicated that strain Q2 exhibited optimal fermenting performance and might be useful for fermentation of Jiang‐flavor Chinese spirits. Although Jiang‐flavor Chinese spirits have a unique soy sauce flavor, the associated key compounds and production mechanism remain unknown. To investigate this process, soy sauce flavour‐production strains were obtained, and their metabolites were evaluated.

BACKGROUND AND AIMS: Many aroma compounds occur as glycosidically bound precursors that do not contribute to fruit/beverage aroma until aglycone release during processing or storage. Existing procedures typically measure glycosidically bound compounds after first isolating the glyocoside fraction. The objectives of this work were to evaluate and develop rapid procedures for measuring glycosidically bound volatiles using direct acid or enzyme hydrolysis of fruit tissues or wine followed by analysis of the free volatiles by headspace solid‐phase microextraction coupled with gas chromatography mass spectrometry. METHODS AND RESULTS: Using a mixture containing free (linalool, ethyl decanoate, β‐ionone) and glycosidically bound standards (n‐octyl‐, n‐dodecyl‐, phenyl‐β‐D‐glucopyranoside), acid hydrolysis released 20–60% of the bound volatiles; significant degradation (>50%) of free volatiles occurred. Enzyme hydrolysis efficiently released glycosidically bound compounds (90–100%) while minimising artefactual changes of the free volatiles and further rearrangements of the aglycones. We also compared direct enzyme hydrolysis with hydrolysis of a glycoside fraction obtained by solid‐phase extraction (SPE). Different SPE columns were not equally effective at retaining glycosides; no column type was effective for all glycosides. CONCLUSIONS: Direct hydrolysis of grape and wine samples (and comparison of volatiles before and after hydrolysis) is a useful approach for measuring ‘aroma potential’ compared with prior SPE isolation of the glycosides. SIGNIFICANCE OF THE STUDY: The method described here provides a rapid tool for characterising changes in glycosidically bound volatiles before and after processing (e.g. winemaking) and as a result of varying fruit maturity and/or other agricultural practices.

Houttuynia cordata Thunb. is a medicinal and edible plant that has been commonly used in traditional Chinese medicine since ancient times. This study used headspace solid-phase microextraction (HS-SPME) and direct injection, combined with gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS), to identify the volatile compounds in H. cordata. Extraction from different parts of the plant using different extraction techniques for the identification of volatile compounds were determined. A total of 93 volatile components were analyzed in the leaves, stems, rhizomes, and whole plant samples of H. cordata. The leaves contained more (Z)-3-hexenal, β-myrcene, (Z)-β-ocimene, and (4E,6E)-allo-ocimene; the stems contained more geranyl acetate and nerolidol; and rhizomes contained more α-pinene, β-pinene, limonene, 2-undecanone, and decanoyl acetaldehyde. Among them, the essential oil extracted by HS-SPME could produce more monoterpenes, while direct injection could obtain higher contents of aliphatic ketones, terpene esters, sesquiterpenes, and was more conducive to the extraction of 2-undecanone and decanoyl acetaldehyde.

Vanilla (Vanilla planifolia) is a precious natural flavoring that is commonly used throughout the world. In the past, all vanilla used in Taiwan was imported; however, recent breakthroughs in cultivation and processing technology have allowed Taiwan to produce its own supply of vanilla. In this study, headspace solid-phase microextraction (HS-SPME) combined with GC-FID and GC-MS was used to analyze the volatile components of vanilla from different origins produced in Taiwan under different cultivation and processing conditions. The results of our study revealed that when comparing different harvest maturities, the composition diversity and total volatile content were both higher when the pods were matured for more than 38 weeks. When comparing different killing conditions, we observed that the highest vanillin percentage was present after vanilla pods were killed three times in 65 °C treatments for 1 min each. From the experiment examining the addition of different strains, the PCA results revealed that the volatiles of vanilla that was processed with Dekkera bruxellensis and Bacillus subtilis was clearly distinguished from which obtained by processing with the other strains. Vanilla processed with B. subtilis contained 2-ethyl-1-hexanol, and this was not detected in other vanillas. Finally, when comparing the vanillin percentage from seven different regions in Taiwan, vanilla percentage from Taitung and Taoyuan Longtan were the highest.

Coffee, one of the most widely consumed commodities globally, embodies a sensory experience deeply rooted in social, cultural, and hedonic contexts. The cold brew (CB) method, characterized by cold extraction, is a refreshing and unique alternative to traditional coffee. Despite its growing popularity, CB lacks defined preparation parameters and comprehensive analysis of its aromatic composition. In this study, we aimed to obtain a representative extract of the volatile matrix of CB and characterize the aroma of sensory-active compounds using advanced techniques such as headspace–solid-phase Microextraction (HS-SPME) and headspace-solid-phase extraction (HS-SPE) for volatile compound extraction, followed by gas chromatography–olfactometry–mass Spectrometry (GC-O-MS) for compound identification. Optimization of the HS-SPME parameters resulted in the identification of 36 compounds, whereas HS-SPE identified 28 compounds, which included both complementary and similar compounds. In HS-SPME, 15 compounds exhibited sensory activity with descriptors such as floral, caramel, sweet, and almond, whereas seven exhibited sensory activity with descriptors such as chocolate, floral, coffee, and caramel. This comprehensive approach to HS-SPME and HS-SPE aroma extraction with GC-O-MS offers an efficient methodology for characterizing the aroma profile of CB, paving the way for future research and quality standards for this innovative coffee beverage.

Monitoring and early detection of stored-grain insect infestation is essential to implement timely and effective pest management decisions to protect stored grains. We report a reliable analytical procedure based on headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME-GC-MS) to assess stored-grain infestation through the detection of volatile compounds emitted by insects. Four different fibre coatings were assessed; 85 µm CAR/PDMS had optimal efficiency in the extraction of analytes from wheat. The headspace profiles of volatile compounds produced by Tribolium castaneum (Herbst), Rhyzopertha dominica (Fabricius), and Sitophilus granarius (Linnaeus), either alone or with wheat, were compared with those of non-infested wheat grains. Qualitative analysis of chromatograms showed the presence of different volatile compound profiles in wheat with pest infestation compared with the wheat controls. Wheat-specific and insect-specific volatile compounds were identified, including the aggregation pheromones, dominicalure-1 and dominicalure-2, from R. dominica, and benzoquinones homologs from T. castaneum. For the first time, the presence of 3-hydroxy-2-butanone was reported from S. granarius, which might function as an alarm pheromone. These identified candidate biomarker compounds can be utilized in insect surveillance and monitoring in stored grain to safeguard our grain products in future.

Lily is one of the most important cut flowers in the world, with a rich floral fragrance. To further explore the fragrance emission mechanisms of lily cultivars, headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS) and organic solvent extraction–gas chromatography–mass spectrometry (OSE-GC-MS) were used to unveil the volatile organic compounds (VOCs) and endogenous extracts of seven lily cultivars. Furthermore, real-time quantitative PCR (qRT-PCR) was used to determine the expression levels of two key genes (TPS and BSMT) related to the biosynthesis of monoterpenoids and methyl benzoate. The results show that forty-five VOCs were detected in the petals of seven lily cultivars, and the main compounds were monoterpenoids and phenylpropanoids/benzenoids. Dichloromethane was the best solvent for extracting the endogenous extracts of Lilium ‘Viviana’ petals and eighteen endogenous extracts were detected using dichloromethane to extract the petals of seven lily cultivars. Each compound’s emission ratio (natural logarithm of the ratio of VOC content to endogenous extract content) was calculated, and linear regression analyses between emission ratios and boiling points were conducted. Significant linear negative correlations existed between the emission ratios and boiling points of compounds, and the regression equations’ coefficients of determination (R2) were all greater than 0.7. TPS was expressed highly in ‘Viviana’, ‘Pink News’, and ‘Palazzo’, and BSMT was expressed highly in ‘Pink News’ and ‘Palazzo’. Correlation analyses between the gene expression levels and the monoterpenoids and methyl benzoate contents found that the TPS expression levels have strong positive correlations with monoterpenoids content, while no correlations were found between the expression levels of BSMT and the contents of methyl benzoate. This study lays the foundation for research on the release patterns of VOCs in the flowers of Lilium, and the breeding of lilies for their floral fragrance.

To understand aroma perception from complex food matrices‚ determination of dynamic aroma release during simulated oral processing is necessary. In this study optimization, validation and application of a novel method coupling headspace-solid phase microextraction (HS-SPME) with gas chromatography-ion mobility spectrometry (GC-IMS) is presented. Thirteen character impact compounds imparting different chemical properties are studied to understand capabilities and limitations of the method. It was shown for the first time that the temperature of the IMS sample inlet can be increased up to 200 °C without instrumental constraints. Linear calibration was possible for eleven of the thirteen compounds with one decade dynamic range. The limit of detection and quantitation were 2.1–63.0 ppb and 7.2–210.1 ppb, respectively. Diacetyl could be detected in negative polarity mode of IMS, however with lower precision compared to the compounds detected in positive mode. Limitations of the method were short HS-SPME extraction time, which in the case of caproic acid was not sufficient for reliable quantification. Additionally, δ-decalactone could not be detected due to maximum GC temperature of 200 °C. Application of the method to determine dynamic aroma release from a dairy matrix was successfully shown for nine compounds. Analysis of complex food matrix was performed with similar precision compared to analysis in aqueous solution, thus proving high robustness of the method towards matrix effects.

•Human scent is an individualizing characteristic.•An individual’s human scent varies from day to day.•Pattern recognition models can be used to associate human scent samples to a donor.•The intra-subject variability of human scent affects source origin determination. A dual effort investigation was conducted to study (a) the naturally occurring variation in same-donor human hand odor samples over time and (b) the accuracy in associating same-donor human hand odor samples. Hand odor samples were collected from 8 donors throughout 5 sampling sessions; samples were collected in triplicate and analyzed by HS-SPME-GC-MS at each sampling session. The resulting human hand odor profiles were analyzed to investigate (a) the variability of human hand odor profiles as a function of time and (b) the ability to determine the source origin of human hand odor samples, determining samples to be from the same source or different sources. The researchers observed greater variation in 2-dimensional human scent profile patterning schemes among inter-day, inter-subject samples and less variation in inter-day, intra-subject samples. Although intra-subject samples revealed less variation than inter-subject samples, there was still notable variability among inter-day, intra-subject human scent profiles, with an observed time dependency. Two proof of concept models for the source determination of human hand odor samples were developed with maximum performance measuring TPR = 0.817/ FPR = 0.308 and TPR = 1.000/ FPR = 0.206 for models one and two, respectively. The study quantified same-donor human hand odor profile variation over time displayed within a larger goal of determining sample source origin.