Gas Chromatography-ion Mobility Spectrometry Research Articles

Characteristic volatile compounds of white tea with different storage times using E-nose, HS-GC-IMS, and HS-SPME-GC-MS.

This paper studied the influence of storage duration on the flavor profile of white tea in detail, with samples produced between 2020 and 2023. Sensory evaluation was performed by quantitative descriptive analysis (QDA), followed by an in-depth aroma components analysis employing an electronic nose (E-nose), headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS), and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The QDA findings revealed a gradual transition in the flavor profile of white tea during storage, shifting from sweet, fruity, and floral to more herbal and stale characteristics. E-nose could well distinguish white tea with different storage times. A total of 55 and 53 volatile compounds were identified by HS-GC-IMS and HS-SPME-GC-MS, respectively. The orthogonal partial least squares-discriminant analysis models, based on HS-GC-IMS (R2Y=0.998, Q2=0.987) and HS-SPME-GC-MS (R2Y=0.984, Q2=0.993), successfully distinguished white tea samples stored for different storage times. Furthermore, 14 and 8 key compounds were screened based on the double variable criterion of one-way analysis of variance (p<0.05) and variable importance in projection (VIP) >1.2, and their content changes were also compared. It is the gradual decrease of important aroma components such as 2-hexenal, 2-methyl-2-hepten-6-one, linalool, and geraniol, which are positively correlated with sweet, fruity, and floral aromas, and the gradual increase of hexanoic acid, thiophene, propanoic acid, dimethyl disulfide, and borneyl acetate, which are positively correlated with herbal and stale flavor, that leads to the changes in flavor and aroma of white tea during storage. The results of the study provided a reference for elucidating the aroma characteristics of white tea at different storage times as well as a theoretical basis for the quality control of white tea.

Determination of Geographical Origin of Southern Shaanxi Congou Black Teas Using Sensory Analysis Combined with Gas Chromatography–Ion Mobility Spectrometry

Southern Shaanxi is one of China’s high-quality congou black tea production areas. However, the differences in geography, cultivation, and management techniques and production processes lead to uneven qualities of southern Shaanxi congou black tea in different production areas. This study used sensory analysis combined with gas chromatography–ion mobility spectrometry (GC-IMS) to determine southern Shaanxi congou black teas’ geographical origin and volatile fingerprints to prevent economic losses caused by fraudulent labeling. A total of 61 volatile compounds were identified and quantified by GC-IMS. Three main aroma types were found by sensory analysis coupled with significant difference analysis, and a clear correlation between volatile compounds, aroma type, and geographical origin was found by sensory and gallery plot analysis. The black tea with a green/grassy-roast aroma type was mainly distributed in production areas with an altitude of 400–800 m and 1-pentanol, cyclohexanone, 1-penten-3-one, 2-heptanone, dihydroactinidiolide and butyrolactone were the key aroma markers. The black teas produced in production areas with an altitude of 800–1000 m mainly presented strong honey and caramel-like aromas, and sotolone, furaneol, and phenylacetaldehyde played an important role. These results will be helpful for discriminating black tea from different tea production areas in southern Shaanxi.

Volatile Substances, Quality and Non-Targeted Metabolomics Analysis of Commercially Available Selenium-Enriched Rice

Selenium is an essential trace element for the human body. However, its intake is usually low. Therefore, the production and utilization of selenium-enriched food are currently a research hotspot. Despite the remarkable scientific interest in this topic, only a few of the numerous studies focus on commercially available products. This study examined the nutritional quality, physical and chemical properties, cooking characteristics, and eating quality of four commercially available hot-selling rice types, both selenium-enriched and non-selenium-enriched, and discovered that selenium-enriched rice outperforms ordinary rice in terms of both nutritional quality and taste. In addition, we employed the gas chromatography–ion mobility spectrometry (GC-IMS) technique to evaluate the volatile chemicals of rice. Some of the chemicals that made selenium-rich rice taste different from regular rice were pentanal, (E)-2-Hexen-1-ol, ethyl-3-methyl butanoate, 2-furan methanol acetate, ethyl heptanoate, ethyl hexanoate, methyl hexanoate, isopentyl pentanoate, and ethyl butyrate. We looked into the metabolite profiles of rice using LC-MS-based untargeted metabolomics to obtain a better idea of the different metabolites that are found in selenium-enriched rice compared to regular rice. We identified a total of 522 metabolites and screened 182, 227, and 100 differential metabolites in selenium-enriched (A) vs. non-selenium-enriched rice (B/C/D) groups, respectively. This study revealed that selenium primarily influenced the metabolism of D-amino acids, starch, sucrose, and linoleic acid in rice. This study systematically analyzed the quality differences between selenium-enriched and non-selenium-enriched rice available on the market. For consumers, it is essential to understand the quality of selenium-rich rice on the market to guide the purchase of rice.

Analysis of the source of abnormal odor components in medium-density fiberboard (MDF)

ABSTRACT To investigate the cause of the abnormal odor emitted by medium-density fiberboard (MDF) when formaldehyde-free diphenylmethane diisocyanate (MDI) adhesive is used, a comparative study of three types of MDF was conducted: MDF made with masson pine wood and MDI adhesive (PW-MDI), MDF made with masson pine wood and urea-formaldehyde resin (PW-UF), and MDF made with mixed hardwoods and MDI adhesive (HW-MDI). Volatile organic compounds (VOCs) emitted were collected and analyzed using gas chromatography-mass spectrometry (GC-MS), identifying 86 VOCs. Results reveal that the PW-MDI specimen contains a higher concentration of acid substances, comprising 56% of the specimen. These acid mainly octanoic and nonanoic acids, were the primary contributors to its abnormal odor. In contrast, the PW-UF and HW-MDI specimens were predominantly composed of alcohol substances, accounting for 33% and 36% respectively. Gas chromatography-ion mobility spectrometry (GC-IMS) was used to obtain VOC fingerprints. Analysis revealed that acids and aldehydes are the primary contributors to the relative odor activity value (ROAV). These compounds are known for their abnormal odor that impact the indoor air quality. This research successfully identified the source of the abnormal odor and provided technical support for the effective control of low abnormal odor VOC emissions from MDF.

How Machine Learning and Gas Chromatography-Ion Mobility Spectrometry Form an Optimal Team for Benchtop Volatilomics.

This invited feature article discusses the potential of gas chromatography-ion mobility spectrometry (GC-IMS) as a point-of-need alternative for volatilomics. Furthermore, the capabilities and versatility of machine learning (ML) (chemometric) techniques used in the framework of GC-IMS analysis are also discussed. Modern ML techniques allow for addressing advanced GC-IMS challenges to meet the demands of modern chromatographic research. We will demonstrate workflows based on available tools that can be used with a clear focus on open-source packages to ensure that every researcher can follow our feature article. In addition, we will provide insights and perspectives on the typical issues of the GC-IMS along with a discussion of the process necessary to obtain more reliable qualitative and quantitative analytical results.

Volatile organic compounds in exhaled breath, blood, and urine detected in patients with thyroid carcinoma using gas chromatography-ion mobility spectrometry—a pilot study

The differentiation between malignant and benign thyroid nodules represents a significant challenge for clinicians globally. The identification of volatile organic compounds (VOCs) has emerged as a novel approach in the field of cancer diagnosis. This prospective pilot study aims to identify VOCs in exhaled breath, blood, and urine that can differentiate benign from malignant thyroid nodules using gas chromatography-ion mobility spectrometry (GC-IMS). Patients with thyroid nodules scheduled for surgery were enrolled at the Maastricht University Medical Center (MUMC+). Breath samples were analyzed using a BreathSpec GC-IMS machine (G.A.S. Dortmund, Germany), specifically designed for breath analysis. All blood and urine samples were analyzed using a separate GC-IMS device, the FlavourSpec® (G.A.S., Dortmund, Germany). In this proof-of-concept study, 70 consecutive patients undergoing thyroid surgery at MUMC+ were included. Of these patients, 29 were confirmed to have thyroid cancer after surgical resection. The overall analysis did not reveal statistically significant differences in VOCs in breath, urine and blood, between patients with benign and malignant thyroid cancer. This proof-of-concept study demonstrated that GC-IMS could not effectively differentiate between the VOC profiles of malignant and benign thyroid nodules. However, due to the small sample size of this study, larger prospective studies are needed to investigate the potential of using VOCs to distinguish between benign and malignant thyroid nodules. Additionally, future research should focus on identifying potential confounding factors that may influence patient VOC profiles. (NCT04883294).

Biological Properties of S. warneri KYS-164 Isolated from Kefir Grains.

Staphylococcus worderi KYS-164, isolated from homemade Tibetan kefir grains, produces bacteriocin-like inhibitory substances (BLIS), which are peptides with antimicrobial properties, but have not been fully characterized. The research on BLIS will lay the foundation for mining new bacteriocins. In this study, the optimal culture conditions for the production of highly active BLIS were found to be incubation at 30 °C and 120 rpm, and the most effective extraction method was ammonium sulfate precipitation (ASP) using ammonium sulfate at 80% saturation. The postantibiotic effect (PAE) of BLIS on Staphylococcus aureus CICC 10384 is significant, with a 4 × MIC BLIS concentration able to prolong the PAE to 2.39 h. BLIS has excellent biosafety, with no deleterious effects observed at 8 × MIC concentration. Gas chromatography-ion mobility spectrometry (GC-IMS) was used to analyze the volatile compounds synthesized by Staphylococcus warneri KYS-164 during its growth. Hydroxycitronellal, ethyl pyruvate, and α-pinene were found to be unique substances produced by this strain, which can provide fresh, refreshing floral and fruity aromas as well as strong pine and resinous aromas in the process of kefir grain fermentation of milk. Analysis of the S. warneri KYS-164 genome provided insights into the major metabolic pathways in which genes expressed in this strain are involved. This study represents the first isolation of S. warneri KYS-164 from kefir grains prepared by Tibetan families, and provides a comprehensive analysis of its physicochemical properties. This research provides a solid foundation for better understanding and utilization of S. warneri KYS-164.

An Integrated Approach to Identify the Q-Markers of Banxia-Houpo Decoction Based on Nontargeted Multicomponent Profiling, Network Pharmacology, and Chemometrics.

The inherent complexity of traditional Chinese medicine (TCM) poses significant challenges in directly correlating quality evaluation with clinical efficacy. Banxia-Houpo Decoction (BHD), a classical TCM formula, has demonstrated efficacy in treating globus hystericus. However, the intricate composition of BHD, which contains both volatile and non-volatile active components, complicates efforts to ensure its consistent quality and clinical effectiveness. The aim of this study was to introduce an integrated approach that combines non-targeted multicomponent analysis, network pharmacology, and multivariate chemometrics to identify quality markers for the effective quality control of BHD. First, a nontargeted high-definition MSE method based on ultraperformance liquid chromatography-quadrupole time-of-flight-mass spectrometry (UHPLC-QTOF-MS) was developed for the comprehensive multi-component characterization of BHD. Next, the quality markers of nonvolatile compounds in BHD were identified through network pharmacology analysis. Subsequently, volatile organic compounds (VOCs) in BHD samples were analyzed via headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS). Finally, the orthogonal partial least squares discriminant analysis (OPLS-DA) model was applied to screen for potential markers. Based on in-house library-driven automated peak annotation and comparison with 25 reference compounds, 128 components were identified for the first time. Additionally, honokiol, magnolol, magnoflorine, 6-gingerol, rosmarinic acid, and adenosine were preliminarily identified as potential quality markers for BHD through network pharmacology analysis. By employing two complementary techniques, HS-SPME-GC-MS and HS-GC-IMS, a total of 145 volatile compounds was identified in the BHD samples. Four potential differential VOCs in the BHD samples were further identified based on the variable importance in projection (VIP ≥ 1.5) using HS-GC-IMS combined with chemometric analysis. In conclusion, this study not only contributes to establishing quality standards for BHD but also offers new insights into quality assessment and identification in the development of classical formulations enriched with volatile components.

Non-targeted volatilomics for the authentication of saffron by gas chromatography-ion mobility spectrometry and multivariate curve resolution

Non-targeted volatilomics for the authentication of saffron by gas chromatography-ion mobility spectrometry and multivariate curve resolution

Effects of enhanced fermentation with high-yielding strains of Tetramethylpyrazine on flavor quality of Douchiba

Douchiba (DCB) is a nutritious food rich in various functional components such as Tetramethylpyrazine (TTMP), and the strain fermentation is crucial for enhancing its quality. This work utilized Bacillus subtilis S2–2 and Hyphopichia burtonii S6-J1 with high TTMP production for fermentation of soybeans to optimize the pre-fermentation process and to evaluate the flavor quality of mature DCB. The concentration of TTMP in DCB fermented by mixed microbial (MG) was 2.95 times higher than that of of the control. Furthermore, the concentrations of taste substances, organic acids, free amino acids, and free fatty acids in MG were significantly increased. 87 flavor compounds were detected by gas chromatography-ion mobility spectrometry. The content of aldehydes, alcohols, esters, acids, and pyrazines flavor compounds was higher in MG, with esters and alcohols being notably higher than in other groups. Additionally, the highest comprehensive score of flavor quality was obtained in MG by principal component analysis.

Analysis of volatile compounds in Xiangjiao baijiu from different storage containers and years based on HS-GC-IMS and DI-GC–MS

The volatile compounds in 16 different storage containers and years of Xiangjiao Baijiu (XJBJ) were compared and analyzed via direct injection (DI) combined with gas chromatography–mass spectrometry (GC–MS) and headspace extraction (HS) coupled with gas chromatography-ion mobility spectrometry (HS-GC-IMS) for the first time. Through HS-GC-IMS analysis, it was found that the succession rules of 14 compounds such as furfural during aging process. A total of 60 compounds were identified using DI-GC–MS. Twenty-five of these compounds were further quantified, and 18 compounds had odor activity values (OAVs) > 1, which were important contributor to aroma of XJBJ. Among them, those with OAVs >1000 included ethyl hexanoate, ethyl octanoate, ethyl butanoate, and ethyl pentanoate. Combining the results of quantitative, OAVs and partial least squares-discriminant analysis (PLS-DA) revealed that 10 compounds such as ethyl octanoate were the important compounds that lead to the differences between different storage types of XJBJ.

Volatile flavor characteristics of scallops (Chlamys farreri) with different drying methods were analyzed based on GC-IMS and GC-O-QTOF

To investigate the effects of different drying methods on the flavor of scallops, headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) combined with gas chromatography-olfactometry-quadrupole time-of-flight (GC-O-QTOF) was used to analyze the flavor of scallops processed by five drying methods. A total of 62 volatile organic compounds (VOCs) were identified by GC-IMS. 27 characteristic aroma compounds were identified by GC-O-QTOF, and the highest content was trimethylamine. 17 aroma compounds with GC-O ≥ 6 were screened by the time-intensity method, and the maximum aroma intensity value of 2-acetyl-1-pyrroline was 9.9 aroma compounds with relative odor activity value (ROAV) ≥ 1 were identified. Using GC-O ≥ 6 and ROAV ≥1 as the criteria, 6 differential aroma compounds were further screened, and the results proved that naturally dried scallops had a heavier fishy odor. These findings will provide deeper insights into the processing of scallops.

The detection and utilization of volatile metabolomics in Klebsiella pneumoniae by gas chromatography-ion mobility spectrometry

This research aimed to analyze the volatile compounds emitted during the proliferation of Klebsiella pneumoniae (K. pneumoniae) in the laboratory setting using gas chromatography-ion mobility spectrometry (GC-IMS) and to investigate the potential of volatile metabolomics for detecting carbapenemase-producing strains of K. pneumoniae. The volatile metabolomics of K. pneumoniae were comprehensively analyzed using GC-IMS in tryptic soy broth (TSB) as the culture medium. Afterward, the growth stabilization period (T2) served as the primary time point for analysis, with the introduction of imipenem and carbapenemase inhibitors (avibactam sodium or EDTA) during the exponential growth phase (T0) to further investigate alterations in volatile molecules associated with K. pneumoniae. Standard strains were utilized as references, while clinical strains were employed for validation purposes. At T2, a total of 22 volatile organic compounds (VOCs) associated with K. pneumoniae were identified (3 VOCs found in both monomer and dimer forms). Significant differences in VOCs were observed between carbapenemase-negative and carbapenemase-positive strains, both standard and clinical, following the introduction of imipenem. Furthermore, the addition of avibactam sodium led to distinct changes in the VOC content of strains producing class A carbapenemase, while the addition of EDTA resulted in specific alterations in the volatile metabolic profiles of strains producing class B carbapenemase. GC-IMS demonstrated significant promise for analyzing bacterial volatile metabolomics, and its application in evaluating the volatolomics of K. pneumoniae may facilitate the timely detection of carbapenemase-producing strains.

Impact of Mild Field Drought on the Aroma Profile and Metabolic Pathways of Fresh Tea (Camellia sinensis) Leaves Using HS-GC-IMS and HS-SPME-GC-MS.

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.

Dynamic evolution of volatile compounds during cold storage of sturgeon fillets analyzed by gas chromatography-ion mobility spectrometry and chemometric methods

This study investigated the changes in quality and volatile flavoring compounds in sturgeon fillets during refrigeration. Potential flavor compounds were identified using orthogonal partial least squares discriminant analysis (OPLS-DA) and gas chromatography– ion mobility spectrometry (GC-IMS). The results showed that TVB-N content, TBARS values, total colony counts, and K-value increased with prolonged refrigeration, reaching spoilage thresholds after approximately eight days. A total of 33 volatile compounds (including monomers and dimers) were detected in sturgeon fillets during different refrigeration periods, including aldehydes, alcohols, ketones, acids, esters, ethers, and other compounds. OPLS-DA further revealed flavor differences in sturgeon fillets across different refrigeration stages, identifying 18 distinct volatile compounds. Correlation analysis showed that trans-2-Pentenal, 2-methylpropanal, and glutaraldehyde were associated with pleasant odor to the frozen sturgeon fillets in the early stage, while hexane nitrile and thiazole were the main substances that caused unpleasant odors.

Faecal Volatile Organic Compounds to Detect Colorectal Neoplasia in Lynch Syndrome-A Prospective Longitudinal Multicentre Study.

Non-invasive biomarkers may reduce post-colonoscopy colorectal cancer (CRC) rates and colonoscopy overuse in Lynch syndrome. Unlike faecal immunochemical test (FIT), faecal volatile organic compounds (VOCs) may accurately detect both advanced and non-advanced colorectal neoplasia. The aim of this study was to evaluate the potential of faecal VOCs-separately and with FIT-to guide optimal colonoscopy intervals in Lynch syndrome. Prospective longitudinal multicentre study in which individuals with Lynch syndrome collected faeces before and after high-quality surveillance colonoscopy. VOC-patterns were analysed using field asymmetric ion mobility spectrometry (FAIMS) and gas chromatography-ion mobility spectrometry (GC-IMS) followed by machine learning pipelines, and combined with FIT at 2.55 μg Hb/g faeces. Gas chromatography time-of-flight mass spectrometry analysed individual VOC abundance. Among 200 included individuals (57% female, median 51 years), 62 had relevant neoplasia at colonoscopy: 3 CRC, 6 advanced adenoma (AA), 3 advanced serrated lesion (ASL), and 50 non-advanced adenoma (NAA). Respective sensitivity and negative predictive value for CRC and AA (and also ASL in case of FAIMS) were 100% and 100% using FAIMS (54% specificity), and 89% and 99% using GC-IMS (58% specificity). Respective sensitivity and specificity for any relevant neoplasia were 88% and 44% (FAIMS) and 84% and 28% (GC-IMS); accuracy did not significantly improve upon VOC-FIT. VOC-patterns differed before and after polypectomy (AUC 0.70). NAA showed decreased faecal abundance of butanal, 2-oxohexane, dimethyldisulphide and dimethyltrisulphide. In Lynch syndrome, faecal VOCs may be a promising strategy for postponing colonoscopy and for follow-up after polypectomy. Our results serve as a stepping stone for large validation studies. NL8749.

Substitution of NaCl by organic sodium salts in cured large yellow croaker (Larimichthys crocea): Improvement of the quality and flavor characteristic

For lowering the daily intake of salt, the study evaluated the impact of various organic sodium salts (OSS), including sodium acetate (SA), sodium citrate (SC), and sodium lactate (SL), on the quality and volatile flavor profiles of large yellow croaker. The results showed that the 5 % SC and 5 % SL treatments significantly improved water holding capacity (WHC), texture, and color (p < 0.05). These groups also demonstrated compact microstructures and maintained strong sensory acceptability. However, as the curing concentration increased, protein unfolding and oxidation intensified, and the transition from bound and immobile water to free water was observed. This shift negatively affected WHC, texture, and cell structure. Additionally, gas chromatography-ion mobility spectrometry (GC-IMS) identified 27 volatile compounds, with OSS treatments notably enhancing flavor intensity. These findings offer valuable insights for developing low-sodium practices in the seafood industry.

Effects of surimi by-product hydrolysates on processing quality and difference analysis of volatile compounds of silver carp surimi gel

The aim of this study was to investigate the effects of surimi by-product hydrolysates (SBPHs) on the processing quality, gel characteristics, microstructure, and volatile compounds of surimi. The results showed that the addition of SBPHs improved the water holding capacity (95.18% and 94.32%), texture property, and gel characteristic (546.04 g cm) of the surimi gel, reduced the cooking loss (7.15%) and aperture area (34.10%) of the surimi gel (P < 0.05), causing no difference in their whiteness (P > 0.05). The SBPHs reduced the free water and increased the immobilized water of the gel. At the same time, SBPHs made tighter cross-linking of the surimi gel proteins. The results of gas chromatography-ion mobility spectrometry showed that 62 volatile flavor compounds were detected in each group of surimi, and the relative contents of aldehydes, alcohols, and ketones were relatively high. A total of 19 volatile flavor compounds were selected as the potential markers in samples by orthogonal partial least square siscriminant analysis. The additions of SBPHs (0.6% and 1.2%) in this study were much lower than those of commercial cryoprotectant (6%). In conclusion, SBPHs emerges as a potential cryoprotectant for the surimi industry and have promising advantages in enhancing the quality of surimi.

Quantitative Determination of Volatile N-Nitrosamines in Meat Products Using Gas Chromatography Coupled to an Ion Mobility Spectrometer with an Ammonia Dopant.

Herein, we develop a novel method using gas chromatography-ion mobility spectrometry (IMS) with an ammonia dopant for the determination of volatile N-nitrosamines in meat products. The IMS system was implemented with Fourier deconvolution multiplexing to simultaneously improve the resolving power and sensitivity. The ammonia dopant mitigated the formation of N-nitrosamine dimer ions, suppressing the ionization of interferents and shifting the reactant peak from hydrated protons to hydrated ammonium ions. The ammonium adduct product ions of N-nitrosamines were confirmed using time-of-flight mass spectrometry. The instrument limits of detection and quantitation for nitrosamines were 0.78-1.79 and 2.60-5.82 ng/mL, respectively, with recoveries between 71.39% and 110.59% using a simple water distillation method. The developed method showed satisfactory performance when applied to the detection of nitrosamines in various meat products.

Evaluation of differences in volatile flavor compounds between liquid-state and solid-state fermented Tartary buckwheat by Monascus purpureus

The differences in volatile flavor compounds (VFCs) between Monascus-solid-state fermented Tartary buckwheat (MSFTB) and Monascus-liquid-state fermented Tartary buckwheat (MLFTB) were investigated using electronic nose and gas chromatography-ion mobility spectrometry (GC-IMS) analysis. The study revealed several significant differences in the composition and abundance of VFCs between the two states. Compared to MSFTB, MLFTB exhibited notable increases in various elements including protein, crude fat, total flavonoids, total polyphenols, Monacolin K, Monascus pigments. Principal component analysis demonstrated significant increases in the production of specific VFCs in MLFTB compared to MSFTB. A total of 25 VFCs were identified through GC-IMS, including 9 esters, 7 alcohols, 5 ketones, and 4 aldehydes. The content of pleasant VFCs in MLFTB was significantly higher than in MSFTB. These compounds served as both VFCs and key aroma components during fermentation. In conclusion, the Monascus fermentation state played a crucial role in enhancing the flavor quality of Tartary buckwheat.