The assessment of halitosis with a new screening tool in medication-related osteonecrosis of the jaw.

OBJECTIVES: This study aimed to identify the levels of halitosis in patients with Medication-related osteonecrosis of the jaw (MRONJ) and osteoporosis and to suggest a new MRONJ screening method using halitosis measurement. MATERIALS AND METHODS: From October 2019 to April 2023, participants aged 19 years or older without periodontal disease were selected. Seventy-five participants, 25 in each group, were divided into an MRONJ group, an osteoporosis group without MRONJ, and a control group without osteoporosis and not taking osteoporosis drugs or antibiotics. Each participant underwent halitosis assessment twice using an exhaled breath analyzer to measure halitosis twice by blowing a straw for 1 min. Measured concentrations of hydrogen, hydrogen sulfide, and methyl mercaptan were compared between groups. RESULTS: Data from 22 patients in the MRONJ group, 25 in the osteoporosis group, and 25 in the control group were analyzed. The concentrations of hydrogen sulfide and methyl mercaptan were significantly higher in the MRONJ group than in the other groups, but the concentrations of hydrogen did not differ between the groups. When comparing the concentrations of hydrogen sulfide and methyl mercaptan in osteoporosis patients and solid cancer patients in the MRONJ group, there was a significant difference in hydrogen sulfide concentration, but there was no significant difference in methyl mercaptan. CONCLUSIONS: Quantifying the level of halitosis can be used to screen for MRONJ in patients taking bisphosphonates, such as patients with osteoporosis, prostate cancer, and breast cancer. CLINICAL RELEVANCE: MRONJ is accompanied by bad breath, and the concentrations of hydrogen sulfide and methyl mercaptan are associated with MRONJ.

Volatile sulfur compounds, biofilm, and salivary parameters in patients with periodontal disease: a cross-sectional study.

This cross-sectional study aimed to evaluate the interplay between volatile sulfur compounds (VSC), biofilm, salivary parameters, and periodontal status in patients with and without periodontal disease. Sixty-four subjects diagnosed with periodontitis and 60 periodontally healthy individuals were included. Probing depth, clinical attachment level, bleeding on probing, tongue coating index, plaque index, number of teeth, spinnability of unstimulated whole saliva, and salivary flow rate were evaluated. The concentrations of VSC were quantified using a portable gas chromatograph. The mean differences in hydrogen sulfide, methyl mercaptan, salivary flow, spinnability, and plaque index did not exhibit statistically significant variances between the two groups. However, a pronounced tongue coating index and a diminished tooth count showed statistical significance in the periodontitis group (p = 0.039; p < 0.001). Unstimulated salivary flow rate less than 0.25 mL/min was statistically significant in the periodontitis group (p = 0.032). After controlling for confounding factors, bleeding on probing remained significant. A positive correlation between periodontal parameters and VSC concentration was found. An inverse correlation was also noted between the spinnability of saliva and tongue coating index (-0.34; p < 0.001). Salivary parameters may contribute to the formation of tongue coating and are correlated with periodontal status. Bleeding on probing, clinical attachment level, and probing depth were identified as potential contributors to VSC formation.

Release characteristics and risk assessment of volatile sulfur compounds in a municipal wastewater treatment plant with odor collection device.

Due to the malodorous effects and health risks of volatile sulfur compounds (VSCs) emitted from wastewater treatment plants (WWTPs), odor collection devices have been extensively utilized; however, their effectiveness has rarely been tested. In the present investigation, the characteristics of VSCs released in a WWTP equipped with gas collection hoods are methodically examined by gas chromatography. The obtained results indicate that the concentration of VSCs in the ambient air can be substantially reduced, and the primary treatment unit still achieves the highest concentration of VSCs. Compared to WWTPs without odor collection devices, the concentration of H2S in this WWTP is not dominant, but its sensory effects and health risks are still not negligible. Additionally, research on the emission of VSCs from sludge reveals that the total VSCs emitted from dewatering sludge reaches the highest level. Volatile organic sulfur compounds play a dominant role in the component and sensory effects of VSCs released by sludge. This study provides both data and theoretical support for analyzing the effectiveness of odor collection devices in WWTPs, as well as reducing the source of VSCs. The findings can be effectively employed to optimize these devices and improve their performance.

Mechanisms underlying the formation of main volatile odor sulfur compounds in foods during thermal processing.

Volatile sulfur compounds (VSCs) significantly influence food flavor and garner considerable attention in flavor research due to their low sensory thresholds, diverse odor attributes, and high reactivity. Extensive research studies have explored VSC formation through thermal processes such as the Maillard reaction, thermal pyrolysis, oxidation, and enzymatic reactions. However, understanding of the specific reaction mechanisms and processes remains limited. This is due to the dispersed nature of existing studies, the undefined intermediates involved, and the complexity of the matrices and processing conditions. Given these limitations, the authors have shifted their focus from foods to sulfides. The structure, source, and chemical characteristics of common precursors (sulfur-containing amino acids and derivatives, thiamine, thioglucoside, and lentinic acid) and their corresponding reactive intermediates (hydrogen sulfide, thiol, alkyl sulfide, alkyl sulfenic acid, and thial) are provided, and the degradation mechanisms, reaction rules, and matrix conditions are summarized based on their chemical characteristics. Additionally, the VSC formation processes in several typical foods during processing are elucidated, adhering to these identified rules. This article provides a comprehensive overview of VSCs, from precursors and intermediates to end products, and is crucial for understanding the mechanisms behind VSC formation and managing the flavor qualities of processed foods.

Hydrogen sulfide production during early yeast fermentation correlates with volatile sulfur compound biogenesis but not thiol release.

Yeasts undergo intensive metabolic changes during the early stages of fermentation. Previous reports suggest the early production of hydrogen sulfide (H2S) is associated with the release of a range of volatile sulfur compounds (VSCs), as well as the production of varietal thiol compounds 3-sulfanylhexan-1-ol (3SH) and 3-sulfanylhexyl acetate (3SHA) from six-carbon precursors, including (E)-hex-2-enal. In this study, we investigated the early H2S potential, VSCs/thiol output, and precursor metabolism of 11 commonly used laboratory and commercial Saccharomyces cerevisiae strains in chemically defined synthetic grape medium (SGM) within 12 h after inoculation. Considerable variability in early H2S potential was observed among the strains surveyed. Chemical profiling suggested that early H2S production correlates with the production of dimethyl disulfide, 2-mercaptoethanol, and diethyl sulfide, but not with 3SH or 3SHA. All strains were capable of metabolizing (E)-hex-2-enal, while the F15 strain showed significantly higher residue at 12 h. Early production of 3SH, but not 3SHA, can be detected in the presence of exogenous (E)-hex-2-enal and H2S. Therefore, the natural variability of early yeast H2S production contributes to the early output of selected VSCs, but the threshold of which is likely not high enough to contribute substantially to free varietal thiols in SGM.

Effect of face masks on salivary parameters and halitosis: Randomized controlled crossover trial.

BACKGROUND: Face masking is associated with self-perceived dry mouth and halitosis. Aim of the study was to measure the effect of different face masks on salivary parameters and halitosis. METHODS: The randomized controlled crossover clinical trial with four periods included 40 oral healthy participants using different face masks (cloth mask, surgical mask, filtering facepiece 2 [FFP2] mask) or no mask (control) for 4 h in random order. Unstimulated salivary flow rate (primary outcome) and stimulated salivary flow rate, salivary pH and buffer capacity of stimulated and unstimulated saliva (secondary outcomes, blinded), and volatile sulfur compounds (secondary outcome) were measured before and after the 4-h periods. Statistical analysis was performed by repeated measures ANOVA (p < 0.05). RESULTS: Of 40 randomized participants, 39 completed the study. Unstimulated salivary flow rate prior to face masking amounted to 0.6 ± 0.3 ml/min. Face masking had no significant effect on unstimulated salivary flow (p = 0.550). Face masking had also no significant effect on the other salivary parameters (p ≥ 0.518). The concentration of volatile sulfur compounds (VSC) prior to face masking amounted to 157.3 ± 59.7 ppb. After face masking, the concentration of VSC increased slightly, but not significantly (p = 0.055): 168.1 ± 76.3 ppb (control), 199.3 ± 132.7 ppb (cloth masks), 188.5 ± 101.1 ppb (surgical masks), and 189.7 ± 90.1 ppb (FFP2 masks). CONCLUSION: Four hours of face masking did not change the salivary flow rate, pH, and buffer capacity, and had no significant effect on VSC's levels. Wearing face masks does not seem to result in measurable side-effects on salivary parameters such as a reduced salivary flow rate or VSC's levels. CLINICAL TRIAL REGISTRATION: The protocol was prospectively registered at ClinicalTrials.gov (NCT04914208) on June 4, 2021.

Effect of lemon essential oil on halitosis.

OBJECTIVES: To evaluate the effect of lemon essential oil (LEO) on salivary bacteria and volatile sulfur compound (VSC) production of patients with halitosis. MATERIALS AND METHODS: Saliva of five patients with halitosis was collected, after adding different concentrations (0.563-9 mg/ml) of LEO, detecting the growth of salivary bacteria, the formation of biofilm, and VSC production, and compare the difference of different concentrations of LEO on bacterial growth and VSC production. 48 volunteers were randomly divided into 4 groups. After gargling with LEO, cetylpyridinium chloride (CPC), chlorhexidine (CHX), and hydrogen peroxide (H2 O2 ) separately measure changes of VSC production and pH values at 30, 45, 60, 90, and 120 min and then compare the differences at different time points within group. RESULTS: Compared with the negative control group, under subinhibitory concentrations of LEO (0.563-2.25 mg/ml), the biofilm formation and VSC production of salivary bacteria in LEO group were significantly inhibited (p < 0.05). Compared with the baseline, the VSC production of subjects decreased after rinsing with the LEO in 60 min (p < 0.05). After gargling with LEO, the pH value rose significantly in 30 min and reverted to the baseline level at 120 min (p < 0.05). CONCLUSIONS: Lemon essential oil can inhibit the growth of salivary bacteria and reduce VSC production of patients with halitosis.

Halitosis: etiology, prevention, and the role of microbiota.

OBJECTIVES: This study aims to review halitosis research, discuss its various causes, and propose effective interventions based on the underlying etiologies and mechanisms. The main research question is to identify the primary factors contributing to halitosis and appropriate strategies to address them. MATERIALS AND METHODS: A comprehensive literature review was conducted on halitosis and its associated causes, including oral pathological factors, oral microbial influences, microbial metabolic pathways, gastrointestinal diseases, and gut microbiota dysbiosis. RESULTS: Unhealthy eating habits and an imbalance of microorganisms in the oral cavity and gastrointestinal tract were identified as primary causes of halitosis. Dental caries, periodontal disease, xerostomia, and digestive disorders like gastritis and irritable bowel syndrome were also found to be related to the development of halitosis. Due to poor oral hygiene or antibiotic use, disruption of microbial communities can result in dysbiosis, inflammation, and halitosis. CONCLUSIONS: Halitosis is a multifactorial condition with various underlying causes, including oral and systemic diseases. Effective interventions should be tailored based on the specific etiologies and mechanisms involved. CLINICAL RELEVANCE: Understanding the factors contributing to halitosis is crucial for developing appropriate treatment strategies. Enhancing oral hygiene habits, using antimicrobial drugs, or administering probiotics may help regulate oral or intestinal flora, thereby improving halitosis and overall oral health.

Multi-dimension analysis of volatile sulfur compound emissions from an urban wastewater treatment plant.

Long-term monitoring of volatile sulfur compounds (VSCs) released at the water-air interface from different treatment units of an anaerobic/oxic (A/O) wastewater treatment plant (WWTP) was carried out to assess the temporal and spatial emission characteristics of VSCs, to explore relationships between wastewater quality and VSC release. The VSC from non-aerated and aerated units were collected using dynamic and static chambers, respectively, and determined using gas chromatography. The VSC emission fluxes diminished in the order of primary sedimentation tank (PST) > anaerobic areas (ANA) > oxic section 1 (OX1). VSCs were not detected in the oxic section 2 (OX2), the oxic areas section 3 (OX3), and the final setting basin (FSB). Release capacities of VSCs descended in the order of summer > fall > spring > winter, with July, August, and September being the months with the highest VSC release capacities. VSC emission fluxes correlated well with wastewater temperatures, sulfate concentrations, and COD. VSC emission flux empirical equations based on wastewater temperature, sulfate concentrations, and COD were established. Based on the established VSC emission empirical equation, a control strategy to reduce the operating costs of deodorization facilities was proposed. This strategy is economically efficient and reduces the consumption of electrical energy.

Effects of thyme on halitosis in gingivitis patients: Can thyme mouthwash prevent halitosis-A randomized trial.

OBJECTIVES: Bad breath is a condition that negatively affects people's social interactions and quality of life. The aim of this study was to evaluate the effect of thyme mouthwash on intraoral halitosis, gingival index (GI) and plaque index (PI) in patients with gingivitis. METHODS: In this retrospective study, 60 gingivitis patients (30 women/30 men) received initial periodontal treatment followed by oral hygiene instructions (OHI) and then were divided into four groups: The control group (C) received only OHI, while chlorhexidine (CHX) mouthwash was prescribed to the CHX group, Zinc acetate and CHX diacetate mouthwash was prescribed to the zinc acetate and CHX diacetate (ZnA) group, and the thyme (T) group was instructed to use thyme mouthwash. GI, PI and volatile sulfur compound (VSC) values were recorded at baseline and at the first week of treatment. RESULTS: The initial values of the recorded parameters did not differ significantly between the groups. In all groups, VSCs, GI and PI decreased after treatment (p = 0.001). There was no significant difference between the PI values of the groups after treatment (p = 0.188). On the contrary, the GI and VSC values after treatment were significantly different between the groups (p = 0.001). GI values were highest in the control group and lowest in the CHX group. In terms of VSCs, a significant difference was found between groups T and C, and between groups T and ZnA (p = 0.001). CONCLUSION: This study showed that the use of thyme mouthwash after periodontal treatment was effective in improving bad breath and gingivitis in gingivitis patients.

ORGANOLEPTIC AND HALITOMETRIC ASSESSMENTS DO NOT CORRELATE WELL IN INTRA-ORAL HALITOSIS: A SYSTEMATIC REVIEW AND META-ANALYSIS.

BACKGROUND: The gold standard method for diagnosing oral halitosis is the subjective organoleptic measurement. Device-supported methods are also widespread worldwide. The challenges and safety concerns around performing organoleptic measurements during pandemics and the diversity of measuring device alternatives raised our clinical question: which halitometer is the most suitable for diagnosing halitosis? METHODS: This systematic review was registered in PROSPERO (ID CRD42022320024). The search was performed on March 23, 2022 in the following electronic databases: MEDLINE, Embase, Scopus, Web of Science, and CENTRAL. Adult populations with or without halitosis were included, and patients with systemic diseases were excluded. Organoleptic (subjective) measurement and the device-supported (objective) methods were compared; the primary outcome was the correlation coefficient, and the secondary was the specificity and sensitivity of the devices. QUADAS-2 and QUADAS-C were used to evaluate the risk of bias in the studies. Random-effects meta analyses were performed on the outcomes, and the secondary outcomes were plotted on a common ROC plot. RESULTS: A total of 1231 records were found in the 5 databases. After the selection process, 76 articles were eligible for the systematic review, and 14,635 patients were involved in the qualitative analysis. The pooled Spearman's correlation coefficient (c.c.) for sulfide monitors was 0.65; 95% CIs: [0.53-0.74]; I2 = 95%, P < .01. The pooled Spearman's c.c. for portable gas chromatographs was 0.69; 95% CIs: [0.63-0.74]; I2 = 12%, P < .01. The pooled Spearman's c.c. for gas chromatographs was 0.76; 95% CIs: [0.67-0.83]; I2 = 0%, P < .01. DISCUSSION: None of the most commonly used halitometers proved to be significantly superior to the others. Halimeter and OralChroma measurements did not correlate well with the organoleptic level of oral halitosis in adults. Therefore, better halitometers need to be developed as an alternative to organoleptic measurements.

Clinical efficacy of photodynamic therapy on halitosis: a systematic review and meta-analysis.

Halitosis is a widespread health problem with complex factors, and therapeutic effects sometimes are unsatisfactory. Plenty of clinical trials have tried to prove the effectiveness of photodynamic therapy (PDT), but the results are indeterminate. This study aimed to evaluate the clinical efficacy of PDT on halitosis. We searched PubMed, Cochrane Library, Embase, Web of Science, and Scopus from inception to August 10, 2022, and only studies about the PDT on halitosis were included. The criteria for meta-analysis comprised randomized controlled trials (RCTs) comparing the treatment of PDT with tongue scraper (TS) immediately after the halitosis therapy and during a 7-, 14-, 30-, and 90-day follow-up. Eight eligible studies involving 345 patients were included in this study. It was shown that PDT (MD = - 34.49, 95% CI [- 66.34, - 2.64], P = 0.03) or PDT + TS (MD = - 67.72, 95% CI [- 101.17, - 34.28], P < 0.001) had better efficacy than TS on the H2S concentration reduction immediately after the halitosis therapy. No significant differences were observed in reducing the H2S among TS, PDT alone, and PDT + TS at the follow-up. Besides, no difference between PDT and TS was found in the reduction of CH3SCH3 and CH3SH. Based on the current evidence, PDT and PDT + TS demonstrate efficacy in the treatment of halitosis in the short term, and PDT was shown to be a beneficial and promising therapeutic method.

Detection of volatile sulfur compounds (VSCs) in exhaled breath as a potential diagnostic method for oral squamous cell carcinoma.

BACKGROUND: Oral squamous cell carcinoma causes a significant proportion of global cancer morbidity and mortality. The aim of this study is to investigate whether the exhaled breath test can be a new, non-invasive, and effective method for diagnosing oral squamous cell carcinoma. METHODS: A comparative analysis of exhaled breath between patients with oral squamous cell carcinoma (OSCC) and healthy controls (HC) was performed with the Twin Breasor II™, a simple gas chromatography system. RESULTS: Both hydrogen sulfide (H2S) and methyl mercaptan (Ch3SH) were significantly higher in the OSCC group than in the HC group. The total sulfur concentration was also higher in the OSCC group, but there was no significant difference in the ratio of Ch3SH to H2S between the two groups. Using logistic regression, we constructed a new variable with an area under the curve (AUC) of 0.740, 68.0% sensitivity, and 72.0% specificity. CONCLUSIONS: Exhaled gas analysis via simple gas chromatography can potentially serve as an accessory non-invasive method for OSCC diagnosis.

How to modulate the formation of negative volatile sulfur compounds during wine fermentation?

Beyond the production of positive aromas during alcoholic fermentation, Saccharomyces cerevisiae metabolism also results in the formation of volatile compounds detrimental to wine quality, including a wide range of volatile sulfur compounds (VSCs). The formation of these VSCs during wine fermentation is strongly variable and depends on biological and environmental factors. First, the comparison of the VSCs profile of 22 S. cerevisiae strains provided a comprehensive overview of the intra-species diversity in VSCs production: according to their genetic background, strains synthetized from 1 to 6 different sulfur molecules, in a 1- to 30-fold concentration range. The impact of fermentation parameters on VSCs production was then investigated. We identified yeast assimilable nitrogen, cysteine, methionine and pantothenic acid contents - but not SO2 content - as the main factors modulating VSCs production. In particular, ethylthioacetate and all the VSCs deriving from methionine catabolism displayed a maximal production at yeast assimilable nitrogen concentrations around 250 mg/L; pantothenic acid had a positive impact on compounds deriving from methionine catabolism through the Ehrlich pathway but a negative one on the production of thioesters. Overall, these results highlight those factors to be taken into account to modulate the formation of negative VSCs and limit their content in wines.

Simple Ion-Gas Mixtures as a Source of Key Molecules Relevant to Prebiotic Chemistry.

Very simple chemistry can result in the rapid and high-yield production of key prebiotic inorganic molecules. The two reactions investigated here involve such simple systems, (a) carbon disulfide (CS2) and acetate (CH3COO¯) and (b) sulfur dioxide (SO2) and formate (HCOO¯). They have been carried out under non-aqueous conditions, either in an organic solvent or with a powdered salt exposed to the requisite gas. Under such dry conditions the first reaction generated the thioacetate anion [CH3COS]¯ while the second produced the radical [SO2·]¯anion. Anhydrous conditions are not rare and may have arisen on the early earth at sites where an interface between different phases (liquid/gas or solid/gas) could be generated. This is one way to rationalize the formation of molecules and ions (such as we have produced) necessary in the prebiotic world. Interpretation of our results provides insight into scenarios consistent with the more prominent theories of abiogenesis.

Calibration methods for VSCs measured on AS-TD-GC-SCD.

Volatile sulfur compounds (VSCs) are key odorous compounds from emissions of various odour sources because they are odorous and generally have very low odour threshold values. Identification and quantification of them through air server-thermal desorber-gas chromatography-sulfur chemiluminescence detector (AS-TD-GC-SCD) become more and more popular, although VSCs can be determined by other detectors. To find a valid, practical and quick calibration method is also an important step in their analytical processes. This study compared three different sample preparation and unity sampling methods using both gas standards (with 10 VSCs balanced in pure nitrogen gas) and liquid standards of 7 VSCs. For liquid standard sample preparation, two solvents (methanol and n-pentane) were tested and their calibration results were compared. The study revealed that the three calibration methods with both manual and dynamic dilution of VSC standard gases can achieve satisfactory calibration results with nice linear regression and correlation coefficient (r2). The dynamic dilution and loop sampling method is recommended because of its better reliability and time-saving processing. For calibration of VSCs with liquid standards, preparing the samples using dissolved VSCs in n-pentane and analysing them using the loop sampling method achieved best calibration results. For dimethyl trisulfide (DMTS), its calibration cannot obtain as good results as other sulfur compounds even using the best performance calibration method.

Halitosis and Associated Risk Factors in Children: A Cross-sectional Study.

AIM: To investigate risk factors associated with halitosis in children using OralChroma™. MATERIALS AND METHODS: Sixty-seven children between the ages of 3 and 8 who attended a pre-general anesthesia assessment at the Dental University Hospital at King Saud University, Riyadh, Saudi Arabia, were enrolled in this study after satisfying the inclusion criteria. Demographic data, medical history, and oral hygiene practices were obtained by a standardized questionnaire completed by the parents of each child. Clinical dental examination was conducted to record the following: caries index (dmft/DMFT), simplified debris index (DI-S), modified gingival index (MGI), and Winkel tongue coating index (WTCI). Clinical halitosis was assessed using the OralChroma™ device that measures the concentration of volatile sulfur compounds (VSCs) including hydrogen sulfide (H2S), methyl mercaptan (CH3SH), and dimethyl sulfide (CH3SCH3). Statistics were completed using Spearman's correlation coefficient and Mann-Whitney U-test to assess the association with the VSC scores with continuous and binary variables, respectively. Then, multivariate linear regression analysis was performed to detect the degree of association. RESULTS: High VSC measures were detected in 58 children (87%). The dmft/DMFT was significantly associated with H2S level (ß = 26.84, p = 0.034) and CH3SH level (ß = 19.96, p = 0.016) after controlling possible confounders. There was no significant association of DI-S, MGI, and WTCI with the VSC measures. CONCLUSION: The result suggested that dmft/DMFT score (children's caries experience) is associated significantly with high levels of H2S and CH3SH in the sample studied. CLINICAL SIGNIFICANCE: Caries experience in children is a significant risk factor for halitosis and should be considered during the management of halitosis.

Risk Factors, Diagnosis, and Management of Halitosis in Children: A Comprehensive Review.

AIM: The present manuscript aims at providing a comprehensive overview of the epidemiology, risk factors, diagnostic aids, and management of halitosis in a pediatric population. BACKGROUND: Halitosis refers to bad breath from the mouth that seems unpleasant or offensive to others. This condition is prevalent worldwide, including all age-groups. However, studies on the pediatric population are limited. Self-confidence and personality development are important factors that the child builds up during their developmental stages. Halitosis may affect them both on personal and social aspects; hence, it is important to have beforehand knowledge and the modes to intercept it, paving the way to a positive growth of the child. REVIEW RESULTS: On reviewing the literature, the common risk factors for halitosis in children constituted predominantly oral factors that varied from poor oral hygiene, gingivitis, periodontal diseases, dental caries, tongue coating, mouth breathing, and so on. Their diagnosis commonly included the organoleptic test, sulfide monitoring, and gas chromatography along with the assessment of questionnaire by the parents and older children. The management was predominantly directed toward the identified source of halitosis along with instructions and counseling on the benefits of a good oral hygiene regime. CONCLUSION: The importance of cultivating a day-to-day practice of oral hygiene regime in the children will not only accustom them toward the benefits of good oral health but also help them to tackle halitosis and in turn their inhibitions associated with it. CLINICAL SIGNIFICANCE: Halitosis, though a prevalent condition experienced at various stages of life, is crucial to identify and manage, especially in the pediatric population owing to its influence on personal and on social aspects of life.

Rapid and accurate determination of trace volatile sulfur compounds in human halitosis by an adaptable active sampling system coupling with gas chromatography.

Halitosis with the main components of trace volatile sulfur compounds widely affects the quality of life. In this study, an adaptable active sampling system with two sample-collection modes of direct injection and solid-phase microextraction was developed for the rapid and precise determination of trace volatile sulfur compounds in human halitosis coupled with gas chromatography-flame photometric detection. The active sampling system was well designed and produced for efficiently sampling and precisely determining trace volatile targets in halitosis under the optimized sampling and detection conditions. The analytical method established was successfully applied for the determination of trace targets in halitosis. The limits of detection of H2 S, CH3 SH, and CH3 SCH3 by direct injection were 0.0140-23.0 µg/L with good recoveries ranging from 82.2 to 118% and satisfactory relative standard deviations of 0.4-9.5% (n = 3), respectively. The limit of detections of CH3 SH and CH3 SCH3 by solid-phase microextraction were 2.03 and 0.186 × 10-3  µg/L with good recoveries ranging from 98.3 to 108% and relative standard deviations of 5.9-9.0% (n = 3). Trace volatile targets in positive real samples could be actually found and quantified by combination of direct injection and solid-phase microextraction. This method was reliable and efficient for the determination of trace volatile sulfur compounds in halitosis.

Addition of volatile sulfur compounds to yeast at the early stages of fermentation reveals distinct biological and chemical pathways for aroma formation.

Volatile sulfur compounds (VSCs) greatly influence the sensory properties and quality of wine and arise via both biological and chemical mechanisms. VSCs formed can also act as precursors for further downstream VSCs, thus elucidating the pathways leading to their formation is paramount. Short-term additions of exogenous hydrogen sulfide (H2S), ethanethiol (EtSH), S-ethylthio acetate (ETA), methanethiol (MeSH) and S-methylthio acetate (MTA) were made to exponentially growing fermentations of synthetic grape medium. The VSC profiles produced from live yeast cells were compared with those from dead cells and no cells. Interestingly, this experiment allowed the identification of specific biochemical and/or chemical pathways; e.g. most of the conversion of H2S to EtSH, and the further step from EtSH to ETA, required the presence of live yeast cells, as did the conversion of MeSH to MTA. In contrast, the reaction from MTA to MeSH and ETA to EtSH was due primarily to chemical degradation. Ultimately, this research unravelled some of the complex interactions and interconversions between VSCs, pinpointing the key biochemical and chemical nodes. These pathways are highly interconnected and showcase the complexity of both the sulfur pathways in yeast and the reactive chemistry of sulfur-containing compounds.