Integrated analysis of time-driven sensory deterioration and microbial dynamics in not-from-concentrate (NFC) pitaya juice during storage.

Mezcal is a distilled beverage with a complex chemical profile defined by volatile organic compounds and physicochemical properties that determine its sensory attrib-utes. This study analyzed nine artisanal mezcals produced from four wild agave species in Oaxaca using solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) to identify key volatile compounds for traceability and quality control. A total of 82 volatile compounds were identified, with esters, terpenes, and higher alcohols being the most abundant. Eight key compounds, including ethyl acetate, acetic acid, 1-butanol, furfural, methanol, and 2-methyl-1-propanol, were quantified due to their significant impact on mezcal's quality and authenticity. Additionally, 1,2,3-trimethyl-benzene, nerolidol, and terpinolene were identified as exclusive compounds for differentiating mezcal by agave species and storage duration. The findings highlight the influence of fermentation, distillation, and storage conditions on mezcal's chemical profile and demonstrate the importance of standardized analytical methods for product authentication. Proper management of variables during fermentation and optimization of the final distillation cuts is necessary to fully comply with regulatory parameters and ensure product quality. By establishing a catalog of compounds that characterize the mezcals, this study provides a scientific basis for improving quality control, ensuring regulatory compliance, and enhancing the traceability of mezcal in high-value markets. The next step is to validate the key volatile compounds with a larger sample and evaluate their reproducibility under different production and storage conditions.

Volatolomics approach for authentication of not-from-concentrate (NFC) orange juice based on characteristic volatile markers using headspace solid phase microextraction (HS-SPME) combined with GC-MS

This study evaluated the volatile organic compounds (VOCs) and taste properties of Gorgon Euryale seeds processed by five methods (steaming, boiling, microwaving, roasting, and stir-frying) using electronic tongue (E-tongue), electronic nose (E-nose), gas chromatography-mass spectrometry (GC-MS), and gas chromatography-ion mobility spectrometry (GC-IMS). A total of 44 and 40 VOCs were identified by GC-MS and GC-IMS, respectively. Pyrazines (2-ethyl-3,5-dimethylpyrazine, 2,3-diethyl-5-methylpyrazine) and furans (2-pentylfuran, 2-ethylfuran) played a major role in the baked aroma characteristics of roasted and stir-fried Gorgon Euryale seeds. Six and seven marker compounds were identified by Orthogonal Partial Least Square Discriminant Analysis (OPLS-DA) models for GC-MS and GC-IMS based on 12 VOCs with odor activity value>1 and 18 VOCs with relative odor activity value>0.1, respectively. OPLS-DA and principal component analysis score plots of the E-tongue and E-nose demonstrated that samples could be effectively distinguished in terms of flavor. This research provides a comprehensive basis for evaluating the impact of processing methods on the changes in flavor of Gorgon Euryale seeds. PRACTICAL APPLICATION: This work demonstrates that the use of E-tongue, E-nose, HS-SPME-GC-MS, and GC-IMS has the capability to thoroughly analyze the flavor profile of Gorgon Euryale seeds at both macro and micro levels. This approach effectively distinguishes Gorgon Euryale products subjected to different processing treatments and provides a reliable reference for evaluating and identifying the flavor quality of Gorgon Euryale seeds.

Evaluation of the flavour properties of cooked chicken drumsticks as affected by sugar smoking times using an electronic nose, electronic tongue, and HS-SPME/GC-MS

Volatile organic compounds (VOCs), such as trichloroethene, toluene and xylenes have been reported to be detected from river water and sediment, because a part of VOCs charged into river can be distributed to river sediment. Fifty-three common VOCs in water have been simultaneously determined with good accuracy and precision by gas chromatography - mass spectrometry (GC/MS) with headspace method as well as purge-and-trap method. However, simultaneous determination methods for the VOCs in sediment have not been established. Several GC or GOMS methods have been reported to determine some VOCs in sediment, purge-and-trap, distillation, headspace and solvent extraction. Among them headspace GC/MS method appears to be the most appropriate method for screening the VOCs in sediments, because of its simplicity in analytical procedure. Hewitt et al. have reported that headspace method gave no statistically different results from purge-and-trap method for GC/MS determination of four VOCs in soil. Voice and Kolb have reported that headspace GC method gave better results to determine nine VOCs in soil than purge-and-trap method or solvent extraction method followed by headspace. However, headspace analysis of some VOCs in sediments could give insufficient recoveries. This is because VOCs adsorb to sediment. To improve their low recoveries from sediment,more » we have previously used a stable isotope-labeled compound as an internal standard to determine eight chlorinated VOCs. However, this method is not proper for determining simultaneously as many as 53 VOCs with various physical properties. Therefore, we investigate headspace GC/MS method with standard addition method for simultaneous screening of them in sediment. In this paper, we describe effects of a few headspace conditions on the VOC recoveries from sediment, and present screening results of the VOCs in sediments from mouths of rivers and a port in Niigata, Japan. 17 refs., 3 figs., 3 tabs.« less

The aim of this study was to evaluate the influence of different factors on the basic physicochemical and microbiological parameters, as well as volatile organic compounds of traditionally (farm) and industrially produced “bryndza” cheese. The samples were obtained from eight producers in different areas of Slovakia during the ewe’s milk production season, from May to September. The physicochemical parameters set by the legislation were monitored by reference methods. The “bryndza” cheese microbiota was determined by using the plate cultivation method. There was analysis of volatile organic compounds carried out by electronic nose, as well as gas chromatography mass spectrometry. Seasonality and production technology (traditional and industrial ones) are the main factors that affect the standard quality of “bryndza" cheese. Lactic acid bacteria were dominated from bacterial microbiota, mostly presumptive lactococci, followed presumptive lactobacilli and enterococci. The numbers of coliform bacteria were higher in traditionally produced “bryndza” cheese than in industrially produced “bryndza” cheese. The presence of Dipodascus geotrichum was detected in all samples. There were key volatile organic compounds such as ethyl acetate, isoamyl acetate, 2-butanone, hexanoic acid, D-limonene, and 2,3-butanedione. The statistically significant differences were found among “bryndza” cheese samples and these differences were connected with the type of milk and dairies.

Comparison of solid-state fermentation with different Bacillus species on the volatile organic compounds and non-volatile metabolites of dark teas.

Volatile organic compounds (VOCs) make up milk flavor and are essential attributes for consumers to evaluate milk quality. In order to investigate the influence of heat treatment on the VOCs of milk, electronic nose (E-nose), electronic tongue (E-tongue) and headspace solid-phase microextraction (HS-SPME)–gas chromatography–mass spectrometry (GC-MS) technology were used to evaluate the changes in VOCs in milk during 65 °C heat treatment and 135 °C heat treatment. The E-nose revealed differences in the overall flavor of milk, and the overall flavor performance of milk after heat treatment at 65 °C for 30 min is similar to that of raw milk, which can maximize the preservation of the original taste of milk. However, both were significantly different to the 135 °C-treated milk. The E-tongue results showed that the different processing techniques significantly affected taste presentation. In terms of taste performance, the sweetness of raw milk was more prominent, the saltiness of milk treated at 65 °C was more prominent, and the bitterness of milk treated at 135 °C was more prominent. The results of HS-SPME-GC-MS showed that a total of 43 VOCs were identified in the three types of milk—5 aldehydes, 8 alcohols, 4 ketones, 3 esters, 13 acids, 8 hydrocarbons, 1 nitrogenous compound, and 1 phenol. The amount of acid compounds was dramatically reduced as the heat treatment temperature rose, while ketones, esters, and hydrocarbons were encouraged to accumulate instead. Furfural, 2-heptanone, 2-undecanone, 2-furanmethanol, pentanoic acid ethyl ester, 5-octanolide, and 4,7-dimethyl-undecane can be used as the characteristic VOCs of milk treated at 135 °C. Our study provides new evidence for differences in VOCs produced during milk processing and insights into quality control during milk production.

ABSTRACTHeadspace solid-phase microextraction/gas chromatography–mass spectrometry (HS-SPME/GC–MS) analysis combined with ‘relative odour activity value (ROAV)’ was used to monitor changes in key volatile compounds in peanut oil, soybean oil, rapeseed oil, and linseed oil during ambient storage. Volatile composition and oxidation process were compared among edible oil samples. The differences in the volatile contents of edible oils led to their characteristic flavour. Aldehydes featured a relatively high content and low odour threshold and mainly contributed to the flavour of edible oils. The key flavour compounds included pentanal, hexanal, octanal, nonanal, trans-2-heptenal, and benzaldehyde, which are important oxidative degradation products of oleic acid and linoleic acid. The formation of key volatile oxidation compounds was affected by different oxidation processes during ambient storage. Certain aldehydes increased with oxidation level, whereas other aldehydes initially increased then decreased. Correlation analysis showed that the concentrations of several volatile compounds progressively increased during oxidation. The key volatile oxidation compounds formed during oil storage at ambient temperature are partly different from those generated at high temperatures. Volatile oxidation compounds can be a marker for monitoring the oxidation degree of edible oils during ambient storage.

Pomegranate (Punica granatum L.), valued for its health benefits and distinctive flavor, derives its characteristic aroma from volatile organic compounds (VOCs) that vary significantly with geographical origin. In this study, VOCs in pomegranates from six Chinese geographical regions were characterized using an electronic nose (E-nose), an electronic tongue (E-tongue), headspace gas chromatography–ion mobility spectrometry (HS-GC-IMS), and headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS). To elucidate geographical variations in odor, taste, and volatile profiles, a comprehensive multivariate statistical analysis integrating principal component analysis (PCA), hierarchical cluster analysis, orthogonal partial least squares-discriminant analysis (OPLS-DA), and variable importance in projection (VIP) was employed. The results demonstrated that the E-nose and E-tongue effectively distinguished pomegranate by geographical origin, with aroma contributing more significantly than taste to regional differentiation. A total of 46 and 58 VOCs were identified using HS-GC-IMS and HS-SPME-GC-MS, respectively, with different characteristic volatile compounds in pomegranate from various origins, and alkenes, esters, and alcohols were the primary contributors to regional variations. Notably, OPLS-DA revealed that HS-GC-IMS exhibited superior discriminatory power in separating pomegranates of different geographical origins, with HY and HL displaying closely related odor profiles while the other samples showed the most pronounced odor differences, but these findings contrasted with HS-SPME-GC-MS results. Additionally, the VIP method and the relative odor activity value (ROAV) further identified six and eight key aroma compounds based on HS-GC-IMS and HS-SPME-GC-MS data; in particular, hexanal, nonanal, β-pinene, 3-hydroxybutan-2-one, and β-ocimene were identified as key aroma compounds in pomegranate as potential regional markers. These findings highlight VOC profiles as potential geographical origin markers, supporting origin traceability and quality control in the pomegranate industry.

Changes in volatile flavor compounds and metabolites during processing of Ginger milk curd from buffalo milk by GC-IMS and LC-MS.

Key volatile compounds in red koji-shochu, a Monascus-fermented product, and their formation steps during fermentation.

According to WHO 2019, Hepatocellular carcinoma (HCC) is the fourth highest cause of cancer death worldwide. More precise diagnostic models are needed to enhance early HCC and cirrhosis quick diagnosis, treatment, and survival. Breath biomarkers known as volatile organic compounds (VOCs) in exhaled air can be used to make rapid, precise, and painless diagnoses. Gas chromatography and mass spectrometry (GCMS) are utilized to diagnose HCC and cirrhosis VOCs. In this investigation, metabolically generated VOCs in breath samples (n = 35) of HCC, (n = 35) cirrhotic, and (n = 30) controls were detected via GCMS and SPME. Moreover, this study also aims to identify diagnostic VOCs for distinction among HCC and cirrhosis liver conditions, which are most closely related, and cause misleading during diagnosis. However, using gas chromatography-mass spectrometry (GC-MS) to quantify volatile organic compounds (VOCs) is time-consuming and error-prone since it requires an expert. To verify GC-MS data analysis, we present an in-house R-based array of machine learning models that applies deep learning pattern recognition to automatically discover VOCs from raw data, without human intervention. All-machine learning diagnostic model offers 80% sensitivity, 90% specificity, and 95% accuracy, with an AUC of 0.9586. Our results demonstrated the validity and utility of GCMS-SMPE in combination with innovative ML models for early detection of HCC and cirrhosis-specific VOCs considered as potential diagnostic breath biomarkers and showed differentiation among HCC and cirrhosis. With these useful insights, we can build handheld e-nose sensors to detect HCC and cirrhosis through breath analysis and this unique approach can help in diagnosis by reducing integration time and costs without compromising accuracy or consistency.

Twelve volatile organic compounds (VOCs) have recently been identified as key compounds in Swiss cheese with split defects. It is important to know how these VOCs interact in binary mixtures and if their behavior changes with concentration in binary mixtures. Selected ion flow tube mass spectrometry (SIFT-MS) was used for the headspace analysis of VOCs commonly found in Swiss cheeses. Headspace (H/S) sampling and quantification checks using SIFT-MS and further linear regression analyses were carried out on twelve selected aqueous solutions of VOCs. Five binary mixtures of standard solutions of VOCs were also prepared and the H/S profile of each mixture was analyzed. A very good fit of linearity for the twelve VOCs (95% confidence level) confirms direct proportionality between the H/S and the aqueous concentration of the standard solutions. Henry's Law coefficients were calculated with a high degree of confidence. SIFT-MS analysis of five binary mixtures showed that the more polar compounds reduced the H/S concentration of the less polar compounds, while the addition of a less polar compound increased the H/S concentration of the more polar compound. In the binary experiment, it was shown that the behavior of a compound in the headspace can be significantly affected by the presence of another compound. Thus, the matrix effect plays a significant role in the behavior of molecules in a mixed solution.

Due to the effect of microorganisms and enzymes during cold storage, the quality of tilapia declined seriously, which impacted the flavor of tilapia negatively with stench volatile compounds. This study explored the changes of volatile compounds in tilapia fillets during cold storage, identified the key volatile compounds, and determined the roles in flavor through correlation analysis with nucleotides, free amino acids (FAAs), and volatile compounds. A total of 64 volatile compounds in 9 categories were detected via thermal desorption coupled with gas chromatography-mass spectrometry (TD-GC-MS). Octane, 2-nonone, isovaleraldehyde, dimethyl sulfide, and indolizine were identified as key volatile compounds through relative odor activity value (ROAV) screening. Correlation analysis showed that nucleotides and FAAs were related closely to volatile compounds in the characteristic odor. Overall, based on TD-GC-MS, this study revealed the changes of volatile compounds of tilapia fillets during cold storage, which helped to further explore the formation mechanisms of characteristic odor and related metabolic pathways of tilapia fillets during cold storage.