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The determination of optimal levels of green tea amount and brewing time would have a crucial role in the accumulation of desired aromatic volatile compounds to meet worldwide market demand. Aroma is the most important factor influencing tea consumers' choices along with taste, price, and brand. This study aims to determine how the brewing time and amount of green tea affect the aroma profile of green tea infusion. The effect of the amount of Turkish green tea (5–10 g) and brewing time (5–60 min) on aromatic volatile compounds was evaluated using solid‐phase microextraction (SPME) and gas chromatography–mass spectrometry (GC–MS) technique. The SPME/GC–MS analysis identified 57 components in the aroma profile of green tea infusions including 13 esters, 12 alkanes, 7 unknowns, 6 ketones, 3 alcohols, 2 terpenes, 2 terpenoids, 1 alkaloid, 1 phenolic compound, 1 lactone, 1 pyrazine, and 1 norisoprenoid. The green tea amount and brewing time had significant effects on the number of chemical compounds. A total of 42, 47, and 36 aromatic volatile compounds were determined by brewing 5, 7.5, and 10 g of green tea. The most abundant constituents in green tea infusions were phytone, 2‐decenal, lauric acid, unknown 1, methoxy‐1‐methylethyl pyrazine, α‐ionone, β‐ionone, and diethyl phthalate (DEP). With this study, the aroma structures of green tea infusion have been revealed for the first time depending on the brewing time and quantity. [ABSTRACT FROM AUTHOR]

BACKGROUND RESULTS CONCLUSION The present study focuses on the aroma and secondary metabolites profiling of three Pelargonium graveolens cultivars, baladi (GRB), sondos (GRS) and shish (GRSH), grown in Egypt. Utilizing a multiplex approach combining high resolution‐ultraperformance liquid chromatography (HR‐UPLC)/tandem mass spectrometry (MS/MS) and gas chromatography (GC)‐MS coupled with chemometrics, the study aims to identify and profile various secondary metabolites and aroma compounds in these cultivars.HR‐UPLC/MS/MS analysis led to the annotation of 111 secondary metabolites, including phenolics, flavonoids, terpenes and fatty acids, with several compounds being reported for the first time in geranium. Multivariate data analysis identified vinylanisole, dimethoxy‐flavonol, and eicosadienoic acid as discriminatory metabolites among the cultivars, particularly distinguishing the GRS cultivar in its phenolics profile. In total, 34 aroma compounds were detected using headspace solid‐phase microextraction coupled with GC‐MS, including alcohols, esters, ketones, ethers and monoterpene hydrocarbons. The major metabolites contributing to aroma discrimination among the cultivars were β‐citronellol in GRB, α‐farnesene in GRS and isomenthone in GRSH.The study provides a comprehensive profiling of the secondary metabolites and aroma compounds in the three Pelargonium graveolens cultivars. The GRS cultivar was identified as particularly distinct in both its phenolics and aroma profiles, suggesting its potential as a premium variety for cultivation and use. Future studies should focus on isolating and investigating the newly detected metabolites and exploring the biological effects of these compounds in food applications and other uses. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The detection of explosives and explosive devices based on the volatile compounds they emit is a long-standing tool for law enforcement and physical security. Toward that end, solid-phase microextraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS) has become a crucial analytical tool for the identification of volatiles emitted by explosives. Previous SPME studies have identified many volatile compounds emitted by common explosive formulations that serve as the main charge in explosive devices. However, limited research has been conducted on initiators like fuses, detonating cords, and boosters. In this study, a variety of SPME fiber coatings (i.e., polydimethylsiloxane (PDMS), polydimethylsiloxane/divinylbenzene (PDMS/DVB), divinylbenzene/carboxin/polydimethylsiloxane (DVB/CAR/PDMS), and carboxin/polydimethylsiloxane (CAR/PDMS)) were employed for the extraction and analysis of volatiles from Composition C-4 (cyclohexanone, 2-ethyl-1-hexanol, and 2,3-dimethyl-2,3-dinitrobutane (DMNB)) and Red Dot double-base smokeless powder (nitroglycerine, phenylamine). The results revealed that a PDMS/DVB fiber was optimal. Then, an assortment of explosive items (i.e., detonation cord, safety fuse, slip-on booster, and shape charge) were analyzed with a PDMS/DVB fiber. A variety of volatile compounds were identified, including plasticizers (tributyl acetyl citrate, N-butylbenzenesulfonamide), taggants (DMNB), and degradation products (2-ethyl-1-hexanol). [ABSTRACT FROM AUTHOR]

Cadophora luteo‐olivacea is the causal agent of the skin‐pitting disease of kiwifruit, a syndrome that appears after 4–5 months of cold storage. However, it is assumed that the infection takes place in the field during fruit development. The present work takes into consideration the production of volatile organic compounds (VOCs) of Actinidia deliciosa 'Hayward' at different phenological phases as potential C. luteo‐olivacea infection biomarkers. In vitro assays were conducted to gain knowledge on the effect of kiwifruit VOCs on pathogen conidial germination and mycelial growth. VOCs produced by kiwifruit either inoculated or not with C. luteo‐olivacea were analysed at different phenological phases by SPME/GC–MS analysis. In particular, ethanol, o‐xylene, d‐limonene and acetic acid showed a significant increase in the presence of fungal inoculation. Ethanol and d‐limonene were also detected as volatile metabolites of the pathogen. The effect of each compound (ethanol, o‐xylene, d‐limonene and acetic acid) was tested on the fungal conidial germination at different concentrations, showing a growth stimulation at lower amounts. These results show how the production of some VOCs can contribute to the knowledge of fruit–pathogen interaction in the field with the aim of developing future tools for early disease detection and consequent effective control. [ABSTRACT FROM AUTHOR]

We present a GC–MS metabolomics workflow for analyzing metabolites in urine samples infected with schistosomiasis. Schistosomiasis, a neglected tropical disease, affects 85% of the global population, with the majority residing in Sub‐Saharan Africa. The workflow utilized in this study involved the utilization of the AMDIS freeware, Metab R for pre‐processing, and multivariate statistical classification through partial least squares‐discriminant analysis (PLS‐DA). This classification aimed to categorize volatile metabolites found in urine samples from humans infected with schistosomiasis. All samples were collected from individuals in Botswana. A solid‐phase microextraction–fused silica fiber was used to adsorb volatile metabolites from the urine samples and inserted into the GC–MS injection port for data acquisition. The acquired data were then subjected to AMDIS auto‐deconvolution, Metab R pre‐processing, and statistical evaluation for metabolite mining. A total of 12 metabolites, including 3‐chloropropionic acid and heptadecyl ester with an AMDIS match factor of 96% at an approximated amount of 0.35% and cyclohexylamine with an AMDIS match factor of 100% and approximated amount of 0.39%, were identified. PLS‐DA was used for the classification of the metabolites. The method showed good sensitivity and specificity as indicated by the receiver operating characteristic measured by the areas under the curves. Results indicated that metabolomics is a useful tool for mining metabolites because of the variance in metabolite composition of infected and non‐infected urine samples. [ABSTRACT FROM AUTHOR]

Fentanyl HCl is of particular interest in forensic cases but there is a notable gap in literature regarding its analysis. This study utilized a multi‐method approach to characterize fentanyl HCl powder, both fresh and following a forced degradation process. Using sensitive liquid chromatography–tandem mass spectrometry (LC–MS/MS) and direct injection gas chromatography–mass spectrometry (GC–MS), five compounds were identified in fresh fentanyl HCl powder. The identified compounds were: N‐phenylpropanamide, 1‐phenethyl‐4‐propionyloxypiperidine (1‐P‐4‐POP), 4‐anilino‐N‐phenethylpiperidine (4‐ANPP), acetylfentanyl, and fentanyl; all identified compounds but acetylfentanyl and fentanyl decreased in quantity as the sample was degraded. Fresh headspace samples analyzed with solid phase microextraction (SPME)‐GC–MS identified four compounds in common with the powder analyses: N‐phenylpropanamide,1‐P‐4‐POP, 4‐ANPP, and fentanyl. Acetylfentanyl was not present in the headspace samples, although two additional compounds were: N‐phenylacetamide and N‐phenethyl‐4‐piperidinone (NPP). Where direct analysis of degraded fentanyl HCl showed decreased quantities of the identified compounds, headspace samples of the degraded fentanyl HCl resulted in higher quantities, implying that the degradation process drove those compounds to volatilize. Notably, fentanyl was identified in the headspace, implying that this could be an appropriate target for standoff detection. Finally, thermogravimetric analysis (TGA) and differential scanning calorimetry (DCS) confirmed that the forced degradation process had little permanent effect on the powder. [ABSTRACT FROM AUTHOR]

Background and Objectives: There is interest in developing value added rice based products with enhanced nutritional value, however organoleptic properties are critical for product acceptance. Five diverse rice varieties, four of which were previously uncharacterized, were evaluated for volatile compounds in whole grain, milled rice, bran, and flour to determine compound differences that may affect flavor. Findings: This is the first report of gas chromatography mass spectrometry volatiles recovered in Rondo (used for beverages and flour), Cahokia (a high protein brown rice), and two new pigmented bran varieties: Scarlett (red) and Tiara (purple) rice. Conclusion: Tiara delivered some of the highest levels for five key aroma‐impact volatiles known in rice (heptanal, 2‐AP, 2‐pentyl furan, benzaldehyde, guaiacol), especially regarding those varieties with pigmented bran. Cahokia also delivered a high volatile load of several compounds that indicate possible postharvest shipping/handling oxidation in the paddy rice. Several compounds were identified that are associated with pleasant fragrances in other commodities. Significance and Novelty: Five diverse rice varieties developed for specialty culinary and nutritional markets were characterized for 19 volatile compounds in whole grain and milled rice and their associated bran and flour. These volatiles may impact organoleptic properties influencing utilization of these varieties for future value added product development. [ABSTRACT FROM AUTHOR]

Background: The characterization of five different types of Italian unifloral honeys was performed by means of headspace solid‐phase microextraction coupled to gas chromatography–mass spectrometry. The main volatile compounds of the honeys were identified and semi‐quantified. Pattern recognition methods such as principal component analysis (PCA) and k‐nearest neighbors (k‐NN) were performed to classify honey samples with different botanical origins, and identify the most discriminating parameters. Results: More than 100 of compounds were unambiguously identified in the honeys sampled. Methyl salicylate was present in honeydew honeys only, and this permitted to differentiate this kind of honeys from the others. Dandelion honeys featured high levels of nitriles, while lime tree honeys displayed the presence of carvacrol and of the terpenes cis and trans‐p‐mentha‐2,8‐dien‐1‐ol. Acacia honeys did not display potential chemical markers but were characterized by low levels of benzaldehyde and high levels of cis‐linalool oxide. Chestnut and rhododendron honeys did not show a volatile profile markedly different from those of other honeys. Application of PCA and k‐NN methods did not allow a complete classification of honeys of different botanical origin on the basis of their volatile profile. Conclusion: Unifloral honeys from Piedmont (Italy) displays a rich and variegate profile of volatile compounds, some of which are candidates as markers. Nonetheless, to classify honeys, further studies are necessary likely comprising a larger set of samples and the determination of different chemical parameters in conjunction with volatile compounds. [ABSTRACT FROM AUTHOR]

BACKGROUND: Volatiles are determinants of fruit aroma and flavor characteristics and also provide valuable information for lemon as ingredient for the food and drinks industry. Volatiles in 'Eureka' lemon and 'Xiangshui' lemon pulps from 130 to 186 days after flowering were enriched by headspace–solid‐phase microextraction (HS‐SPME), and analyzed by gas chromatography–mass spectrometry (GC‐MS). RESULTS: Seventy‐seven volatiles of two lemon cultivars at the different ripening stages were identified and divided into six categories. Varieties and ripening stages had significant effects on individual volatiles in each category. The proportion of monoterpenes was found to be higher in 'Eureka' lemon, while 'Xiangshui' lemon had a higher proportion of sesquiterpenes, aldehydes and alcohols. The proportion of monoterpene fluctuation decreased during fruit ripening, while fluctuation of sesquiterpenes, alcohols, aldehydes and esters increased. Among the hydrocarbons, monoterpenes decreased their relative abundance from 91.67% to 81.04% in 'Eureka' lemon, and from 83.01% to 60.04% in 'Xiangshui' lemon; conversely, sesquiterpenes increased from 0.73% to 2.89% in 'Eureka' lemon, and from 3.21% to 8.48% in 'Xiangshui' lemon. Among the oxygenated volatiles, the proportions of alcohols, aldehydes and esters were higher at 186 days after flowering in both two cultivars. CONCLUSION: The volatile organic compounds during fruit ripening of lemon varieties with different resistance were elucidated. The proportion of oxygenated volatiles increased during fruit ripening, and disease‐resistant varieties had a higher proportion. These results provided important theoretical support for the utilization of lemon fruits and the innovation of disease‐resistant germplasm resources. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The human respiratory system is a highly complex matrix that exhales many volatile organic compounds (VOCs). Breath‐exhaled VOCs are often "unknowns" and possess low concentrations, which make their analysis, peak digging and data processing challenging. We report a new methodology, applied in a proof‐of‐concept experiment, for the detection of VOCs in breath. For this purpose, we developed and compared four complementary analysis methods based on solid‐phase microextraction and thermal desorption (TD) tubes with two GC–mass spectrometer (MS) methods. Using eight model compounds, we obtained an LOD range of 0.02–20 ng/ml. We found that in breath analysis, sampling the exhausted air from Tedlar bags is better when TD tubes are used, not only because of the preconcentration but also due to the stability of analytes in the TD tubes. Data processing (peak picking) was based on two data retrieval approaches with an in‐house script written for comparison and differentiation between two populations: sick and healthy. We found it best to use "raw" AMDIS deconvolution data (.ELU) rather than its NIST (.FIN) identification data for comparison between samples. A successful demonstration of this method was conducted in a pilot study (n = 21) that took place in a closed hospital ward (Covid‐19 ward) with the discovery of four potential markers. These preliminary findings, at the molecular level, demonstrate the capabilities of our method and can be applied in larger and more comprehensive experiments in the omics world. [ABSTRACT FROM AUTHOR]

Total Vaporization Solid‐Phase Microextraction (TV‐SPME) relies on the same technique as standard SPME but completely vaporizes a sample extract, and analytes are sorbed directly from the vapor phase. On‐fiber derivatization may also be performed using TV‐SPME, where the fiber is first exposed to the headspace of a vial containing the derivatization agent, then exposed to a new vial containing the sample. ɣ‐Hydroxybutyric acid (GHB) and ɣ‐butyrolactone (GBL) are drugs of concern in that they may be used in drug facilitated sexual assault by surreptitiously spiking them into a victim's beverage. These drugs cause sedation, memory loss, and are difficult to detect in biological samples. One challenge in their analysis is that they can interconvert in aqueous samples, which was demonstrated in samples allowed to stand at room temperature for long periods. A volume study of GBL in water was performed with volumes ranging from 1 to 10,000 µl to compare the efficacy of TV‐SPME, headspace SPME, and immersion SPME. Lastly, water, beer, wine, liquor, and mixed drinks were spiked with either GHB or GBL with realistic concentrations (mg/ml) and microliter quantities were analyzed using a TV‐SPME Gas Chromatography‐Mass Spectrometry method. The GBL volume study demonstrated an increased sensitivity in GBL detection when TV‐SPME was utilized. Additionally, GHB and GBL were identified in various beverages at realistic concentrations. Overall, TV‐SPME is beneficial because it requires no sample preparation and uses smaller sample volumes than immersion and headspace SPME. [ABSTRACT FROM AUTHOR]

SUMMARY: Volatile organic compounds (VOCs) released by plants serve as information and defense chemicals in mutualistic and antagonistic interactions and mitigate effects of abiotic stress. Passive and dynamic sampling techniques combined with gas chromatography–mass spectrometry analysis have become routine tools to measure emissions of VOCs and determine their various functions. More recently, knowledge of the roles of plant VOCs in the aboveground environment has led to the exploration of similar functions in the soil and rhizosphere. Moreover, VOC patterns have been recognized as sensitive and time‐dependent markers of biotic and abiotic stress. This focused review addresses these developments by presenting recent progress in VOC sampling and analysis. We show advances in the use of small, inexpensive sampling devices and describe methods to monitor plant VOC emissions in the belowground environment. We further address latest trends in real‐time measurements of volatilomes in plant phenotyping and most recent developments of small portable devices and VOC sensors for non‐invasive VOC fingerprinting of plant disease. These technologies allow for innovative approaches to study plant VOC biology and application in agriculture. [ABSTRACT FROM AUTHOR]

A capillary atmospheric pressure photoionization (cAPPI) source was used to analyze polycyclic aromatic hydrocarbons (PAHs) in complex matrices like grilled meat extract and urban dust reference material, as well as screening for PAHs in aqueous samples such as tap and lake water. A high‐throughput workflow was developed that allowed rapid screening of unknown samples by direct solid‐phase microextraction (SPME) coupled with cAPPI‐MS, with confirmatory gas chromatography performed only for samples containing trace amounts of PAHs. Extraction times were as low as 15 s, with a total analysis time of 2 min per sample for screening. Limits of detections were in the low pg/ml range and in the subpg/ml range for the direct and chromatographic approach, respectively, with a linear dynamic range between two and three orders of magnitude, as determined for 15 model PAHs. This rapid approach represents an attractive way to screen samples containing nonpolar compounds using an ambient ionization source. [ABSTRACT FROM AUTHOR]

Conventional detection and identification of the fungi causing postharvest diseases in fruits are time‐consuming, laborious, and can only be performed after the manifestation of symptoms. In this work, an alternative method based on headspace analysis, and which allows the early detection of fungi species frequently found papaya fruit, is presented. Volatile compounds of four in vitro fungi cultures (Alternaria alternata, Colletotrichum gloeosporioides, Fusarium solani, and Lasiodiplodia theobromae) were extracted using solid‐phase microextraction (SPME) and analyzed by gas chromatography coupled with mass spectrometry. The resulting chromatographic fingerprints were explored by conventional principal component analysis (PCA) and analysis of variance (ANOVA)–PCA. Decomposition of the original matrix, according to the factors proposed in the experimental design, by ANOVA before applying the PCA improved the distinction of the control and fungi samples. The main chromatographic peaks referring to the metabolites produced by each species were successfully identified using the proposed analysis. A primary alcohol with five carbons and phenylethyl alcohol were observed in all fungi species and so could be used as an indicative of postharvest disease. Although unique metabolites were detected for all fungi species, only those from C. gloeosporioides and another from F. solani could be surely identified, such as thymolmethyl and 3,6‐dimethylhept‐6‐en‐4‐yn‐3‐ol, respectively. The in vitro results obtained are promising, and it is expected that the biomarkers detected in this work will be useful in future development of methods for the early detection and classification of papaya fungi species. Volatile metabolites produced by papaya fungi inoculated on PDA medium were analyzed through HS‐SPME‐GC‐MS. ANOVA‐PCA has shown to be more efficient in distinguishing fungi species compared with conventional PCA. Biomarkers were detected for each individual fungal species by ANOVA‐PCA. [ABSTRACT FROM AUTHOR]

Vanilla is one of the most popular spices in the world and is therefore often added to food products to enhance the taste with its desirable flavour. Vanilla flavour is highly susceptible to economically motivated food fraud since the main component 'vanillin' can easily be produced by much cheaper synthetic processes. The determination of the vanillin source is not always an easy task, especially when very low concentrations are incorporated in complex food matrices. Here, we present an easy sample preparation procedure that includes a solid‐phase extraction clean‐up to determine the isotopic carbon ratio of vanillin in food products by headspace solid‐phase microextraction and gas chromatography coupled to isotope ratio mass spectrometry. Isotopic fractionation during the sample preparation procedure was carefully evaluated. The method was applied to 23 commercial food samples including vanilla sugar, dairy and soy products. The study illustrates the potential and limitations of the authentication of vanilla flavour by the isotopic carbon ratio of vanillin. Further, the complexity of the authenticity assessment of vanilla flavours in composite food is demonstrated. [ABSTRACT FROM AUTHOR]

The determination of urinary S-phenylmercapturic acid (S-PMA) represents the most reliable biomarker to monitor the intake risk of airborne benzene. Recently, the European Chemical Agency deliberated new occupational exposure limits for benzene and recommended an S-PMA biological limit value of 2-µg/g creatinine. This limit is an order of magnitude lower than the previous one, and its determination constitutes a challenge in the analytical field. We developed and validated a method that allows the fully automated and sensitive determination of S-PMA by the use of gaschromatography negative chemical ionization tandem mass spectrometry in isotopic dilution. For negative chemical ionization, we selected a mixture of 1% isobutane in argon as reactive gas, by studying its chemical ionization mechanism and optimal parameters compared with pure isobutane or pure methane. This gas mixture produces a more abundant signal of the target analyte than isobutane or methane, and it extended the operative lifetime of the ion source, enabling us to start a high-throughput approach of the S-PMA analysis. Moreover, energy-resolved mass spectrometry experiments were carried out to refine the MS/MS analysis conditions, testing nitrogen and argon as collision gases. The method optimization was pursued by a chemometric model by using the experimental design. The quantification limit for S-PMA was 0.10 µg/L. Accuracy (between 98.3% and 99.6%) and precision (ranging from 1.6% to 6.4%) were also evaluated. In conclusion, the newly developed assay represents a powerful tool for the robust, reliable, and sensitive quantification of urinary S-PMA, and because of its automation, it is well suited for application in large environmental and biological monitoring. [ABSTRACT FROM AUTHOR]

BACKGROUND: There is a lack of information on the presence of volatile organic compounds including p‐cymene in foods for dietary exposure assessment. p‐Cymene is a monoterpene found in many plant species, which has been used as a flavouring agent in foods and also exhibits antioxidant and antimicrobial properties. While the Joint FAO/WHO Expert Committee on Food Additives (JECFA) has no safety concerns at current levels of intake when used as a flavouring, the current study examines p‐cymene levels in foods in general, not just from possible uses as a flavouring, as there could still be a potential health concern if there were high levels of exposure. RESULTS: 159 food composite samples from the 2014 Canadian Total Diet Study were analysed for p‐cymene using a gas chromatographic–mass spectrometric method after headspace solid‐phase microextraction. Concentrations of p‐cymene in the composite samples of most food types were generally low, with a maximum level of 73.5 μg g−1, detected in the composite sample of herbs and spices. Dietary exposures to p‐cymene were estimated for different age groups of Canadian populations. CONCLUSIONS: Although p‐cymene was detected in various foods, estimated dietary exposures to p‐cymene for different age groups are well below the human intake threshold of toxicological concern established by JECFA of 1800 μg per person per day for structural class I flavours, which includes p‐cymene. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Some green extraction methods were selected and tested for the extraction of volatile compounds from different samples of the microalga Chlorella vulgaris: ultrasound‐assisted liquid–liquid extraction using environment‐friendly solvents (LLE) and solid‐phase microextraction (SPME). The obtained profiles of volatile chemical compounds were different. Only one molecule was found in common to both extractions. Using the SPME method, the main chemical classes of identified volatile compounds were sulfuric compounds, aldehydes, and alcohols. Using the LLE method, the volatile profile was more balanced with alkanes, fatty acids, terpenes, alcohols, and aldehydes. Multivariate data analyses permitted discrimination among samples. Additionally, the relationship between the physicochemical properties of identified volatile compounds and the methods of extraction was studied. The results showed that the LLE extraction allowed the extraction of volatile compounds having a high boiling point (>160°C) and a high log P (>3). The SPME method was more effective to extract volatile compounds with a low boiling point (<160°C) and a low log P (<3). It is thus necessary to combine several extraction methods to obtain a complete view of the volatile profile for microalgae samples. Green extraction methods were selected for the extraction of volatile compounds from different samples of the microalga Chlorella vulgaris: ultrasound‐assisted liquid–liquid extraction using environment‐friendly solvents (LLE) and solid‐phase microextraction (SPME). LLE extraction allowed the extraction of volatile compounds having a high boiling point (>160°C) and a high log P (>3). The SPME method was more effective to extract volatile compounds with a low boiling point (<160°C) and a low log P (<3). [ABSTRACT FROM AUTHOR]

Volatile compounds of argan oils obtained from raw and roasted kernels and subjected to accelerated storage test at 60 °C were profiled by means of headspace solid‐phase microextraction with gas chromatography coupled with high‐resolution time‐of‐flight mass spectrometry (HS‐SPME‐GC‐HRToFMS), followed by statistical multivariate analysis (MVA). Main volatile markers differentiating oils during storage were identified as 2‐methylbutanal, acetic acid, pentanal, hexanal, 2,5‐dimethylpyrazine, methyl pyrazine, 2,3‐butanediol, and 1‐methyl‐1H‐pyrrole. Principal component analysis (PCA) results show that MVA is suitable for differentiating between raw and roasted argan oils of various degrees of oxidation. Key odorants in both oils were determined by gas chromatography‐olfactometry (GC‐O) analysis, indicating butanal as the most prominent odorant for raw argan oil (flavor dilution [FD] = 8), whereas 3‐isopropyl‐2‐methoxypyrazine and 2‐ethyl‐3,5‐dimethylpyrazine with FD values of 1024 were the most prominent among 23 odorants in argan oil obtained from roasted kernels. Peroxide values (PV) indicate that argan oil obtained from roasted kernels is significantly less prone to oxidation than oil obtained from unroasted kernels. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the volatile flavor compounds of nkui, a Cameroonian food, using solid phase microextraction (SPME) and a two‐dimensional gas chromatography time of flight mass spectrometry GC×GC‐TOF‐MS system. Using SPME, volatile compounds were extracted from nkui and analyzed by GC×GC‐TOF‐MS. The data retrieved revealed the presence of flavor volatiles including acids (20%), alcohols (4%), aldehydes (10%), aromatic compounds (4%), esters (7%), furans (4%), ketones (11%), terpenes and terpernoids (27%). Although the terpene compounds were the most predominant, an ester (linalyl acetate) had the highest percentage of 19%, conferring a sweet, green and citrus flavor. Results obtained from this study suggest that the characteristic flavor of nkui was due to the combination of different volatile flavor compounds, which contributed to its aroma. Considering the medicinal importance of these compounds, their presence positions nkui as a vital food source with health benefits and medicinal properties. The volatile flavor components of Nkui, a Cameroonian food was investigated using SPME‐GC×GC‐TOF‐MS. Results indicated that the characteristic flavor of Nkui was due to the combination of different volatile flavor compounds, which contributed to its aroma. [ABSTRACT FROM AUTHOR]

Abstract: BACKGROUND: Propolis is a complex mixture that honey bees produce from the exudates of various plants and presents many medicinal properties. Its chemical composition varies according to the phytogeography characteristics of each region, among others. The aim of this study was to identify and characterize the volatile organic compounds (VOCs) present in Venezuelan propolis and compare with reference samples such as Brazilian and Argentinian propolis. RESULTS: A total of 90 VOCs were identified in a series of propolis samples using both solid‐phase microextraction and dynamic headspace (DHS), both coupled to a gas chromatograph–electron ionization mass spectrometer. In the case of Venezuelan propolis, sesquiterpenes, esters, aromatic compounds, and aliphatic hydrocarbons were identified. Limonene was found only in Venezuelan samples, this being the first time it has been identified in samples from this country. In the case of green propolis, β‐caryophyllene and nerolidol were the major compounds. As for the Argentinian samples, prenyl acetate, benzyl acetate, and 2‐phenylethyl acetate were detected only in these samples. CONCLUSIONS: Possible chemical markers of natural sources such as limonene were detected using DHS extraction. Several compounds have also been identified for the first time in Venezuelan propolis. Cluster analysis allowed the relating of the propolis VOCs profile to their provenance. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND A headspace solid-phase microextraction method with gas chromatography-mass spectrometry was used to profile the aroma volatiles of mature fruiting bodies of Morchella importuna grown in Israel. RESULTS We tentatively identified 40 aroma compounds and seven unknown volatiles. The M. importuna aroma profile consisted of 14 aldehydes, six alcohols, 10 methyl esters, four heterocyclic/sulfur compounds, 10 carbohydrates and three other compounds (i.e. one acid, one ketone and one butyl ester). The most abundant volatiles were carbohydrates, with a total relative peak area of 29.3%, followed by alcohols (27.7%), aldehydes (21.6%), methyl esters (10.8%), heterocyclic/sulfur compounds (3.1%) and other compounds (5.8%). The 8-carbon (C8) compounds imparting typical mushroom-like aroma were very abundant in M. importuna, accounting for 27.9% of the total peak area and including, amongst others, 1-octen-3-ol (80% of total C8), octanal and 2-octenal ( Z- and E-). CONCLUSION The aroma volatile profile of morels has much in common with that of other mushrooms, with a few unique characteristics. To our knowledge, this is the first detailed report of the aroma profile of M. importuna. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Abstract: Flavor compounds have been shown to interact with packaging materials either by scalping, the movement of flavorings from the food product to the package, or by flavor release, movement of flavorings from the package to the food. Work has elucidated the parameters important for the scalping of flavor compounds to polyolefin packaging materials, but very little work has been conducted examining the scalping of flavor compounds by can lining materials. Can linings composed of three different polymers, polyolefin, acrylic, epoxy, were studied for binding of volatile flavor compounds (octanal, nonanal, decanal, eugenol, d‐limonene) at room temperature over a 2‐week period. Solid phase microextraction (SPME) was used with gas chromatography mass spectrometry to identify and quantify volatile compounds. Flavor compounds were studied at concentrations around 4–1,000 ppb. Fourier transform infrared spectroscopy was used to verify can lining polymer chemistry. Almost complete binding of all five of the volatile compounds studied was observed over 9–14 days at room temperature for each of the can lining chemistries. The number of time data points limited our ability to determine the order and rate constants of binding. This model system appears to be a valuable for investigating flavor binding of polymeric can lining materials. [ABSTRACT FROM AUTHOR]

BACKGROUND During an investigation of the chemical profile of Greek figs ( Ficus carica L.), several aqueous ethanol extracts (liquors) were prepared from dried Smyrna fig varieties cultivated in the two major fig-producing geographical areas in Greece: Peloponnese and Evia Island. The distinctive aroma observed among the prepared fig liquors led to the investigation of the odor profile of the different fig cultivars through HS-SPME coupled with GC/ MS analysis, with focus on the factors that affect it before and during the preparation of the respective liquors. RESULTS Significant variation in volatiles was noticed among all fig cultivars, as also between each fig cultivar pulp and the respective liquor. The observed diversity was a result of chemical reactions taking place in the ethanol matrix during the preparation of the liquor. The 'key' odor compound of dried fig aroma was found to be β-damascenone. Owing to its low detection threshold and minute quantity in fig cultivars, the presence of β-damascenone was furthermore confirmed through GC/ MS/ MS and GC/ TOF-MS. β-Damascenone was identified in variable quantities among fig varieties and their liquors, predominating in Kalamon fig cultivar of Peloponnese region, while its amount was found to be dependent on the postharvest storage time and preservation process of dried figs. CONCLUSION Each of the studied fig cultivars and liquors showed a unique aroma profile, and the obtained results were used for the preparation of the first dried fig liqueur for potential commercial use with the highest content of β-damascenone. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

In this study, the analysis of organic compounds in the products obtained from hydrothermal liquefaction (HTL) of microalgae ( Dunaliella tertiolecta) was carried out, with particular attention on the identification of compounds in aqueous phases via the integration of two pre-treatment methods namely dried aqueous extracts (DAE) and solid-phase micro-extraction (SPME) along with GC-MS analysis. The results showed that the strong polar compounds in aqueous phases, such as carboxylic acids, alcohols, amides, glycerol, and N-containing compounds were determined through DAE method. The weak polar compounds like phenols, cyclic hydrocarbons, and indoles were identified via SPME method. In addition, CO2 and CO are the main components of the gaseous phase products, the rest of components include CH4, N2, H2, C2H4, C2H6, etc. Bio-oil is mainly composed of ketones, phenols, alcohols, hydrocarbons and N-containing compounds. Based on the compounds in the bio-oil, aqueous and gaseous phases compared with the other previous published works, the plausible pathways of Dunaliella tertiolecta HTL are proposed. © 2016 American Institute of Chemical Engineers Environ Prog, 36: 259-268, 2017 [ABSTRACT FROM AUTHOR]

The aim of this study was to compare three different collection methods; purge and trap, solid phase micro extraction and automated dynamic headspace/thermal desorption, all followed by GC-MS analysis used for the measurements of concentrations of volatile oxidation products in three different food matrices, namely oil, emulsion and milk. The linearity ranges of calibration curves obtained by the three different methods were compared for oil samples. Overall, the results showed that the three collection methods were comparable, although there were large differences in the linearity range of the calibration curves depending on the collection method. However, some challenges were observed for solid phase micro extraction and automated dynamic headspace/thermal desorption, namely, competition problems and overestimation of concentration by calibration curves, respectively. Based on the results, we suggest mainly to apply solid phase micro extraction on simple matrices and to be cautious with more complex matrices such as enriched milk and highly oxidized oils. Thereby, the study confirmed some challenges observed by other authors regarding competition problems on the fiber when using solid phase micro extraction. Furthermore, we observed that purge and trap, and automated dynamic headspace/thermal desorption were excellent for extraction of volatile compounds in all three matrices. However, automated dynamic headspace/thermal desorption calibration curves did provide an overestimation for oil samples so results must be interpreted with caution. [ABSTRACT FROM AUTHOR]

A fast and simple method for authenticating raspberry flavors from food products was developed. The two enantiomers of the compound (E)- α-ionone from raspberry flavor were separated on a chiral gas chromatographic column. Based on the ratio of these two enantiomers, the naturalness of a raspberry flavor can be evaluated due to the fact that a natural flavor will consist almost exclusively of the R enantiomer, while a chemical synthesis of the same compound will result in a racemic mixture. Twenty-seven food products containing raspberry flavors where investigated using SPME-chiral- GC- MS. We found raspberry jam, dried raspberries, and sodas declared to contain natural aroma all contained almost only R-(E)- α-ionone supporting the content of natural raspberry aroma. Six out of eight sweets tested did not indicate a content of natural aroma on the labeling which was in agreement with the almost equal distribution of the R and S isomer. Two products were labeled to contain natural raspberry flavors but were found to contain almost equal amounts of both enantiomers indicating a presence of synthetic raspberry flavors only. Additionally, two products that were labeled to contain both raspberry juice and flavor showed equal amounts of both enantiomers, indicating the presence of synthetic flavor. [ABSTRACT FROM AUTHOR]

Negative aromas such as rancid, fusty, winey-vinegary and frozen are sensory attributes of defective virgin olive oil recognized by the International Olive Council. Solid phase microextraction-gas chromatography/mass spectrometery (SPME-GC/MS) was employed to establish a flavour profile for each defective oil. The potential contribution of the identified compounds to the overall aromas of oil samples was assessed by calculating the ratio relative area/odour threshold in air - Relative Area over Threshold (RAOT). The relevant compounds of each defective sensory attributes were suggested: a series of C7-C12 unsaturated aldehydes, such as 2, 4-heptadienal, E-2-nonenal and E-2-octenal, were found to be responsible for rancidity, Z-3-hexenyl acetate and nonanoic acid were related to fusty defects, acetic acid and butyric acid were responsible for winey-vinegary defects, and limonene was found as a relevant compound in frozen oil. [ABSTRACT FROM AUTHOR]

Until recently, multiple solid-phase microextraction fibers could not be automatically desorbed in a single gas chromatographic sequence without manual intervention from an operator. This drawback had been a critical issue, particularly during the analysis of numerous on-site samples taken with various fiber assemblies. Recently, a Multi-Fiber Exchange system, designed to overcome this flaw found in other commercially available autosamplers, was released. In the current research, a critical evaluation of the Multi-Fiber Exchange system performance in terms of storage stability and long-term operation is presented. It was established in the course of our research that the Multi-Fiber Exchange system can operate continuously and precisely for multiple extraction/injection cycles. However, when the effect of residence time of commercial fibers on the Multi-Fiber Exchange tray was evaluated, results showed that among the evaluated fiber coatings, Carboxen/polydimethylsiloxane was the only coating capable of efficient storage on the tray for up to 24 h after field sampling without suffering significant loss of analytes (≤10% for benzene, toluene, ethylbenzene, o-xylene, decane, and limonene). Additionally, the system capability for high-throughput analysis was demonstrated by the unattended desorption of multiple fibers after on-site sampling of toluene, indoor air levels, in a polymer synthesis lab. [ABSTRACT FROM AUTHOR]

Black cumin and hazelnut oils were subjected to a heating process in a microwave oven for a duration of 2, 4, 6 and 8 min at a constant frequency of 2450 MHz and a power of 0.45 kW. The ultraviolet absorption and volatile products of the oils were investigated in detail during the processes. The experimental evidences obtained show that K and K parameters reach values of 4.69 and 1.30 for black cumin oil, 3.22 and 1.75 for hazelnut oil, respectively with the increment of heating time. The headspace SPME method was used to analyze volatile compounds extracted from black cumin and hazelnut oils being exposed to the microwave heating process. The SPME-GC/MS method allowed the detection of 17 identified volatile compounds (hexanal, α-thujene, α-pinene, sabinene, β-pinene, 2-heptenal, α-terpinene, limonene, p-cymene, γ-terpinene, E-2-octenal, nonanal, 4-terpineol, thymoquinone, E, E-2,4-decadienal, α-longipinene and isolongifolene) in black cumin oils. Of the products, hexanal, 2-heptenal, E-2-octenal, nonanal and E, E-2,4-decadienal were determined to be the predominant volatile oxidation products. In fact, the hexanal was found as a major volatile oxidation compound and reached a local maximum point of 7.41 × 10 AU at the end of heating. On the other hand, only 8 volatile oxidation products (hexanal, heptanal, 2-heptenal, nonanal, E-2-decenal, E, Z-2,4-decadienal, E, E-2,4-decadienal and E-2-tridecenal) were identified in hazelnut oils as a consequence of the heating process. Based on the experimental evidence observed, it is reasonable to conclude that the nonanal content dramatically increased at the end of heating and reached a value of 9.22 × 10 AU. [ABSTRACT FROM AUTHOR]

The abundant production of methyl tert-butyl ether (MTBE) and its widespread use have led to an increase in the potential for human exposure. This work described a simple, fast, sensitive, reliable and low-cost method for the simultaneous measurement of MTBE and its metabolite, tert-butyl alcohol (TBA) in human serum by headspace solid-phase microextraction gas chromatography-mass spectrometry. Extraction conditions were optimized and 40 °C, 10 min, 250 rpm and 0.3 g NaCl for a 1 mL sample were the optimal conditions. This method showed good analytical performance in terms of sensitivity with limits of detection in serum (1 mL) of 0.03 µg/L for MTBE and 0.05 µg/L for TBA, accuracy (mean recovery values) from 75.8% to 85.8%, precision (relative standard deviations) <10% and sample stability (biodegradation) <10% after 28 days. A verification experiment proved the reproducibility and stability of this method as well. Finally the method was used to detect 212 specimens, and the internal dose levels for MTBE in human serum were presented in China. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The oils of olive fruits, pulps and seeds from main Tunisian cultivars of olive trees (Chemlali and Oueslati) were extracted at two different indices of maturity. The free acidity, peroxide value, spectrophotometric indices, chlorophyll content, squalene, fatty acids, aroma, and sensory profiles of the oils were analyzed. Fruit and pulp oils are similar in fatty acid compositions, while seed oils have fatty acid profiles that are different from both varieties. For the first time in this work, squalene content in the fruit, pulp, and seed oils was measured by gas chromatography and was found to decrease during maturation. Squalene concentration in the seed oils was lower than that found in fruit and pulp oils. The volatile profiles of twelve Tunisian olive oils obtained from different parts of the fruit were established by solid phase micro-extraction (SPME) coupled with gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Sixty-six compounds were identified and characterized, representing 92.4 and 97.6% of the total volatiles. Principal component analysis showed that olive oil quality is strongly affected by olive cultivar, maturity index and the different olive parts. [ABSTRACT FROM AUTHOR]

Monoterpene olefins such as limonene are plant compounds with applications as flavouring and fragrance agents, as solvents and potentially also in polymer and fuel chemistry. We engineered baker's yeast Saccharomyces cerevisiae to express a (−)-limonene synthase from Perilla frutescens and a (+)-limonene synthase from Citrus limon. Both proteins were expressed either with their native plastid targeting signal or in a truncated form in which the plastidial sorting signal was removed. The yeast host strain for expression was AE9 K197G, which expresses a mutant Erg20 enzyme. This enzyme catalyses the formation of geranyl diphosphate, which is the precursor for monoterpenes. Several methods were tested to capture limonene produced by the yeast. Extraction from the culture medium by pentane, or by the addition of CaCl2 followed by solid-phase micro-extraction, did not lead to detectable limonene, indicating that limonene is rapidly lost from the culture medium. Volatile terpenes such as limonene may also be trapped in a dodecane phase added to the medium during fermentation. This method resulted in recovery of 0.028 mg/l (+)-limonene and 0.060 mg/l (−)-limonene in strains using the truncated Citrus and Perilla synthases, respectively. Trapping the headspace during culture of the limonene synthase-expressing strains resulted in higher titres, at 0.12 mg/l (+)-limonene and 0.49 mg/l (−)-limonene. These results show that the volatile properties of the olefins produced require specific methods for efficient recovery of these molecules from biotechnological production systems. Gene Bank Nos were: KM015220 ( Perilla limonene synthase; this study); AF317695 ( Perilla limonene synthase; Yuba et al., ); AF514287.1 ( Citrus limonene synthase; Lucker et al., ). Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

BACKGROUND: Dry-cured 'lacón' is a traditional cured meat productmade in the north-west of Spain fromthe pigs' foreleg, with similar manufacturing process to that used in dry-cured ham. The aim of this studywas to assess the influence of cross-breeding of Celta pig with Landrace or Duroc breeds on the formation of volatile compounds through themanufacture of 'lacón'. RESULTS: 'Lacón' fromthe crosseswith Duroc presented lower finalmoisture (534 g kg-1) and higher intra-muscular fat content [144 g kg-1 drymatter (DM)] than 'lacón' from Celta pure breed (587 g kg-1 and 36 g kg-1 DM, respectively). Volatile compounds were extracted by solid-phase microextraction and analysed by gas chromatography-mass spectrometry. Volatile compounds from 'lacón'were affected by cross-breeding. The total amount of volatile compounds significantly (P <0.001) increased during the manufacturing process, this increase being more marked in samples from the Landrace cross-breed. The most abundant group of flavour compounds at the end of the manufacturing process was esters in the three batches, followed by aldehydes, hydrocarbons and alcohols. The most abundant ester at the end of the process was hexanoic acid methyl ester, while the aldehyde found in a higher amount was hexanal. CONCLUSIONS: The profile of volatile compounds was affected by cross-breed, especially at the end of the 'lacón' dry-curing process. [ABSTRACT FROM AUTHOR]

1. The decomposition of biological material produces a plethora of volatile organic compounds ( VOCs), which are implicated in the foraging behaviour of coprophagous and necrophagous insects. Dung beetles ( Coleoptera: Scarabaeidae: Scarabaeinae) have an acute olfactory system used to locate food resources. Accordingly, identification of food resource VOCs potentially used in food location is integral to understanding dung beetle foraging ecology. 2. In this study, volatile emissions from dung and carrion of native and introduced animals in New Zealand were analysed using solid-phase microextraction ( SPME) and gas chromatography-mass spectrometry ( GC-MS). Volatile profiles were compared via principal component analyses ( PCAs) and cluster solutions based on attractiveness using canonical discriminant analysis ( CDA). 3. A total of 115 compounds were detected from 21 food types. Statistical analyses showed that dung and carrion volatile profiles clustered according to attractiveness to the dung beetle Saphobius edwardsi, and that different dung types formed distinct clusters and grouped separately from carrion. 4. This study suggests that volatile profiles emitted by food resources used by dung beetles are complex, producing distinct odours, which potentially mediate foraging decisions. [ABSTRACT FROM AUTHOR]

The brown marmorated stink bug ( BMSB), Halyomorpha halys ( Stål), native to Northeastern Asia, is a serious invasive pest in the United States, Canada, Switzerland, Germany and France. Several common essential oils and their compositions were tested against BMSBs as potential repellents. All the tested individual essential oils and a ternary oil blend showed significant repellency to both BMSB nymphs and adults. Clove oil, lemongrass oil, spearmint oil, ylang-ylang oil, and the ternary oil mixture (clove, lemongrass and spearmint) almost completely blocked attraction of BMSBs to the stink bug attractant-baited traps; whereas wintergreen oil, geranium oil, pennyroyal oil and rosemary oil resulted in 60-85% trap catch reductions. Over 20 BMSB antennally active compounds were identified from SPME headspace samples of the eight repellent essential oils using GC- EAD and GC- MS techniques. Among the synthetic EAD-active compounds tested in the field, eugenol, l-carvone, p/l-menthone, pulegone, methyl salicylate, trans/ cis-citral, methyl benzoate and β-caryophyllene significantly reduced trap catches of BMSBs by 72-99%; these compounds are likely responsible for the repellency of their corresponding essential oils. Surprisingly, a synthetic mixture of the predacious spined soldier bug ( SSB) [ Podisus maculiventris (Say)] aggregation pheromone ( trans-2-hexenal, α-terpineol and benzyl alcohol) also showed a significant inhibition of BMSB response to its attractants. These repellent essential oils and their active compounds, as well as the synthetic SSB pheromone, are potentially useful as part of an efficient, environmentally sound semiochemical-based IPM programme to combat this serious invasive stink bug. [ABSTRACT FROM AUTHOR]

BACKGROUND Very-early apricot cultivars are interesting owing to the fact that they will be available in markets before any other cultivar. In order to achieve good fruit quality, very-early apricots require appropriate size, weight and color, good balance of sugars and organic acids, proper content of bioactive compounds, relatively strong apricot aroma as well as acceptable sensory quality. RESULTS Physical, chemical, antioxidant and sensory properties showed important variations among apricot cultivars. These differences were basically attributed to genetic reasons. Four very-early apricot cultivars were studied, namely 'Mirlo Blanco', 'Mirlo Anaranjado', 'Colorao' and 'Mogador'. All of them showed proper size and weight, but their contents of organic acids, sugars and bioactive compounds were low and the number of volatile compounds was also low. However, very-early apricots showed an appropriate sensory profile for fresh consumption. CONCLUSION Regarding physical, chemical and volatile composition and sensory properties, very-early apricot cultivars could be recommended for fresh consumption. However, future research must be focused on increasing their contents of sugars, organic acids and bioactive and volatile compounds, perhaps via cultural practices such as deficit irrigation and/or mulching. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The present contribution is focused on the evaluation of a high-speed triple quadrupole mass spectrometer, carried out under moderately fast GC conditions (analysis time: 16.6 min). The mass spectrometric instrument can be operated under high-speed GC conditions, in both full-scan (maximum scan speed: 20 000 amu/s) and multiple reaction monitoring ( MRM) modes (minimum dwell time: 0.01 s). Additionally, the mass spectrometric system can generate full scan and MRM information, simultaneously and rapidly. A headspace solid-phase microextraction with fast GC coupled to triple quadrupole MS approach was developed for the: (i) qualitative untargeted analysis of brewed tea volatiles, and (ii) MRM qualitative and quantitative analysis of targeted volatiles (also in brewed tea), namely 30 phytosanitary contaminants. The performance of the triple quadrupole instrument was satisfactory both for identification and quantification purposes. Furthermore, the method sensitivity was more than sufficient for the requirements of current legislation. Method validation, related to the MRM analysis, was performed considering: precision of quantification data (maximum coefficient of variation value: 12.0%) and quantification/qualification ion ratios (maximum coefficient of variation value: 14.4%), along with limits of detection (4 parts per trillion-5 parts per billion range) and quantification (14 parts per trillion-16 parts per billion range). [ABSTRACT FROM AUTHOR]

Background The study objectives were: (1) to field test potential repellency of common essential oils against several pestiferous social wasps (Hymenoptera: Vespidae), using attractant-baited traps; (2) to identify vespid antennally active compounds from the repellent essential oils; (3) to determine potential repellency of these electroantennographic detection ( EAD) active compounds in the field. Results Of the 21 essential oils tested, 17 showed significant repellency on yellowjackets [mainly Vespula pensylvanica (Saussure)] and paper wasps [mainly Polistes dominulus (Christ)]: clove, pennyroyal, lemongrass, ylang ylang, spearmint, wintergreen, sage, rosemary, lavender, geranium, patchouli, citronella, Roman chamomile, thyme, fennel seed, anise and peppermint. Two essential oil mixtures - 3EO-mix (clove, geranium and lemongrass) and 4EO-mix (clove, geranium, lemongrass and rosemary) - totally blocked the attraction of vespid workers. Twenty-nine vespid antennally active compounds were identified from solid-phase microextraction ( SPME) samples of 11 strongly repellent essential oils by GC-EAD/ MS techniques. Among the synthetic EAD-active compounds field tested, eugenol, P/ I-menthone, pulegone, α/ β-thujone, l-carvone, E/ Z-citral, citronellal, methyl benzoate, benzyl acetate, methyl salicylate and 3-octanol showed a significant repellency on vespid workers. These compounds are likely responsible for the repellency of their corresponding essential oils. Conclusion These repellent essential oils and their active compositions have great potential for efficient, environmentally sound semiochemical-based IPM of pestiferous vespid wasps. © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Abstract: BACKGROUND: For selecting Chungkook‐jang products with a less undesirable odour, the volatile compounds that affect the overall consumer acceptance of Chungkook‐jang products were analysed. The volatile compounds of Chungkook‐jang were extracted by using solid phase microextraction and direct solvent extraction and were detected by using gas chromatography‐olfactometry. The results were represented as the mean of the log3 flavour dilution factors; principal component analysis was used to determine the effective components. RESULTS: Fifteen and 14 volatile compounds were detected in the extracts using solid phase microextraction and direct solvent extraction, respectively. The Bacillus species 2‐M1L, which has the most overall acceptance, might have a nutty initial top note and nutty and cheesy long‐lasting note aromas. In correlation analysis between the characteristic aromas and the overall acceptance, trimethyl pyrazine (nutty, pungent), butanoic acid (cheesy, butyric), and methyl pyrazine (burnt, roasted) were positively correlated with overall acceptance. In contrast, 3‐hydroxy‐2‐butanone (buttery, fatty) and 2,3‐butanediol (chemical, fatty) were negatively correlated with overall acceptance. CONCLUSION: Consumers might prefer Chungkook‐jang that has a more nutty and cheesy flavour and a less fatty one. Copyright © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Despite its many health benefits, many consumers avoid fish oil supplements due to fishy tastes and odors. Common chemical measures of oxidation have little correlation with sensory properties, making it difficult to determine the sensory quality of fish oil without the use of an expensive sensory panel. Here we investigate an alternative method to assess oxidation using solid phase microextraction and gas chromatography-mass spectrometry. Fish oils containing different amounts of eicosapentaenoic acid and docosahexaenoic acid were oxidized, and headspace volatiles were monitored over time and compared to sensory evaluations by a taste panel. Peroxide value and anisidine value were also measured. Sensory panel scores and headspace volatile data were analyzed using principal component analysis and linear regression to identify key volatiles responsible for changes in sensory degradation of oils over time. A total of eight compounds were identified, primarily aldehydes and ketones. By monitoring these volatiles, it may be possible to create a simple method to assess oxidation in fish oils that correlates well with sensory properties of the oil without the use of a sensory panel. [ABSTRACT FROM AUTHOR]

Headspace-solid-phase microextraction-gas chromatography was used to identify in total 55 volatile lipid oxidation compounds in thermally stressed conventional and high-oleic rapeseed oil samples. Out of this profile, 17 volatile compounds with low odor threshold values were selected as target compounds for the assessment of lipid oxidation in rapeseed and high-oleic rapeseed oils. Additionally, other lipid oxidation parameters such as fatty acid composition, peroxide value, anisidine value, and induction time (Rancimat analysis) were determined. Multivariate statistical methods (principal component analysis in combination with agglomerative hierarchical cluster analysis) were applied to identify sensitive volatile lipid oxidation indicators enabling the differentiation of rapeseed oil samples of different varieties (high-oleic versus conventional). Moreover, these statistical methods were capable of differentiating rapeseed oils of different oxidative properties. Octanal and 3-octanone showed the highest ability to differentiate between samples of different rapeseed varieties, whereas propanal, E,E-2,4-hexadienal, and E-2-heptenal were most suitable in differentiating rapeseed oil samples with different oxidative properties from each other. Clustering of rapeseed oil samples according to their volatile compound composition was comparable with results of sensory duo-trio and paired comparison tests, but the analytical approach of the volatile compound analysis in combination with chemometric methods detected changes sooner in relation to the flavor composition of rapeseed oils and high-oleic rapeseed oil samples. Practical applications: The combination of volatile compound analysis by HS-SPME-GC with multivariate statistical methods and complementary sensory duo-trio and one-sided paired comparison tests are sensitive tools in differentiating conventional and high-oleic rapeseed oil samples with different lipid oxidation properties. The presented methods are suitable techniques for the detection of initial changes of lipid oxidation progress in edible oils. [ABSTRACT FROM AUTHOR]

BACKGROUND: The origin of the raw spirits influences the sensory quality of rectified spirits that are subsequently used for the production of vodka. The aim of this research was to evaluate the effectiveness of two methods based on the comparison of profiles of volatile compounds [solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) and gas chromatography with flame ionisation detection (GC-FID)] for the determination of origin of raw spirits obtained from rye, corn (maize) and potato. RESULTS: Profiles obtained for the volatile compounds by using these methods were different and were influenced by the sample introduction method. The main groups of volatiles obtained using SPME-GC-MS method were fatty acid ethyl esters, while in the case of GC-FID fusel alcohols and ethyl acetate dominated. Data obtained from these methods were treated using principal component analysis and linear discriminant analysis to test the possibility of sample differentiation and classification. It was relatively easy to differentiate potato spirits from the remainder; however, it was not possible to fully distinguish the corn samples from rye samples. The classification ability of the SPME-GC-MS method was 95% but the prediction ability was 97.4%. For the GC-FID method the classification ability was 90.1%, whereas the prediction ability was 94.27%. CONCLUSIONS: The methods presented can be used for reliable differentiation of potato spirits from corn and rye spirits. Copyright © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Flavor is one of the most important characteristics of chocolate products and is due to a complex volatile fraction, depending both on the cocoa bean genotype and the several processes occurring during chocolate production (fermentation, drying, roasting and conching). Alkylpyrazines are among the most studied volatiles, being one of the main classes of odorant compounds in cocoa products. In this work, a mass spectrometric approach was used for the comparison of cocoa liquors from different countries. A headspace solid-phase microextraction gas chromatography-mass spectrometry method was developed for the qualitative study of the volatile fraction; the standard addition method was then used for the quantitative determination of five pyrazines (2-methylpyrazine, 2,3-dimethylpyrazine, 2,5-dimethylpyrazine, 2,3,5-trimethylpyrazine and tetramethylpyrazine). Satisfactory figures of merit were obtained: Limits of quantitation were in the range 0.1-2.7 ng/g; repeatability and reproducibility varied between 3% and 7% and between 8% and 14%, respectively. The total content of the pyrazines was remarkably different in the considered samples, ranging from 99 to 708 ng/g. Tetramethylpyrazine showed the highest concentration in all samples, with a maximum value of 585 ng/g. A preliminary study was also performed on the nonvolatile fraction using LC-MS/MS, identifying some flavanols such as catechin, epicatechin and procyanidins. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

BACKGROUND: Coconut ( Cocos nucifera L.) water is a refreshing tropical drink whose international market has recently been growing. However, little is yet known about its physicochemical composition, particularly its aroma. This study set out to characterise the volatile profile of water from five coconut varieties. RESULTS: Aroma compounds were characterised by headspace solid phase microextraction gas chromatography (HS-SPME-GC) analysis. An experimental design was established to optimise SPME conditions, leading to an equilibration time of 10 min followed by an extraction time of 60 min at 50 °C. Accordingly, immature coconut water from WAT (West African Tall), PB121 (MYD × WAT Hybrid), MYD (Malayan Yellow Dwarf), EGD (Equatorial Guinea Green Dwarf) and THD (Thailand Aromatic Green Dwarf) palms was analysed and described. Ketones were mainly present in the Tall and Hybrid varieties, whereas aldehydes were most abundant in the Dwarf palms. Tall coconut water was characterised by a high lactone content. THD exhibited a high ethyl octanoate level. The cluster analysis of the volatile fraction from the five coconut cultivars was found to be related to their genetic classification. CONCLUSION: The volatile compounds of immature coconut water from five varieties were characterised for the first time. Volatile profile analysis could be a useful tool for the selection of Dwarf coconut varieties, which are mainly consumed as a beverage. Copyright © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Fast, reliable, and inexpensive analytical techniques for detection of airborne chemical warfare agents are desperately needed. Recent advances in the field of molecularly imprinted polymers have created synthetic nanomaterials that can sensitively and selectively detect these materials in aqueous environments, but thus far, they have not been demonstrated to work for detection of vapors. The imprinted polymers function by mimicking the function of biological receptors. They can provide high sensitivity and selectivity but, unlike their biological counterparts, maintain excellent thermal and mechanical stability. The traditional imprinted polymer approach is further enhanced in this work by the addition of a luminescent europium that has been introduced into the polymers to provide enhanced chemical affinity as well as a method for signal transduction to indicate the binding event. The europium in these polymers is so sensitive to the bound target; it can distinguish between species differing by a single methyl group. The imprinted polymer technology is fiber optic-based making it inexpensive and easily integratable with commercially available miniature fiber optic spectrometer technologies to provide a shoebox size device. In this work, we will describe efforts to apply these sensors for detection of airborne materials and vapors. Successful application of this technology will provide accurate low level vapor detection of chemical agents or pesticides with little to no false positives. Published 2012. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

The high level of PUFA in fish oil, primarily eicosapentaenoic acid (EPA) and DHA result in rapid oxidation of the oil. Current methods used to assess oxidation have little correlation with sensory properties of fish oils. Here we describe an alternative method using solid phase microextraction (SPME) combined with GC-MS to monitor volatile oxidation products. Stepwise discriminant function analysis (DFA) was used to classify oils characterized as acceptable or unacceptable based on sensory analysis; a cross-validated success rate of 100% was achieved with the function. The classification function was also successfully validated with tasted samples that were not used to create the method. A total of 14 variables, primarily aldehydes and ketones, were identified as significant discriminators in the classification function. This method will be useful as a quality control method for fish oil manufacturers. Practical applications: This paper describes an analytical method that can be used by fish oil manufacturers for quality control purposes. Solid phase microextraction and GC-MS were used to monitor volatile oxidation products in fish oil. These data, combined with results of analyses by a sensory panel, were used to create a function that classified fish oil samples as acceptable or unacceptable. The volatile oxidation products used to in the function were primarily aldehydes and ketones. This method can be used by fish oil manufacturers as an alternative to expensive sensory panels. [ABSTRACT FROM AUTHOR]

A fully automated combination of solid-phase microextraction and on-fiber derivatization coupled with gas chromatography-mass spectrometry was developed to determine 17 chlorophenols in aqueous samples. Optimal parameters for the automated process, such as fiber coating (polyacrylate), derivatization reagent ( N,O-bis(trimethylsilyl) trifluoroacetamide), extraction time (60 min), derivatization time (5 min), incubation temperature (35°C), sample pH (3), and ionic strength (300 g L−1 of NaCl), as well as desorption time (5 min) and desorption temperature (270°C) were established. The whole procedure took only 90 min and was performed automatically. The shortcomings of silylation derivatives, like incompleteness and instability, were overcome by using solid-phase microextraction on-fiber silylation in this study. The results from both pure water and river water samples showed that the method had a good linearity ( r2 = 0.9993-1.0000), ranging from 0.01 to 100 μg L−1. The related standard deviations were between 3.6 and 10.0%. The limits of detections and qualifications ranged from 0.03 to 3.11 ng L−1 and 0.09 to 10.4 ng L−1 for the CPs, respectively. The proposed method is superior to traditional solid phase extraction procedure. [ABSTRACT FROM AUTHOR]

The hydrocarbons 1,7-hexadecadiene (1,7-C16:2) and 8-heptadecene (8-C17:1), which are used as markers for identifying irradiated chilled beef, were easily detectable in chilled beef irradiated at 0.5 kGy or higher by using a new method of headspace solid-phase microextraction, gas chromatography and mass spectrometry (HS-SPME–GC–MS). The conditions for using SPME were optimized in this study for qualitative and quantitative determination of 1,7-C16:2 and 8-C17:1 produced by γ-radiation in chilled beef. The relationship between irradiation dose and production of hydrocarbons was also studied, which showed good linear correlation with the coefficients of 0.9942 and 0.9943 for 1,7-C16:2 and 8-C17:1, respectively. HS-SPME–GC–MS is a simple and sensitive method for the analysis of hydrocarbons in irradiated chilled beef. [ABSTRACT FROM AUTHOR]

Array-based gas sensors now offer the potential of a robust analytical approach to odor measurement for medical use. We are developing a fast reliable method for detection of microbial infection by monitoring the headspace from the infected wound. In this paper, we present initial results obtained from wound-state monitoring for burn patients using an electronic nose incorporating an automated solid-phase microextraction (SPME) desorption system to enable the system to be used for clinical validation. SPME preconcentration is used for sampling of the headspace air and the response of the sensor module to variable concentrations of volatiles emitted from SPME fiber is evaluated. Gas chromatography-mass spectrometry studies prove that living bacteria, the typical infectious agents in clinical practice, can be distinguished from each other by means of a limited set of key volatile products. Principal component analysis results give the first indication that infected patients may be distinguished from uninfected patients. Microbial laboratory analysis using clinical samples verifies the performance of the system. [ABSTRACT FROM AUTHOR]