Headspace Solid-phase Microextraction Coupled To Gas Chromatography Mass Spectrometry Research Articles

Quality evaluation of four Ferula plants and identification of their key volatiles based on non-targeted metabolomics.

Ferula is a traditional, edible, and important medicinal plant with high economic value. The distinction between edible and non-edible Ferula remains unclear. In this study, headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME/GC-MS) and ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) non-targeted metabolomics techniques were used to systematically and comprehensively analyse secondary metabolites in the leaves and roots of four species of Ferula, considering their edibility. A total of 166 leaf volatile organic compounds (VOCs) and 1,079 root metabolites were identified. Additionally, 42 potential VOCs and 62 differential root metabolites were screened to distinguish between edible and non-edible Ferula. Twelve volatile metabolites were specific to F. feurlaeoides, and eight compounds were specific to the three edible Ferula species. The results showed that compounds containing sulphur, aldehydes, and ketones, which produce pungent odours, were the primary sources of the strong odour of Ferula. The root differential metabolites include 13 categories, among which the high concentration group is organic acids, amino acids, terpenoids and fatty acids. The bioactive metabolites and VOCs in the roots exhibited species-specific characteristics. VOCs with various odors were linked to the distribution of root metabolites in both edible and non-edible Ferula plants. The screened root markers may contribute to the formation of characteristic VOCs. This study identified the difference in flavour between edible and non-edible Ferula plants and, for the first time, demonstrated the contribution of the efficacy of Ferula root to the unique flavour of the above-ground parts of Ferula. These results provide a theoretical basis for selecting Ferula for consumption and help evaluate the quality of different species of Ferula. Our findings may facilitate food processing and the further development of Ferula.

The impact of dosage sugar-type and aging on Maillard reaction-associated products in traditional method sparkling wines

Liqueur d’expedition (dosage) is a final sugar addition made to sparkling wine which determines the sweetness and balance of the finished product. In the present study, the influence of dosage sugar composition on Maillard reaction-associated products and precursors in traditional method (bottle-fermented) sparkling wines was evaluated over 18-months of storage in climate-controlled cellar conditions (14 °C, 70 % relative humidity). Evaluated dosage sugar-types included glucose, fructose, cane-derived sucrose, beet-derived sucrose, maltose, and Must Concentrate Rectified (MCR) Sucraisin®, which were compared to a zero dosage (no sugar added) control. Maillard reaction-associated products were quantified by headspace solid-phase microextraction coupled to gas-chromatography-mass spectrometry (HS-SPME-GC/MS), and precursors including sugars and amino acids, were measured by enzymatic assay and proton (1H) nuclear magnetic resonance (NMR) spectroscopy, respectively. Partial least squares discriminant analysis (PLS-DA) was used to effectively discriminate between wines based on aging duration but did not adequately separate wines treated with different dosage sugar-types. Decreases in alanine and glycine were observed after 18-months of cellar aging, suggesting that Maillard reaction product formation may be partially related to their depletion. Benzaldehyde and ethyl-3-mercaptopropionate were identified as discriminatory Maillard reaction-associated compounds when comparing 0- and 18-month aged wines, with benzaldehyde increasing and ethyl-3-mercaptopropionate decreasing over the aging period. This research contributes to an increased understanding of Maillard reaction pathways in the unique low-temperature and low pH sparkling wine matrix and establishes the relatively greater effect of aging duration compared to dosage sugar-type on the formation of Maillard reaction-associated products. The combined application of HS-SPME-GC/MS and 1H NMR based metabolomics presents new insights into the chemical composition of sparkling wines during aging.

Headspace Solid-Phase Microextraction: A Useful and Quick Tool for the Traceability and Quality Assessment of Wine Cork Stoppers

Natural cork remains a favored option for sealing high-quality wine bottles, despite its high cost for wineries. The cork industry faces the challenge of certifying the quality and traceability of these corks, with physical–chemical characterization being a valuable tool in establishing these parameters. While cork taint compounds must be absent or in low concentrations, the volatile fraction of cork contains numerous compounds that, even in small amounts, can impact the wine’s final aroma. Moreover, these volatile compounds are indicative of the geographical origin of the cork planks used to make the stoppers. In this work, a total of 68 volatile compounds (alkanes, terpenes, benzenic compounds, aldehydes, ketones, acids, esters, alcohols and furanic and pyranic compounds) from natural corks of different qualities and origins were identified, using a fast and sensitive technique: headspace solid-phase microextraction coupled to gas chromatography–mass spectrometry (HS-SPME-GC-MS). Based on these volatile compounds, it was possible to establish differences between corks of different origins, although no discernible differences were detected in the samples of differing visual qualities, as this is a subjective parameter largely dependent on the cork’s external appearance. These findings show that the analysis of the volatile composition of corks via HS-SPME-GC-MS can be used as a quick tool for tracking their traceability and selecting the most appropriate parameters at each stage of processing to minimize the increase in unwanted compounds.

Monitoring the Evolution of the Aroma Profile of Lager Beer in Aluminium Cans and Glass Bottles during the Natural Ageing Process by Means of HS-SPME/GC-MS and Multivariate Analysis

Headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME/GC-MS), sensory evaluation, and multivariate analysis were applied to monitor and compare the evolution of the aromatic profile of a lager beer in different types of containers (aluminum cans and glass bottles) during the natural ageing process. Samples were aged naturally for a year in the absence of light with a controlled temperature of around 14 °C +/- 0.5 °C. The sensory evaluation applied was a blind olfactometric triangle test between canned and bottled samples at different periods of aging: fresh, 6 months, and 11 months. The sensory evaluation showed that the panelists were able to differentiate between samples, except for the fresh samples from the brewery. A total of 34 volatile compounds were identified using the HS-SPME/GC-MS technique for both packaging types in this experiment. The application of multivariate analysis to the GC-MS data showed that the samples could not be differentiated according to the type of packaging but could be differentiated by the ageing time. The results showed that the combination of sensory, HS-SPME-GC-MS, and multivariate analysis seemed to be a valuable tool for monitoring and identifying possible changes in the aroma profile of a beer during its shelf life. Furthermore, the results showed that storing beer under optimal conditions helped preserve its quality during its shelf life, regardless of the type of packaging (aluminum can and glass bottle).

Machine Learning Algorithms Applied to Semi-Quantitative Data of the Volatilome of Citrus and Other Nectar Honeys with the Use of HS-SPME/GC-MS Analysis, Lead to a New Index of Geographical Origin Authentication.

The scope of the current study was to monitor if semi-quantitative data of volatile compounds (volatilome) of citrus honey (ch) produced in different countries could potentially lead to a new index of citrus honey authentication using specific ratios of the identified volatile compounds in combination with machine learning algorithms. In this context, the semi-quantitative data of the volatilome of 38 citrus honey samples from Egypt, Morocco, Greece, and Spain (determined by headspace solid phase microextraction coupled to gas chromatography mass spectrometry (HS-SPME/GC-MS)) was subjected to supervised and unsupervised chemometrics. Results showed that honey samples could be classified according to the geographical origin based on specific volatile compounds. Data were further evaluated with additional nectar honey samples introduced in the multivariate statistical analysis model and the classification results were not affected. Specific volatile compounds contributed to the discrimination of citrus honey in different amounts according to geographical origin. These were lilac aldehyde D, dill ether, 2-methylbutanal, heptane, benzaldehyde, α,4-dimethyl-3-cyclohexene-1-acetaldehyde, and herboxide (isomer II). The numerical data of these volatile compounds was summed up and divided by the total semi-quantitative volatile content (Rch, Karabagias-Nayik index) of citrus honey, according to geographical origin. Egyptian citrus honey had a value of Rch = 0.35, Moroccan citrus honey had a value of Rch = 0.29, Greek citrus honey had a value of Rch = 0.04, and Spanish citrus honey had a value of Rch = 0.27, leading to a new hypothesis and a complementary index for the control of citrus honey authentication.

Effect of Hop β-Acids Extract Supplementation on the Volatile Compound Profile of Roasted Chicken Meat

The increased interest in greener sources of antioxidants has spurred the research on natural alternatives to enhance poultry production. This study aimed to investigate the effects of natural antioxidant extracts’ (hop β-acids extract) diet supplementation at different concentrations (0, 30, 60, and 120 mg kg−1) on the volatile compound profile of roasted chicken meat. A method based on headspace solid-phase micro-extraction coupled to gas chromatography-mass spectrometry (HS-SPME-GC-MS) was optimized by response surface design to extract the volatile compounds. The optimum extraction conditions were 80 °C and 45 min. A total of 95 volatile compounds were identified in roasted chicken meat, especially aldehydes, alkanes, alcohols, esters, and pyrazines. Principal component analysis (PCA) separated the samples as a function of β-acid supplementation, indicating that increased levels of supplementation lead to distinct volatile profiles in roasted chicken meat. Aldehydes such as octanal and hexanal (8.94% and 17.63%, respectively, for 30 mg kg−1 treatment) played an important role in distinguishing the samples. Those compounds are the main oxidation products of unsaturated fatty acids, which are possibly protected by the antioxidant properties of hop β-acid extracts. Some other compounds with odoriferous importance detected for this level of supplementation were: 2,6-dimethyl pyrazine (5.12%), 2-pentylfuran (2.94%), and 1-octen-3-ol (1.88%). This study significantly contributes to the elucidation of the impact of hops β-acids supplementation in the chicken meat aroma profile, opening new venues for its potential application.

HS-SPME-GC-MS combined with chemometrics to assess the impact of germination, dehulling, and milling on flavor attributes of brown and green lentils (Lens culinaris subsp. culinaris)

The volatile profiles of raw, dehulled, and germinated seeds and flours of green and brown lentils ( Lens culinaris subsp. culinaris ) were assessed using headspace solid-phase micro-extraction coupled to gas chromatography-mass spectrometry (HS-SPME-GS-MS). The total identification percentages of the extracted volatiles ranged between 96.3% and 99.8%. Fifty-five aroma compounds were detected and, among them, 42 were determined in the emission of whole legume seeds and 37 from legume flours; they were classified in seven chemical classes, including monoterpene hydrocarbons (MH), oxygenated monoterpenes (OM), sesquiterpene hydrocarbons (STH), phenylpropanoids (PP), apocarotenes (AC), non-terpene derivatives (NTD), nitrogen/sulfur derivatives (NSD). OM volatiles increased during the germination process in both cultivars, while MH decreased significantly. In raw and germinated seeds and flours, the most representative class was NTD, except for germinated green flour (GGF), which emitted much more STH. Besides, milling the seeds resulted in an increase of MH (except for GGF), OM (except for GGF and germinated brown flour GBF ), STH, and PP and a decrease of NTD. The beany flavors associated with the volatile components increased because of germination and milling. Significant differences in the volatile profiles of the cultivars and their flours were evidenced due to the type of cultivar and processing conditions. This information may be of interest to industries involved in the development of specific pulse-based food product. • The aroma compounds of two lentil cultivars were evaluated using HS-SPME-GC-MS. • Effect of dehulling, germination, and milling on volatiles were assessed. • 55 emmited volatiles, which are divided into seven chemical groups, were detected. • A wide difference in the emission profiles of whole seeds and flours was observed. • This is useful in the conception of legume-based ingredients related to specific aroma.

New Biodegradable Mulching Films for Strawberry (Fragaria × Ananassa Duch.): Effects on the Volatile Profiles of the Fruit

The effects of mulching films on the profiles of volatile organic compounds (VOCs) from two strawberry cultivars, namely Elide and Sabrina, were evaluated by headspace solid-phase micro-extraction coupled to gas chromatography mass spectrometry (HS-SPME/GC-MS). Strawberries were grown on two biodegradable mulching films, named N5 and N18, in comparison to black polyethylene (PE). PCA models, separately performed on the VOCs dataset of the two cultivars, showed that the observations for each of the three mulching films lie in corresponding regions of the PCA plot, suggesting that the mulching films represented the main source of data variation, and hence, the variability of the VOCs profile induced by the mulching films overcame the cv-related one. For both the cultivars, a higher number of VOCs with a positive impact on the “sweet” taste sensation and consumers’ preference were positively correlated with strawberries produced on the biodegradable films compared to PE. However, there was an interaction between the type of cultivar and the mulches, as Elide responded better to N18 and N5 mulching films, while Sabrina responded better only to N18. Altogether, these results could contribute to assessing the effects of mulching type on putative volatile markers of the desirable sensory perception and consumers’ acceptability of strawberries.

Migration of mineral oil aromatic hydrocarbon (MOAH) from hot melt adhesives used in food packaging materials

This article studies the migration of MOAH from hot melt adhesives used in multilayer laminates into food simulants. First, the initial concentration of a group of compounds selected as MOAH markers in several adhesives was determined by headspace solid phase microextraction coupled to gas chromatography mass spectrometry (HS-SPME-GC-MS), using the previously optimised method. Then, the migration of the MOAH fraction and MOAH markers from the laminates was studied. The MOAH fraction was analysed by gas chromatography with flame ionisation detection (GC-FID), and the MOAH markers were analysed by HS-SPME-GC-MS. Twelve MOAH markers were detected, and their initial concentrations were between 0.46 and 33.8 μg g-1. Only eight were identified after migration, ranging between 0.62 and 21.33 μg dm-2, with a migration percentage of 12–75%. The fraction of MOAH that migrated eluted mainly in the C16-C25 range and reached concentrations of 19.65 μg dm-2 from the laminate.

Rapid and Non-Destructive Techniques for the Discrimination of Ripening Stages in Candonga Strawberries.

Electronic nose (e-nose), attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy and image analysis (IA) were used to discriminate the ripening stage (half-red or red) of strawberries (cv Sabrosa, commercially named Candonga), harvested at three different times (H1, H2 and H3). Principal component analysis (PCA) performed on the e-nose, ATR-FTIR and IA data allowed us to clearly discriminate samples based on the ripening stage, as in the score space they clustered in distinct regions of the plot. Moreover, a correlation analysis between the e-nose sensor and 57 volatile organic compounds (VOCs), which were overall detected in all the investigated fruit samples by headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME/GC-MS), allowed us to distinguish half-red and red strawberries, as the e-nose sensors gave distinct responses to samples with different flavours. Three suitable broad bands were individuated by PCA in the ATR-FTIR spectra to discriminate half-red and red samples: the band centred at 3295 cm−1 is generated by compounds that decline, whereas those at 1717 cm−1 and at 1026 cm−1 stem from compounds that accumulate during ripening. Among the chemical parameters (titratable acidity, total phenols, antioxidant activity and total soluble solid) assayed in this study, only titratable acidity was somehow correlated to ATR-FTIR and IA patterns. Thus, ATR-FTIR spectroscopy and IA might be exploited to rapidly assess titratable acidity, which is an objective indicator of the ripening stage.

A comparative HS-SPME/GC-MS-based metabolomics approach for discriminating selected japonica rice varieties from different regions of China in raw and cooked form

Japonica rice is widely planted in different regions of China. Rice of different geographical origins may have substantially different economic values. In this study, An untargeted metabolomics based approach using headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME/GC-MS) was applied to distinguish 27 japonica rice varieties originated from South, Northern and Northeastern China in raw and cooked form, respectively. Orthogonal partial least-squares discriminant analysis (OPLS-DA) models exhibited good geographic discrimination. Sixteen and twenty-two volatiles were selected as the discriminant markers in raw and cooked rice, respectively. However, only hexanal, 3,5-octadien-2-one and 2-butyl-2-octenal were selected both in raw and cooked rice. Markers in raw rice mainly involved in terpenes, lipoxygenases, indole, and shikimate and benzoic acid pathways. Markers in cooked rice were mainly derived from lipid oxidation. The results provided a deeper understanding of volatiles variation of rice in China from different geographic origins.

Restoring trilinearity with the purpose of advanced modeling: towards a more effective analysis of Pericarpium Citri Reticulatae during storage periods

To accurately quantify Pericarpium Citri Reticulatae samples, trilinear structure was restored in the stacked fingerprints for more robust modeling. Initially, liquid chromatography - diode array detector - mass spectrometry (LC-DAD-MS) and head space-solid phase micro extraction coupled to gas chromatography - mass spectrometry (HS-SPME/GC-MS) were utilized to analyze Pericarpium Citri Reticulatae. Faced with the time-shifts in two-dimensional (2D) matrices across different samples, three algorithms were developed to synchronize them. Furthermore, bilinear and trilinear models were used to realize the quantifications with different principles. Through real cases based on LC-DAD, the advantages and disadvantages of trilinear decomposition over multivariate curve resolution-alternating least-squares can be clarified in the quantification of raw or synchronized fingerprints. Also in the data processing, a modification version of multi-scale peak alignment (mMSPA) was proved to be more suitable for trilinearity restoring than the other two algorithms. Recognizing these facts, restoring trilinearity were developed for more robust modeling in the application of the Pericarpium Citri Reticulatae fingerprints from different storage periods. After effective analysis, the upward/downward trend of 13 flavonoids were drawn accurately; and several flavour components having the highest contribution rate during storage were outlined reasonably. In conclusion, more robust modeling can be realized in trilinear data synchronized by appropriate algorithms, leading to an accurate quantification in herbal quality researches.

Comprehensive Evaluation of the Volatomic Fingerprint of Saffron from Campania towards Its Authenticity and Quality.

The volatile profiles of eight saffron samples (seven cultivated and one spontaneous) grown in different geographical districts within the Campania region (southern Italy) were compared. Using headspace solid-phase microextraction coupled to gas chromatography–mass spectrometry (HS-SPME/GC-MS), overall, 80 volatiles were identified in the eight landraces. Among them, safranal and its isomers and other related compounds such as isophorones, which are not only key odorants but also pharmacologically active metabolites, have been detected in all the investigated samples. Principal Component Analysis performed on the volatiles’ compounds revealed that the spontaneous sample turned out to be an outlier. In particular, the volatile organic compounds (VOCs) profile of the spontaneous saffron presented four lilac aldehydes and four lilac alcohol isomers, which, to the authors’ knowledge, have never been identified in the volatile signature of this spice. The multivariate statistical analysis allowed the discrimination of the seven cultivate saffron ecotypes in four well-separated clusters according to variety. Moreover, 20 VOCs, able to differentiate the clusters in terms of single volatile metabolite, were discovered. Altogether, these results could contribute to identifying possible volatile signature metabolites (biomarkers) or patterns that discriminate saffron samples grown in Campania region on a molecular basis, encouraging future biodiversity programs to preserve saffron landraces revealing valuable genetic resources.

Comprehensive Metabolome and Volatilome Analyses in Eggplant and Tomato Reveal Their Differential Responses to Tuta absoluta Infestation.

The South American tomato pinworm, Tuta absoluta, is one of the most destructive insect pests in Solanaceae crops, particularly in tomatoes. Current methods of management have proven somewhat effective but still require a more efficacious management strategy to limit its havoc on crop yield. Tomato is much more predisposed to T. absoluta as compared with other plants such as eggplants, but the underlying causes have not been fully determined. We conducted this study to unravel the volatile organic compounds (VOCs) and primary/secondary metabolites that account for the differential response of tomatoes and eggplants to T. absoluta infestation. We performed widely targeted comparative metabolome and volatilome profiling by ultraperformance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) and headspace solid-phase microextraction coupled to gas chromatography–mass spectrometry (HS-SPME/GC-MS), respectively, on eggplants and tomatoes under control and T. absoluta infestation conditions. Overall, 141 VOCs and 797 primary/secondary metabolites were identified, largely dominated by aldehyde, alcohols, alkanes, amine, aromatics, a heterocyclic compound, ketone, olefin, phenol, and terpenes. Most of the VOCs and primary/secondary metabolites from the terpene class were largely differentially regulated in eggplants compared with tomatoes. Eggplants emitted several compounds that were lower or completely absent in tomatoes either under control conditions or after T. absoluta infestation. The results from an electroantennogram showed that 35 differentially accumulated VOCs could elicit female T. absoluta response, implying that these volatile compounds significantly alter the behavior of this pest. These findings demonstrated that differentially accumulated metabolites and volatile compounds play major roles in eggplant resistance to T. absoluta infestation as these compounds were regulated upon attack by T. absoluta. Our findings can assist in integrated pest management efforts by developing appropriate control measures against T. absoluta in Solanaceae production.

Tangerines Cultivated on Madeira Island-A High Throughput Natural Source of Bioactive Compounds.

Tangerines (Citrus reticulata) are popular fruits worldwide, being rich in many bioactive metabolites. The setubalense variety cultivated on Madeira Island has an intense aroma easily distinguishable from other tangerines, being traditionally used to enrich several foods and beverages. Nonetheless, setubalense volatile composition has never been characterized, and we aimed to unveil the bioactive potential of peels and juices of setubalense tangerines and compare them with the murcott variety grown in Portugal mainland. Using headspace solid-phase microextraction coupled to gas chromatography mass spectrometry (HS-SPME/GC-MS), we identified a total of 128 volatile organic metabolites (VOMs) in the juice and peels, with d-limonene, γ-terpinene, β-myrcene, α- and β-pinene, o-cymene, and terpinolene, the most dominant in both cultivars. In contrast, setubalense juices are richer in terpenes, many of them associated with health protection. Discriminant analysis revealed a pool of VOMs, including β-caryophyllene and E-ocimene, with bioactive properties able to differentiate among tangerines according to variety and sample type (peel vs. juice). This is the first report on the volatile composition of setubalense tangerines grown on Madeira Island revealing that its pungent aroma is constituted by secondary metabolites with specific aroma notes and health properties. This is strong evidence of the higher nutraceutical value of such fruit for the human diet.

Analysis of volatile compounds in Paracentrotus lividus by HS-SPME/GS-MS and relation to its sensorial properties

This study characterizes the sensory features and odour active volatile organic compounds (VOC) profile of P. lividus, taking into consideration the sex and harvest location. Sensory evaluation was performed by an experienced panel through the application of Projective Mapping paired with Ultra Flash Profile. VOC were determined by headspace solid-phase microextraction coupled to gas chromatography mass spectrometry (HS-SPME/GC-MS). Data showed that sea urchin gonad's sensory properties were mainly influenced by sex, while their volatile profile was affected both by sex and harvest location. Males tended to be sweeter, softer and with a pale-yellow colour, while females revealed an intense sweet tropical taste and a bright-orange colour. PCA unveiled variations in the levels of p-xylene, 1,2,4-trimethylbenzene and m-xylene between locations, whereas levels of β-pinene, 2,4-dimethyl-1-heptene, d-limonene and heptane discriminate sex. This study contributes to a better characterization of the sensory profile of sea urchin gonads aiming the selection of premium gonads.

Use of Lactobacillus paracasei strain for zearalenone binding and metabolization

The study investigated the zearalenone (ZEA) neutralization process as a consequence of metabolization and binding process by the probiotic bacterial strain Lactobacillus paracasei using high performance liquid chromatography (HPLC). In order to determine the nature of the binding process the kinetic and spectroscopic approach were used. Moreover, the influence of ZEA on L. paracasei metabolism was examined by the determination of the proteome profile of cells and the profile of volatile compounds (VOCs) produced by bacteria cells. For this purpose the Matrix-Assisted Laser Desorption/Ionization-Time of Flight mass spectrometry (MALDI-TOF MS) and headspace solid-phase microextraction coupled to gas chromatography/mass spectrometry (HS-SPME/GC-MS) techniques were used. The obtained results indicate that in the mechanism of ZEA neutralization both – metabolization/biotransformation and binding/biosorption processes are involved. Furthermore, the biotransformation of ZEA to both α- and β-ZOL with a predominance of β-ZOL by lactic acid bacteria strain was recorded. The results suggest that the tested microorganism can be used as a potential detoxification agent for grain and feed.

Phosphine fumigation – Time dependent changes in the volatile profile of table grapes

Industrial and agricultural goods are fumigated in transport containers in order to control pest infestations and to avoid the transmission of alien species. Phosphine is increasingly used prior to the export as fumigant for table grapes, fruit cultures and dried fruits to control active table grapevine insect pests. Less knowledge exists for fumigants about the desorption time of toxic gases and factors that affect the composition of the fumigated good. Therefore, red and white table grapes (´Thompson seedless´, ´Scarlotta´ and ´Flame seedless´) were chosen to represent the allowed group of phosphine fumigated foods and were treated with a concentration of 2000 vpm phosphine (PH3) at different temperatures. In the present study, sorption and desorption behavior of PH3 by table grapes and possible changes in their VOC (volatile organic compounds) profiles were investigated. The PH3 concentration was monitored before and after the fumigation process and was determined under the maximum residue level 0.005 ppm after 35 days. The adsorbed amount of PH3 was not influenced by fumigation parameters. For analysis of the influences on the volatile profile after fumigation, a headspace solid-phase micro-extraction coupled to gas chromatography mass spectrometry (HS-SPME-GC/MS) was used. Small differences in volatile profiles of fumigated and subsequently outgassed table grapes compared to non-fumigated table grapes could be observed. A slight influence on the aldehyde group directly after fumigation could be perceived by a decrease of hex-2-en-1-ol and 1- hexanol in PH3-treated table grapes. The concentrations of both compounds increase again after completion of the desorption process. On the other hand terpenes are not significantly influenced by the fumigation process. Overall these changes are likely to affect table grape aroma characteristics directly after a treatment with PH3 and it could be demonstrated that phosphine alters the volatile profile of fumigated table grapes qualitatively and quantitatively.

The influence of different closures on volatile composition of a white wine

Abstract The impact of different closures on wine volatile composition was assessed by headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME-GC/MS) analysis of a white wine. The sealing systems studied comprised 1 + 1 cork, microagglomerated cork and synthetic closures. A descriptive sensory analysis and measurement of some oenological parameters were also performed. The main differences on wine volatile profile were observed between cork and synthetic closures, comprising statistically significant alterations in the levels of six volatile compounds. Two compounds, namely 2,4-di-tert-butylphenol and trans-4-tert-butylcyclohexanol, were identified for the first time, to our knowledge, in wines sealed with synthetic closures and a microagglomerated cork, respectively. In addition, the sensory analysis of wine sealed with cork stoppers unveiled highest scores in aroma intensity, aroma quality and balance. On the other hand, wine sealed with synthetic closures were described with oxidative sensory attributes, lowest levels of SO2 and highest colour intensity.

Monitoring of Bactericidal Effects of Silver Nanoparticles Based on Protein Signatures and VOC Emissions from Escherichia coli and Selected Salivary Bacteria.

Escherichia coli and salivary Klebsiella oxytoca and Staphylococcus saccharolyticus were subjected to different concentrations of silver nanoparticles (AgNPs), namely: 12.5, 50, and 100 µg mL−1. Matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry (MALDI-TOF MS) spectra were acquired after specified periods: 0, 1, 4, and 12 h. For study of volatile metabolites, headspace solid-phase microextraction coupled to gas chromatography/mass spectrometry (HS-SPME-GC-MS) was employed—AgNPs were added to bacteria cultures and the headspace was analyzed immediately and after 12 h of incubation. Principal components analysis provided discrimination between clusters of protein profiles belonging to different strains. Canonical correlation, network analysis, and multiple linear regression approach revealed that dimethyl disulfide, dimethyl trisulfide, 2-heptanone, and dodecanal (related to the metabolism of sulfur-containing amino acids and fatty acids synthesis) are exemplary molecular indicators, whose response variation deeply correlated to the interaction with bacteria. Therefore, such species can serve as biomarkers of the agent’s effectiveness. The present investigation pointed out that the used approaches can be useful in the monitoring of response to therapeutic treatment based on AgNPs. Furthermore, biochemical mechanisms enrolled in the bactericidal action of nanoparticles can be applied in the development of new agents with enhanced properties.