Novel eco-friendly methodology to determine polycyclic aromatic hydrocarbons in polyurethane foam for air monitoring: Application to spatial and temporal distribution survey.

This study aimed at developing a new method for the extraction of polycyclic aromatic hydrocarbons (PAHs) in polyurethane foam (PUF). In the field of PAH monitoring, passive samplers using PUF disks are widely used. However, current extraction methods are time and solvent consuming. This new method employs 3 times a sixteenth of the PUF disk, with method detection limits (MDL) values below 5 and 13 ng/sampler for 3- and 4-rings PAHs, respectively. The use of only parts of the disk allows extraction by ultrasounds using exclusively 120 mL of ethanol, making it environmentally friendly. Ethanolic extracts are then purified and concentrated using microextraction by packed sorbent (MEPS) before GC-MS analyses. This method was applied for an environmental survey in a French urban area with an oceanic climate. Variations in PAH concentrations were observed depending on the site studied (urban, traffic, periurban and rural), as well as temporal variations.

Phages Shape Microbial Dynamics and Metabolism of a Model Community Mimicking Cider, a Fermented Beverage.

Model microbial communities are often studied to better understand interactions and fluxes during fermentation processes. However, models that take into account the potential impact of bacteriophages (phages), which are recognized as drivers of microbial communities, are scarce, especially in fermented foods. This study aimed at investigating the behavior of a cider model microbial community, which was subjected to disturbance in the presence or absence of phages and at two different temperatures (25 °C and 15 °C). The model microbial community was composed of three lactic acid bacteria (LAB) strains belonging to the species Liquorilactobacillus mali, Leuconostoc mesenteroides and Oenococcus oeni, and of a Saccharomyces uvarum yeast strain. Two phages were selected, targeting L. mali and Ln. mesenteroides strains. In order to follow the behavior of the microbial community model, the phages and microbial strains were enumerated at several time points, and the metabolic signatures (sugar consumption, production of organic acids and volatile organic compounds) of the model microbial community were monitored. At 25 °C, the community with phages (P) was significantly closer to the control condition (C) than to the condition without phages (D). Microbial levels were similar between conditions C and P, which were characterized by high concentrations of compounds such as 2-phenylethanol, ethyl octanoate and isoamyl alcohol, and more globally by a more complex metabolic signature than that of condition D. In condition D, L. mali and Ln. mesenteroides were dominant while S. uvarum and O. oeni were less present, and this condition was characterized by a high concentration of ethyl lactate. At 15 °C, condition P differed from conditions C and D, as Ln. mesenteroides was not detected while the other strains all reached approximately the same levels. The metabolic range of condition P was less important than for conditions C and D. The current study showed that the influence of phages on the model microbial community dynamics and metabolisms after a disturbance phenomenon was temperature-dependent.

Air Mapping of Polycyclic Aromatic Hydrocarbons and Their Uptake by Crops in the Urban Area of Nice, France.

Urban gardening is becoming increasingly popular. Air pollution, which is a major concern in cities might, however, threaten food safety and thus must be assessed. Health risks arise particularly from toxic persistent organic pollutants such as Polycyclic Aromatic Hydrocarbons (PAHs) which are formed by incomplete combustion. A first assessment of crop contamination in two different atmospheric environments in the urban area of Nice reveals a predominance of light PAHs. These pollutants present in the gaseous phase, seem to bioaccumulate while heavy PAHs are absent in vegetation. By understanding the PAH sources and their behavior in the atmosphere but also by analyzing the spatial and temporal data since the European directive in 2004, a link between concentrations found in vegetables grown in experimental gardens and PAH cadastral emission data is presented. The first results could be used as a possible guidance for urban agriculture.

Impact of biomass combustion on occurrence and distribution of aromatic hydrocarbons in apples.

Forest fires and biomass burning are known to generate aromatic hydrocarbons via incomplete combustions, due to high moisture, insufficient temperature, and oxygen content. These emission sources are particularly concerning because generated smokes cannot be treated and aromatic hydrocarbons can deposit on plant foods.The aim of this work was to study the potential deposition and absorption of monocyclic and polycyclic aromatic hydrocarbons in plant after exposure to smokes generated by burning wood. Thus, apples, used as a representative plant food model, were intentionally exposed to wood burning emissions for lengths of time varying from 1 to 2 h. Among benzene, toluene, ethylbenzene, xylenes, toluene appeared to be the most abundant compound. Concerning PAHs, linden wood combustion led to predominant deposition of compounds with molecular weights lower than 202 g/mol with the highest levels detected for phenanthrene.Aromatic hydrocarbons from wood combustion were mainly deposited on apple epicarp, and their transfer to the mesocarp was limited. Diagnostic ratio, used for the determination of PAHs emission source, was calculated with PAHs contents deposited on apple skin. Results were consistent with values proposed in the literature for the identification of biomass combustion.

Oxy-PAHs: occurrence in the environment and potential genotoxic/mutagenic risk assessment for human health.

Structurally modified polycyclic aromatic hydrocarbons (PAHs) such as nitrated PAHs (nitro-PAHs) and oxygenated PAHs (oxy-PAHs) can be incriminated in the total toxicity of polycyclic aromatic compounds (PACs) fraction in the environment. Compared to nitro-PAHs, oxy-PAHs have been poorly studied. Oxy-PAHs covers compounds with different moieties such as polycyclic aromatic ketones (PAKs) and polycyclic aromatic quinones (PAQs). In this review, we have compiled exhaustively all the data available on the sources, the fate, and the occurrence of oxy-PAHs focusing on the most ubiquitous ones in the environment, ie PAKs and PAQs. Data concerning their genotoxicity, mutagenicity and tumor promotion potential for humans are also provided based on the mode-of-action analysis framework. Mutagenicity results based on the limited number of oxy-PAHs tested, are unequivocal on the concern they represent. Their omission in mutagenic/carcinogenic risk has caused a dramatic underestimation of cancer risk. On the basis of environmental and genotoxicological data, we suggest prioritized 4 major oxy-PAHs molecules in ecotoxicological and toxicological studies, namely 6 H-benzo[cd]pyren-6-one (BPO), 7,12-benz[a]anthracenequinone (BAQ), 5,12-naphthacenequinone (NCQ) and 11 H-benzo[b]fluoren-11-one (B[b]FO). We also propose to develop biomarkers of exposure and/or risk for these compounds, for example by quantification of DNA adducts.

Polycyclic aromatic hydrocarbons in fruits and vegetables: Origin, analysis, and occurrence.

Feed intake, for non-smokers, is the first route of contamination to polycyclic aromatic hydrocarbons (PAHs), which are potentially toxic compounds via ingestion. Investigations are focused on the presence of PAHs in fruits and vegetables. Transfer of PAHs can occur from air and soil during cultivation. They can also appear prior to consumption during storage, transport or cooking processes. Rather low amounts of PAHs are usually detected in raw fruits and vegetables. Quantities are between 0.01 and 0.5 µg kg-1 (wet weight) for compounds classified as priority pollutants by the US Environmental Protection Agency (EPA). However, several studies point out that concentrations of some PAHs can exceed 0.5 µg kg-1 wet weight in diverse fruits and vegetables and even reach 5 µg kg-1. Amounts can be very different depending on the surrounding area of the crops, the aromatic hydrocarbon, or even the product itself. PAHs content is usually higher for products grown near roadways or in urban regions than in rural areas. Trace level of compounds such as phenanthrene, fluoranthene and pyrene have been found in quite every raw fruit and vegetable. Relative high amounts of lighter PAHs such as naphthalene, acenaphthylene, and acenaphthene have been found in some of them.

Impact of carbon source and variable nitrogen conditions on bacterial biosynthesis of polyhydroxyalkanoates: evidence of an atypical metabolism in Bacillus megaterium DSM 509.

Twenty bacterial strains were examined on their ability to produce polyhydroxyalkanoates (PHA) from different carbon sources under rich and depleted nitrogen conditions. Preliminary experiments with glucose as sole carbon source allowed to select PHA producing bacteria using FTIR spectroscopy. They were further tested with eight additional carbon substrates including organic, fatty acids or sugars. PHA content and monomer composition of four chosen strains (Pseudomonas putida mt-2, Bacillus megaterium DSM 90 and DSM 509, Corynebacterium glutamicum DSM 20137) were assessed by gas chromatography techniques for two cultural conditions: during growth phase on a mineral medium (MM) and after transfer of cells on a fresh MM without nitrogen (MM-N). For several carbon substrates, substantial amounts of PHA (up to 53% of the cell dry weight: CDW) were already obtained in MM for C. glutamicum DSM 20137 and the two B. megaterium strains; after transfer in MM-N, PHA contents remained constant except for B. megaterium DSM 509 where PHA production increased whatever the carbon source. P. putida mt-2 synthesized PHA under deprived nitrogen conditions. Highest PHA accumulation reached 48 and 77% of CDW with octanoic acid as substrate in B. megaterium DSM 90 and P. putida mt-2, respectively. Surprisingly, an atypical metabolic shift was observed for B. megaterium DSM 509 cultivated with nearly all unrelated carbon sources: whereas short chain length PHA (scl-PHA) were synthesized in MM, medium chain length PHA (mcl-PHA) were produced after transfer of cells into MM-N supplemented with the same substrate.

Implications of Lactobacillus collinoides and Brettanomyces/Dekkera anomala in phenolic off-flavour defects of ciders.

Different Lactobacillus collinoides and Brettanomyces/Dekkera anomala cider strains were studied for their ability to produce volatile phenols in synthetic medium. All strains were able to produce 4-ethylcatechol (4-EC), 4-ethylphenol (4-EP) and 4-ethylguaiacol (4-EG) from caffeic, p-coumaric and ferulic acids, respectively. Interestingly, D. anomala and L. collinoides were also able to produce 4-EC, 4-EP and 4-EG in cider conditions. The quantities of ethylphenols produced by these two species were similar in both tested ciders. The impact of precursor quantities was studied and it showed that the addition of caffeic and p-coumaric acids in ciders allowed for higher 4-EC and 4-EP production by D. anomala and L. collinoides. In parallel, D. anomala and L. collinoides strains were isolated from a phenolic off-flavour defective bottled cider after ethylphenol production hence confirming the implication of these two species in this cider spoilage. Finally, detection thresholds of the main ethylphenols were determined in ciders by orthonasal and retronasal sampling. The 4-EC and 4-EP detection thresholds (close to 20-25mg/l and 1.5-2.0mg/l, respectively) were matrix dependant.

Screening of representative cider yeasts and bacteria for volatile phenol-production ability.

Representative cider microorganisms (47 yeast strains and 16 bacterial strains) were studied for their ability to produce volatile phenols in a synthetic medium simulating cider conditions and supplemented with the necessary precursors. The various strains were tested for cinnamoyl esterase activity and only Lactobacillus collinoides were able to hydrolyse chlorogenic acid. Phenolic acid decarboxylase (PAD) activities were observed for 6 yeasts and 4 bacterial species allowing them to produce vinylphenols from hydroxycinnamic acids. On the other hand, 4 bacterial species exhibited phenolic acid reductase (PAR) activities leading to the formation of hydroxyphenylpropionic acids. Brettanomyces/Dekkera anomala and L. collinoides were able to produce 4-ethylcatechol (4-EC) and 4-ethylphenol (4-EP) from caffeic and p-coumaric acid, respectively, indicating that both species exhibit PAD and vinylphenol reductase (VPR) activities. In the experimental conditions used, the production of ethylphenols by L. collinoides was faster than the one observed for D. anomala.

Differences in the volatile compositions of French labeled brandies (Armagnac, Calvados, Cognac, and Mirabelle) using GC-MS and PLS-DA.

A total of 207 volatile compounds were identified in extracts of four French labeled brandies: Armagnac, Cognac, Calvados, and Mirabelle. Relative levels of all components were determined using GC-MS after integration of a selected peak of the mass spectrum of each. Each type of brandy could be clearly discriminated using PLS-DA statistical analyses based on these levels. French Mirabelle spirit, which was studied for the first time, was characterized by higher levels of many aldehydes and acetals and by the presence of compounds having an odd number of carbons together with benzaldehyde and some of its derivatives. Many possible derivatives of acrolein and high amounts of butan-2-ol were rather specific for the volatile composition of Calvados. The most important difference between the two wine-based samples seemed to be directly linked to the distillation system used. Many furanic compounds are specific to Cognac, whereas two or three compounds such as 1-(ethoxyethoxy)-2-methylbutane and gamma-eudesmol were specific to Armagnac. These two brandies presented rather high distributions of isobutanol and isopentanols, whereas Mirabelle and Calvados compositions offer more concentrated aliphatic linear alcohols.

Influence of growth phase and geographic origin on the essential oil composition of Pituranthos chloranthus from Tunisia.

The chemical compositions of the essential oils of Pituranthos chloranthus harvested at the vegetative, flower budding, flowering and fruiting stages from three distinct geographical areas of Tunisia were investigated using GC-FID and GC-MS. One hundred and fifty compounds were identified in which alpha-pinene, beta-pinene, alpha-phellandrene, beta-myrcene, beta-phellandrene, p-cymene, 8-methyldecanal, exo-2-hydroxycineole acetate and carvacrol could reach more than 10% of the total amount. However, this composition varied with respect to both the geographical area and the season. A clear discrimination of samples could be achieved by submitting the results to PLS discriminant analysis. p-Cymenene was only detected at the floral budding stage (February), whereas high amounts of exo-2-hydroxycineole and exo-2-hydroxycineole acetate were specific for the flowering period (April). Carvacrol was showed to be characteristic mainly of the fruiting period (August), whereas the vegetative state (November) could be distinguished from the others by the presence of alpha- and beta-pinene. Limonene, camphene, geraniol and beta-damascenone were likely to be specific for the essential oils of this species collected from the different regions of Tunisia.

A comparative evaluation of mutagenic, antimutagenic, radical scavenging and antibacterial activities of essential oils of Pituranthos chloranthus (Coss. et Dur.).

The Salmonella typhimurium/microsome assay is a widely used bacterial genotoxicity assay to test potential carcinogens. The aim of this work was to evaluate the mutagenic and antimutagenic activities with and without the addition of an extrinsic metabolic activation system of essential oils obtained from an aerial part of Pituranthos chloranthus harvested from different stations in Tunisia. The oils showed no mutagenicity when tested with S. typhimurium strains TA98, TA100, and TA1535. On the other hand, we showed that these essential oils reduced significantly Benzo [a] pyrene (B[a] P) and sodium-azide-induced mutagenicity. The scavenging capacity of these essential oils was also estimated by evaluating the inhibition of DPPH radical. Essential oils harvested at Medenine and Gabes in November were more effective in scavenging activity. The essential oils were tested for their antimicrobial properties against five different bacteria, and were found to be weakly active, with MIC and MBC values in the range 0.6-4 and 2.2-5 mg/mL, respectively.

Comparative study of Cyperus rotundus essential oil by a modified GC/MS analysis method. Evaluation of its antioxidant, cytotoxic, and apoptotic effects.

Gas chromatography coupled with mass spectrometry (GC/MS), using both electron impact (EI) and chemical ionization (CI) detection modes on apolar and polar stationary phases, led to the determination of the volatile composition of the essential oil obtained from tubers of Cyperus rotundus (Cyperaceae). In this study, more than 33 compounds were identified and then compared with the results obtained in our previous work. Cyperene, alpha-cyperone, isolongifolen-5-one, rotundene, and cyperorotundene were the principal compounds comprising 62% of the oil. An in vitro cytotoxicity assay with MTT indicated that this oil was very effective against L1210 leukaemia cells line. This result correlates with significantly increased apoptotic DNA fragmentation. The oxidative effects of the essential oil were evaluated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH), xanthine/xanthine oxidase assays, and the scavenging of superoxide radical assay generated by photo-reduction of riboflavin. The antimutagenic activity of essential oil has been examined by following the inhibition of H(2)O(2) UV photolysis which induced strand-break formation in pBS plasmid DNA scission assay. Based on all these results, it is concluded that C. rotundus essential-oil composition established by GC/MS analysis, in EI- and CI-MS modes, presents a variety of a chemical composition we were not able to detect with only GC/MS analysis in our previous work. This essential oil exhibited antioxidant, cytotoxic, and apoptotic properties.

Gas chromatographic quantification of aliphatic aldehydes in freshly distilled Calvados and Cognac using 3-methylbenzothiazolin-2-one hydrazone as derivative agent.

A new precise and sensitive method was used for the quantification of aliphatic aldehydes from C5 to C11 in highly ethanolic beverages such as freshly distilled spirits. Carbonyl compounds were derivatized using 3-methylbenzothiazolin-2-one hydrazone (MBTH) and then separated and detected by gas chromatography-mass spectrometry (GC-MS). Selective mass spectrometric detection of molecular ions of derivatives was performed to obtain a good sensibility (0.2-1.2 microg l(-1)) and a good selectivity. For a concentration of 20 microg l(-1), relative standard deviations were lower than 10% except for heaviest compounds (decanal and undecanal) where RSD were between 11 and 13%. The concentrations of aliphatic aldehydes were determined in nine samples of freshly distilled Calvados and two samples of freshly distilled Cognac with highest concentrations reported for 3-methylbutanal (from 170 to 1220 microg l(-1) in Calvados and from 1540 to 5500 microg l(-1) in Cognac). 3-Methylbutanal and hexanal, due to their low detection thresholds, could be important olfactive markers of these two products. Less than 1h30 is required to quantify the nine studied aliphatic aldehydes in freshly distilled spirits.

Determination of key odorant compounds in freshly distilled cognac using GC-O, GC-MS, and sensory evaluation.

This aim of this work was to identify the odorant compounds responsible for the typical sensory descriptors attributed to freshly distilled Cognac spirits, not matured in barrels. Panelists were first selected and trained for gas chromatography-olfactometry. Among the 150 volatile compounds identified by gas chromatography-mass spectrometry analysis, only 34 are mainly responsible for the odors detected in the spirits. The "butter" descriptor is explained by the presence of diacetyl, the "hay" descriptor by nerolidol, the "grass" descriptor mainly by Z-3-hexen-1-ol, but also by other compounds, the "pear" and "banana" descriptors by 2- and 3-methylbutyl acetates, the "rose" descriptor by 2-phenylethyl acetate, and the "lime tree" descriptor by linalool. This study demonstrated that many odorant molecules are already present in freshly distilled Cognac, thereby giving the spirit its specific aroma.

Identification of trace volatile compounds in freshly distilled Calvados and Cognac using preparative separations coupled with gas chromatography-mass spectrometry.

Gas chromatography coupled with mass spectrometry (GC-MS) using both electron impact and chemical ionization detection modes led to the determination of the volatile composition of two samples of freshly distilled Cognac and two samples of freshly distilled Calvados. A total of 169 volatile compounds were directly identified in dichloromethane extracts obtained by liquid-liquid extraction. Trace compounds present in both spirits were characterized with the help of preparative separations. In a first step, groups of compounds were separated by preparative GC, and the fractions were analyzed on a polar stationary phase by GC-MS. In a second step, silica gel fractionation was used to separate them by polarity. In this study, 331 compounds, of which 162 can be considered as trace compounds, were characterized in both freshly distilled Cognac and Calvados. Of these, 39 are common to both spirits; 30 are specific to Cognac with numerous hexenyl esters and norisoprenoidic derivatives, whereas 93 are specific to Calvados with compounds such as unsaturated alcohols, phenolic derivatives, and unsaturated aldehydes.

Chemical and sensorial aroma characterization of freshly distilled Calvados. 1. Evaluation of quality and defects on the basis of key odorants by olfactometry and sensory analysis.

Eight freshly distilled samples of Calvados, a fermented and distilled apple juice, were analyzed by sensory evaluation and direct injection GC to determine the composition of higher alcohols, esters, and aldehydes. The composition determined by direct injection was tentatively related to sensory descriptors. Esters have a probable maximum level around 500 g/hl of pure alcohol (PA). This level also corresponds to the threshold of the main ester constituent, ethyl acetate. A high ratio of esters to ethyl acetate seems to be of prime importance for good quality. Total aldehydes, with a maximum level between 8 and 11 g/hl of PA and mainly comprising acetal (maximum between 5 and 9 g/hl of PA), were related to a "green" descriptor. Higher alcohols do not have a direct impact on quality, but other volatile compounds with a positive impact on flavor should probably be present at a high level. As overall quality was not well related to sensory quality, it was necessary to perform more a precise analysis to determine the key odorants. The Calvados samples were thus extracted using pentane. Gas chromatography, employing both a flame ionization detector and an olfactometry port, was used to analyze the obtained extracts. Seventy-one odors were detected and distributed according to Calvados quality determined by sensory evaluation. Nineteen odors common to all Calvados samples constituted the "skeleton" of the aroma. Twenty-eight odors were specific to a quality class: 6 for good quality, 4 for neutral, and 18 for defective. Twenty-four other odors had either too low an odor impact or no evident specificity.

Chemical and sensorial aroma characterization of freshly distilled Calvados. 2. Identification of volatile compounds and key odorants.

Eight samples of freshly distilled Calvados were extracted using pentane. Gas chromatography with either a mass spectrometer or flame ionization detector was used to determine the volatile compounds composition of the extracts. More than 120 molecules were identified in Calvados and then correlated with results obtained by olfactometric analysis in our earlier work [Guichard, H.; Lemesle, S.; Ledauphin, J.; Barillier, D.; Picoche, B. Chemical and Sensorial Aroma Characterization of Freshly Distilled Calvados. 1. Evaluation of Quality and Defects on the Basis of Key Odorants by Olfactometry and Sensory Analysis. J. Agric. Food Chem. 2002, 50, 424-432 (preceding paper in this issue)]. Of these, 16 of the 19 molecules that constitute the "aroma skeleton" were identified, including 5 esters, 2 ketones, 5 phenolic derivatives, 2 alcohols, and 2 carboxylic acids. Numerous compounds were also associated with odors found in part 1. These molecules can be considered as being responsible for the good quality of Calvados or, in contrast, for defects. Relative levels of some major olfactive compounds were also estimated and tentatively compared with olfactometric indices found in part 1. A good correlation was found in many cases. Two important markers of defects in Calvados were also identified. 3-Methylbut-2-en-1-ol leads to an "herbaceous" defect, and 1,1,3-triethoxypropane seems to give an "acrolein" defect in the product. "Floral" notes of the aroma of freshly distilled Calvados seem to be due to the presence of phenolic derivatives such as 2-phenylethanol and 2-phenylethyl acetate. Low-molecular-weight esters such as ethyl 2-methylpropanoate, ethyl 2-methylbutanoate, and 3-methylbutyl acetate give, in general, the "fruity" notes. However, the overall aroma of Calvados seems likely to be a subtle balance of various functionalized compounds.