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This article contains data related to the research article entitled “Quantitative assessment of specific defects in roasted ground coffee via infrared-photoacoustic spectroscopy” (Dias et al., 2018) [1] . A method potentially able for assessing the quality of roasted ground coffees is described in the origin paper. Infrared spectroscopy and photoacoustic detection (FTIR-PAS) associated with multivariate calibration were used. The samples were obtained blending whole and healthy coffee beans (C. arabica and C. canephora) with specific blends of defects, named selections, which contain broken, sour, and black beans, skin, woods and healthy beans still not collected. In addition to a reduction in commercial value, the presence of defects compromises the sensory attributes of coffee. On the other hand, selections are commonly found in coffee crops and can be added intentionally to the product. Twenty-five selections were used to obtain a panel of 154 blends. The FTIR-PAS spectra of each sample generated the prediction model of Partial Least Squares Regression parameters, which are also presented here.

This study presents an experimental approach to study the kinetics and fast release of volatile organic compounds (VOCs) upon reconstitution of instant coffee products. A sampling setup coupled to PTR-ToF-MS (Proton Transfer Reaction Time-of-Flight Mass Spectrometry) for the automated and reproducible reconstitution of instant coffee products was developed to monitor the dynamic release of VOCs. A rapid release of aroma compounds was observed in the first seconds upon hot water addition ("aroma burst"), followed by subsequent decrease in headspace (HS) intensities over the course of analysis. Differences in time-intensity release profiles of individual VOCs were correlated to their Henry's Law constant, vapor pressure and water solubility. The setup and approach proposed here have shown to be sensitive and to respond to fast dynamic changes in aroma release. It allows studying VOCs release upon reconstitution and supports the development of novel technologies and formulations for instant products with improved aroma release properties.

This article is part of the special issue of the Flavour and Fragrance Journal entitled “On‐line monitoring of odorants using direct‐injection mass spectrometry” edited by Jean‐Luc Le Quere., Changes in the headspace volatile profile of tea infusion during brewing were determined by analysing the aliquots taken every 30 s using proton transfer reaction time‐of‐flight mass spectrometry in conjunction with principal component analysis and hierarchical cluster analysis. The effect of three different brewing temperatures (60, 70 and 80°C), two leaf sizes (broken and full leaves) and two water mineralizations (soft and hard), on the concentration of volatile compounds in the headspace of tea, was studied as a function of infusion time. An increase in brewing temperature resulted in increased volatile content in the headspace, reflecting an increase in extraction efficiency. Such differences on extraction efficiency were more pronounced with increasing brewing times. Leaf size had also a big impact on the extraction of volatile compounds, but mainly during the early phase of brewing. Water mineralization had a low but noticeable impact on the volatile content. Furthermore, clusters of samples prepared with different combinations of brewing parameters but resulting in analogous volatile profiles could be identified using hierarchical clustering analysis.

The objective of this paper is to elucidate the variables that govern coffee extraction from single serve coffee capsules. The study was conducted on 43 Nespresso and Nespresso-compatible capsules of the same geometry, from all of which the coffee was extracted on the same machine. This allowed the link between a range of coffee and capsule (input) parameters with coffee brew (output) variables to be studied. It was demonstrated that the most efficient way to increase total dissolved solids in the brew is to use more coffee for extraction, and/or to grind the coffee more finely. However, grinding too finely can lead to excessive flow restriction. The most significant new insight from this study is the importance of the proportion of fines (particles smaller than 100 µm) regarding the capsule extraction dynamics. Capsules with a higher share of fines, for similar median particle size of the ground coffee, led to longer extraction times. General rules applicable for capsule coffee product development were established, although fine-tuning of parameters for successful capsule coffee extraction remains specific to production line and type of coffee.

Water is an essential ingredient for coffee extraction, typically making up more than 90% of the final beverage. This chapter introduces the basic characteristics of water and the most common dissolved contents. The concepts of water hardness and alkalinity are explained while discerning between technical and sensory aspects with regards to coffee extraction. The existing recommendations on the optimum water composition are discussed as well as the potential off-flavors that can arise from nonideal composition. As a link between a given water composition and a targeted recommendation the most common water treatment methods are systematically characterized. The chapter concludes with practical examples on the impact of different water compositions in a cupping experiment and espresso extraction.

Since the early days of the specialty coffee movement, freshness has been one of its central pillars. Freshness is best defined as having original unimpaired qualities. In coffee, it is most often seen as freshly roasted, ground within a few days, immediately extracted, and consumed. But despite this pivotal role of freshness for high quality coffee, the objective and scientific measurement of freshness have often been vague and elusive. How can one measure the level of freshness of coffee? In this chapter we will outline two approaches. One is based on the degassing of the freshly roasted coffee and the other on the evolution of its aroma profile during storage. In terms of the evolution of the aroma profile, we will introduce one particular freshness index: the ratio of dimethyl disulfide to methanethiol, suited to assess the evolution of freshness of roasted coffee during storage. Although this ratio has been shown to increase during storage, the speed at which this freshness index increases depends on the packaging and storage temperature. This has opened the possibility to use this index to assess the freshness of roasted coffee and compare the quality of different packaging materials for preserving the freshness of the coffee inside.

Volatile profiles of 63 black and 38 green teas from different countries were analysed with Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS) both for tea leaves and tea infusion. The headspace volatile fingerprints were collected and the tea classes and geographical origins were tracked with pattern recognition techniques. The high mass resolution achieved by ToF mass analyser provided determination of sum formula and tentative identifications of the mass peaks. The results provided successful separation of the black and green teas based on their headspace volatile emissions both from the dry tea leaves and their infusions. The volatile fingerprints were then used to build different classification models for discrimination of black and green teas according to their geographical origins. Two different cross validation methods were applied and their effectiveness for origin discrimination was discussed. The classification models showed a separation of black and green teas according to geographical origins the errors being mostly between neighbouring countries. Fil: Yener, Sine. Instituto Agrario San Michele all'Adige Fondazione Edmund Mach; Italia. Universidad de Innsbruck; Austria Fil: Sánchez-López, José A.. Universitat Zurich; Suiza. Universität Rostock; Alemania Fil: Granitto, Pablo Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas. Universidad Nacional de Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas; Argentina Fil: Cappellin, Luca. Instituto Agrario San Michele all'Adige Fondazione Edmund Mach; Italia Fil: Märk, Tilmann D.. Universidad de Innsbruck; Austria Fil: Zimmermann, Ralf. Universität Rostock; Alemania. Technische Universitat Munchen; Alemania Fil: Bonn, Günther K.. Universidad de Innsbruck; Austria. Austrian Drug Screening Institute; Austria Fil: Yeretzian, Chahan. Universitat Zurich; Suiza Fil: Biasioli, Franco. Instituto Agrario San Michele all'Adige Fondazione Edmund Mach; Italia

We introduce a real-time method to monitor the evolution of oak aromas during the oak toasting process. French and American oak wood boards were toasted in an oven at three different temperatures, while the process-gas was continuously transferred to the inlet of a proton-transfer-reaction time-of-flight mass spectrometer for online monitoring. Oak wood aroma compounds important for their sensory contribution to oak-aged wine were tentatively identified based on soft ionization and molecular mass. The time-intensity profiles revealed toasting process dynamics illustrating in real-time how different compounds evolve from the oak wood during toasting. Sufficient sensitivity was achieved to observe spikes in volatile concentrations related to cracking phenomena on the oak wood surface. The polysaccharide-derived compounds exhibited similar profiles; whilst for lignin-derived compounds eugenol formation differed from that of vanillin and guaiacol at lower toasting temperatures. Significant generation of oak lactone from precursors was evident at 225 oC. Statistical processing of the real-time aroma data showed similarities and differences between individual oak boards and oak wood sourced from the different origins. This study enriches our understanding of the oak toasting process and demonstrates a new analytical approach for research on wood volatiles.

The quality of green coffee is influenced by the degree of ripeness of the fruit at harvest. The aim of this study was to identify chemical markers differentiating between degrees of ripeness. Two coffee varieties, Catuai and Tipica, from the same farm were analysed using the following parameters and methods: caffeine and chlorogenic acid content using high-performance liquid chromatography (HPLC), sucrose content using hydrophilic interaction chromatography, high-molecular weight fraction (HMW) using high-performance size-exclusion chromatography (HPSEC) and volatile compounds using headspace solid phase micro extraction gas chromatography/mass spectrometry. The best method for differentiating between degrees of ripeness was found to be principal component analysis (PCA) based on HPLC data. HPSEC showed differences in the HMW fraction for different degrees of ripeness and both coffee varieties. Volatile profiles allowed separation of both varieties; yet, except for ripe Catuai, no separation was achieved for the degree of ripeness.

This chapter briefly reviews the roles played by free radical processes during the roasting and storage of coffee beans and solid coffee products. During roasting, free radical production occurs in distinct phases, possibly related to the Maillard and caramelization reactions. At the same time there is also generation of large quantities of molecules with antioxidant properties, thus demonstrating that antioxidant production does not necessarily equate to free radical scavenging, insofar as it is measured by current assays. Furthermore, with respect to chemical components that are associated with desirable sensory properties of coffee, free radical processes may have both beneficial and detrimental effects.

Using proton-transfer-reaction time-of-flight mass-spectrometry (PTR-ToF-MS), we investigated the extraction dynamic of 95 ion traces in real time (time resolution: 1 second) during espresso coffee preparation. Fifty-two of these ions were tentatively identified. This was achieved by on-line sampling of the volatile organic compounds (VOCs) in close vicinity to the coffee flow, at the exit of the extraction hose of the espresso machine (single serve capsules). Ten replicates of six different single serve coffee types were extracted to a final volume of between 30 - 110 mL, according to the recommended cup size of the respective coffee capsule (Ristretto, Espresso and Lungo), and analyzed. The results revealed considerable differences in the extraction kinetics between compounds, which led to a fast evolution of the volatile profiles in the extract flow and consequently to an evolution of the final aroma balance in the cup. Besides exploring the time-resolved extraction dynamics of VOCs, the dynamic data also allowed the coffees types (capsules) to be distinguished from one another. Both Hierarchical Cluster Analysis (HCA) and Principal Component Analysis (PCA) showed full separation between the coffees types. The methodology developed provides a fast and simple means of studying the extraction dynamics of VOCs and differentiating between different coffee types.

Coffee is a major source of dietary antioxidants; some are present in the green bean, whereas others are generated during roasting. However, there is no single accepted analytical method for their routine determination. This paper describes the adaption of three complementary assays (Folin-Ciocalteu (FC), ABTS and ORAC) for the routine assessment of antioxidant capacity of beverages, their validation, and use for determining the antioxidant capacities of extracts from coffee beans at different stages in the roasting process. All assays showed a progressive increase in antioxidant capacity during roasting to a light roast state, consistent with the production of melanoidins having a higher antioxidant effect than the degradation of CGAs. However, the three assays gave different numbers for the total antioxidant capacity of green beans relative to gallic acid (GA), although the range of values was much smaller when chlorogenic acid (CGA) was used as reference. Therefore, although all three assays indicated that there was an increase in antioxidant activity during coffee roasting, and the large differences in responses to GA and CGA illustrate their different sensitivities to different types of antioxidant molecule.

The influence of roasting and storage conditions on free radical contents of individual Arabica coffee beans was examined during storage of whole, half and ground beans in air over a 1-month period. Free radical contents increased with increasing roasting time (roasting degree), but the atmosphere (air vs. N 2 ) used in the roasting and cooling process had little effect. There was a progressive increase in free radical contents with storage time, but the rate was much lower in whole beans than with half and fully ground beans, for which the rate was similar. These results suggest that exposure to O 2 , rather than physical grinding is the main mechanism for storage-related free radical generation, and strongly indicate that roasted coffee is best kept as whole beans in order to minimise changes during prolonged periods of aerobic storage. Furthermore, they demonstrate that EPR measurements can contribute to understanding the process and storage related changes in coffee.

Because of the roles of free radicals in the formation of Maillard reaction products and as markers of oxidation processes in foods, the dynamics of free radical generation during the roasting of coffee beans have been measured, and some exploratory investigations conducted on the extent to which these are influenced by the bean type, and the atmosphere (air vs. N2), in which the beans were roasted and cooled. The intensities of the free radical signals from individual Arabica and Robusta coffee beans were measured continuously in an EPR spectrometer, whilst beans underwent heating/cooling cycles in air or N2 atmospheres. Additional EPR measurements were performed on the products of coffee beans roasted in a laboratory, convectional hot air roaster. Two sets of experiments were performed: (i) single/half bean roasting in air or N2, and real time, in situ EPR analysis of the free radical content – with a very high flow of roasting gas (convective roasting); (ii) batch roasting in air or N2, and EPR measurements of individual roasted beans – in a rather low flow of gas. Large differences in intermediate and final free radical EPR signal intensities were observed between the specimens of Arabica and Robusta beans that were investigated, irrespective of the roasting atmosphere. During the heating phase of the roasting process, only minor differences were observed between beans of the same type roasted in air or nitrogen, but the presence of oxygen in the cooling cycle resulted in major increases of free radical levels compared to those observed in an inert atmosphere, although this O2-related effect was not observed in beans from the convectional hot air roaster. Large bean to bean variations were observed with a standard blend roasted in the convectional hot air roaster, but much smaller variations were observed with beans from a single batch. Three major conclusions can be drawn from this study: (i) when roasting with a very strong flow of hot gas, the atmosphere (air vs. N2) had a very limited impact (during the heating phase) on free radical formation, but a dramatic and fast increase during the cooling phase, irrespective of the type of coffee beans. (ii) It appears that the relative masses of coffee beans and air during the roasting process are critical for oxidation and hence the free radical content of the final product. Indeed, the dramatic increase in free radicals during air-cooling was only observed if roasting was performed with a very high flow of hot air. (iii) There are wide variations in the free radical dynamics of different types of coffee bean. Arabica beans showed stronger free radical formation during roasting and higher EPR intensities at the end of the roasting cycle, than did Robusta beans. Yet, as the sampling over different Arabicas and Robustas was limited here, a more systematic study is needed to ascertain this observation.

A robust and reproducible model was developed to predict the sensory profile of espresso coffee from instrumental headspace data. The model is derived from 11 different espresso coffees and validated using 8 additional espressos. The input of the model consists of (i) sensory profiles from a trained panel and (ii) on-line proton-transfer reaction mass spectrometry (PTR-MS) data. The experimental PTR-MS conditions were designed to simulate those for the sensory evaluation. Sixteen characteristic ion traces in the headspace were quantified by PTR-MS, requiring only 2 min of headspace measurement per espresso. The correlation is based on a knowledge-based standardization and normalization of both datasets that selectively extracts differences in the quality of samples, while reducing the impact of variations on the overall intensity of coffees. This work represents a significant progress in terms of correlation of sensory with instrumental results exemplified on coffee.

Personal dietary choices are largely based on flavor preferences. Thus understanding individual flavor perception and preference is vital to understanding the basis of human diet selection. We have developed novel tools to measure in real time and at an individual level volatile aroma compounds delivered breath-by-breath to the nose while eating and drinking. The same food may deliver different aromas to different people, due the specificities of their in-mouth environment (inter-individual differences). Moreover, a person may eat a given food in a different manner, leading to variations in the aroma profile reaching the nose (intra-individual differences). Understanding the basis of these differences opens the door to an individualized aroma science and the road to delivering nutritional value and health through products consumers prefer. The challenge to the food industry is to align what the consumer wants with what the consumer needs, delivering nutritional value and health through products they prefer.

Recently we introduced a dynamic approach to determine Henry’s law constants (HLCs) of volatile organic compounds (VOCs) in water, and applied it to a series organic compounds dissolved in pure water. Here, we first discuss a further development of the original approach such that it can be applied to complex liquid food systems (coffee). Second, we examine the impact of non-volatile constituents on the HLC. More specifically, we evaluate the impact of non-volatile coffee constituents on the HLC of 2-methylpropanal, 3- and 2-methylbutanal, dimethylsulfide, dimethyldisulfide and ethyl-2-methylbutyrate. Finally, we demonstrate that the concentration on the VOC in solution does not affect the HLC, over the investigated concentration range of 10−4 to 10 ppm.

An extensive analysis of the headspace (HS) of coffee brew using proton-transfer-reaction mass-spectrometry (PTR-MS) is presented. In particular, we present a set of methods that link mass spectral peaks, as observed in PTR-MS, to chemical compounds in the HS of coffee. Combining all this information, a tentative assignment and rough quantification of liquid coffee HS is presented. Coffee was chosen because it contains a large number of chemically diverse volatile organic compounds (VOCs), representing a challenging system for on-line analysis by PTR-MS.

Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch), Volatile organic compounds (VOCs), emitted from green coffee beans, during coffee roasting and from a cup of coffee, were all analysed by proton-transferreaction mass spectrometry. Firstly, the headspace (HS) of green beans was investigated. Alcohols dominate the HS, but aldehydes, hydrocarbons and organic acids were also abundant. Secondly, we roasted coffee under two different conditions and monitored on-line the VOCs emitted during the process. In a first roasting series, a batch of beans was roasted. After an initial drying phase, dominated by evaporation of water and methanol, the HS concentrations of VOCs such as acetic acid, acetaldehyde, pyridine and methylbutanal rapidly increased and went through a maximum at medium roast level. In a second series, just six beans were roasted. We observed sporadic bursts of some volatiles (furans, butanal, 2,3- pentanedione), coinciding with popping sounds. Other VOCs showed smooth time-intensity profiles (pyridine, pyrazine). These experiments gave a real-time insight into the complex processes taking place during roasting. Finally, the HS of coffee extracts, prepared from beans roasted to different roast levels, were analysed. Most VOCs showed a maximum concentration at medium roast level (e.g. pentanedione, furfural, 5-methyl furfural), while others showed a gradual increase (e.g. pyrrol) or decrease (e.g. methanol).

Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch), The aromas of a reference green Mexican coffee (Arabica) and of a coffee from the same origin, but having a pronounced earthy/mouldy off-taint, were characterised. From comparison of the two aroma profiles, the compounds causing the defect were detected by gas chromatography olfactometry, isolated and concentrated by preparative bi-dimensional gas chromatography, and characterised by gas chromatography mass spectrometry. Six compounds participated in the off-flavour. Geosmin, 2-methylisoborneol, 2,4,6-trichloroanisole were found to be the main culprits, while three methoxy pyrazines (2-methoxy-3-isopropyl/-3-sec-butyl/-3-isobutyl pyrazine) contributed to a lesser extent to the earthy/ green undertone. The occurrence of the off-flavour could tentatively be linked to post-harvest drying.

Resonance-enhanced multi-photon ionization time-of-flight mass spectrometry (REMPI/TOFMS) has been applied to the detection of volatiles in the headspace of brewed coffee and in the coffee roasting process-gas. A frequency quadrupled Nd:YAG laser (266 nm) was used for REMPI ionization (REMPI@266nm) of the volatiles in an effusive molecular beam inside the ion source of a linear TOF mass spectrometer. A special sampling system provided a time correlated sampling. Under these circumstances REMPI@266nm is highly selective for ionization of phenolic compounds. Several phenolic compounds, such as the flavour-active 4-vinylguaiacol, can be detected in the headspace of coffee brew as well as in the roast off-gas with the application of this approach. Moreover, the nitrogen heterocyclic compounds, indole and caffeine, were detected in both cases. During the roasting process the relative changes in concentration of some volatile components of coffee have been recorded by EMPI@266nm with a time resolution of 1 Hz. The different volatiles exhibit characteristic concentration profiles as a function of the roast time. These results demonstrate the applicability of REMPI-TOFMS for on-line monitoring of coffee processing technologies. Such an on-line monitoring technique is of particular interest for process-control purposes, e.g. quality-protection or feedback process control. For example, monitoring of off-gases from the coffee roast process or monitoring of certain unit operations during the instant-coffee manufacturing could be promising industrial applications.

Density functional studies of the abundant cluster Na6Pb and of its analogue Na6Mg are reported. The structure of Na6Pb has been optimized for a series of symmetry constraints (Oh, D3d, D3h, C5v, C3v and C2v). The resulting binding energies fall within a narrow range of less than 0.1 eV whereas a spread of more than 0.5 eV is calculated for Na6Mg. These findings indicate a high structural flexibility of Na6Pb. The Pb atom exhibits a propensity to occupy a highly coordinated site in contrast to Mg which, in the most stable structures, is attached to the ‘outside’ of a Na6 moiety. Analysis of the bonding mechanism revealed two major contributions which increase the atomization energy of Na6Pb compared to Na6Mg: an enhanced charge transfer from the Na6 subsystem and a stronger polarization of the Pb atom. A significant contribution to the overall cluster stability comes from the interaction between the alkali atoms.

Recently we reported on vibrationally resolved spectra of the ionic ground state of Ag 2 + via ZEKE spectroscopy. The vibronic intensity distributions could not be interpreted within the Franck-Condon scheme. Here, we show that it is possible to overcome this discrepancy by invoking the breakdown of the Born-Oppenheimer approximation in the ZEKE states of silver dimer. A comparison of the spectral structure of the direct ion signal with simultaneously recorded ZEKE band profiles further illustrates this non-Franck-Condon behavior.

Mass-spectral results on alkali clusters containing one host-atom with ns2 valence-shell configuration (Mg, Ca, Sr, Ba, Zn, Eu, and Yb) are presented. They allow uncoupling of the number of atoms in the cluster from the number of its valence electrons by probing with elements with more than one valence electron and different ionization potential and atomic radius. Prominent intensity maxima for specific cluster sizes are observed. Based on an electronic shell model, a systematic interpretation of the intensity maxima as a function of the incorporated heteroatom is presented. Although most of the gross features can be rationalized within a purely electronic model, a more refined analysis prompts one to geometric structure effects which have to be included to more fully describe the spectra.

We report on mass-analyzed ZEKE spectra of Ag+2 via resonance-enhanced two-color excitation. To the best of our knowledge, this is the first metal dimer and at the same time the heaviest system (218 amu) ever investigated by mass-analyzed ZEKE. The adiabatic ionization potential, vibrational energies for v+ = 1, 2, 3 and 4 as well as the vibrational constants ωe, ωeχe of the ionic ground state X2Σ+g are determined with high accuracy. The surprising intensity pattern of vibrational progressions cannot be rationalized within a Franck—Condon picture and points to the unique properties of ZEKE states.

In this article, recent cluster—surface collision experiments are reviewed from the perspective of fullerene research. A detailed description of the method and the reflectron time-of-flight surface collider (reflectron collider), designed and built in Los Angeles, will be given first, to show how pulsed cluster-ion-beams are mass and energy selected, collided with specific surfaces and the various outcomes studied. In the second part, we outline several applications together with the scientific impact surface collision experiments have had on several fullerene-related research subjects. This includes impact-induced dissociation experiments, to probe stability and structural resilience, rebound velocity distributions from solid surfaces to reveal energetic and dynamic aspects of the scattering process, and rates of delayed electron emission from impact-heated fullerenes. Impact experiments also have turned out to be a useful tool to examine structural hypotheses as demonstrated on coalescence products from fullerene—fullerene reactions, fullerene derivatives and on metallo-fullerenes.

Recent experiments have demonstrated that large fullerenes can form by coalescence in the hot and dense vapor produced by pulsed UV-laser desorption of a fullerene film. The abundance spectra exhibit masses both at and close to the primary coalescence product. We suggest a rate equation that reproduces this pattern, applicable to the nearly symmetric abundance distributions observed in coalescence with high laser fluence and also to the strongly asymmetric case of coalescence with low fluence. The equation is parameterized by three rates, which in the completely symmetric and in the completely asymmetric case reduces to two. In these two cases the relative abundances can be expressed by a single dimensionless parameter.

This article reviews recent work in Los Angeles on elementary processes in fullerene vapors. The production of fullerene molecules typically involves extreme high-temperature conditions and processes which are poorly understood at date [1–3]. Once generated, these molecules may represent the most stable molecules known [4,5]. In a recent work [C. Yeretzian et al., Nature 359, 44 (1992)] we presented clear evidence for coalescence reactions between fullerene molecules. Mass spectrometric measurements on hot, dense vapors of small fullerenes (C60 and C70) reveal the formation of stable higher fullerenes which are multiples of the initial masses. These processes are shown to occur in the gas-phase rather than in the solid film and their dependences on laser fluence and He-gas pressure are investigated. Three distinct reactions are proposed—coalescence, emission and capture—to account for the observed distributions at higher fullerene sizes. Specifically, the heat of coalescence is released through emission of small, even-numbered fragments which, in a very dense vapor, are efficiently captured by other coalesced fullerenes. These findings have implications for the long-time stability of the fullerene vapor, and for the mechanism of fullerene formation and growth, and may open new ways to the synthesis of selected higher fullerenes and encapsulation compounds.

The disintegration and coalescence processes of fullerenes have not yet been established, although certain aspects have been known for years. For example, the energy required to fragment C 60 has been calculated to lie in the 11–14 eV range, making it the most stable large molecule known, while reported experimental values are in the 4.5–7 eV range. In this report, we show that surface-impact heating of fullerene-ion beams, when properly calibrated, gives values in agreement with theory. In the last section, new mass spectrometric results on the coalescence reactions of hot fullerene vapors are presented.

The soluble molecule La2C80 recently reported by Alvarez et al. exhibits a robustness similar to other fullerenes. It survives intact for ≈ 10−6s following impact against solid surfaces Si(100) at up to 200 eV, yielding an estimate Ef>4 eV for fragmentation processes. The high threshold for electron emission suggests that the electron affinity in La2C−80 is significantly larger than in C60. These facts seem to rule out an external site for either La atom and disfavor a network-site interpretation, and thus favor endohedral (encapsulation) sites. Among the possible cages, the Ih-C80 fullerene appears to be highly favorable for the oxidation state (La3+)2C6−80.

The preparation of a cup of coffee may vary between countries, cultures and individuals. Here, an analysis of nine different extraction methods is presented regarding analytical and sensory aspects for four espressi and five lunghi. This comprised espresso and lungo from a semi-automatic coffee machine, espresso and lungo from a fully automatic coffee machine, espresso from a single- serve capsule system, mocha made with a percolator, lungo prepared with French Press extraction, filter coffee and lungo extracted with a Bayreuth coffee machine. Analyti- cal measurements included headspace analysis with HS SPME GC/MS, acidity (pH), titratable acidity, content of fatty acids, total solids, refractive indices (expressed in � Brix), caffeine and chlorogenic acids content with HPLC. Sensory analysis included visual, aroma, flavor and textural attributes as well as aftersensation. The technical differ- ences in the extraction methods led to a higher concen- tration of the respective quantities in the espressi than in the lunghi. Regarding the contents per cup of coffee, the lunghi generally had a higher content than the espressi. The extraction efficiency of the respective compounds was mainly driven by their solubility in water. A higher amount of water, as in the extraction of a lungo, generally led to higher extraction efficiency. Comparing analytical data with sensory profiles, the following positive correlations were found total solids $ texture/body, headspace inten- sity $ aroma intensity, concentrations of caffeine/chloro- genic acids $ bitterness and astringency.

Recent mass spectroscopic studies of continuous cluster beams resulting from supersonic expansions of alkali metal vapor have led to the postulation of islands of enhanced thermodynamic stability among the clusters produced. We discuss the various assumptions being made in converting ion abundances measured in these mass spectra into information about neutral stabilities. In this connection a number of experiments are described which allow insight into unimolecular dissociation of alkali cluster ions and into neutral cluster growth.

Controversy regarding the interpretation of photoionization efficiency measurements obtained for alkali clusters provided impetus for higher-resoln. (3.3 nm) studies . The new data cover the full range of cluster sizes: Nax, x

International audience; The perception of thousands of odours by about 380 human olfactory receptors (ORs) results from a combinatorial coding, in which one OR recognizes multiple odorants and odorants are recognized by different combinations of ORs. We used data of 95 odorant molecules tested on two human ORs, OR1G1 (class II) and OR52D1 (class I), to perform a 3D molecular modelling study of ligands using Catalyst/HypoGen software. The sorting-out procedure previously used for OR1G1 ligands was transposed to OR52D1 ligands. The 3D-QSAR models obtained for OR1G1 and OR52D1 ligands essentially differ by distance between their features. This result suggests a path to decipher the odotopes of OR1G1 and OR52D1 agonists in order to investigate the role of ORs in olfactory coding.

International audience; Rice from two scented (Aychade, Fidji) and one nonscented (Ruille) cultivars from Camargue area (France) together with one Asian scented rice (Thai) were cooked and volatile compounds were extracted by dichloromethane/pentane (1;2, v/v) solvent mixture. 40 odorous compounds were noticed during GC-O analysis of the organic extracts, amongst which oct-1-en-3-one and 2-acetyl-1-pyrroline were altmost constantly perceived. Hierarchical cluster analysis (HCA) of perceived odours enabled to distinguish the groups of rice cultivars. 60 compounds were identified and quantified by GC-MS. New odour-active components of cooked rice were detected for the first time including oct-3-en-2-one, 2-methylpropanoic acid, y-decalactone and o-decalactone. A principal component analysis (PCA) differentiated scented cultivars from a non-scented one and scented rice cultivars from Camargue from Thai sample.