Dominique Langlois

French National Institute for Agricultural Research, Lutetia Parisorum, Île-de-France, France

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Publications (19)26.61 Total impact

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    ABSTRACT: Several studies have focused on perceptual interactions in binary odor mixtures, but few on more complex mixtures. The aroma of wine is an example of a complex odor mixture. Our aim was to assess the impact of ethanol on the perception of mixtures of Woody (whiskey lactone) and Fruity (isoamyl acetate) odorants commonly found, physico-chemically and perceptually, in wine. Physico-chemically, reduced whiskey lactone volatility was observed in hydro-alcoholic solutions. Perceptually, a synergy effect by the Woody on the Fruity odor was observed in aqueous solutions, which disappeared with the addition of ethanol. Conversely, the Woody odor was masked in both aqueous and dilute alcohol solutions. In addition, mixed Woody and Fruity odors were found to mask the so-called Alcohol odor. These results underline the importance of perceptual interactions in the perception of wine bouquet.
    Full-text · Article · Sep 2007 · Food Quality and Preference
  • I. LESSCHAEVE · D. LANGLOIS · P. ETIÉVANT
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    ABSTRACT: Volatile constituents of strawberry jam were identified and their olfactive impact estimated by HRGC effluent sniffing. Amounts of volatiles in jam were only slightly affected by addition of sugar, but were closely related to design of the cooker and to the pressure used. Losses by evaporation during cooking were studied. Different types of behaviour were observed for the specific aromatic components. Cooker design largely influenced flavor losses at low pressures. Condensation of vapors during cooking and incorporation of the condensate in pectin solutions could result in a more flavorfull product.
    No preview · Article · Aug 2006 · Journal of Food Science
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    ABSTRACT: In order to test the hypothesis that woody odorants at sub- and peri-threshold concentrations could modify the olfactory perception of supra-threshold fruity notes in wine, three binary mixtures of fruity and woody odorants were studied. In these mixtures, a single supra-threshold concentration level, close to the one usually found in wine, was used for the fruity note whereas three peri-threshold concentration levels of the woody note were tested. The ability to discriminate odour stimuli on the basis of the presence or absence of the woody odorants in the mixtures was investigated with a triangular test.For the three binary mixtures the results showed that subjects were able to differentiate between samples containing a woody odorant at all concentration levels from samples without a woody odorant. These findings confirmed the impact of sub- and peri-threshold components on the olfactory perception of odour mixtures, especially in the case of wine woody odorants.
    Full-text · Article · Sep 2005 · Food Quality and Preference
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    ABSTRACT: The qualitative perceptual interactions in three binary mixtures of wine odorants were studied: isoamyl acetate (fruity note)/whisky lactone (woody note), ethyl butyrate (fruity note)/whisky lactone (woody note) and ethyl butyrate (fruity note)/guaiacol (woody note). For each binary mixture, the perceived quality and intensity of 24 stimuli (four supra-threshold concentration levels of each of the two compounds and their 16 possible combinations) were evaluated in five replications by a trained panel of 13 subjects. The application of the Olsson predictive model for odour intensity and quality perception gave quite a good estimation of the evolution of single component identification in the mixture when the intensity proportion of unmixed components varied. However, this model was unable to account for the odour quality dominance in mixtures of iso-intense components. An alternative linear logistic model was proposed to study the qualitative dominance of the woody note in the three mixtures when the perceived intensities of each unmixed compound were equal.
    Full-text · Article · Apr 2005 · Chemical Senses
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    ABSTRACT: The quantitative olfactory interactions in three binary mixtures of wine aroma compounds were studied. For the first two mixtures, whisky lactone (woody note) was mixed separately with two esters (fruity note), ethyl butyrate and isoamyl acetate. For the third mixture, guaiacol (woody note) was mixed with ethyl butyrate (fruity note). Perceived odour intensity of 24 stimuli (four supra-threshold concentration levels of two compounds and the respective 16 mixtures) were evaluated in five replications, by a trained panel of 13 subjects. The results showed that for the three binary mixtures studied, quantitative perceptual interactions were non-level independent, non-symmetrical, and reached the compromise level of hypo-addition. The experimental data highlighted that generally mixtures with high whisky lactone levels led to the compromise level of mixture intensity perception, whereas mixtures with high fruity note intensity proportions did not. A tendency to hyper-addition was observed in iso-intense mixtures only at the lowest intensity level. Copyright © 2004 John Wiley & Sons, Ltd.
    Full-text · Article · Nov 2004 · Flavour and Fragrance Journal
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    ABSTRACT: Two experimental procedures recommended for the evaluation of the psychophysical characteristics of odorous compounds, olfactory matching with the 1-butanol scale and cross-modality matching with the finger span are compared. The intensity of ethyl butyrate and guaiacol solutions presented at four different concentration levels was evaluated by a panel of sixteen subjects over five repetitions using the two methods. Each stimulus was delivered to the subject from a Teflon bag through a nose-shaped glass sniffing port. The discrimination ability, repeatability, panel homogeneity and within-subject variability of the methods were assessed. Results indicate that with both methods, subjects were able to highly discriminate the presented concentration levels of the odorants. There were no great difference in repeatability and the same individual variability was observed between both methods. However, the smaller within-subject variability highlighted for the 1-butanol scale method suggested that this method is potentially more powerful than finger-span method.
    No preview · Article · Sep 2004 · Journal of Sensory Studies
  • G. Callement · M. Bouchet · D. Langlois · P. Etiévant · C. Salles

    No preview · Chapter · Mar 2001
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    ABSTRACT: This paper describes the potential of evaluating odor intensities in a gas chromatographic effluent by cross-modality matching with the finger span (GC-O-FSCM). A simple prototype is described that allows the precise measurement and acquisition of the distance between the thumb and another finger during the analysis. The stimulation of panelists at the sniffing port with ethyl butyrate shows a log-log relation between peak height values obtained from finger span and stimulus concentrations. It also shows that all panelists are able to perform this task but with different precision, which is used to select them. A triplicate evaluation by GC-O-FSCM of the intensity of flavor constituents in synthetic solutions shows that a four-member panel is perfectly able to determine most of the characteristics of the solutions and to create a finger span multidimensional space highly correlated with the theoretical intensity space.
    Preview · Article · May 1999 · Journal of Agricultural and Food Chemistry
  • D. Langlois · M. Malterre · P. Etievant
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    ABSTRACT: Vacuum distillation is a safe and powerful way to extract flavour compounds from food. Cryoconcentration of this vacuum distillate allows a gentle concentration of volatile compounds while avoiding thermal degradation and the use of solvents. The resulting concentrate is, moreover, perfectly suitable for a sensory analysis after incorporation into a neutral medium. Cryoconcentration involves crystallization of a fraction of the water, and separation of the crystals from the liquid phase containing the dissolved flavour compounds. The present experiment aimed to determine the best conditions to cryoconcentrate, on the laboratory scale, an aqueous model solution simulating a distillate. Three final levels of ice (0.5, 0.7, and 0.9 of the initial weight of the solution), and three different programs for temperature of freezing (a constant temperature of - 2.6°C, a temperature decreasing at a rate of - 1°C.h-1, or - 5°C.h-1) were tested. At a final level of crystallized water equal to 0.9 of the initial weight of the water, the recovery of all volatile compounds experimental was higher than 75%, corresponding to a final concentration factor of 8.
    No preview · Article · Jan 1997 · Sciences des Aliments
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    ABSTRACT: Ten tomato varieties, i.e. Cencara, Daniella, Elena, Ibiza, Lemon Boy, Lucy, Melody, Perfecto, Raf and Rondello, were studied over two consecutive years by GC and GC-sniffing for their differences in flavour composition. Precautions were taken to avoid differences due to the growth conditions and stage of matu-rity. The aroma profiles obtained from dilutions of the extracts confirm the importance of most compounds previously reported as being key flavour compounds in tomatoes. Moreover, they outline a greater number of other key compounds which had not been identified or reported as such in the literature. Among them, 2-methoxyphenol, eugenol, decanal and geranylacetone were identified. Among 39 compounds quantified, 27 were found to permit discrimination between varieties both in 1992 and 1993. Six varieties were characterised in both years by specific flavour compositions. The differences between varieties is due to particular relative amounts of volatile compounds arising from the metabolism of aliphatic amino acids and carotenoids. Volatile compounds arising from each metabolic processes were found to be highly correlated with each other.
    No preview · Article · Oct 1996 · Zeitschrift für Lebensmittel-Untersuchung und -Forschung
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    ABSTRACT: The intensity perceived by sniffing after GC elution of six volatile compounds was measured by ten judges using two pieces of apparatus: a PC mouse which is moved on a 60-cm length scale and a rheostat apparatus which measures the finger span. The choice of the components mixed was influenced by purity, elution time, presence in food and known Steven's slopes. The histograms obtained by summing the responses (determined by measuring the areas under the peaks) of ten people show no significant differences between the two pieces of apparatus. Histograms realised in parallel by Charm analysis with three other judges showed great differences between subjects. However, the mean of the three Charm analysis histograms was very similar to those histograms obtained with the two previously described pieces of apparatus. The same concentrations of ethyl butyrate, 3-methyl butanoic acid and 2,3,5-trimethyl pyrazine had the greatest odour intensity and thiophene, 2,6-dimethyl pyrazine and acetophenone had the lowest odour intensity.
    No preview · Article · Jan 1995 · Zeitschrift für Lebensmittel-Untersuchung und -Forschung
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    ABSTRACT: The odour impact compounds of raw, pasteurized and UHT bovine milk were investigated using vacuum extraction and extract dilution sniffing analysis using CharmAnalysis™. Fifteen odour peaks with Charm values between 10 and 3443 were detected. Of these peaks, twelve were identified as hexanal, ethyl butanoate, 2-heptanone, heptanal, dimethyl sulphone, l-octen-3-ol, ethyl hexanoate, 2-nonanone, nonanal, benzothiazole, 2-undecanone, indole and one as a mixture of 2-tridecanone and δ-decalactone. Dimethyl sulphone, indole and one unknown compound (retention index 1154) were the only ones detected as odour impact compounds in all three types of milk. Ethyl butanoate and ethyl hexanoate were found as powerful odorants only in raw milk. A further predominant odorant for this milk was dimethyl sulphone, which was the most important odorant in pasteurized milk. 2-Hexanone and 2-nonanone were identified as the most intense volatile flavour compounds of UHT milk. The powerful odorants described can be used as indicators of the aroma quality of heated milk.(Received February 04 1993)(Accepted July 07 1993)
    No preview · Article · Jul 1994 · Journal of Dairy Research
  • Nerida. Abbott · Patrick. Etievant · Sylvie. Issanchou · Dominique. Langlois
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    ABSTRACT: The data from the extract dilution sniffing analysis of beer samples have been treated by two methods of analysis to give either ''charm'' or ''FD'' values. The results obtained from these two methods were compared and demonstrated that the rank order of intensity of the odor-active regions was different for most panelists when the data were presented as charm rather than FD values. Points of uncertainty observed while using this method such as between- and within-individual reproducibility and gaps in the coincident response have also been discussed.
    No preview · Article · Oct 1993 · Journal of Agricultural and Food Chemistry
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    ABSTRACT: The importance of obtaining and proving that the odor of an extract is representative of the odor of the original product from which it was obtained, before analysis by GC-FID, GC-MS, or GC sniff, is discussed. The sensory methods, such as triangle tests, matching tests, and quantitative analysis, used to determine the representativeness of the odor of an extract are described. Beer extracts obtained by three methods were used to illustrate the interest of the sensory tests. A method using a mixture of XAD resins was proved by sensory analysis to give some extracts with sensory characteristics representative of the particular beers from which they were obtained. Such sensory evaluation of the quality of the aroma of extracts has to be systematically made when sniffing analysis is applied to new types of beer or to different types of products.
    No preview · Article · May 1993 · Journal of Agricultural and Food Chemistry
  • Luigi Moio · Dominique Langlois · Patrick Etievant · Francesco Addeo
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    ABSTRACT: The main compounds responsible for the aroma of bovine, ovine, caprine and water buffalo freshly secreted milk have been identified by means of a gas chromatography–olfactometry technique. Of the fourteen odour-active volatile compounds detected, eight were present in all milks studied. Ethylbutanoate and ethylhexanoate (fruit-like aroma), among the neutral odorants, were the major contributors to the odour of bovine, ovine and caprine milk. The aroma of water buffalo milk was less dependent on ethylhexanoate and was also due to l-octen-3-ol (aroma of raw mushrooms), nonanal (freshly cut grass), indole (stable, animals) and an unidentified constituent, characterized by a retention index of 828, with a typical odour of warm milk and/or smoked cheese. Other aroma components were specific for some types of milk, contributing to the complexity and richness of flavour.(Received June 22 1992)(Accepted October 29 1992)
    No preview · Article · Apr 1993 · Journal of Dairy Research
  • D. Langlois · P. Mielle · P. Etievant
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    ABSTRACT: Headspace techniques have proved to be of great interest in flavor research. Usually, the headspace is preconcentrated by trapping on adsorbents with subsequent desorption of volatiles by heating or by solvent elution. Heat desorption permits direct injection on to a WCOT column with neither loss of volatiles nor of resolution. Such a device, which implies only minor modification of the basic injection system of a gas chromatograph, is described in this article.
    No preview · Article · Aug 1984 · Journal of High Resolution Chromatography

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  • L. Moio · D. Langlois · P.X. Etievant · F. Addeo

    No preview · Article · · Italian Journal of Food Science
  • D. Langlois · M. Malterre · P.X. Etiévant

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