Dominique Langlois

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

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Publications (9)22.16 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.
    Food Quality and Preference 09/2007; · 2.73 Impact Factor
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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.
    Food Quality and Preference 09/2005; · 2.73 Impact Factor
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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.
    Chemical Senses 04/2005; 30(3):209-17. · 3.28 Impact Factor
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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.
    Flavour and Fragrance Journal 10/2004; 19(6):476 - 482. · 1.82 Impact Factor
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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.
    Journal of Sensory Studies 09/2004; 19(4):307 - 326. · 2.28 Impact Factor
  • Journal of Agricultural and Food Chemistry 04/2002; 41(10). · 3.11 Impact Factor
  • Journal of Agricultural and Food Chemistry 04/2002; 41(5). · 3.11 Impact Factor
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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.
    Journal of Agricultural and Food Chemistry 05/1999; 47(4):1673-80. · 3.11 Impact Factor
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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.
    Zeitschrift für Lebensmittel-Untersuchung und -Forschung 01/1995; 201(4):344-350.