METHOD AND DEVICE FOR OBTAINING THE TEMPORAL OLFACTORY SIGNATURE OF A SAMPLE AND USES OF THE METHOD

Abstract

The present invention relates to a method for characterising, by means of an electronic nose, the release kinetics of odorous compounds from a sample, comprising the following series of steps: (a) supplying a sample; (b) at a time t1, exposing the sensor array of the electronic nose to some of the gaseous medium comprising the odorous compounds released from the sample, and processing the response emitted by the sensor array of the electronic nose, after said exposure, in the form of a signal; and (c) repeating step (b) at least once, at a time t2 different from the time t1, whereby an olfactory kinetic signature characterising the sample is obtained. The present invention also relates to the use of this method for anti-counterfeiting and/or quality control purposes and for generating a data bank or database of temporal olfactory signatures. The present invention finally relates to certain devices used when implementing such methods.

Claims

1. A method for characterizing, by means of an electronic nose, kinetics of release of odorant compounds from a sample, comprising the following successive steps of: a) providing a sample; b) at a time t.sub.1, exposing a network of sensors of said electronic nose to a portion of the gaseous medium comprising the odorant compounds released from said sample, and processing the response emitted by the network of sensors of said electronic nose, following said exposure, in the form of a signal; and c) repeating step b) at least once, at a time t.sub.2 different from the time t.sub.1, thereby obtaining a temporal olfactory signature which characterizes said sample, wherein said odorant compounds characterized for their release kinetics are not the result of biological, catalytic and/or enzymatic development of the sample during said method, and wherein the release of said odorant compounds from said sample is promoted or accelerated by using a sample quantity of less than 1000 μl, by applying the sample to a porous solid support, by heating the sample, by agitating the sample and/or by using a container in which the sample is placed that has an unclosed opening or a forced flow system.

2. The method of claim 1, wherein said sample is a solid sample.

3. The method of claim 1, wherein said sample is a liquid sample applied to a solid support.

4. The method of claim 3, wherein said solid support is synthetic or non-synthetic, animal or human skin; porous glass; or a cellulosic paper strip in the form of a perfumery smelling strip.

5. The method of claim 1, wherein said sample or said solid support is placed in a container.

6. The method of claim 1, wherein step c) comprises repeating said step b) at a plurality of separate times.

7. The method of claim 5, further comprising a step of introducing air into the container, wherein said introduction may be concomitant with or consecutive to each withdrawal from the gaseous medium containing the odorant compounds released by the sample.

8. A method for comparing the kinetics of release of odorant compounds from two samples E1 and E2, comprising the steps of characterizing the kinetics of release of the odorant compounds from the sample E1 by the method of claim 1, and obtaining a temporal olfactory signature which characterizes said sample E1; characterizing the kinetics of release of the odorant compounds from the sample E2 by the method of claim 1, and obtaining a temporal olfactory signature which characterizes said sample E2; and comparing the temporal olfactory signature which characterizes said sample E1 and the temporal olfactory signature which characterizes said sample E2.

9. The comparison method of claim 8, wherein said step of characterizing the kinetics of release of the odorant compounds from the sample E1 and said step of characterizing the kinetics of release of the odorant compounds from the sample E2 are performed simultaneously.

10. The comparison method of claim 8, wherein said step of characterizing the kinetics of release of the odorant compounds from the sample E1 and said step of characterizing the kinetics of release of the odorant compounds from the sample E2 are separated in time.

11. The comparison method of claim 8, wherein the comparison is used for studying conditions liable to influence the kinetics of release of the odorant compounds from a sample; for determining whether sample E1 or E2 is a counterfeit; or for quality control in the fields of perfumery, essential oils, flavors, synthetic odorant products, synthetic deodorant products, or spirits.

12. A method for generating a bank or database of temporal olfactory signatures, comprising the steps of characterizing the kinetics of release of the odorant compounds from a plurality of samples by the method of claim 1, and obtaining a plurality of temporal olfactory signatures which characterize said samples; and from the plurality of temporal olfactory signatures which characterize said samples, obtained in the preceding step, generating a bank or database of temporal olfactory signatures.

13. A device used in implementing the method of claim 1, comprising (i) at least one container in which a sample is disposed; (ii) an electronic nose having a fluidic system capable of transporting the gaseous medium comprising the odorant compounds released from said sample to the detection system of the electronic nose, which comprises a network of sensors with cross-reactivity for the odorant components present in said gaseous medium, and a computer system carrying out the processing of the responses emitted by the sensors in the form of signals; (iii) a means for processing the signals generated by the computer system of said electronic nose so as to obtain a temporal olfactory signature; and (iv) a means for promoting or accelerating the release of the odorant compounds from said sample.

14. The device of claim 13, wherein said means (iv) for promoting or accelerating the release of the odorant compounds from said sample takes the form of an agitator plate and/or hot plate, a heating system, an unclosed opening traversing said container and/or a forced flow system for accelerating the renewal of the gaseous medium containing the odorant compounds released from the sample.

15. The device of claim 13, further comprising a means for withdrawing from said container the gaseous medium comprising the odorant compounds released from said sample, said means being fluidically connected to the fluidic system of said electronic nose and in that a valve is installed at the fluidic connection between the withdrawal means and the fluidic system of the electronic nose and is programmed so as to pump the gaseous medium comprising the odorant compounds released from said sample at predetermined times.

16. The device of claim 13, further comprising a plurality of containers in which identical or different samples are disposed.

17. The device of claim 13, further comprising a container to which a reference composed of a pure volatile product has been added.

18. The device of claim 13, further comprising a means for introducing air into the internal volume of the container, concomitantly with or consecutively to each withdrawal from this volume; and/or a means for rinsing the network of sensors of the electronic nose after each contact of said nose with a withdrawal.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0117] FIG. 1 already described the development of an index y as a function of time, with y defining a sum or a product of differences or a cosine (similarity index for a scalar product of vectors). Two known standards are measured at each time, from which a mean and a standard deviation are calculated. By measuring the sample for comparison at the same time t, it is possible to calculate a difference δ from the mean of the indices of the two known standards. At times t.sub.1 to t.sub.3, therefore, δ<3σ, and the samples are therefore compliant. At the time t.sub.4, a non-compliance is measured, since δ>3σ.

[0118] FIG. 2 is a schematic representation of a device according to the present invention.

[0119] FIG. 3 shows the comparison of three perfumes (A, B and C) by successive withdrawals (labeled 0 to 17) at high frequency on a Neose Pro electronic nose from Aryballe Technologies. MDS analysis enables a two-dimensional representation of the evolution of complex signatures having 68 dimensions [8].

[0120] FIG. 4A shows the 3D representation of a replica “a” of an original perfume “L”.

[0121] FIG. 4B shows the 3D representation of a replica “a” of a copy of the perfume “L”, copy “LL”.

[0122] FIG. 4C shows the 3D representation of a replica “b” of the perfume “L”.

[0123] FIG. 4D shows the 3D representation of a replica “b” of the copy “LL”.

[0124] FIG. 5 represents the development, over time, of the distance between samples which are two duplicates of the same authentic perfume (TrueR1 and TrueR2) and a copy of this perfume (FalseR1). This visualization technique enables a decision to be made on the basis of a criterion of type 3σ.

[0125] FIG. 6A shows the temporal diffusion, for a reference perfume, with two types of aging: normal (A and B) and accelerated (C).

[0126] FIG. 6B shows the temporal diffusion, for a test perfume, with two types of aging: normal (A and B) and accelerated (C).

[0127] FIG. 7A shows the 3D representation of a replica “a” of the original perfume “L” with normal aging.

[0128] FIG. 7B shows the 3D representation of a replica “b” of the perfume “L” with normal aging.

[0129] FIG. 7C shows the 3D representation of a replica “c” of the perfume “L” with accelerated aging.

[0130] FIG. 8A shows the 3D representation of a replica “a” of a copy of the perfume “L”, copy “LL”, with normal aging.

[0131] FIG. 8B shows the 3D representation of a replica “b” of the copy “LL” with normal aging.

[0132] FIG. 8C shows the 3D representation of a replica “c” of the copy “LL” with accelerated aging.

DESCRIPTION OF CERTAIN EMBODIMENTS

I. Example of a Device Usable in the Context of the Invention

[0133] FIG. 2 shows a device which can be used in the context of the present invention.

[0134] The samples 1 for analysis, which are liquid or solid, are placed in containers such as bottles 2 (five are represented in FIG. 2). The liquid samples are applied beforehand to solid supports as defined above, which are placed in the bottles 2. These bottles are disposed on a magnetic stirring plate 3 intended to agitate them and, in so doing, to agitate the solid samples or the solid supports bearing the liquid samples, so as to promote evaporation of the odorant compounds contained or produced and to homogenize the composition of the head space and advantageously of the gaseous medium contained in each bottle 2.

[0135] The bottles 2 are closed with stoppers 4. Each stopper 4 has a septum which contains at least two through-holes. At the first of these holes, the means for withdrawing the headspace 5 from the internal volume of the bottle 2 is introduced. This withdrawal means 5 takes the form of a hollow needle or a tube. At the second opening in the septum, the means for introducing air 5 into the internal volume of the bottle 2, concomitantly with or consecutively to each withdrawal from said volume, is introduced. This means 6 takes the form of a vent such as a hollow needle or a tube.

[0136] Each withdrawal means 5 is connected fluidically to a multiway valve 7 such as an eight-way valve. This multiway valve 7 is also connected fluidically to the NeOse Pro electronic nose 8 from Aryballe Technologie, and more particularly to the fluidic system of such an electronic nose 8. The multiway valve 7 is connected fluidically, furthermore, to a source 9 of a neutral gas, such as ambient air, which is used for rinsing the sensor network of the electronic nose 8 between two contacting procedures with withdrawals.

[0137] The operation of the multiway valve 7 is controlled by a computer 10 so as to withdraw, at determined times, the gaseous medium present in the internal volume of each of the bottles 1, to inject each withdrawal into the electronic nose 8, and lastly, after each injection of a withdrawal, to rinse the network of sensors of the electronic nose 8 with the neutral gas.

II. Differentiation of Three Perfumes in Terms of Temporal Olfactory Signatures

[0138] The objective is to study the development of the olfactory notes of three separate perfumes, denoted perfumes A, B and C. This study was carried out using a multiple sampler and a stirring plate.

[0139] 50 μl of sample are withdrawn and applied to the end of a smelling strip. Each strip is left in the open air for 30 seconds, and then 7.5 cm of the strip, comprising the end to which the sample has been applied, are inserted into a 50 ml brown bottle. The other end is placed on the thread, and hence on screwing, the cap holds the strip in suspension in the bottle.

[0140] The stopper is formed by a septum allowing the introduction of two stainless steel needles, one enabling the withdrawal of the headspace and the other acting as a vent for renewal of the air in the bottle on each withdrawal.

[0141] Each sample is analyzed in duplicate, i.e., two strips bearing a single sample are placed in two separate bottles. Analysis by multidimensional scaling (MDS) enables a two-dimensional representation of the development of complex signatures having 68 dimensions [8].

[0142] The results are shown in FIG. 3, where each point corresponds to the two-dimensional value obtained for the complex signature of a given perfume on a given withdrawal or injection. Thus the point A12 corresponds to the two-dimensional value obtained for the 12th withdrawal of perfume A.

[0143] For the first withdrawal, the perfumes are very close, owing in particular to the ethanol remnant. After 14 to 17 withdrawals, the three perfumes are correctly separated.

III. Qualitative Analysis of a Perfume and of a Copy in Terms of Temporal Olfactory Signatures

[0144] The objective is a qualitative analysis of two perfumes through observation of the development of their notes. The focus is on an original perfume (perfume L) and a copy of said perfume (perfume LL).

[0145] The protocol the same as that used in section II above was implemented with two replicas, for the perfume and its copy. The results, however, are presented in a different form, specifically as an olfactory tunnel for a perfume (3D). The form presented in FIG. 4 enables a very rapid visualization of the difference between the perfume and its copy.

[0146] Very readily observable, on the olfactory tunnels of the perfume (FIGS. 4A and 4C), are the base notes of the perfume, corresponding to a greater signal amplitude at long times, especially after time 25. On the olfactory tunnels of the perfume copy (FIGS. 4B and 4D), the intensity is much weaker for these same long times.

IV. Differentiation Based on Development of the Distance of Measurements on Different Samples, Made by the Electronic Nose

[0147] Each measurement at time t generates an n-dimensional response, with 68 dimensions in the case of the NeOse Pro [8], from which a normalized signature can be extracted. It is therefore possible to construct a distance between two normalized signatures, this being very much a conventional process of data analysis in electronic noses.

[0148] For a set of measurements, accordingly, a matrix of distances is obtained which describes all of the distances between all of the measurements made. This matrix of distances forms the basis for the MDS algorithm, enabling two-dimensional visualization of a distance matrix much larger in size.

[0149] The other technique involves plotting only the absolute value of the distances as a function of time. In FIG. 5, the distance between the duplicates of the same authentic perfume (TrueR1 TrueR2) is represented over time and corresponds to the measurement of two known standards of perfume. This distance represents the standard deviation, or the reliability of the instrument for the same type of samples at the time t. By convention, three times this distance is selected as the decision threshold. Beyond the distance 3σ, the sample is considered to be different from the two standards measured.

[0150] Accordingly, from the measurements obtained, it is possible to plot the distance curves between the copy (FalseR1) and each of the two duplicates of the reference perfume (TrueR1 and TrueR2). These two curves correspond to the plots TrueR1 FalseR1 and TrueR2 FalseR1. It is found that below the time t=50 min, these two curves are contained in the interval 3σ described above. Conversely, after this time, the two curves become more distant and are beyond the defined threshold. According to this example, therefore, it may be stated that the counterfeit is detectable after 50 min for these given samples.

V. Acceleration of the Temporal Diffusion of a Perfume

[0151] The accelerated aging of the perfumes is performed using a hotplate on which the bottles containing the perfumes are placed, or by imposing a headspace renewal stream, whereas the normal, i.e., nonaccelerated, aging of the perfumes is performed in the absence of a hotplate or without a headspace renewal stream. The volumes of liquid analyzed are identical in all the bottles.

[0152] The results are given in the form of an MDS representation in FIG. 6. In this figure, it is seen that the temporal diffusion of the samples of perfume or of counterfeit perfume in the pierced bottles with septum (points C in FIGS. 6A and 6B, respectively) are accelerated, since the signatures develop more quickly over time, compared with those obtained for the perfume duplicates or counterfeit perfume duplicates in the unpierced bottles with septum (points A and B in FIGS. 6A and 6b, respectively).

[0153] FIG. 7 represents the comparison of the olfactory diffusion in the case of three replicas (a, b and c) of the perfume “L”, of which replicas a and b are subjected to standard aging (FIGS. 7A and 7B) and the replica c to accelerated aging (FIG. 7C). The replica c of the perfume L is quicker to stabilize with regard to the base notes. Between times 10 and 15, the replica is already well stabilized in terms of the base notes, whereas replicas a and b are still developing significantly. Over long times, conversely, the intensity is still significant, which may be interpreted as the presence of the base notes in this perfume.

[0154] FIG. 8 represents the comparison of the olfactory diffusion in the case of 3 replicas (a, b and c) of a perfume copy “LL”, of which replicas a and b are subjected to standard aging (FIGS. 8A and 8B) and replica c to accelerated aging (FIG. 8C). In this example, the replica c of the perfume copy “LL” is less intense from the start, and the intensity reduces very rapidly. Over long times, the intensity is virtually zero.

VI. Differentiation of Two Whiskeys in Terms of Olfactory Signatures

[0155] Equipment:

[0156] For analysis and comparison of two whiskeys, an 8-way valve, 50 ml brown glass bottles equipped with a stopper with septum, magnetic stirrers, a stirring plate, and paper smelling strips were used. The experimental scheme is the same as before; the NeOse Pro instrument from Aryballe Technologies is set for “dynamic measurement” with a cycle of 180 seconds.

Sample Preparation:

[0157] The samples analyzed are two whiskeys C and B. In parallel, a 40% vol/vol ethanol solution is likewise used. For the analysis, 100 μl of sample are applied to a paper smelling strip, the strip is left in the open air for 30 seconds, and then the end bearing the sample is placed in a bottle, with the other end being held on the thread, after which the stopper is screwed over the strip. The whiskeys are prepared in duplicate.

[0158] The vent used is a 1.20×40 mm Sterican® needle. The 6.5 cm PTFE tube is brought into each bottle. Additionally, the bottles are placed under slow stirring for 15 min before analysis is commenced.

BIBLIOGRAPHIC REFERENCES

[0159] [1] International patent application WO 2015/181257 A2 [0160] [2] International patent application WO 2017/167407 A1 [0161] [3] Patent CN105572202 B [0162] [4] Cano et al., Sensors & Actuators: B. Chemical 2011, 156, 319-324 [0163] [5] Gebicki et al., Measurement Science and Technology 2015, 26, 125103 [0164] [6] Li et al., J. Sensors 2017, 17, 272 [0165] [7] Eklöv et al., J. Sci. Food Agri 1998, 76, 525-532 [0166] [8] Brenet et al., Analytical Chemistry 2018, 90, 9879-9887 [0167] [9] Brenet et al., ISOCS/IEEE International Symposium on Olfaction and Electronic Nose 2017.