METHOD FOR DETECTING A VOLATILE ANALYTE FOR CLASSING AND SORTING CORK STOPPERS DEPENDING ON THE CONCENTRATION OF THE ANALYTE

Abstract

A method for detecting a volatile analyte to class and sort cork stoppers depending on concentration of the analyte, detection being performed of concentrations in the order of ng/L (parts per trillion), in a concentrated gas applied to the cork stoppers in closed containment. Under said method, cork stoppers are conveyed individually or groups to an incubation chamber (1); air/nitrogen is injected into the incubation chamber (1), the gas enriched with cork volatile compounds is entrained and carried to the concentration system containing a trap (4) heated by desorption of volatile compounds; the volatile compounds are carried by entraining gas to a detection system (6) recording a signal associated with presence of the analyte, the signal being used for classing the stopper/groups of stoppers; a software receives and compares the signal with a minimum limit, deciding to approve or reject the stopper. A system for implementing this method is described.

Claims

1. Method for detecting a volatile analyte for categorization and separation of cork stoppers according to the concentration of the said analyte, characterized in that the said method comprises at least one cycle in which: a) the cork stoppers are separately or jointly taken to the incubation chamber (1) wherein an incubation period begins, and which remains closed during the incubation period by means of a selector valve (2) which will be opened to remove the gas sample for analysis; b) air or nitrogen is injected into the incubation chamber (1), dragging the gas enriched in the cork volatile compounds and leading it to the concentration system which contains a trap (4), the latter being at a temperature equal to or lower than the room temperature, and concentrates the volatile compounds for analysis by adsorption or affinity; c) the trap is heated to a temperature within the range of 80° C. to 300° C. for a period of time of 10 to 60 seconds, for desorption of the volatile compounds; d) the volatile compounds are led by the dragging gas to the detection equipment (6) by means of a heated tube; e) the detection system (6) registers a signal related to the presence of the analyte, the said signal being used for purposes of classifying the cork stopper or groups of cork stoppers; f) a software receives the signal and compares it with the established minimum limit, taking the decision of approval of rejection.

2. Method for detecting a volatile analyte for categorization and separation of cork stoppers depending on the concentration of the said analyte according to claim 1, characterized in that the volatile analyte is 2,4,6-trichloroanisole (TCA).

3. Method for detecting a volatile analyte for categorization and separation of cork stoppers depending on the concentration of the said analyte according to the claim 1, characterized in that the incubation is performed at temperatures within the range of 30° C. to 100° C. and for a period varying from 10 seconds to 2 hours.

4. Method for detecting a volatile analyte for categorization and separation of cork stoppers depending on the concentration of the said analyte according to the claim 1, characterized in that the trap (4) is provided with an adsorbent material and a heating/cooling system which performs cold/hot cycles in a few seconds, typically from 10 to 60 seconds.

5. Method for detecting a volatile analyte for categorization and separation of cork stoppers depending on the concentration of the said analyte according to the claim 1, characterized in that the trap (4) contains an adsorbent material and the differentiation is reached by thermal effect.

6. Method for detecting a volatile analyte for categorization and separation of cork stoppers depending on the concentration of the said analyte according to claim 1, characterized in that the cycle is optimized according to the limiting step of obtaining the signal which indicates the presence or absence of the analyte.

7. Method for detecting a volatile analyte for categorization and separation of cork stoppers depending on the concentration of the said analyte according to claim 1, characterized in that the optimization of the cycle is performed by means of valves which are duly installed in the circuit, successively leading the flows to the detection system.

8. An installation intended for executing the method of claim 1, characterized in that it is comprised of: a) a chamber for incubation (1) and conditioning of the cork stoppers to be tested; b) a selector valve (2) of the gas flow from the incubation chamber (1) to the trap (4); c) a selector valve (3) for sending the gas stream to the detector line or for cleaning the circuit; d) a trap (4) with a heating/cooling system and high temperature variations; e) a selector valve (5) of the gas flow from the trap (4), of multiple units, to the detection system (6); f) a detection system (6) of the volatile analyte.

9. Installation according to claim 8, characterized in that the incubation chamber (1) is configured in series and is provided with independent gas flow and heating in each compartment.

10. Installation according to claim 8, characterized in that the trap (4) optionally contains adsorbent material of volatile compounds from the gas stream to be analysed.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0027] The FIGS. 1a, 1b, 1c and 1d represent the operation of the method for detection of the volatile analyte [0028] (1)—incubation chamber—each circle in FIG. 1b represents one incubation unit, in different steps of the analytical cycle, being synchronized as described in FIG. 4 [0029] (2)—selector valve of the gas flow from the incubation chamber (1) to the trap (4) [0030] (3)—selector valve (3) for sending gas stream to the detector line or for cleaning the circuit [0031] (4)—trap [0032] (5)—selector valve (5) of the gas flow from the trap (4), of multiple units, to the detection system (6) [0033] (6)—detector [0034] (7)—selector valve of the circuit to be used to send the volatile compounds for analysis [0035] (8)—vacuum pump [0036] (9)—controller; [0037] (A)—supply of cork stoppers [0038] (G)—assembly containing N incubation chambers

[0039] More specifically, FIG. 1a relates to the first step of the detection method, namely ventilation; FIG. 1b represents the second step and relates to the connection between the trap and the compartment with the stoppers, wherein the vacuum is previously established for a pre-determined period of time; FIG. 1c represents the third step of the method and relates to the heating of the trap at pre-established conditions of temperature and time; at last, FIG. 1d represents the fourth step and relates to the valve (3) (six-part valve) which connects the trap to the controller (9) and to the detector, with heating of the trap.

[0040] FIG. 2a: Operation of the method for detection of the volatile analyte using a conception illustrated in FIG. 3, with the following references: [0041] (1)—incubation chamber—each circle in the figure on the right represents one incubation unit, in different steps of the analytical cycle, being synchronized as described in FIG. 4; [0042] (2)—selector valve of the gas flow from the incubation chamber (1) to the trap (4); [0043] (3)—selector valve for sending gas stream to the detector line or for cleaning the circuit; [0044] (4)—trap; [0045] (5)—selector valve of the gas flow from the trap (4), of multiple units, to the detection system (6); [0046] (6)—detection system; [0047] (7)—selector valve of the circuit to be used to send the volatile compounds for analysis; [0048] (A)—supply of cork stoppers [0049] (G)—assembly containing N incubation chambers

[0050] FIG. 2b: Detailed view of the incubation set and wherein each circle of the figure on the right represents one incubation unit, in different steps of the analytical cycle, being synchronized as described in FIG. 4, with the following references: [0051] (A)—supply of cork stoppers [0052] (G)—assembly containing N incubation chambers

[0053] FIG. 3: Example of the conception of a system for the analysis of volatile compounds in cork stoppers to the pilot-scale, with the following references: [0054] (1)—incubation chamber [0055] (A)—supply of cork stoppers [0056] (B)—exit for cork stopper or group of cork stoppers with a positive result in the presence of the analyte [0057] (C)—exit for cork stopper or group of cork stoppers with a negative result in the presence of the analyte [0058] (D)—exit of cork stopper or group of cork stoppers for which the analysis has generated any kind of error [0059] (E)—position in the proposed configuration wherein the incubation chamber is cleaned before entering new cork stoppers [0060] (F)—suction point from the sample (gas containing the analyte) to the trap [0061] (G)—assembly containing N incubation chambers

[0062] FIG. 4: Synchronization of events using a proposed configuration

[0063] FIG. 5: Representation of an installation for industrial processing

SUMMARY OF THE INVENTION

[0064] This invention relates to a method which allows the volatile analyte to be detected, in this particular case the 2,4,6-trichloroanisole (TCA), by means of a non-invasive and non-destructive proceeding, the said analyte being possibly found in very low concentrations (ppt) and accumulating in the gaseous phase over cork stoppers and confined to a closed conditioning system. This invention provides categorization and separation of the cork stoppers according to parameters established as the levels of acceptance of the said analyte.

[0065] The technical solution presented also offers a rhythm which is compatible with the industrial needs, since it allows 1,000 to 10,000 cork stoppers to be analysed on an hourly basis.

[0066] The perspective disclosed by this invention is based upon non-invasive and non-destructive controlling methods, an approach that is essential considering the heterogeneous character of the cork as well as the market requirements concerning the bottle-to-bottle—i.e., stopper-to-stopper—warranty, which are not compatible with the statistical control.

[0067] Although the cork industry has developed preventive and curative procedures aimed at avoiding the presence of compounds with organoleptic impact, traces of those compounds still continue to be detected in cork stoppers.

[0068] In particular, the presence of TCA is hardly avoided due to the combination of factors such as:

1. the waterproofing properties of cork;
2. the need to reach concentration values within the range of ppt, an extraordinarily low value, due to the compound's low sensorial perception threshold;
3. the compound's high chemical stability.

[0069] In the industrial scope, cork stoppers are subject to washing which can be made by using oxygenated water or peracetic acid, for cleaning and disinfecting purposes. After washing/disinfection, the humidity content is stabilized, thus providing an optimal performance of the stopper as sealant and simultaneously reducing the microbiological contamination. However, as regards the issue of volatile compounds, namely TCA, these methods are not enough (Gil, 2006).

[0070] This invention also allows to: [0071] Reduce the energy consumption associated to techniques intended for extracting 2,4,6-TCA from the cork; [0072] Carry out a 100% control in the batches of cork stoppers, in a rhythm which is compatible with the industrial activity; [0073] Ensure levels of contamination which are under the sensorial detection limit.

DETAILED DESCRIPTION OF THE INVENTION

[0074] This invention relates to the detection of a volatile analyte in cork stoppers by means of a non-destructive and non-invasive methodology in which the said analyte is detected in concentrations within the range of ng/l (parts per trillion—ppt), as well as to the inspection and categorization of the cork stoppers according to the parameters defined as the acceptance levels of the said analyte, offering the possibility of analysing 1,000 to 10,000 cork stoppers on an hourly basis. In this particular case, the analyte to be detected is 2,4,6-trichloro-anisole (TCA).

[0075] Comparatively to the known methods of analysis, the one being described in this invention distinguishes from the others due to the possibility of keeping the analysed cork stoppers intact and also the possibility of using it by taking into account the industry requirements, since the said method allows 1,000 to 10,000 cork stoppers to be analysed on an hourly basis.

OBJECT OF THE INVENTION

[0076] A first object of this invention is to provide a method for detection, categorization and separation according to the concentration levels of the volatile analyte (TCA) which causes the so-called “cork taste” to be noticed, wherein:

[0077] a) the cork stoppers are separately or jointly taken to the incubation chamber (1) wherein an incubation period begins, and which remains closed during the incubation period by means of a selector valve (2) which will be opened to remove the gas sample for analysis;

[0078] b) air or nitrogen is then injected into the incubation chamber (1), dragging the gas enriched in the cork volatile compounds and leading it to the concentration system which contains a trap (4), the latter being at room temperature or at a lower temperature, and concentrates the volatile compounds for analysis by adsorption;

[0079] c) the trap (4) is heated to a temperature within the range of 80° C. to 300° C. for a period of time of 10 to 60 seconds, depending on the trap's material characteristics, for desorption of the volatile compounds;

[0080] d) the volatile compounds are led by the dragging gas to the detection equipment (6) by means of a heated tube;

[0081] e) the detection system (6) registers a signal related to the presence of the analyte, the said signal being used for purposes of classifying the cork stopper or groups of cork stoppers;

[0082] f) a software receives the signal and compares it with the established minimum limit, taking the decision of approval of rejection.

[0083] Preferably, the incubation is carried out at a temperature within the range of 30° C. to 100° C. and for a variable period of time ranging from 10 seconds to 2 hours, depending on the amount of analyte released by the cork stoppers.

[0084] In a preferred embodiment of this invention, the trap (4) is comprised of an adsorbent material and a heating/cooling system which allows the cold/hot cycles to be performed in few seconds, typically from 10 to 60 seconds.

[0085] Usually, the trap (4) is heated at a temperature within the range of 120° C. to 300° C. for a period of time of 10 to 20 seconds, for desorption of the volatile compounds.

[0086] The method for detection herein disclosed allows 1,000 to 10,000 cork stoppers to be analysed per hour, as well as the detection of the analyte (TCA) in concentrations within the range of ng/L (parts per trillion).

[0087] In a preferred embodiment of the invention, the cycle is repeated for each one of the cork stoppers (individually considered or in groups), with the whole cycle being optimized according to the limiting step of obtaining the signal which indicates the presence or absence of the analyte.

[0088] Preferably, the optimization of the cycle is performed by means of selector valves which are adequately installed (2), (3), (5) in the circuit, successively leading the flows to the detection system.

[0089] A second object of this invention is to provide an installation intended for executing the method of detection, categorization and separation of the volatile analyte (TCA) which is comprised of a:

[0090] a) chamber for incubation (1) and conditioning of the cork stoppers to be tested;

[0091] b) selector valve (2) of the gas flow from the incubation chamber (1) to the trap (4);

[0092] c) selector valve (3) for sending the gas stream to the detector line or for cleaning the circuit.

[0093] d) trap (4) with a heating/cooling system;

[0094] e) selector valve (5) of the gas flow from the trap (4), of multiple units, to the detection system (6);

[0095] f) Detection system (6).

[0096] In a preferred embodiment of the invention, the incubation chamber (1) is configured in series and is provided with independent gas flow and heating in each compartment.

[0097] Preferably, the trap (4) has high temperature variations, from 80° C. to 300° C., and is provided with material which adsorbs the volatile compounds from the gas stream to be analysed.

EXAMPLES

[0098] This invention is hereinafter illustrated with the following examples which have a non-limiting character as regards the protection scope of this patent application.

Example 1

[0099] In a carousel-type incubation chamber (1), with 18 positions and a capacity for 30 analysis/hour, the samples, i.e. the cork stoppers, are inserted for a 16-minutes incubation period to be started. The incubation chamber (1) is kept closed during the said period by means of a selector valve (2) which will be opened to remove (suction) the gas sample for analysis, this air being led to the concentration system which contains the traps (4) wherein the volatile compounds concentrate for analysis by adsorption. The samples remain in the traps (4) for 20 minutes. The volatile compounds will be carried to the detection equipment (6) which registers a signal related to the presence of the analyte. The analysis will be performed for 2 minutes/sample.

[0100] In this installation 2 traps (4) were used, which allowed a rate of 30 samples/hour.

Example 2

[0101] In a carousel-type incubation chamber (1), with 60 positions and a capacity for 180 analysis/hour, the samples, i.e. the cork stoppers, are inserted for a 15-minutes incubation period to be started. The incubation chamber (1) is kept closed during the said period by means of a selector valve (2) which will be opened to remove (suction) the gas sample for analysis, this air being led to the concentration system which is comprised of the traps (4) wherein the volatile compounds concentrate for analysis by adsorption. The volatile compounds will be carried to the detection equipment (6) which registers a signal related to the presence of the analyte. The analysis will be performed for 20 seconds/sample.

[0102] In this installation, 6 traps (4) were used which allowed a rate of 180 samples/hour.

[0103] As will be evident to a person skilled in the art, several detail modifications can be made, which however shall be included in the scope of this invention.

[0104] This invention is to be limited only by the spirit of the following claims.