EP4713674A1 - Sensor device - Google Patents

Sensor device

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Publication number
EP4713674A1
EP4713674A1 EP24728925.9A EP24728925A EP4713674A1 EP 4713674 A1 EP4713674 A1 EP 4713674A1 EP 24728925 A EP24728925 A EP 24728925A EP 4713674 A1 EP4713674 A1 EP 4713674A1
Authority
EP
European Patent Office
Prior art keywords
sensor
gas
boar
semiconductor
fat
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP24728925.9A
Other languages
German (de)
French (fr)
Inventor
Marc Debliquy
Driss Lahem
Ahmadou LY
Clément BURGEON
Marie-Laure FAUCONNIER
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Universite de Liege
Universite de Mons
Materia Nova ASBL
Original Assignee
Universite de Liege
Universite de Mons
Materia Nova ASBL
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB2307515.3A external-priority patent/GB2630563A/en
Application filed by Universite de Liege, Universite de Mons, Materia Nova ASBL filed Critical Universite de Liege
Publication of EP4713674A1 publication Critical patent/EP4713674A1/en
Pending legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/02—Food
    • G01N33/12—Meat; Fish
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
    • G01N33/0029—Cleaning of the detector
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
    • G01N33/0031—General constructional details of gas analysers, e.g. portable test equipment concerning the detector comprising two or more sensors, e.g. a sensor array
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/007—Arrangements to check the analyser
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/02—Devices for withdrawing samples
    • G01N1/22—Devices for withdrawing samples in the gaseous state
    • G01N1/24—Suction devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G01N1/44—Sample treatment involving radiation, e.g. heat

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Food Science & Technology (AREA)
  • Medicinal Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Combustion & Propulsion (AREA)
  • Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)

Abstract

A gas sensor device (10) is configured to detect boar taint in a gas sample of volatised boar fat (5) by using a difference between i) a change in a first signal of a first sensor (2) over a sampling period and ii) a change in a second signal of a second sensor (2) over a sampling period to differentiate between a presence and an absence of boar taint. The gas sensor device (10) comprises a hemispherical enclosure (3) configured to be put in close contact with the surface of the boar fat (5) in order to sample VOCs being volatised from the boar fat (5). The VOCs are volatised by placing a heating device (1) in contact with the surface of the boar fat (5) and heating up to a temperature in the range from 200°C to 500°C. The gas sensor device (10) is designed to be used at line on the production line of a slaughterhouse.

Description

Sensor device
[0001] This invention relates to a method of detecting boar taint in a gas sample of volatised boar fat and a gas sensor device for detecting boar taint.
[0002] During the cooking of meat from uncastrated male pigs (also called boar), a strong and unpleasant smell, similar to a strong urine and/or faecal smell, may be released. Due to this, even if the meat is edible, it is considered spoiled. It is thus an important issue in the meat industry to prevent the production of boar taint compounds and to avoid selling boar meat subjected to the release of such unpleasant smells.
[0003] Two molecules have been found to be primarily responsible for this smell and taste: androsterone and skatole. These molecules are mainly contained in boar fat and the concentration of those increases with boar age, notably when the pig reaches puberty. The concentration may also depend on the boar. Boar taint occurs when molecules responsible for this odour and flavour, notably skatole and androsterone, are present in the fat above a certain threshold; although the threshold at which boar fat is considered tainted is variable from one research to another, fat is frequently considered tainted when androsterone is > 1000 ng/g fat and/or skatole is > 200 ng/ g fat.
[0004] In the past, in order to prevent the production of boar taint compounds (and hence storage of these compounds in the meat), surgical castration of piglets was frequently performed. However, in recent years and due to European animal welfare laws this method is increasingly being abandoned and replaced by other practices.
[0005] These practices include i) immunocastration (also known as chemical castration) and ii) rearing of particular species of pigs which are known to produce reduced concentration of boar taint compounds. However, immunocastration presents up to 3% of non-responders (pigs in which immunocastration has no effect), mainly due to an inadequate administration of the vaccine. These immunocastrated males must therefore still be checked for boar taint in slaughterhouses. It has also been shown that immunocastration leads to an increase in feed intake, accompanied by an increase in daily weight and an alteration in carcass and meat quality. Moreover, in some countries like Denmark, this practice is not allowed.
Rearing of particular species of pigs known to produce reduced concentration of boar taint compounds still leads to a significant percentage of males presenting boar taint (these percentages are variable but have been considered to reach 10% of entire males). Additionally, selecting only female pigs (also called gilts or sows depending on whether they have not or have already farrowed) is not practical and economically viable.
[0006] These alternative practices are increasing throughout Europe and the occurrence of boar tainted carcasses increases accordingly. The correct detection of such carcasses is therefore now more than ever a topic of high interest in research and a problem which requires solutions in a very near future. Currently, the standard method is the following: a trained person (a boar taint evaluator) heats a piece of pork fat, typically a piece of neck fat, with a soldering iron and after a few seconds (to remove the smoke) smells the carcass. If the smell is judged good, the carcass continues the way. If boar taint is detected, the carcass is marked and sent another way to produce other meat products which may undergo practices to reduce boar taint prior to commercialisation (e.g. dry fermented sausages). These practises to reduce boar taint tend to expand meat production and increase costs. Typically, the frequency for a boar taint evaluator to evaluate the presence or the absence of boar taint is of one carcass every 10-15 seconds, which is very short.
[0007] One main drawback of the current detection method is that it is too vulnerable to human errors. The boar taint evaluator must be trained, he must be replaced every two hours (due to olfactive fatigue) and subjective discrimination between two different boar taint evaluators leads to a high risk of errors.
[0008] Alternative “rapid” detection methods have been tested, for example laser diode thermal desorption - tandem mass spectrometry (LDTD-MS/MS) which has been disclosed in WO2016139291 and WO2017147709. However, this method requires high initial investment and high slaughtering rates to allow costs per analysis to be sufficiently small to replace human detection.
[0009] Gas sensors configured to be reactive to boar taint compounds in a gaseous atmosphere are also available. However, these are slow and/or inaccurate when used to detect or determine the amount of boar taint compounds in the environment of slaughterhouse.
[0010] It is thus desired to provide an improved method of detecting boar taint which can be implemented in slaughterhouses, in particular without any interruption of the slaughtering line, notably a method that is easier to implement in a slaughter house and which is more reliable than human detectors without requiring more time.
[0011] In accordance with one of its aspects, the present invention provides a method of detecting boar taint as defined in claim 1. Additional aspects of the invention are defined in independent claims. The dependent claims define preferred and/or alternative embodiments.
[0012] One aspect of the present invention is to provide a method of detecting boar taint in a gas sample of volatised boar fat comprising:
- exposing a first sensor and a second sensor to the gas sample for a sampling period, the first sensor providing a first signal indicative of VOCs detected in the gas sample by the first sensor, the second sensor providing a second signal indicative of VOCs detected in the gas sample by the second sensor and the first sensor being more reactive to target gas(es) indicative of boar taint than the second sensor;
- using a difference between i) a change in the first signal over the sampling period and ii) a change in the second signal over the sampling period to differentiate between a presence and an absence of boar taint.
[0013] This aspect of the invention is based, at least in part, firstly on the realisation that when volatising boar fat, a great number of volatile organic compounds are present in the volatised gas, including the boar taint compounds, if present and that as the possible boar taint compounds in gaseous state are blended with other VOCs, it is difficult to quickly and efficiently detect their presence with gas sensors configured to be reactive to boar taint compounds, and secondly on the realisation that this difficulty can be surmounted by the method of the present invention.
[0014] The method preferably further comprises a step of volatising a sample of boar fat. The sample of boar fat is preferably volatised, for example with a heating resistance, at a temperature in the range between 200 °C and 500 °C, preferably in the range between 200 °C and 400 °C, more preferably in the range 300-400°C . At a temperature below 200 °C, the concentration of boar taint compounds (if present) will be quite low; volatising at or about 200°C provides a concentration of boar taint compounds which facilitates accurate detection by the first and/or the second sensor. At a temperature above 500 °C, the amount of volatilised organic compounds released from the boar fat sample may tend to saturate the first and/or second sensor. Without wishing to be bound by theory, it is believed that a temperature in the range 430-470°C, notably about 450°C, is optimum for volatising gas(es) indicative of boar taint, such as skatole and androstenone, notably under a reduced pressure atmosphere, particularly a reduced pressure atmosphere between 1 Pa and 1000 Pa. However, it is also believed that such temperatures may not actually be optimum for detection boar taint in a gas sample of volatised boar fat, for example on-line in a slaughterhouse, because of the other gas(es) volatilised from the sample of boar fat which may appear in too high a concentration and may mask the detection of volatising gas(es) indicative of boar taint, such as skatole and androstenone. It is thought that the optimum temperature at which the sample of boar should be volatised for the detection of volatising gas(es) indicative of boar taint is actually in the range 330-370°C, notably about 350°C, notably under a reduced pressure atmosphere, particularly a reduced pressure atmosphere between 1 Pa and 1000 Pa. Consequently, it is preferably this volatising temperature which is used, particularly for on-line detection.
[0015] Before or upon exposing the first sensor and the second sensor to the gas sample for a sampling period, the distance between the volatized boar fat and the first and second sensors may be less than 20cm, preferably less than 15cm, more preferably less than 10cm. This greatly increases accuracy of the detection by the sensors as the gas sample is formed at the vicinity of the sensors.
[0016] The sample of boar fat may be volatised by a volatising device, notably a heating device, for example a heating resistance, hot pressurized air, hot pressurized water steam, or a heating laser. The heating device is preferably controlled by a processing device configured to set parameters such as temperature, pressure, energy and/or exposure time so that the sample of boar fat is volatised, notably at a temperature in the range between 200 °C and 500 °C.
[0017] When the heating device is a heating resistance, the heating resistance is preferably a heating grid. A heating grid comprising apertures is preferred as it allows a higher amount of volatised boar fat to flow towards the first sensor and the second sensor through its apertures.
[0018] As used herein, the term “more reactive” in the context “the first sensor being more reactive to target gas(es) indicative of boar taint than the second sensor” means that when in contact
- for the first time (i.e. no prior exposure to target gas(es)) ;
- with substantially the same amount of the same target gas representative of a boar fat having at least 200 ng/g of skatole and/or at least 1000 ng/g of androstenone; and
- over substantially the same predetermined time of at least 10s, the change of the physical parameter measured by the first sensor (for example resistance or conductance) is at least 10% greater than the physical parameter measured by the second sensor.
[0019] The target gas(es) in the gas sample indicative of boar taint comprise(s) gas(es) derived from the boar taint compounds in the sample of boar fat and may be selected from indole, skatole, androstenone or derivatives thereof (for example androstanol, alpha- androstanol or beta-androstanol), and combination thereof.
[0020] The method may further comprise, before volatising boar fat, a step in which a purging gas, for example an inert gas (for example argon and/or nitrogen) or air is blown towards the sample of boar fat. This can be useful to clean the surface of the sample of boar and/or to repulse any VOCs present in the surrounding atmosphere of the sample of boar fat, which may interfere with the detection in a slaughterhouse. The blowing step may be performed via a gas inlet provided with the gas sensor device or by a separate blowing apparatus. Particularly when the inert gas is air, the inert gas may be used to clean the surface of the sample of boar fat (for example at low, room or high temperature) and to volatise the sample of boar fat (at high temperature).
[0021] The gas sensor device may comprise an enclosure inside which the first sensor and the second sensor, and the optional heating resistance are preferably provided. The enclosure may be configured to substantially confine the gas sample of volatised boar fat within, notably by preventing the gas sample flowing away from the sensors during the sampling period. In particular, the enclosure may substantially confine the gas sample of volatised boar fat at the vicinity of the first and second gas sensor. The enclosure may have open side configured to be put in contact with the sample of boar fat.
[0022] Particularly when the gas sensor device comprises a heating resistance, a portion of the heating resistance may project out of the open side of the opened enclosure. In this configuration, the portion of the heating resistance may be adapted to contact the sample of boar fat. The heating resistance may be connected to the enclosure with one or more rods, notably spring rods, secured within the enclosure.
[0023] Particularly when the gas sensor device comprises a laser, the laser may be located in the vicinity of the first and the second sensors, preferably within the enclosure if present.
[0024] The enclosure may be substantially made in a plastics material, for example PET, PE or better PTFE (e.g. Teflon). This is particularly advantageous as it can be manufactured at great numbers at low costs. Alternatively, the enclosure may comprise a ceramic.
[0025] The enclosure may comprise, notably at the opposed end to its open side, connection means configured to connect the gas sensor device to a signal processing device, notably a connecting wire connected to the signal processing device. Preferably the enclosure of the gas sensor device is removably attached to the signal processing device, notably by the connecting wire connected to the signal processing device. When necessary, the gas sensor device can be easily replaced by replacing the opened enclosure comprising the first sensor and the second sensor, and the optional heating device.
[0026] In a preferred embodiment, the signal processing device is also configured to control the volatising device and is configured to set parameters such as temperature, pressure, energy and/or exposure time so that the sample of boar fat is volatised, notably at a temperature in the range between 200 °C and 500 °C.
[0027] The enclosure may comprise a gas inlet. The gas inlet may be used to blow a purging gas, for example an inert gas (for example argon and/or nitrogen) or air inside the enclosure, notably towards the sample of boar fat. The gas inlet may also be used, to provide a reduced pressure atmosphere within the opened enclosure. Blowing the purging gas and/or reducing pressure atmosphere within the enclosure is preferably performed before volatising the sample of boar fat. The purging gas and/or reducing pressure atmosphere within the opened enclosure of the gas sensor device may be used to reduce the concentration of pollutant VOCs. When a reduced pressure atmosphere is provided, it may be between 1 Pa and 1000 Pa.
[0028] The enclosure may have a hemi-spherical shape or an elongated shape, for example a cylinder, a cone, notably a truncated cone. Preferably, the enclosure has the form of a cone, notably a truncated cone. Particularly when the enclosure is in the form of a cone, notably a truncated cone having a large opening and a small opening, the (large) opening of the cone is placed towards the sample of boar fat. In this configuration, the gas sample is led towards the sensors provided within the enclosure as the diameter of the cone decreases. Particularly when the gas sensor device comprises an enclosure, the gas sensor device may comprise a wall, notably a substantially sealing wall separating the part of the gas sensor device in contact with the gas sample and the part of the gas sensor comprising the electronic part of the gas sensor device, for example the connection means of the gas sensor device to a signal processing device.
[0029] In an alternate embodiment, the enclosure comprises a gas outlet and is free of sensors. When a gas sample of volatised boar fat is provided within the enclosure, the gas sample is sucked out the opened enclosure through the gas outlet to be analysed by sensors remotely connected to the gas outlet by, for example, a pipe in which the gas sample flows.
[0030] The open side of the enclosure may have a surface area of at least 10cm2, at least 20 cm2, at least 30cm2 and/or less than 100 cm2, less than 80cm2 or less than 60cm2. Preferably, the open side of the enclosure has a surface area in the range 10 cm2-40 cm2. When the open side of the enclosure has a surface area in the range 10-100 cm2 and below, a sufficient amount of gas sample of volatised boar fat may flow towards the sensors.
[0031] The method preferably comprises, before and/or after the sampling period, a pyrolyzing step of substantially removing any traces of VOCs deposited on surface(s) of the first and/or second sensors. When the method of detecting boar taint is performed, VOCs present in the gas sample of volatised boar fat tend to deposit and accumulate as an organic layer on surface(s) of the sensors in contact with the gas sample. This organic layer may interfere with the signals generated by a subsequent gas sample. It is thus desired to remove such an organic layer, notably with a pyrolyzing step. Preferably, the sensors comprise pyrolysis means adapted to provide a pyrolyzing step and removing any organic layer deposited on the surface of the sensors.
[0032] The first sensor providing a first signal indicative of VOCs detected in the gas sample by the first sensor is configured to be more reactive to target gas(es) indicative of boar taint than the second sensor providing a second signal indicative of VOCs detected in the gas sample. The combination of two sensors, one of which being more reactive to target gas(es) indicative of boar taint, allows detecting presence or absence of boar taint without the necessity to wait the for the signals to fully stabilize. Typically, upon contact with the gas sample, the property of the sensor to be measured (for example resistance, conductance, resistivity, conductivity) has i) a transitional phase in which the signal progressively varies (increases or decreases) over a first period and subsequently ii) a stabilisation phase in which the signal is substantially stable which may reflect, for example, the amount of target gas(es) within the gas sample. It has been found that, contrary to previous methods which rely upon the stabilisation phase to detect presence or absence of boar taint, it is possible to detect presence or absence of boar taint during the transitional phase, by using a difference between i) a change in the first signal over the sampling period and ii) a change in the second signal over the sampling period to differentiate between a presence and an absence of boar taint. This greatly accelerates the detection of boar taint whilst maintaining a desired level of accuracy.
[0033] The change in the first (or second) signal over the sampling period reflects the slope of the first (or second) signal, the sampling period being a period which comprises the transitional phase and is preferably completed prior to the stabilisation phase.
[0034] The first sensor (i.e. the sensor more reactive to target gas(es)) is preferably a semiconductor type sensor. Particularly when the first sensor is a semiconductor type sensor, the semi-conductor material is selected from a n-type semiconductor or a metal oxide semiconductor. The metal oxide may be a metal oxide comprising ZnO, a metal oxide comprising WO3, a metal oxide comprising SnC>2, a metal oxide comprising ln2Oa, and combination thereof.
[0035] The second sensor (i.e. the sensor less reactive than the first sensor) may be a semiconductor type sensor. Particularly when the second sensor is a semiconductor type sensor, the semiconductor material may be selected from notably from a p-type semiconductor, lanthanum ferrite, lanthanum ferrate, nickel oxide, copper oxide, cobalt oxide, or combination thereof. Alternatively, it may be a n-type semiconductor.
[0036] The sampling period for the first sensor preferably substantially overlap the sampling period for the second sensor. It is preferable that the first and the second sensors are exposed to the gas sample during the same sampling period. [0037] The sampling period may be less than 60 seconds, preferably less than 30 seconds, more preferably less than 20 seconds.
[0038] In order to differentiate the presence or the absence of boar taint, the difference between i) a change in the first signal over the sampling period and ii) a change in the second signal over the sampling period to differentiate between a presence and an absence of boar taint is preferably compared to a predetermined threshold value, which is predetermined by the user prior to performing the method.
[0039] Preferably, the difference is the ratio S1(t)/S2(t) between the change in the first signal to be measured S1 (t) over the sampling period and the change in second signal to be measured S2(t) over the same sampling period. The ratio is then compared to a threshold value which differentiate the presence from the absence of boar taint. Preferably, the curve representing the ratio S1(t)/S2(t) is assimilated to a linear equation S1 =A*S2+E and the slope A is compared to the threshold value to differentiate the presence from the absence of boar taint. The threshold value is determined by the user and will depend on the selection of sensors used. The threshold value is representative of the concentration of boar taint compounds in the sample of boar fat.
[0040] The sample of boar fat may be considered as tainted when the concentration of:
- skatole is above 200 ng/g of fat; and/or
- androstenone is above 1000 ng/g of fat; and the method and/or gas sensor device is preferably configured to differentiate between a presence and an absence of boar taint on this basis.
Nevertheless, the values of concentration of skatole and/or androstenone at which the boar fat is considered as tainted may vary depending on limits fixed by the user and/or on country regulations.
[0041] Preferably, the gas sensor device comprises a third sensor providing a third signal indicative of VOCs detected in a gas sample by the third sensor, the third sensor being less reactive to target gas(es) indicative of boar taint than the first sensor and the second sensor. The preferred use of this third sensor is to measure the global concentration of the VOCs and to check if the test is valid, notably if there are enough VOCs in the gas sample of volatised boar fat.
[0042] The sample of boar fat is preferably a sample from an animal carcass, a meat product, or a sample from a meat product, each of which having fat. Preferably the sample of boar fat is a sample of backfat.
[0043] Preferably, the method is performed on-line. As used herein the term “on-line” means that the method is performed in a slaughterhouse, preferably upon a boar carcass whilst the boar carcass is on a conveyor, or during processing of the boar carcass in the slaughterhouse, as opposed to the boar fat being removed from the carcass and tested in a remote laboratory.
[0044] According to another aspect, the present invention further provides a method of detecting boar taint in a gas sample of volatised boar fat with a gas sensor device for detecting boar taint in the gas sample of volatised boar fat comprising i) a first sensor being configured to provide a first signal indicative of VOCs detected in the gas sample by the first sensor and a second sensor being configured to provide a second signal indicative of VOCs detected in the gas sample by the second sensor, wherein the first sensor is more reactive to target gas(es) indicative of boar taint than the second sensor; and ii) a heating device, notably a heating resistance or a laser; wherein the method comprises:
- preferably removing traces of VOCs deposited on the surface of the first and/or second sensors; - preferably blowing a purging gas towards the sample of boar fat;
- subsequently volatising the sample of boar fat, preferably by a heating resistance, at a temperature in the range 200-500 °C to form a gas sample of volatised boar;
- subsequently exposing the first sensor and the second sensor to the gas sample for a sampling period, the first sensor providing a first signal indicative of VOCs detected in the gas sample by the first sensor, the second sensor providing a second signal indicative of VOCs detected in the gas sample by the second sensor and the first sensor being more reactive to target gas(es) indicative of boar taint than the second sensor; and
- using a difference between i) a change in the first signal over the sampling period and ii) a change in the second signal over the sampling period to differentiate between a presence and an absence of boar taint.
[0045] In this further embodiment, the method may comprise additional step(s) previously disclosed and/or the gas sensor device may comprise additional feature(s) previously disclosed.
[0046] An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings of which:
Fig 1 is a schematic drawing of a gas sensor device according to an embodiment of the invention;
Fig 2 is a photograph of a gas sensor device according to another embodiment of the invention;
Fig 3 is a graph showing change of resistivity over time by varying heating temperature of the sample of boar fat;
Fig 4 is a graph showing variation of the first gas sensor with respect to the second gas sensor;
Fig 5 is a chart graph comparing samples of tainted and untainted boar fat.
[0047] Fat 5 from sow fat and tainted boar are firstly collected from a slaughterhouse. Sow fat (fat from female pigs) is randomly selected as sow fat does not develop boar taint. Four samples of tainted boar fats (P1 , P2, P3, P4) are selected after having been tested for boar taint by a trained assessor through the human nose method. The presence of boar taint is also confirmed through the measurement of skatole and androstenone in the boar fat by high-performance liquid chromatography fluorescence detection (HPLC-FD). Boar fat is considered tainted if skatole or androstenone concentrations are above the thresholds of 200 ng/g of fat or 1000 ng/g of fat respectively. Four samples of untainted sow fate are also selected (N1 , N2, N3, N4).
[0048] As illustrated in Fig 2, the gas sensor device 10 comprises a plastics enclosure 3 in the form of a truncated cone having a large opening at one end and a small opening at the opposed end, the openings being substantially parallel to each other. The large opening is adapted to face and to be in contact with the sample of boar fat. The small opening comprises connection means for connecting and transmitting signals from the sensors 2 to a signal processing device connected to the gas sensor device via the connection means. A concave wall is located within the enclosure, separating the large opening and the small opening of the enclosure. The sensors 2 and gas inlets 4 are provided on the surface of the wall towards the large opening. The provision of the wall prevents the gas contacting the connection means located at the small opening and allows the gas to be in the vicinity of the sensors 2. As the sensors 2 are provided within the enclosure, the enclosure (including the sensors) can be easily replaced on site when the sensors are malfunctioning or too dirty.
[0049] A first sensor and a second sensor are secured to the surface of the wall facing the large opening of the enclosure 3, the first sensor being more reactive to skatole and/or androstenone than the second sensor. The first sensor is a semiconductor type sensor having ZnO as the reactant material. The second sensor is sensor having ferrite lanthanum as the reactant material. A third sensor as a reference to validate the signals is also provided within the opened enclosure, in the proximity of the first and second sensors. It is sensitive to the total amount of VOCs and validates the contact between the heater and the fat sample.
[0050] The heating resistance is a heating metallic grid 1 secured to the concave wall by two opposed metallic spring rods. On the opposed surface of the concave wall, the spring rods are connected to the signal processing device through the connecting means located at the small opening of the enclosure. The signal processing device, in addition to being used to analyse the signals provided by the sensors 2, comprises a control system configured to set and keep the heating resistance at a set temperature. The heating grid 1 projects beyond the large opening. As the heating grid projects beyond the large opening, the heating grid 1 can contact the sample of boar fat 5, notably on a boar carcass, in front of the periphery of the large opening.
[0051] The concave wall also comprises a gas inlet 4 configured to blow clean purging air towards the sample of fat 5, purging the area surrounding the sample of fat 5 from VOC’s.
[0052] The head of the gas sensor device 10 is placed into contact with a fat sample 5, the heating metallic grid 1 being at room temperature (about 20 °C) and purging air is blown towards the fat sample 5, blown from the gas inlet 4. Once the fat sample is purged, the fat sample 5 is heated by the heating metallic grid 1 , the fat sample 5 being in contact with the heating grid 1 during heating, as shown in Fig 1.
[0053] Fig 3 illustrates the electrical resistance R1 , R2 and R3 of the sensors 2 versus time during heating of the fat. The temperature of the heating grid for the purpose of data collection illustrated in Fig 3 is firstly set at 150 °C for 6 minutes, then raised up to 250 °C (the time until the temperature reaches 250 °C is 30 seconds) for 2.5 minutes and further increases up to 350 °C (the time until the temperature reaches 350 °C is 30 seconds). R1 is the electrical resistance of the third sensor. R2 is the electrical resistance of the sensor more reactive to the boar taint compounds (the first sensor) and R3 is the electrical resistance of the sensor less reactive to the boar taint compounds (the second sensor).
[0054] Fig 4 illustrates the signal of the first sensor (measured as electrical resistance) with respect to the signals of the second sensor (measured as electrical conductance) at a temperature of 350 °C for the four samples of boar fat (P1 , P2, P3, P4) and the four samples of sow fat (N1 , N2, N3, N4).
[0055] As shown in Fig 4, the evolution of the ratio of signals for each sample of fat is substantially linear, and a linear equation has been derived from the evolution of the ratio for each sample (P1 , P2, P3, P4, N1 , N2, N3, N4).
[0056] The slope A, determining the difference between i) a change in the first signal over the sampling period and ii) a change in the second signal over the sampling period, has been compared to a threshold value of 0.06 to differentiate between a presence and an absence of boar taint. In this case, fat providing a slope A below 0.06 is considered untainted (represented in the lower box in Fig 5) and fat providing a slope A equal or above 0.06 is considered tainted (represented in the upper box in Fig 5).

Claims

1. A method of detecting boar taint in a gas sample of volatised boar fat comprising:
- exposing a first sensor and a second sensor of a gas sensor device to the gas sample for a sampling period, the first sensor providing a first signal indicative of VOCs detected in the gas sample by the first sensor, the second sensor providing a second signal indicative of VOCs detected in the gas sample by the second sensor and the first sensor being more reactive to target gas(es) indicative of boar taint than the second sensor;
- using a difference between i) a change in the first signal over the sampling period and ii) a change in the second signal over the sampling period to differentiate between a presence and an absence of boar taint.
2. The method of claim 1 , wherein the boar fat is volatised at a temperature in the range 200-500 °C, preferably by a laser or a heating resistance, notably a heating grid.
3. The method of any preceding claim, wherein the target gas(es) in the gas sample is selected from: indole, skatole, androstenone, derivatives of indole, derivatives of skatole, derivatives of androstenone, and combination thereof.
4. The method of any preceding claim, wherein the method comprises, before volatising boar fat, blowing a purging gas, notably an inert gas or air, towards the boar fat.
5. The method of any preceding claim, wherein the first sensor and the second sensor are provided within an enclosure configured to substantially confine the gas sample of volatised boar fat during the sampling period.
6. The method of any claim 5, wherein the method comprises providing a reduced pressure atmosphere within the enclosure.
7. The method of any preceding claim, wherein the method further comprises, before and/or after the sampling period, a pyrolyzing step of substantially removing any traces of VOCs deposited on surface(s) of the first and/or second sensors.
8. The method of any preceding claim, wherein the first sensor is a semiconductor type sensor, notably wherein the semiconductor of the semiconductor type sensor is selected from n-type semiconductor, a metal oxide, a metal oxide comprising ZnO, a metal oxide comprising WO3, a metal oxide comprising SnC>2, a metal oxide comprising ln2O3.
9. The method of any preceding claim, wherein the second sensor is a semiconductor type sensor, notably wherein the semiconductor of the semiconductor type sensor is selected from a p-type semiconductor, a semiconductor comprising lanthanum ferrite, a semiconductor comprising lanthanum ferrate, a semiconductor comprising nickel oxide, a semiconductor comprising copper oxide, a semiconductor comprising cobalt oxide.
10. The method of any preceding claim, wherein exposing the first sensor and the second sensor to the gas sample for a sampling period comprises exposing the first sensor and the second sensor to the gas sample for the same sampling period.
11. The method of any preceding claim, wherein the sampling period is less than 60 seconds, preferably less than 30 seconds, more preferably less than 20 seconds.
12. The method of any preceding claim, further comprising exposing the gas sample of volatised boar fat to a third sensor for a sampling period, preferably for the same sampling period as for the first and the second sensors, the third sensor providing a third signal indicative of VOCs detected in the gas sample by the third sensor, wherein the amount of VOCs detected by the third sensor is used to validate the first signal and the second signal.
13. A gas sensor device for detecting boar taint in a gas sample of volatised boar fat comprising:
- a first sensor configured to provide a first signal indicative of VOCs detected in the gas sample by the first sensor,
- a second sensor configured to provide a second signal indicative of VOCs detected in the gas sample by the second sensor; wherein the first sensor is more reactive to target gas(es) indicative of boar taint than the second sensor; and
- a volatizing device, notably a heating device, configured to volatise boar fat.
14. The gas sensor device of claim 13, wherein the first and the second sensors are provided within an enclosure, and wherein an opening of the enclosure is configured to be in contact with boar fat.
15. The gas sensor device of any of claims 13-14, wherein the volatizing device, notably a heating device, is configured to volatize boar fat at a temperature in the range 200-500 °C, preferably in the range 200-400 °C, more preferably in the range 300-400 °C.
16. The gas sensor device of any of claims 13-15, wherein the volatizing device is a heating device, preferably a heating grid.
17. The gas sensor device of any of claims 13-15, wherein the volatizing device is a laser.
18. The gas sensor device of any of claims 13-17, wherein the first sensor is a semiconductor type sensor, notably wherein the semiconductor of the semiconductor type sensor is selected from n-doped type semiconductor, a metal oxide, a metal oxide comprising ZnO, a metal oxide comprising WO3.
19. The gas sensor device of any of claims 13-18, wherein the second sensor is a semiconductor type sensor, notably wherein the semiconductor of the semiconductor type sensor is selected from a p-doped type semiconductor, a semiconductor comprising lanthanum ferrite, a semiconductor comprising nickel oxide, a semiconductor comprising copper oxide, a semiconductor comprising cobalt oxide.
20. The gas sensor device of any of claims 13-19, wherein the gas sensor device comprises a gas inlet configured to blow a purging gas, notably an inert gas or air, towards the boar fat.
21. The gas sensor device of claim 14 or of any of claims 15 to 19 as dependent on claim 14, wherein the gas sensor device comprises a gas outlet configured to provide a reduced pressure atmosphere within the enclosure.
22. The gas sensor device of any of claims 13-21 , wherein the gas sensor device comprises a third sensor configured to provide a third signal indicative of VOCs detected in the gas sample by the third sensor, the third sensor being less reactive to target gas(es) indicative of boar taint than the first sensor and the second sensor.
23. The gas sensor device of any of claims 13-22, wherein the gas sensor device is connected to a signal processing device, notably removably connected, wherein the signal processing device is configured to use a difference between i) a change in the first signal over a sampling period and ii) a change in the second signal over a sampling period to differentiate between a presence and an absence of boar taint.
EP24728925.9A 2023-05-19 2024-05-17 Sensor device Pending EP4713674A1 (en)

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GB2307515.3A GB2630563A (en) 2023-05-19 2023-05-19 Sensor device
GBGB2312860.6A GB202312860D0 (en) 2023-05-19 2023-08-23 Sensor device
PCT/EP2024/063752 WO2024240671A1 (en) 2023-05-19 2024-05-17 Sensor device

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JP2000221182A (en) * 1999-01-29 2000-08-11 Sanyo Electric Co Ltd Apparatus for measuring maturation degree of beef
US9547968B2 (en) * 2010-10-15 2017-01-17 Nevada Nanotech Systems Inc. Pre-smoke detector and system for use in early detection of developing fires
ES2973644T3 (en) 2015-03-03 2024-06-21 Teknologisk Inst Simultaneous detection of compounds related to unpleasant or boar odor in animal tissue
US20180292375A1 (en) 2016-03-03 2018-10-11 Phytronix Technologies Inc. Method for detecting boar taint
GB201702643D0 (en) * 2017-02-17 2017-04-05 Micromass Ltd Analysis of food samples
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