Method for examining alteration of onions and method for identifying pathogen in onions

Abstract

To easily, sensitively, and accurately determine whether onions have altered, or the type of the alteration of onions, and / or identify the pathogen in onions in sites where manufacturing, processing, or distributions is being done.SOLUTION: Gas generated from an onion is supplied to a smell sensor array. On the basis of plural signals obtained from the smell sensor array, the presence or absence of an alteration of the onion or the type of the alteration is determined. Also, a pathogen in the onion is identified. The smell sensor array has a plurality of surface stress sensor elements having different sensitive films which respond to a specific smell molecule, and the signals can be obtained from the surface stress sensor elements.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for inspecting onions for deterioration and a method for identifying onion pathogens. [Background technology]

[0002] Previously, research has focused on the relationship between volatile organic compounds (VOCs) emitted by harvested onions and the deterioration and disease of onions.

[0003] For example, Non-Patent Document 1 discloses that a gas sensor array consisting of a plurality of metal oxide semiconductor (MOS) sensors is used to analyze gases generated from an onion sample, thereby detecting deterioration and lesions in the onions.

[0004] Furthermore, Non-Patent Documents 2 and 3 disclose that, based on the results of analyzing gases generated from onions inoculated with pathogens causing diseases that occur in harvested onions using a gas chromatograph mass spectrometer (GC / MS), the presence of volatile metabolites characteristic of deteriorated or diseased onions. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2011 / 148774 [Patent Document 2] International Publication No. 2017 / 098862 [Non-patent literature]

[0006] [Non-Patent Document 1] T. Konduru et al., "A Customized Metal Oxide Semiconductor-Based Gas Sensor Array for Onion Quality Evaluation: System Development and Characterization," Sensors, 15, 1252-1273 (2015). [Non-Patent Document 2] A. Vikram et al., "Volatile metabolites from the headspace of onion bulbs inoculated with postharvest pathogens as a tool for disease discrimination," Can. J. Plant Pathol., 27, 194-203 (2005). [Non-Patent Document 3] B. Prithiviraj et al., "Volatile metabolite profiling for the discrimination of onion bulbs infected by Erwinia carotovora ssp. carotovora, Fusarium oxysporum and Botrytis allii," Eur. J. Plant Pathol., 110, 371-377 (2004). [Non-Patent Document 4] K. Shiba et. al., "Controlled growth of silica-titania hybrid functional nanoparticles through a multistep microfluidic approach," Chem. Commun. 51, 15874-15857 (2015). Summary of the Invention [Problem to be solved by the invention]

[0007] According to Non-Patent Document 1, the prototype system was able to distinguish a 10-fold difference in concentration between two types of volatile compounds released from rotten onions. However, semiconductor sensors are generally known to have low selectivity (the ability to respond specifically to specific gas molecules). To improve the selectivity of semiconductor sensors, a method has been used in the past to combine an oxide semiconductor with a metal or metal oxide catalyst, but the types of sensor materials that can be applied are limited.

[0008] In addition, the GC / MS used in Non-Patent Documents 2 and 3 is useful mainly for research purposes in laboratories, but is not practical to use in actual production, processing, distribution, etc., such as for quality inspection of agricultural products.

[0009] Therefore, an object of the present invention is to determine the presence or absence of deterioration of onions and the type of deterioration and / or to identify pathogens infecting onions simply, with high sensitivity and high accuracy at actual sites of production, processing, distribution, etc. [Means for solving the problem]

[0010] In order to solve the above problems, the inventors conducted extensive research and found that the above-mentioned determination and / or identification is possible by using an odor sensor array having a plurality of surface stress sensor elements with different sensitive films that respond to specific odor molecules based on the composition of the gas generated from onions, thereby completing the present invention.

[0011] The present invention relates to the following items [1] to

[16] .

[0012] [1] A method for inspecting onions for deterioration, comprising: supplying gas generated from onions to an odor sensor array; and determining the presence or type of deterioration of the onions based on multiple signals obtained from the odor sensor array, wherein the odor sensor array has multiple surface stress sensor elements having different sensitive films that respond to specific odor molecules; and the multiple signals are obtained from the multiple surface stress sensor elements. [2] An onion pathogen identification method comprising: supplying gas generated from onions to an odor sensor array; and identifying pathogens infecting the onions based on a plurality of signals obtained from the odor sensor array, the odor sensor array having a plurality of surface stress sensor elements having different sensitive films that respond to specific odor molecules; and the plurality of signals are obtained from the plurality of surface stress sensor elements. [3] The method according to [2], wherein the pathogen is a bacterium or a filamentous fungus that causes a disease that can occur in onion plants after harvest. [4] The method according to [3], wherein the pathogen is a bacterium or a fungus causing at least one disease selected from the group consisting of onion scale rot, onion rot, onion soft rot, gray rot, dry rot, and black mold. [5] The method according to [4], wherein the pathogenic bacterium is at least one bacterium or filamentous fungus selected from the group consisting of Pantoea ananatis, Burkholderia gladioli; Burkholderia ambifaria, Burkholderia cenocepacia, Burkholderia cepacia, Burkholderia pyrrocinia, Erwinia persicina, Erwinia rhapontici, Pseudomonas allii, Pseudomonas marginalis pv. marginalis, Pseudomonas viridiflava; Pectobacterium carotovorum; Botrytis aclada, Botrytis allii; Fusarium oxysporum f. sp. cepae, Fusarium proliferatum var. minus, Fusarium solani; and Aspergillus niger. [6] The method according to [4], wherein the pathogen is a bacterium causing at least one disease selected from the group consisting of onion scale rot, onion rot disease, and onion soft rot disease. [7] The method according to [6], wherein the pathogenic bacterium is at least one bacterium selected from the group consisting of Pantoea ananatis, Burkholderia gladioli; Burkholderia ambifaria, Burkholderia cenocepacia, Burkholderia cepacia, Burkholderia pyrrocinia, Erwinia persicina, Erwinia rhapontici, Pseudomonas allii, Pseudomonas marginalis pv. marginalis, Pseudomonas viridiflava; and Pectobacterium carotovorum. [8] The method according to any one of [1] to [7], wherein the plurality of surface stress sensor elements include at least a first surface stress sensor element using a material selected from the group consisting of Poly(2,6-diphenyl-p-phenylene oxide), Poly(4-methylstyrene), a metal porphyrin derivative having the following structure, Polystyrene, Poly(vinylidene fluoride), Cellulose Acetate Butyrate, and octadecyl group-modified silica / titania composite nanoparticles for a sensitive film, and a second surface stress sensor element using another material selected from the group for a sensitive film. [ka] [9] The method according to [8], wherein the sensitive film of the first surface stress sensor element responds to at least one odor molecule selected from the group consisting of organic acids, alcohols, ketones, and aldehydes, and the sensitive film of the second surface stress sensor element responds to at least one odor molecule selected from the group.

[10] The method according to [9], wherein the group consists of organic acids, alcohols, and ketones, the organic acids being acetic acid, propionic acid, and butyric acid, the alcohols being methanol and ethanol, and the ketones being acetone.

[11] The method according to any one of [1] to

[10] , wherein the plurality of surface stress sensor elements are a plurality of membrane-type surface stress sensor elements.

[12] The method according to any one of [1] to

[11] , which comprises inspecting onions for deterioration or identifying onion pathogens based on a pattern of time change in the multiple signals.

[13] The method according to any of [1] to

[12] , comprising passing a gas substantially free of components that affect the deterioration test of the onions and / or the identification of onion pathogens through a container containing the onions, and supplying the resulting gas to the odor sensor array as the gas generated from the onions.

[14] The method according to any one of [1] to

[13] , further comprising testing for deterioration of onions or identifying onion pathogens using the plurality of signals generated after starting the supply of gas generated from the onions to the odor sensor array.

[15] The method according to any of [1] to

[14] , comprising alternately applying the gas generated from the onions and a purge gas to the odor sensor array, and using the plurality of signals corresponding to the gas generated from the onions and the plurality of signals corresponding to the purge gas, inspecting the onions for deterioration or identifying onion pathogens.

[16] The method according to any one of [1] to

[15] , wherein the plurality of signals are subjected to machine learning to inspect for onion deterioration or identify onion pathogens. Effect of the Invention

[0013] According to the present invention, by using an odor sensor array having a plurality of surface stress sensor elements each having different sensitive films that respond to a specific odor molecule, it is possible to provide a method which can easily, with high sensitivity and high accuracy, determine the presence or absence of deterioration of onions and the type of deterioration, and / or identify pathogens infecting onions, by targeting gas generated from onions, at actual production, processing, distribution, etc. sites. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a measurement system that can be used in the present invention. [Diagram 2] FIG. 1 shows an example of an optical microscope photograph of an MSS element. [Diagram 3] A conceptual diagram explaining the change over time in signal intensity when a sample gas is applied to a surface stress sensor element such as an MSS element. [Figure 4] FIG. 2 is a diagram showing the results of analyzing gas generated from a specimen piece of sample X using a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) in Example 1. [Diagram 5] FIG. 13 is a diagram showing the results of analyzing gas generated from a specimen piece of Sample Y by PTR-TOF-MS in Example 1. [Figure 6] FIG. 13 is a diagram showing the results of a PTR-TOF-MS analysis of gas generated from a specimen piece of Sample Z in Example 1. [Figure 7] 1 is a diagram showing the results of analyzing the components of gases generated from the sample pieces of sample X, sample Y, and sample Z in Example 1. Horizontal axis: number of cycles, vertical axis: concentration (ppb)×100. [Figure 8] FIG. 13 is a graph showing the change over time (unit: seconds) of the signal (unit: mV) from the MSS element of ChA for Example 1. [Figure 9] FIG. 13 is a graph showing the change over time (unit: seconds) of the signal (unit: mV) from the MSS element of ChB in Example 1. [Figure 10] FIG. 13 is a graph showing the change in signal (unit: mV) from the MSS element of ChC over time (unit: seconds) for Example 1. [Figure 11] FIG. 1 shows the change over time (in seconds) of the signal (in mV) from the MSS element of ChD for Example 1. [Figure 12] FIG. 1 shows the change over time (unit: seconds) of the signal (unit: mV) from the MSS element of ChE for Example 1. [Figure 13] FIG. 13 is a graph showing the change over time (unit: seconds) of the signal (unit: mV) from the MSS element of ChF in Example 1. [Figure 14] FIG. 1 shows the change over time (unit: seconds) of the signal (unit: mV) from the MSS element for ChG in Example 1. [Figure 15] FIG. 1 shows the change over time (unit: seconds) of the signal (unit: mV) from the MSS element of ChH in Example 1. [Figure 16]13 shows the results of analyzing the data set obtained from the measurement results of the gases and water vapor generated from samples A to D using principal component analysis (PCA) for Example 2. The figure on the left shows the score plot of the first principal component (PC1) and the second principal component (PC2) and their respective contribution rates, and the figure on the right shows the score plot of the first principal component (PC1) and the third principal component (PC3) and their respective contribution rates. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described in detail. The following description of the components may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment.

[0016] The first embodiment of the present invention relates to a method for inspecting onions for deterioration. The onion deterioration inspection method according to this embodiment (hereinafter also referred to simply as the "deterioration inspection method") supplies gas generated from onions to an odor sensor array, and determines the presence or absence of deterioration of the onion and the type of deterioration based on multiple signals obtained from the odor sensor array.

[0017] A second embodiment of the present invention relates to a method for identifying an onion pathogen. The onion pathogen identification method according to this embodiment (hereinafter also simply referred to as the "pathogen identification method") supplies gas generated from an onion to an odor sensor array, and identifies the pathogen that has infected the onion based on a plurality of signals obtained from the odor sensor array.

[0018] In the deterioration inspection method and pathogen identification method of the present invention, the odor sensor array has a plurality of surface stress sensor elements having different sensitive films that respond to specific odor molecules, and the plurality of signals are obtained from the plurality of surface stress sensor elements.

[0019] In this specification, "onion" typically refers to a harvested onion plant (mainly a portion including stems and leaves and a bulb. The bulb is also called an onion bulb). On the other hand, the application scope of the present invention is not limited to a harvested onion plant. For example, the present invention may be applicable for the purpose of detecting the occurrence or signs of disease in plants before harvest (during cultivation) in greenhouse cultivation or evaluating the health of seedlings before planting. Types of onions include, but are not limited to, yellow onions, red onions, white onions, etc., which are classified according to differences in the pigments contained therein.

[0020] In this specification, the term "spoilage" used in relation to onions typically refers to a change in properties caused by a chemical change and / or a chemical reaction with oxygen (oxidation) occurring in onions. The cause of the chemical change is not particularly limited and may be disease, pests, various microorganisms present in the cultivation environment (soil, air, etc.), damage (wounds) during transportation / carrying or storage, etc. Furthermore, the "kind" of spoilage includes the type of spoilage (name of disease, details of disease), the progress of a particular spoilage (disease) (for example, progress of disease, degree of decay), etc.

[0021] In this specification, the term "pathogens" infecting onions refers to bacteria, filamentous fungi, etc. that parasitize onions and cause diseases. Specifically, examples of pathogens that can occur in onion plants after harvest include the pathogens Pantoea ananatis and Burkholderia gladioli, which cause a disease called onion scale rot (center rot). Some of these diseases are also called slippery skin. The pathogens Burkholderia ambifaria, Burkholderia cenocepacia, Burkholderia cepacia, Burkholderia pyrrocinia, Erwinia persicina, Erwinia rhapontici, Pseudomonas allii, Pseudomonas marginalis pv. marginalis, and Pseudomonas viridiflava, which cause a disease called onion soft rot. Some onion soft rots are also called sour skin / spring rot. The pathogenic bacterium Pectobacterium carotovorum causes a disease called onion soft rot (bacterial soft rot, soft rot). The pathogenic bacterium Botrytis aclada and Botrytis allii cause a disease called gray-mold neck rot. The pathogenic bacterium Fusarium oxysporum f. sp. cepae, Fusarium proliferatum var. minus, and Fusarium solani cause a disease called fusarium basal rot. Fusarium basal rot is also called fusarium disease or bulb rot in Japanese. The pathogenic bacterium Aspergillus niger causes a disease called black mold rot. Here, the types of diseases to which the present invention can be applied and the types of bacteria and fungi that cause them are not limited to those mentioned above.For example, the present invention may be suitable for application to pathogens of the above-mentioned diseases that have been newly discovered or reported after the filing date of this application, or diseases that refer to lesions appearing on onion plants after harvest (during storage or preservation) and that are called by names different from those mentioned above. In the following, the term "bacteria" is used to refer to pathogens as a comprehensive term including the above-mentioned bacteria, filamentous fungi, etc.

[0022] In this specification, "identification" of an onion pathogen means not only determining (distinguishing) that the pathogen infecting the target onion is a specific type of bacteria (group) that causes a specific disease in onions, but also determining (distinguishing) that the pathogen belongs to the bacterial group. For example, there are three types of diseases P, Q, and R that occur in onions, and the pathogen groups for each disease are p1, p2, ..., p n , for disease Q, q1, q2, q n , for disease R, r1, r2, r n In one aspect of the present invention, it is possible to determine (distinguish) whether the pathogen infecting the target onion is p1, q1, or r1. In another aspect of the present invention, it is possible to determine (distinguish) the pathogen group (p1, p2, . . . p n The composition of gases produced by onions infected with bacteria belonging to the group (q1, q2, q n ), it can be determined (distinguished) whether the pathogen infecting the onion in question is a bacterium belonging to the group of pathogens of disease P or a bacterium belonging to the group of pathogens of disease Q. In yet another aspect of the present invention, the pathogens infecting the onion in question are a bacterium belonging to the group of pathogens of disease R (r1, r2, . . . r n), when there is a distinguishable difference between the composition of gas generated from an onion infected with r1 and the composition of gas generated from an onion infected with r2, it may be possible to determine (discriminate) whether the pathogen infecting the target onion is r1 or r2. In the present invention, the determination (discrimination) in these aspects is treated as "identification" of the onion pathogen. However, it should be noted that "identification" in the present invention does not only mean complete identification of an individual disease / pathogen, but also includes incomplete identification, such as when there is a possibility of erroneous identification with another disease / pathogen, or when the composition of gas generated from the target onion is insufficient to be distinguished from one another and the onion can only be identified as one of several diseases / pathogens.

[0023] In this specification, "gas generated from onions" refers comprehensively to gas components which volatilize or evaporate from onions under a certain environment, i.e., volatile and evaporated components of onions. The volatile and evaporated components include both aroma components that can be detected by the human olfactory sense and non-aroma components that cannot be detected by the human olfactory sense. It should be noted that since human olfactory sense varies greatly from person to person and the components that can be detected also differ greatly from person to person, it is not intended to classify the volatile and evaporated components contained in the gas generated from onions, which are the subject of the deterioration test method and pathogen identification method of the present invention, according to the presence or absence of aroma, nor to limit them to any one of them. In the following, for convenience, the volatile and evaporated components will also be referred to as "odor molecules".

[0024] Specifically, examples of odor molecules contained in the gas generated from onions include alcohols such as methanol, ethanol, propanol, and butanol; ketones such as acetone and methyl ethyl ketone; organic acids such as formic acid, acetic acid, propionic acid, and butyric acid; aldehydes such as formaldehyde, acetaldehyde, and hexanal; nitriles such as acetonitrile; ethers including furans; and water (water vapor), nitric oxide, nitrogen, oxygen, and carbon dioxide. Note that, although mainly low molecular weight molecules are listed here as examples of various odor molecules, molecules with larger molecular weights are also included. Furthermore, as shown in the Examples described later, the present inventors performed proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) on three types of onions which differ in the presence or absence of deterioration and the type of deterioration (degree of decay) due to inoculation of an onion pathogen, and found from the results that the odor molecules contained in the gas emitted from onions may contain, in addition to the above-mentioned substances, esters such as methyl acetate and ethyl acetate; sulfur-containing compounds such as allicin and methyl mercaptan; terpene compounds such as pinene and limonene; hydrocarbon compounds such as alkanes; and aromatic compounds such as ethyl cinnamate and syringol.

[0025] Here, in the above-mentioned conventional MOS sensor and GC / MS analysis, butyric acid is not included as an odor molecule contained in the gas generated from onions, and for example, according to Non-Patent Document 1, methyl propyl sulfide and 2-nonanone are considered to be important volatile compounds emitted from spoiled onions. In contrast, in the deterioration inspection method and pathogen identification method of the present invention, as shown in the examples described later, the concentration of butyric acid contained in the gas generated from onions differs (changes) depending on the presence or absence of deterioration due to inoculation of onion pathogens and the type of deterioration, and a surface stress sensor element having a sensitive film that responds to butyric acid can be used.

[0026] The surface stress sensor element constituting the odor sensor array used in the present invention comprises a surface stress sensor body and a sensitive film coated on the surface of the surface stress sensor body, as described below, and the sensitive film has a specific responsiveness (reactivity due to physical adsorption and / or chemical adsorption) to the detection target molecule (odor molecule), and the surface stress sensor body generates a signal with high sensitivity, so that the two elements constituting the sensor element share the main function of the sensor. Therefore, when producing a plurality of surface stress sensor elements, the same material is used for the surface stress sensor body, while the material of the sensitive film applied to the surface of the surface stress sensor body is changed in various ways, thereby realizing new specificity and high sensitivity response to the target detection target molecule.

[0027] In other words, the surface stress sensor element used in the present invention has a high degree of freedom in selecting the material of the sensitive film coated on the surface of the surface stress sensor body due to the configuration of the sensor element. Therefore, it is easier to optimize the deterioration test and / or pathogen identification than conventional semiconductor sensors, such as selecting a material that responds to the target odor molecule (e.g., butyric acid) from a wide range of material candidates such as various polymers and fine particles, or further modifying the material (such as introducing a specific functional group) to increase its specificity for the odor molecule.

[0028] The surface stress sensor element constituting the odor sensor array used in the present invention can obtain signals for a plurality of target substances from one sensitive film in a superimposed form by selecting an appropriate sensitive film material. In other words, by appropriately selecting a sensitive film material for many target substances, the amplitude and response waveform of the surface stress sensor element in response to each target substance can be made different from each other. Therefore, by combining signals obtained from a plurality of surface stress sensor elements, it is possible to obtain a measurement value that appropriately combines parameters corresponding to a plurality of target substances. In this case, by performing pattern matching or machine learning of the signals of the surface stress sensor elements, features can be appropriately extracted from these signals, and it is possible to realize an alteration inspection and / or pathogen identification based on a larger number of parameters than the number of surface stress sensor elements by using only a relatively small number of surface stress sensor elements.

[0029] In a preferred embodiment of the deterioration inspection method and pathogen identification method of the present invention, the surface stress sensor element is a membrane surface stress sensor (MSS) element.

[0030] Fig. 1 is a diagram showing the schematic configuration of a measurement system that can be used in the deterioration inspection method and pathogen identification method of the present invention. Note that Fig. 1 shows a configuration in which MSS elements are used as surface stress sensor elements that constitute an odor sensor array, but this does not of course cause a loss of generality.

[0031] In the schematic configuration shown in FIG. 1, an inert gas (also called a purge gas or a reference gas) that is not the gas component (odor molecule) to be measured and that does not affect the measurement of the gas component as much as possible is supplied to two gas flow paths, as shown by the white arrows from the left side of the figure. For example, nitrogen gas or air can be used as the purge gas, and in the embodiment described later, nitrogen gas is used as the purge gas. When performing a simple measurement using air as the purge gas, the air at the measurement site (such as a place where onions are stored or kept) may be slightly contaminated with gases (such as organic acids and ammonia) that may affect the deterioration test and / or pathogen identification. In such a case, if the influence of the concentration of such gas on the test and identification results is not adversely affected by the realization of the intended measurement accuracy (such a case is also referred to as "substantially free of components that affect the deterioration test of onions and / or onion pathogen identification"), the inclusion of such gases can be ignored. The flow rate of these two gas flows is controlled by a mass flow controller (MFC) installed in each gas flow path. Specifically, the gas flows in the two gas flow paths are alternately switched at desired time intervals, and the gas flow rate is controlled to be constant on the time axis. It goes without saying that the gas flow control is not limited to MFC, but may be a system combining various pumps and valves. In this case, the pumps and valves may be installed upstream or downstream of the sample, and it goes without saying that they may be configured in any order, including the positions of the sample and the sensor. In addition, as will be described later, it is also possible to install a sensor near the sample without using a device for controlling the gas flow such as an MFC or a pump / valve, and to grasp the state of the sample by observing the fluctuation of the sensor signal at that time. It goes without saying that the sample gas may be supplied to the sensor in any manner like this.

[0032] In Fig. 1, the gas flow path shown on the upper side supplies a purge gas that does not contain the gas components to be measured to the odor sensor array, thereby performing a purge process to desorb various gases diffused in the sensitive film that covers the surface of the main body of the MSS element and initialize the MSS element. Meanwhile, the gas flow passing through the gas flow path on the lower side of Fig. 1 is supplied to the odor sensor array as sample gas, containing gas components volatilized and evaporated from the sample (sample piece obtained from an onion) in a vial placed immediately after the MFC. Alternatively, if a sample piece is not obtained from an onion, but gas is obtained from a container or space containing one or more onions, and the gas is supplied to the measurement system, a configuration that does not use the above-mentioned vial can be adopted. The gas flows from the two gas flow paths are joined in another vial, and then supplied to the odor sensor array as sample gas.

[0033] In addition, since the rate of gas adsorption / desorption by the sensitive film on the surface of the main body of the MSS element is affected by temperature, it is preferable to maintain the temperature of the measurement system shown in Fig. 1 at a desired value. As a means for achieving this, for example, the entire measurement system may be housed in a thermostatic bath, incubator, etc., or the odor sensor array including the MSS element may be housed in a thermostatic bath, incubator, etc., and the entire measurement system including the odor sensor array may be placed in a space controlled at a predetermined temperature. Alternatively, as long as the temperature of the measurement system is maintained at a desired value, the entire measurement system or a part of the measurement system may be an open system. In the examples described below, the odor sensor array was housed in an incubator, and the entire measurement system was placed in a temperature- and humidity-controlled room for measurement.

[0034] It is also preferable to maintain the temperature of the vial containing the sample in FIG. 1 at a desired value. This can reduce the variation in the concentration of gas components volatilized and evaporated from the sample, and can further improve the measurement accuracy. In this case, the temperature of the vial may be the same as or different from the temperature of the measurement system described above. Specifically, the set value of the temperature of the vial may be, for example, 5°C, 10°C, 20°C, 25°C, 30°C, 40°C, or 50°C, but is not limited thereto. In general, the higher the temperature of the vial containing the sample, the higher the concentration of gas components volatilized and evaporated from the sample. However, when the temperature of the gas supplied to the odor sensor array is higher than the temperature of the measurement system (more specifically, the temperature of the MSS element constituting the odor sensor array), the partition coefficient at the solid-gas interface on the surface of the sensitive film covering the surface of the main body of the MSS element is inclined toward the gas phase, so that the amount of gas components (odor molecules) to be measured adsorbed to the sensitive film decreases, and the signal intensity obtained from the odor sensor array may decrease. In addition, depending on the temperature difference and the gas component concentration, the gas components may condense on the surface of the sensitive film, etc., which may cause a decrease in measurement accuracy. Therefore, in a configuration in which MSS elements are used as surface stress sensor elements that constitute an odor sensor array, it is desirable to set the temperature of the measurement system and the temperature of the vial bottle taking into consideration the above-mentioned factors.

[0035] In addition, this system also includes an information processing device that controls the operation of various devices within the system, such as the MFC, and performs various processes such as capturing, recording, and analyzing signals from the surface stress sensor element to realize the deterioration inspection method and pathogen identification method described below, as well as interfaces and communication devices for exchanging information, commands, etc. with external devices, but these are not shown in the figure.

[0036] An example of an optical microscope photograph of an MSS element is shown in FIG. 2. The sensor chip (MSS chip) including the MSS element shown in FIG. 2 is formed from a silicon wafer used in the field of semiconductor element technology, which is cut from a silicon single crystal. The MSS element has a structure in which a circular part shown in the center (which may be another shape such as a square) is connected and fixed to a frame-shaped part around the circular part at four points on the top, bottom, left and right of the circular part. When gas components given to the MSS element are adsorbed and desorbed to the sensitive film applied to the surface of the circular part (main body), the surface stress applied to the MSS element is concentrated in these four fixed areas, and the electrical resistance of the piezoresistance elements provided in these fixed areas changes. These piezoresistance elements are interconnected by a conductive area (shown as a bright sand-grained area in FIG. 2) provided in the frame-shaped part to form a Wheatstone bridge. A voltage is applied between two opposing nodes of this Wheatstone bridge, and the voltage appearing between the remaining two nodes is taken out of the MSS element as a signal output from the MSS element and the required analysis is performed. The structure and operation of such an MSS element are described in detail in, for example, Patent Document 1. In FIG. 2, the sensitive film is applied not only to the circular portion of the MSS element but also widely over the MSS chip surface, including the frame-shaped portion. This is the state seen when the sensitive film is applied by spray coating, but since the sensitive film applied to the frame-shaped portion etc. does not substantially contribute to the signal of the sensor element, it can be used as a sensor element without any problems even when applied in this way. Of course, it is also possible to use an MSS element in which the sensitive film is applied only to the circular portion by an inkjet or dispenser.

[0037] Figure 3 shows a conceptual diagram of the change in signal intensity over time when a sample gas is applied to a surface stress sensor element such as an MSS element. Figure 3(a) shows on the time axis whether the gas applied to the MSS element is a sample gas or a purge gas. Specifically, the concentration of the measurement target gas in the gas applied to the MSS element is a concentration Cg greater than 0 during the sample gas injection period when the sample gas is applied, and the sample gas concentration is 0 during the purge period when the purge gas is applied to flush out the sample gas in the downstream gas flow path and to desorb the sample gas components adsorbed on the sensitive film of the MSS element (and the tube wall of the gas flow path, etc.). Figure 3(b) shows the signal intensity from the MSS element when the type of gas shown in Figure 3(a) is switched, with the time axis aligned with Figure 3(a). The signal intensity is governed by many factors, but the main factor is the rate of adsorption and desorption of the component between the gas and the sensitive film, which is caused by the difference between the concentration of the component in the gas near the sensitive film on the MSS element and the concentration of the same component on the surface of the sensitive film. Therefore, the time change of the signal intensity starts immediately after the gas is switched as shown in Figure 3(a), and is close to a curve that asymptotically approaches exponentially toward the upper and lower saturation values. Figure 3(b) shows the curve in an ideal case. The actual shape of the curve and the maximum value of the curve vary considerably depending on the adsorption and desorption rate to the sensitive film and the type of component adsorbed and desorbed to the sensitive film, and the range of signal change often differs greatly. Furthermore, the signal may show more complex changes over time due to the viscoelastic properties of the sensitive film, the diffusion of the measured gas to the sensitive film, or the physicochemical interaction between the sensitive film material and the measured gas. In this way, it is possible to determine the amount and concentration of various components in the sample and the ratio between multiple components based on the time change and amplitude of the signal from the MSS element. Specifically, among the gases generated by onions, there are sensitive film materials that give signals suitable for measuring ketones, there are sensitive film materials that give signals suitable for measuring alcohols, and there are also sensitive film materials that give signals suitable for measuring organic acids.Therefore, a surface stress sensor element coated with an appropriate material selected from these materials can be used alone to measure the gas generated by onions, or similar measurements can be performed using multiple types of surface stress sensor elements each coated with a different material, thereby making it possible to perform deterioration tests and / or pathogen identification based on the composition of the gas generated by onions.

[0038] Here, the adsorption and desorption characteristics of the materials that form the sensitive film are diverse, and there are also sensitive film materials that show responses that deviate from the above simplified model. However, when analyzing the response of a surface stress sensor element, it can be said that it is often useful to perform an initial study using the above model.

[0039] In addition, although Fig. 3 shows that the sample gas is given to the MSS element only once, in a measurement using a surface stress sensor element such as an MSS element, it is normal to repeat the measurement shown in Fig. 3 multiple times by alternately supplying the sample gas and the purge gas. Hereinafter, a set of a sample gas injection and a purge associated with the injection is called a measurement cycle (details will be described later). In addition, unless there are circumstances such as a large difference between the adsorption rate and the desorption rate of a certain component in the sample gas, the sample gas injection period and the purge period are often the same length of time, but of course the sample gas injection period and the purge period may be different lengths of time.

[0040] Usually, it may take a relatively long time to obtain a valid signal value among the signals generated by the adsorption and desorption of odor molecules contained in the gas generated from the target onion to the sensor element. In addition, if a component that is difficult to desorb remains in the sensor element, the reproducibility of the signal value of the sample gas to be measured next may decrease. Therefore, in the present invention, it may be effective to make the sample gas injection period and the purge period in one measurement cycle different in length, and it is preferable to make the purge period longer than the sample gas injection period while ensuring a sufficient time for obtaining a valid signal value as the sample gas injection period. Specifically, in the embodiment described later, the sample gas injection period is set to 120 seconds, and the purge period is set to twice that, that is, 240 seconds. In addition, it is also effective to make one measurement cycle a measurement sequence of "purge period-sample gas injection period-purge period", so that when multiple measurements are performed, purge is essentially performed twice before the second or subsequent sample gas injections. In the examples described later, this measurement sequence is also adopted, and a purge period of 480 seconds (240 seconds + 240 seconds) is ensured from the end of the most recent sample gas injection before the second or subsequent sample gas injection. In this way, by making the purge period longer than the sample gas injection period, the components adsorbed on the sensitive film on the main body surface of the MSS element during sample gas injection can be desorbed sufficiently easily, and the baseline (here, the signal level immediately before switching from the purge period to the sample gas injection period) can be made more stable, which is particularly effective in ensuring the accuracy of determination when the measurement is repeated multiple times.

[0041] In other words, if the purge period is short relative to the sample gas injection period, there is a possibility that it will have a negative effect on the inspection and identification accuracy. In actual measurements, a long measurement time not only has the disadvantage of lowering the measurement throughput, but also has the problems of making it difficult to stabilize various parameters (flow rate, gas pressure, temperature, etc.) in the environment inside and outside the measurement system for a long period of time, and of causing the measurement system to become larger and more expensive. Furthermore, since the measurement system usually includes active components such as pumps, long-term temperature changes due to heat generation from these components may also have a negative effect on the inspection and identification accuracy. Therefore, in the present invention, it is desirable to allocate the measurement cycle time as short as possible for the sample gas injection period (sampling time) within a range in which a valid signal value can be obtained, and to make the purge period (purge time) as long as possible. Alternatively, as a countermeasure when baseline drift is a problem, it is possible to eliminate or reduce the adverse effects of short-term purging by preparing a standard sample (details will be described later) in which the amount of components that may affect the testing and identification accuracy is specified in advance, and measuring the gas generated from the standard sample before each measurement to perform calibration.

[0042] As described above, in the measurement system having the schematic configuration shown in FIG. 1, the gas flows in the two gas flow paths are usually alternately switched at desired time intervals and controlled by the MFC (or pump, etc.) so that the gas flow rate is constant on the time axis. However, depending on the configuration of the measurement system and the specifications of the surface stress sensor element (MSS element in FIG. 1), it may be possible to make the baseline more stable by making the gas flow rate during the purge period greater than the gas flow rate during the sample gas injection period.

[0043] In this embodiment, a measurement result of the time change in signal intensity as shown in FIG. 3 (hereinafter, simply referred to as the "measurement result") obtained by supplying a sample gas to a surface stress sensor element such as an MSS element is used to perform a deterioration test of onions and / or identify onion pathogens based on the composition of the gas generated from the onions.

[0044] Specifically, the measurement results may be used as they are, or may be subjected to any data analysis processing. For example, a point selected arbitrarily from the time range of the measurement cycle is set as a reference point, and offset processing is performed based on this point. Then, another arbitrary point from the above time range is set as a judgment point, and a feature amount is obtained from the judgment point or a value in the vicinity of the judgment point, thereby determining the presence or absence of deterioration of the onion or the type of deterioration, or identifying a pathogenic bacterium infecting the onion. Examples of the feature amount include the signal intensity after offset processing at the judgment point, the slope of the signal graph at the judgment point, the average slope or curvature of the signal graph in the vicinity of the judgment point, etc. Note that raw signals that have not been subjected to offset processing of the signal contain unique information such as long-term changes over time of the sensor and the current state of the sensor signal as an absolute value, and therefore, the raw signal values ​​may be used as they are without performing offset processing, or any feature amount may be extracted from the raw signal for analysis.

[0045] Note that the offset process here refers to a process of calculating the signal intensity after offset process S'(t) = S(t) - S(t0) by translating the signal intensity graph along the intensity axis so that the signal intensity S(t0) at the reference point t0 becomes 0 (generally an arbitrary constant).

[0046] The reference point may be, for example, a time point immediately before the start of the sample gas injection period (i.e., the end of the purge period) or a time point immediately before the start of the purge period (i.e., the end of the sample gas injection period), but may be any other time point. However, since the gas given to the surface stress sensor element is switched at the time of switching between purge and injection, the signal from the surface stress sensor element may be disturbed near this boundary point. Even if the switching is performed, there may be a non-negligible time delay until the gas around the surface stress sensor element, which is located at a position via a gas flow path of a certain length from a switching mechanism such as a valve, is actually switched. If the influence of instability such as this signal disturbance or time delay can be a problem, a time point slightly shifted in time from the time of this switching may be used as the reference point.

[0047] Furthermore, a time point arbitrarily selected from the time range of the measurement cycle is set as a reference point, and offset processing is performed based on the selected time point. Thereafter, another arbitrary time point within the above time range is set as a judgment point, and a feature amount is obtained from a value at or near the judgment point, thereby making it possible to perform onion deterioration inspection and / or onion pathogen identification. Examples of the feature amount may include the signal intensity after offset processing at the judgment point, the slope of the signal graph at the judgment point, and the average slope or curvature of the signal graph in the vicinity of the judgment point. Note that if the signal offset amount is sufficiently small or the feature amount obtained from the signal intensity before offset is sufficiently large, the offset processing may be omitted. However, the decision point that satisfies such a condition may differ not only depending on the length of the measurement cycle, the length of the sample gas injection period, and the purge period, but also on the configuration of the measurement system (gas flow path, form of gas supply to the measurement system, gas flow rate, etc.) and measurement conditions, and further on the type of sensitive film material of the surface stress sensor element (more specifically, MSS element). Therefore, it is desirable to confirm in advance using a standard sample or the like, a combination of reference point and decision point from which feature quantities effective for inspecting onions for deterioration and / or identifying onion pathogens can be extracted for each sensitive film material.

[0048] As described above, in this embodiment, the baseline fluctuation can be suppressed and the baseline can be stabilized by appropriately setting the time allocation of the measurement cycle and the configuration of the measurement sequence, so that the judgment accuracy can be ensured even when the difference in the extracted feature amount is small. Specifically, by lengthening the purge period, gas is sufficiently desorbed from the sensitive film, so that the state before the injection of the sample gas can be restored to a similar state every time. That is, lengthening the purge period is useful for sufficiently resetting the measurement system. The time point at which the reset is sufficiently performed is the time point immediately before the injection of the sample gas, and by setting this point as the reference point for offset, signal reproducibility is ensured, and as a result, highly accurate judgment can be easily performed. In particular, by performing the offset process based on the purge signal immediately before the start of the injection of the sample gas and setting the judgment point at the time a short time has passed since the end of the injection period, the fluctuation in the signal intensity at the judgment point becomes clearer, and it is easy to obtain a feature amount effective for onion deterioration inspection and / or onion pathogen identification.

[0049] In the above description, the measurement was performed based on a measurement sequence in which the sample gas and the purge gas were switched, but the present invention is not limited to this. For example, it is possible to insert a measurement of another gas (standard gas) that contains a component that is contained in the sample gas and whose concentration may affect the onion spoilage test and / or onion pathogen identification into the measurement sequence, and to perform onion spoilage test and / or onion pathogen identification based on the signal from the measurement in which the three types of gas are switched.

[0050] Such a standard gas may be a gas having the same component composition as the sample gas components generated from a normal onion (standard sample) that is not suspected of being spoiled or infected with a pathogenic bacteria. Such a standard sample may be, for example, an onion grown in the same environment as the onion under test, and in this case, the standard sample is preferably the same variety as the onion under test.

[0051] Alternatively, various compositions can be set as necessary, such as using a gas with the same composition for some of the components of the assumed sample gas (for example, a component for which slight differences in the amount of the component are to be measured with particularly high accuracy). Furthermore, the standard gas may be gas (water vapor) generated from water, in which case the water may be the water used to grow the target onions. The supply sequence of these three types of gas is then set appropriately, taking into consideration various requirements and constraints on the measurement. For example, a measurement sequence including the repetition of the following gas supply time intervals is possible: A. Supply purge gas → [Supply either sample gas or standard gas → Supply purge gas → Supply the other sample gas or standard gas → Supply purge gas] (or repeat the steps in [ ]) B. Supply purge gas → [supply sample gas and standard gas alternately → supply purge gas] (or repeat the steps in [ ]) C. Supply purge gas → [Repeat alternate supply of sample gas, standard gas, and purge gas → Supply purge gas → Repeat alternate supply of sample gas, standard gas, and purge gas] (or repeat the contents in [ ]) In addition to the above, various gas supply sequences for the gas supply time section are possible. In any gas supply sequence, it is considered that the measurement conditions such as temperature, gas pressure / flow rate, and changes in sensor characteristics over time do not change significantly during a series of measurement sequences, so by comparing the sample gas with the standard gas, minute differences in composition between the two gases can be precisely measured, and the effect of disturbances on the measurement results can be reduced, improving the stability of the measurement.

[0052] When a standard gas is also used, a gas flow path for the standard gas is added to the gas supply system of the measurement device, but this can be easily realized by using various existing technologies for gas supply systems. For example, the standard gas can be prepared in a gaseous state from the beginning, or it can be introduced into the gas supply system by evaporating it from a liquid or solid. When providing the standard gas, another gas such as a purge gas can be mixed with the gas originally prepared or the gas generated from a liquid or solid. In addition, these three gas flow paths need to be ultimately joined, but the three flow paths can be joined at one point, or a part of the upstream side of the sample gas flow path can be made to flow to form a standard gas flow path, and after the standard gas is introduced there, both gas flow paths can be joined just before the joining point with the purge gas.

[0053] Furthermore, if the reproducibility of the measurement is high as long as the required accuracy of the determination can be achieved and the variation between the sensor chips and the measuring devices can be calibrated, it is possible to construct a measurement procedure and a measurement system for the measurement in which the measurement of the sample gas and the measurement of the standard gas are independent of each other and performed at different convenient times. For example, the measurement of the standard gas and the measurement of the sample gas may be performed separately, rather than simultaneously or successively in a series of measurement sequences, and the standard gas measurement data and the sample gas measurement data obtained from these measurements may be compared. Here, as long as the condition in the preface is satisfied, that is, the condition that the reproducibility of the measurement is high as long as the required accuracy of the inspection and identification can be achieved and the variation between the sensor chips and the measuring devices can be calibrated, the sensor chip and the measuring device used to measure the sample gas may be the same individual, or a sensor chip and a measuring device different from those used for one measurement may be used. Moreover, the measurement may be performed using only the sample gas and the standard gas without using a purge gas. In this case, the measurement may be performed using the standard gas as a purge gas. Furthermore, the measurement may be performed using only the sample gas or only the standard gas. In this case, you can expose the sample gas or standard gas to the sensor element for a long enough time so that each gas is sufficiently adsorbed and diffused into the sensitive film and the sensor element shows a certain signal value. You can use the absolute value of this signal as a feature value as it is, or you can measure the signal when exposed to the atmosphere for a long enough time before measurement and use it as a reference point.

[0054] For example, without being limited thereto, in the case of targeting gases generated from a group of onions stored in the same place for a certain period of time, if the gas generated from the group of onions at the start of storage is measured and stored as data on the standard gas, then the gas generated from the same group of onions at a specific time point can be similarly digitized as a sample gas, thereby making it possible to compare the above gases for the same group of onions, so long as reproducibility of the measurement and the possibility of calibrating various variations can be ensured. Note that there is no particular limit to the way in which the measurement results of each gas are digitized. As a non-limiting example, the signal from the sensor element when each gas and the purge gas are alternately switched may be simply digitized as is, or the signal from the sensor element during other types of measurement may be digitized, or, for example, the digital value resulting from the digitization as described above may be further processed.

[0055] Examples of materials for the sensitive film of the surface stress sensor element include, but are not limited to, Poly(2,6-diphenyl-p-phenylene oxide), Poly(4-methylstyrene), porphyrin derivatives and metal porphyrin derivatives having a spiro ring skeleton, Polystyrene, Poly(vinylidene fluoride), Cellulose Acetate Butyrate, and octadecyl group-modified silica / titania composite nanoparticles.

[0056] Poly(2,6-diphenyl-p-phenylene oxide) is a material also known as "Tenax" (registered trademark), and several types are commercially available depending on its purity and additives. For example, Tenax TA and Tenax GR (Tenax GR is Tenax polymerized with 23% graphite carbon) are examples of the suffix added to Tenax, and any of these can be used in the present invention. Tenax is provided in various particle size distributions, and the particle size range is expressed by mesh, for example, Tenax TA 20 / 35. In the examples described later, Tenax TA 60 / 80 (obtained from GL Sciences Inc.) was used as Poly(2,6-diphenyl-p-phenylene oxide).

[0057] The porphyrin derivatives and metal porphyrin (metalloporphyrin) derivatives having a spiro ring skeleton are porous biradical compounds, and are molecules having two peripheral substituents bonded to a porphyrin or metal porphyrin (metalloporphyrin) via a spiro-type linkage (a single quaternary carbon atom is included, and two heterocycles are bonded only by this carbon atom).Specific examples of such compounds include metal porphyrin (metalloporphyrin) derivatives having a spiro ring skeleton, which have the following structure:

[0058] [ka]

[0059] Among them, the compound having the following structure (denoted as "27c-(Ni)" for ease of identification. Hereinafter, for convenience, this compound will also be referred to as "NiOX3"), in which nickel (Ni) is coordinated to the center of the porphyrin skeleton and the structure corresponding to the symbol X in the above structural formula is the structure shown by the symbol "27c", can be used in the present invention as a preferred embodiment.

[0060] [ka]

[0061] In addition, examples of methods for producing the above-mentioned porphyrin derivatives and metal porphyrin (metalloporphyrin) derivatives having a spiro ring skeleton, including compounds having the structures exemplified above, are described in the specification of Patent Application No. 2021-111892, the contents of which are incorporated by reference into this specification.

[0062] The octadecyl group-modified silica / titania composite nanoparticles can be synthesized based on the method shown in Non-Patent Document 4. Specifically, for example, the nanoparticles can be synthesized according to the procedure described in paragraphs

[0025] to

[0026] of Patent Document 2.

[0063] In a preferred embodiment of the present invention, a plurality of types of sensitive film materials are selected from the above-mentioned materials, and a plurality of surface stress sensor elements each having the material as a sensitive film are fabricated to constitute an odor sensor array. In this case, each sensitive film may respond to different odor molecules, or may respond to the same odor molecule. In the former case, inspection and identification based on the concentration of a plurality of types of odor molecules contained in the gas generated from onions is possible, and in the latter case, inspection and identification based on the response of a plurality of surface stress sensor elements to the same odor molecule is possible. In either case, it is possible to ensure the accuracy of the deterioration inspection and / or pathogen identification, but in the former case, more multifaceted inspection and identification is possible by using a plurality of types of odor molecules as parameters used in the inspection and identification. On the other hand, in the latter case, it is suitable for inspection and identification focusing on a specific odor molecule, for example, when it is known in advance that there is a one-to-one relationship between a certain pathogen and an odor molecule contained in the gas generated from an onion infected with the pathogen.

[0064] Alternatively, as shown in the examples described later, a certain sensitive film material may be suitable for determining both the presence or absence and the type of deterioration of onions, and another sensitive film material may be particularly suitable for determining the presence or absence of deterioration of onions. Therefore, by using a sensitive film of one surface stress sensor element of a plurality of surface stress sensor elements constituting an odor sensor array as a sensitive film material suitable for determining both the presence or absence and the type of deterioration of onions, and using a sensitive film of another surface stress sensor element as a sensitive film material particularly suitable for determining the presence or absence of deterioration of onions, it is possible to perform a composite determination of the presence or absence and the type of deterioration of onions with one odor sensor array. Alternatively, it is possible to perform a multi-stage determination by using a first odor sensor array composed of a plurality of surface stress sensor elements each having as a sensitive film a plurality of types of sensitive film materials that are particularly suitable for determining whether or not onions have deteriorated, and a second odor sensor array composed of a plurality of surface stress sensor elements each having as a sensitive film a plurality of types of sensitive film materials that are suitable for determining both the presence or absence and the type of deterioration of onions, in which the first odor sensor array determines whether or not onions have deteriorated, and the sample gas determined to have deteriorated is further measured by the second odor sensor array, thereby confirming the deterioration of the onions and determining the type of deterioration.

[0065] The above-mentioned selection of the sensitive film material, the configuration of the sensitive film of the surface stress sensor element, and the configuration and use of the odor sensor array are also applicable to the identification of onion pathogens. For example, assuming the three types of diseases P, Q, and R and their pathogenic groups described above with respect to the identification of onion pathogens, a certain sensitive film material may be suitable for identifying individual pathogens (for example, determining (discriminating) whether the pathogen infecting the target onion is p1, q1, or r1). Another sensitive film material may be suitable for identifying pathogenic groups of different diseases (for example, determining (discriminating) whether the pathogen infecting the target onion is a bacterium belonging to the pathogenic group of disease P or a bacterium belonging to the pathogenic group of disease Q). Therefore, by using a sensitive film of one surface stress sensor element of the multiple surface stress sensor elements constituting an odor sensor array as a sensitive film material suitable for identifying individual pathogens and a sensitive film of another surface stress sensor element as a sensitive film material suitable for identifying pathogenic groups of different diseases, it is possible to perform multiple identification of onion pathogens with one odor sensor array. Alternatively, by using a first odor sensor array composed of a plurality of surface stress sensor elements each having as a sensitive film a plurality of types of sensitive film materials suitable for identifying pathogenic groups of different diseases, and a second odor sensor array composed of a plurality of types of sensitive film materials suitable for identifying individual pathogens, it is possible to perform multi-stage identification by identifying the type of disease to which the pathogen infecting the onion belongs (for example, whether it is a bacterium belonging to the pathogenic group of disease P or a bacterium belonging to the pathogenic group of disease Q) with the first odor sensor array, and then measuring the same sample gas with the second odor sensor array to identify the individual pathogens (for example, whether it is p1 or q1). Furthermore, when there are distinguishable differences in the composition of gases emitted by onions infected with multiple pathogens belonging to the same pathogen group for the same disease, if there is a sensitive film material suitable for identifying the multiple pathogens (for example, determining (discriminating) whether the pathogen infecting the target onion is r1 or r2), it may be possible to increase the variety of the above-mentioned composite or multi-stage identification by further combining the sensitive film materials.

[0066] In addition to the method of sequentially identifying three or more types of pathogens as described above, it is also possible to perform identification from three or more types of candidates in one step by treating the signals from multiple surface stress sensors on the odor sensor array as one group. For example, as is commonly done in pattern recognition, it is possible to classify the multidimensional space spanned by feature vectors based on these signals in correspondence with pathogens, determine which class the feature vector obtained from a specific sample belongs to, and perform the desired identification here. Also, in machine learning, a similar one-step identification can be performed by treating multiple signals as one group.

[0067] The present invention will be described in more detail below with reference to examples. Note that the following examples are not intended to limit the present invention, but are intended to aid in understanding the present invention. EXAMPLES

[0068] [Example 1] In Example 1, the following three types of onions were prepared as onion samples. The onion variety used in the experiment was Momiji No. 3 (Shippou Co., Ltd.), which is one of the varieties currently widely cultivated in Japan. This variety is a type of yellow onion. Normal onions: Onions that have not been inoculated with onion pathogens. Onions that have no discoloration or damage on the outside and are sufficiently hard to the touch (hereinafter referred to as "sample X"). - Deteriorated onions: Onions that have developed onion rot disease caused by inoculation with the pathogen Burkholderia cepacia. Onions that have turned reddish brown in appearance, either partially or entirely, and feel soft to the touch, either partially or entirely (hereinafter referred to as "sample Y"). Rotten onions: Onions that have soft rot disease caused by inoculation with the pathogen Pectobacterium carotovorum. The onions are generally discolored reddish brown to brownish water-soaked, and generally very soft (squishy) to the touch (hereinafter referred to as "sample Z").

[0069] A sample piece weighing approximately 2.5 g was cut out from each sample, and the sample piece was placed directly in a vial for measurement.

[0070] <Component analysis of sample gas> In the measurement using the measurement system described below, the gas generated from each sample was analyzed by a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS).

[0071] The results are shown in Figures 4 to 6. 4, 5 and 6 are diagrams showing the results of PTR-TOF-MS analysis of gases generated from specimen pieces of sample X, sample Y and sample Z, respectively. The upper part of each figure shows signal intensities in the range of mass-to-charge ratios (m / z values) from zero to 200, and the lower part shows signal intensities in the range of m / z values ​​from zero to 100.

[0072] From the results shown in Figures 4 to 6, in the m / z value range from approximately 8 to approximately 40, the signal intensity profiles tended to be similar between samples because this range includes primary ions (hydronium ions) used to ionize the molecules to be measured in PTR-TOF-MS. On the other hand, when the m / z value exceeds about 40, it is found that different signal intensity profiles are obtained depending on the sample. This suggests that the chemical composition of the gases emitted by onions varies depending on the presence or absence of deterioration due to inoculation (infection with onion pathogens), the type of infecting onion pathogen, and the type of deterioration (degree of decay).

[0073] Based on the results of the PTR-TOF-MS, the components of the gas generated from each sample were specifically analyzed, and seven components (methanol, acetaldehyde, ethanol, acetone, acetic acid, propionic acid, and butyric acid) were identified as being present in high concentrations in all samples.

[0074] Figure 7 shows the results of analyzing the components of the gas generated from each sample. The numbers "1" to "7" in Fig. 7 respectively indicate 1: methanol, 2: acetaldehyde, 3: ethanol, 4: acetone, 5: acetic acid, 6: propionic acid, and 7: butyric acid. In other words, for sample X, the concentrations of the corresponding components increase in the order of the numbers. In addition, in Table 1 below, the concentrations of the above seven components are shown with the concentration in sample X as the standard, and the relative concentrations of each component in sample Y and sample Z are shown by the number of symbols *.

[0075] [Table 1]

[0076] As shown in FIG. 7 and Table 1, a comparison of the results for sample X and sample Y shows that when onions deteriorate due to infection with the onion pathogen (Burkholderia cepacia), the concentrations of all components increase. For example, methanol, acetaldehyde and ethanol, which have the first, second and third highest concentrations in sample X, are higher in sample Y. In addition, it was found that the concentration of acetone in onions deteriorated due to infection with the onion pathogen (Burkholderia cepacia) (sample Y) increased more significantly than in normal onions (sample X), reaching a concentration almost equal to that of acetaldehyde, and further that the concentration of butyric acid was higher than that of propionic acid.

[0077] In contrast to this, the results for sample Z showed, like sample Y, increases in the concentrations of methanol and ethanol accompanying deterioration (rot) of onions due to infection with the onion pathogen (Pectobacterium carotovorum), but the concentration of acetaldehyde was roughly the same as that of sample X. Rather, what is particularly noteworthy is that in sample Z, the concentration of butyric acid, which was the seventh and sixth highest in samples X and Y, respectively, increased significantly to become the fourth highest. On the other hand, the concentration of acetone, which increased significantly in sample Y, was lower in sample Z than the above-mentioned concentration of butyric acid and slightly higher than the concentration in sample X.

[0078] The findings regarding the gas emitted by onions based on these results can be roughly summarized as follows: (1) There are several components in the gas emitted by onions that are found in high concentrations regardless of the presence or absence of deterioration due to infection with onion pathogens, the type of infecting onion pathogens, and the type of deterioration. The top seven of these components are methanol, acetaldehyde, ethanol, acetone, acetic acid, propionic acid and butyric acid. (2) When onions deteriorate due to infection with onion pathogens, the concentrations of all seven components listed above in the gas emitted from the onions increase. (3) The concentrations of the above seven components in the gas emitted from onions change depending on the type of infected onion pathogen and / or the type of spoilage of onions. In particular, the concentrations of acetone and butyric acid increase significantly in a relatively early stage of infection with the onion pathogen (Burkholderia cepacia) and / or spoilage, whereas in a more advanced state of spoilage where infection with the onion pathogen (Pectobacterium carotovorum) and / or spoilage has progressed, the concentration of butyric acid increases significantly, while the concentration of acetone is only slightly higher than that in the gas emitted from normal onions. (4) The concentrations of the organic acids acetic acid, propionic acid and butyric acid, and the ketone acetone, in the gas emitted from onions vary depending on the presence or absence of deterioration due to infection with onion pathogens, the type of infecting onion pathogens, and the type of deterioration. (5) The concentrations of methanol and ethanol, which are alcohols, in the gas emitted by onions vary depending on the presence or absence of deterioration due to infection with onion pathogens. However, there are no significant differences in the concentrations depending on the type of infecting onion pathogens and / or the type of deterioration (degree of decay).

[0079] Although no comparative experiment was conducted, based on the onion cultivation experience of the present inventors, it is believed that as long as the onion variety belongs to the yellow onion family, there will be no significant difference in symptoms caused by the same pathogen even if the variety is different from the variety used in the above experiment. Therefore, if the pathogen is the same, it is predicted that the composition of gases generated by various types of infected yellow onions will also be similar to each other.

[0080] <Analysis of sample gas using a measurement system> Next, the results of analysis of the gas (sample gas) generated from each sample using the measurement system will be described.

[0081] In this embodiment, a measurement system whose schematic configuration is shown in FIG. 1 was used. The odor sensor array used was an assembly of multiple MSS elements, each coated with a different sensitive film material. The MSS element using poly(2,6-diphenyl-p-phenylene oxide) is called "ChA". The MSS element using octadecyl-modified silica / titania composite nanoparticles was named "ChB." The MSS element using Poly(4-methylstyrene) is called "ChC". The MSS element using poly(methyl vinyl ether-alt-maleic anhydride) is called "ChD" and The MSS element using Polystyrene is called "ChE". The MSS element using Poly(vinylidene fluoride) is called "ChF", The MSS element using Cellulose Acetate Butyrate is called "ChG" and The MSS element using the metal porphyrin derivative (NiOX3) with a spiro ring skeleton having the above-mentioned structure is called "ChH". This is explained as follows.

[0082] The odor sensor array was placed in an incubator set at 30°C, and the entire measurement system was placed in a temperature- and humidity-controlled room (air conditioner set at 30°C). The flow rates of the sample gas and purge gas were 30 sccm for ChA, ChB, ChC, and ChD, and 10 sccm for ChE, ChF, ChG, and ChH. The sampling time (the time during which the sample gas was injected in each measurement cycle) was 120 seconds. The measurement was performed with a ratio of the sampling time to the purge time (the time during which the purge gas was applied to the odor sensor array (MSS element) and purged in each measurement cycle) of 1:4. Specifically, the measurement sequence in each measurement cycle was configured such that the purge gas was first flowed for 240 seconds, the sample gas was then flowed for 120 seconds, and then the purge gas was again flowed for 240 seconds. In other words, because each measurement was performed consecutively, the purge gas that was passed after the sample gas was passed and the purge gas that was passed before the next sample gas were passed flowed continuously without interruption. Therefore, the purge time was the sum of the above two purge times, and the ratio of the sampling time to the purge time was essentially 1:4. Note that these measurement conditions can be adjusted as appropriate depending on the configuration of the measurement system.

[0083] The procedure for switching samples (e.g., switching to another onion sample) during the above measurement sequence is described here. After the sampling time has elapsed, the vial containing the sample is separated from the gas flow path by the switching valve. This allows the sample to be switched to the next sample at any time without affecting the measurement.

[0084] The operation of changing the measurement sample (such as changing the vial) takes several tens of seconds, and since an input operation is required to reflect the fact that the sample has been changed in the data settings of the measurement system, the sensor module needs to be stopped between two measurements of different samples. However, the module temperature drops when the sensor module is stopped, causing the baseline to fluctuate. This baseline fluctuation becomes a large noise in measuring minute signal differences, so it is ideal to keep the module stop between measurements to within one second. Here, as described above, by disconnecting the vial containing the sample (of course, the same applies to other types of sample containers, etc.) from the gas flow path after the sampling time has ended, the vial can be replaced and other operations associated with this replacement can be performed while it is disconnected. Therefore, in this method, the sample switching can be performed in parallel with the purging process, so that the sample switching time does not appear substantially in the measurement sequence. Alternatively, it goes without saying that a system for automatically changing samples may be used.

[0085] The results are shown in Figures 8 to 15.

[0086] FIG. 8 shows the change over time (unit: seconds) of the signal (unit: mV) from the MSS element of ChA. In Fig. 8, the measurement results of sample X are shown in black with a standard line width, the measurement results of sample Y are shown in light gray with a thick line width, and the results of sample Z are shown in dark black with a thick line width. In other words, please note that the width of the lines showing the measurement results of sample Y and sample Z is a process to facilitate comparison with the measurement results of sample X on the same graph, and does not mean that there is any fluctuation (shaking) in the measurement results themselves. In addition, the results shown in Fig. 8 are plotted as typical results of the results of multiple measurements of the same sample, with the start point of the sample gas injection period of the above measurement sequence (i.e., the end point of the first purge period) set as the starting point of the offset. The same applies to Figs. 9 to 15 described later.

[0087] As can be seen from FIG. 8, when the ChA sensitive membrane material was used, the signal intensity rose sharply immediately after the start of the sample gas injection period. Thereafter, the signal intensity of sample X stabilized between 1.4 mV and 1.45 mV, whereas the signal intensity of samples Y and Z gradually increased, and in the latter half of the sample gas injection period (from approximately 310 seconds to 360 seconds), different gradual increase behaviors were observed, and the saturation values ​​of the two samples were also different. There are also differences in the behavior (tendency of signal intensity to decrease) from the sharp drop in signal intensity immediately after switching from the sample gas injection period to the purge period to the convergence (return) to the baseline. Specifically, in sample X, the signal intensity decreased to less than 0.1 mV immediately after switching to the purge period, and converged to the baseline early in the purge period. In contrast, samples Y and Z are similar in that they converge more gradually from a higher signal intensity value toward the baseline than sample X, but sample Y converges from a lower signal intensity value in a shorter time than sample Z and returns to the baseline.

[0088] These results show that it is possible to determine the presence or absence of deterioration due to infection with onion pathogens, the type of the infected onion pathogen, and / or the type of deterioration from the measurement results using the MSS element using the ChA sensitive film material. More specifically, it is possible to clearly identify the presence or absence of deterioration due to inoculation of onion pathogens, the type of the infected onion pathogen, and / or the type of deterioration by applying an appropriate offset process to the measurement results.

[0089] FIG. 9 shows the change over time (unit: seconds) of the signal (unit: mV) from the MSS element of ChB.

[0090] As can be seen from FIG. 9, when the sensitive film material of ChB is used, the signal intensity rises sharply immediately after the start of the sample gas injection period, although the rise is somewhat more gradual than in the case of ChA described above. Thereafter, in sample X, the signal intensity increased and approached the saturation value (about 6.0 mV), whereas in samples Y and Z, the signal intensity approached asymptotically toward a higher saturation value (about 6.2 mV). In addition, when examining the behavior (tendency for signal intensity to decrease) from the sharp drop in signal intensity immediately after switching from the sample gas injection period to the purge period to the convergence (return) to the baseline, samples Y and Z exhibited almost similar behavior, gradually converging toward the baseline, whereas sample X exhibited a greater drop in signal intensity immediately after switching to the purge period, and the signal intensity converged and returned to the baseline in a shorter time.

[0091] These results show that it is possible to determine the presence or absence of deterioration due to infection with onion pathogens from the measurement results using an MSS element that uses a ChB sensitive film material. More specifically, it was found that by applying an appropriate offset process to the measurement results, it is possible to clearly identify the presence or absence of deterioration due to infection with onion pathogens, regardless of the type of deterioration in the onions.

[0092] FIG. 10 shows the change over time (unit: seconds) of the signal (unit: mV) from the MSS element of ChC.

[0093] As can be seen from FIG. 10, when the sensitive film material of ChC is used, the signal intensity rises sharply immediately after the start of the sample gas injection period, similar to the case of ChA described above. Thereafter, the signal intensity of sample X stabilized between 1.55 mV and 1.6 mV, whereas the signal intensity of samples Y and Z gradually increased, and in the latter half of the sample gas injection period (from approximately 300 seconds to 360 seconds), different gradual increase behaviors were observed, and the saturation values ​​of the two samples were also different. Also, differences are observed in the behavior (tendency of signal intensity to decrease) from the sharp drop in signal intensity immediately after switching from the sample gas injection period to the purge period to the convergence (return) to the baseline. Specifically, in sample X, the signal intensity decreased to about 0.1 mV immediately after switching to the purge period, and converged to the baseline at an early stage of the purge period. In contrast, samples Y and Z are similar in that they converge more gradually from a higher signal intensity value toward the baseline than sample X, but sample Y's signal intensity converges from a lower signal intensity value in a shorter time than sample Z and returns to the baseline.

[0094] These results show that it is possible to determine the presence or absence of deterioration due to infection with onion pathogens, the type of the infected onion pathogen, and / or the type of deterioration from the measurement results using the MSS element using the ChC sensitive film material. More specifically, it is possible to clearly identify the presence or absence of deterioration due to infection with onion pathogens, the type of the infected onion pathogen, and / or the type of deterioration by applying an appropriate offset process to the measurement results.

[0095] FIG. 11 shows the change over time (unit: seconds) of the signal (unit: mV) from the MSS element of ChD.

[0096] As can be seen from Figure 11, when the ChD sensitive membrane material was used, the signal intensity rose sharply immediately after the start of the sample gas injection period, and then remained relatively stable between 17.5 mV and 18 mV for all samples. Although there were differences in the signal intensity values ​​between the samples when focusing on a specific time period, no characteristic behavior was observed that would allow the samples to be clearly distinguished from each other. In addition, when examining the behavior (tendency for signal intensity to decrease) from the sharp drop in signal intensity immediately after switching from the sample gas injection period to the purge period to the convergence (return) to the baseline, for all samples, the signal intensity decreased to less than 0.5 mV immediately after switching to the purge period and converged to the baseline early in the purge period.

[0097] These results suggest that it is difficult to determine the presence or absence of deterioration due to infection with onion pathogens, the type of infecting onion pathogens, and / or the type of deterioration from the measurement results using the MSS element with the ChD sensitive film material.

[0098] FIG. 12 shows the change over time (unit: seconds) of the signal (unit: mV) from the MSS element of ChE.

[0099] As can be seen from FIG. 12, when the ChE sensitive membrane material was used, the signal intensity rose sharply immediately after the start of the sample gas injection period, and then asymptotic behavior toward the saturation value was observed for all samples. However, focusing on the final stage of the sample gas injection period (from about 340 seconds to 360 seconds), it can be seen that the saturation value of sample X is significantly lower than that of sample Y and sample Z. In addition, with regard to the behavior (tendency of signal intensity decreasing) from the sharp drop in signal intensity immediately after switching from the sample gas injection period to the purge period to the convergence (return) to the baseline, focusing particularly on the early part of the purge period (range from about 370 seconds to 420 seconds), it can be seen that, compared with samples X, Y, and Z, sample X's signal intensity converged from a lower signal intensity value in a shorter time and returned to the baseline.

[0100] These results show that it is possible to determine the presence or absence of deterioration due to infection with onion pathogens from the measurement results using an MSS element that uses a ChE sensitive film material. More specifically, it was found that by applying an appropriate offset process to the measurement results, it is possible to clearly identify the presence or absence of deterioration due to infection with onion pathogens, regardless of the type of deterioration in the onions.

[0101] FIG. 13 is a diagram showing the change over time (unit: seconds) of the signal (unit: mV) from the MSS element of ChF.

[0102] 13, when the ChF sensitive film material was used, the signal intensity rose sharply immediately after the start of the sample gas injection period, and then stabilized between about 4.2 mV and about 4.3 mV in sample X, whereas asymptotic behavior toward the saturation value was observed in samples Y and Z. Regarding samples Y and Z, although there are differences in the signal intensity values ​​between the samples when focusing on a specific time section, considering that the saturation values ​​of both are almost the same, it can be said that no characteristic behavior that allows samples Y and Z to be clearly distinguished is observed. In addition, when examining the behavior (tendency of signal intensity decreasing) from the sharp drop in signal intensity immediately after switching from the sample gas injection period to the purge period to the convergence (return) to the baseline, it can be seen that, compared with samples X, Y, and Z, sample X showed a faster signal intensity convergence from a lower signal intensity value and return to the baseline in a shorter time.

[0103] These results show that it is possible to determine the presence or absence of deterioration due to infection with onion pathogens from the measurement results using an MSS element that uses a ChF sensitive film material. More specifically, it was found that by applying an appropriate offset process to the measurement results, it is possible to clearly identify the presence or absence of deterioration due to infection with onion pathogens, regardless of the type of deterioration in the onions.

[0104] FIG. 14 shows the change over time (unit: second) of the signal (unit: mV) from the ChG MSS element.

[0105] 14, when the ChG sensitive film material was used, the signal intensity rose sharply immediately after the start of the sample gas injection period, and then asymptotic behavior toward the saturation value was observed for all samples, but throughout the entire sample gas injection period, sample X reached the saturation value (about 36 mV) while maintaining a lower signal intensity than samples Y and Z. Regarding samples Y and Z, although there are differences in the signal intensity values ​​between the samples when focusing on a specific time period, considering that the saturation values ​​of both are almost the same, it can be said that no characteristic behavior that allows samples Y and Z to be clearly distinguished is observed. In addition, when examining the behavior (tendency of signal intensity decreasing) from the sharp drop in signal intensity immediately after switching from the sample gas injection period to the purge period to the convergence (return) to the baseline, it can be seen that, compared with samples X, Y, and Z, sample X showed a faster signal intensity convergence from a lower signal intensity value and return to the baseline in a shorter time.

[0106] These results show that it is possible to determine the presence or absence of deterioration due to infection with onion pathogens from the measurement results using an MSS element that uses a ChG sensitive film material. More specifically, it was found that by applying an appropriate offset process to the measurement results, it is possible to clearly identify the presence or absence of deterioration due to infection with onion pathogens, regardless of the type of deterioration in the onions.

[0107] FIG. 15 is a diagram showing the change over time (unit: second) of the signal (unit: mV) from the MSS element of ChH.

[0108] As can be seen from FIG. 15, when the ChH sensitive film material was used, the signal intensity rose sharply immediately after the start of the sample gas injection period. Thereafter, the signal intensity of sample X stabilized between 3.85 mV and 3.95 mV, whereas the signal intensity of samples Y and Z gradually increased, and in the latter half of the sample gas injection period (from approximately 310 seconds to 360 seconds), different gradual increase behaviors were observed, and the saturation values ​​of the two samples were also different. Also, differences are observed in the behavior (tendency of signal intensity to decrease) from the sharp drop in signal intensity immediately after switching from the sample gas injection period to the purge period to the convergence (return) to the baseline. Specifically, in sample X, the signal intensity suddenly decreased to zero (or temporarily below zero) immediately after switching to the purge period, and converged to the baseline at an early stage of the purge period. In contrast, samples Y and Z are similar in that they converge more gradually from a higher signal intensity value toward the baseline than sample X, but sample Y's signal intensity converges from a lower signal intensity value in a shorter time than sample Z's signal intensity and returns to the baseline.

[0109] These results show that it is possible to determine the presence or absence of deterioration due to infection with onion pathogens, the type of the infected onion pathogen, and / or the type of deterioration from the measurement results using the MSS element using the ChH sensitive film material. More specifically, it is possible to clearly identify the presence or absence of deterioration due to infection with onion pathogens, the type of the infected onion pathogen, and / or the type of deterioration by applying an appropriate offset process to the measurement results.

[0110] So far, we have described the measurement results using the MSS elements using each sensitive film material and the determination of the presence or absence of deterioration due to infection with onion pathogens, the type of infected onion pathogens, and / or the type of deterioration based on the measurement results. However, in the present invention, it is possible to improve the accuracy of determining the presence or absence of deterioration due to infection with onion pathogens, the type of infected onion pathogens, and / or the type of deterioration by combining a plurality of measurement results obtained from an odor sensor array having a plurality of surface stress sensor elements, each of which is coated on the surface of a surface stress sensor body with a sensitive film material, rather than using individual (single) measurement results using each sensitive film material.

[0111] Alternatively, it is possible to use one or more sensitive film materials depending on the purpose of inspecting the onions for deterioration, etc. For example, sensitive film materials such as ChB, ChE, ChF, and ChG that have the characteristic of judging the presence or absence of deterioration due to infection with onion pathogens can be used alone or in combination to detect signs that normal onions will deteriorate due to infection with onion pathogens and take countermeasures such as removing onions that have deteriorated at a relatively early stage.Alternatively, they can be used for screening tests to pick out onions that have undergone some kind of deterioration (or may have undergone deterioration) due to infection with onion pathogens from a specific group of onions. Meanwhile, sensitive film materials such as ChA, ChC and ChH, which have the characteristics of determining the presence or absence of deterioration due to infection with onion pathogens, the type of the infected onion pathogen and the type of deterioration, can be used alone or in combination to monitor over time how normal onions deteriorate due to infection with onion pathogens and progress to spoilage. Alternatively, they can be used to identify the presence or absence of deterioration due to infection with onion pathogens, the type of the infected onion pathogen and / or the type of deterioration, for onions picked up as having deteriorated (or possibly having deteriorated) as described above.

[0112] Combining this with the results of the PTR-TOF-MS analysis of the three types of onion samples described above, the relationship between each sensitive film material and the odor molecules it responds to can be inferred as follows. The ChA, ChC, and ChH sensitive membrane materials respond to odor molecules that are present in different concentrations in the gases emitted by each onion sample. The odor molecules in question can be acetic acid, propionic acid, butyric acid (all organic acids), and acetone (a ketone). The sensitive membrane materials ChB, ChE, ChF, and ChG respond to odor molecules whose concentrations differ in the gases emitted from an unaltered onion sample (sample X) and a deteriorated onion sample (sample Y and sample Z). The odor molecules in question may be methanol and ethanol (both of which are alcohols). Among the odor molecules listed above, acetaldehyde was found to have approximately the same concentration in sample X and sample Z, and a clear concentration difference was observed between sample Y and sample Z. Therefore, it is not considered to be a major component of odor molecules to which the surface stress sensor element coated with the sensitive film material used in this embodiment responds. However, this does not deny or exclude the fact that surface stress sensor elements coated with other sensitive film materials respond to acetaldehyde (aldehydes), and it should be noted that it is possible to find or develop such sensitive film materials.

[0113] [Example 2] In Example 2, we will specifically explain the deterioration test or pathogen identification according to the above-mentioned embodiment by combining multiple measurement results obtained from an odor sensor array having multiple surface stress sensor elements, each of which is coated with multiple sensitive film materials on the surface of the surface stress sensor body.

[0114] <Sample preparation> Yellow onions (Momiji No. 3 (Shippou Co., Ltd.)) of the same variety as used in Example 1 were prepared, and multiple sample pieces weighing approximately 2.5 g were cut from one onion, divided into four groups (hereinafter also referred to as "Sample A," "Sample B," "Sample C," and "Sample D"), and placed in sterilized vials. More specifically, the sample pieces were cut out in the following procedure. 1. Remove the outer skin (brown part) of the onion bulb and sterilize the surface with 70% ethanol. 2. After air drying, remove the upper part (neck) and lower part (stem disk) of the bulb with a sterilized knife, then cut in half lengthwise. 3. Counting from the outside of the bulb, remove the third or fourth bulb and cut a piece weighing approximately 2.5 g into a sterile petri dish to use as a sample piece.

[0115] 200μL of the bacterial solution was added to a vial containing each group of onion sample pieces, the sample pieces were punctured several times with a sterilized dissection needle, and the pieces were left to stand (cultured) at room temperature for a certain period of time, after which measurements were made. The bacterial solutions used for samples A to D were as follows: Sample A: Sterile distilled water (control) Sample B: A suspension containing Pantoea ananatis, the causative agent of onion scale rot. Sample C: A suspension containing Burkholderia cepacia, the causative agent of onion rot. Sample D: A suspension containing Pectobacterium carotovorum, the causative agent of onion soft rot. The bacterial suspension used for samples B to D was prepared by culturing fresh bacteria at 28°C for 24 hours on a PPGA (Potato peptone glucose agar) slant medium (Koji Nishiyama and Akinori Ezuka (1977) Isolation of a bacterium causing halo blight of ryegrass producing rough colonies. The Japanese Journal of Plant Pathology, 43, 426-431). 8 The cells were suspended in sterile distilled water to a concentration of approximately cfu / mL.

[0116] <Measurement system configuration and measurement conditions, etc.> A measurement system similar to that used in Example 1 was used (see FIG. 1). The odor sensor array used was the assembly described in Example 1 having MSS elements of ChA, ChB, ChC and ChE. Using this measurement system, measurements were performed using the gas generated from samples A to D in each vial and the gas (water vapor) from a vial containing only sterile distilled water as sample gases. Note that the measurement conditions other than those described above were the same as those described in the section "Analysis of sample gas using the measurement system" in Example 1.

[0117] <Results and Discussion> For the multiple measurement results obtained by the above-mentioned measurements, the signals (signal waveforms) from each MSS element were digitized, and the resulting set of digital data (data set) was analyzed using principal component analysis (PCA). Here, multiple parameters were extracted as feature quantities from each of the measurement results that had been subjected to offset processing in the same manner as shown in Figures 8 to 15 for Example 1. Specifically, principal component analysis was performed on a 16-dimensional data set in which four types of feature quantities were extracted from each of the sensitive film materials of the above-mentioned four types of MSS elements (ChA, ChB, ChC, and ChE).

[0118] The results are shown in FIG. 16. The left side of FIG. 16 shows the score plots of the first principal component (PC1) and the second principal component (PC2) and their respective contribution rates (PC1: 77.4%, PC2: 17.0%), and the right side of FIG. 16 shows the score plots of the first principal component (PC1) and the third principal component (PC3) and their respective contribution rates (PC1: 77.4%, PC3: 3.0%). In the left side of FIG. 16, it can be seen that the plots for samples A to D and water (water vapor) are each grouped in a region that does not overlap with each other. In addition, in the right side of FIG. 16, although there is a portion where sample B and sample C overlap, they do not overlap with the other groups, and it can be seen that the plots corresponding to each group are grouped well together.

[0119] From these results, it was found that the deterioration test or pathogen identification according to the embodiment of the present invention can be performed with sufficient accuracy for practical use not only by using the individual (single) measurement results using each sensitive film material mentioned in Example 1, but also by combining multiple measurement results obtained from an odor sensor array having multiple surface stress sensor elements in which multiple sensitive film materials are respectively coated on the surface of the surface stress sensor body, as in this embodiment. [Industrial Applicability]

[0120] According to the present invention, it is possible to easily determine the presence or absence of deterioration of onions and the type of deterioration and / or identify pathogens infecting onions with high sensitivity and accuracy at actual sites of production, processing, distribution, etc. This makes it possible to easily perform deterioration tests and / or pathogen identification of onions in places such as warehouses and storage facilities where harvested onions are stored, and is expected to contribute to improving food safety and security and reducing food waste.

Claims

1. In a method for inspecting the deterioration of onions, in which gas generated from onions is supplied to an odor sensor array, and based on multiple signals obtained from the odor sensor array, the presence or absence of deterioration of the onions or the type of deterioration is determined, The odor sensor array has a plurality of surface stress sensor elements, each having a different sensitive film that responds to a specific odor molecule. The plurality of signals are obtained from the plurality of surface stress sensor elements. Methods for testing onions for spoilage.

2. In a method for identifying onion pathogens, in which gas generated from an onion is supplied to an odor sensor array, and pathogens infecting the onion are identified based on multiple signals obtained from the odor sensor array, The odor sensor array has a plurality of surface stress sensor elements, each having a different sensitive film that responds to a specific odor molecule. The plurality of signals are obtained from the plurality of surface stress sensor elements. Methods for identifying onion pathogens.

3. The method according to claim 2, wherein the pathogen is a bacterium or filamentous fungus that causes a disease that may occur in onion plants after harvest.

4. The method according to claim 3, wherein the pathogen is a bacterium or filamentous fungus that causes at least one disease selected from the group consisting of onion scale rot, onion rot, onion soft rot, gray rot, dry rot, and black mold.

5. The method according to claim 4, wherein the pathogenic bacterium is at least one bacterium or filamentous fungus selected from the group consisting of Pantoea ananatis, Burkholderia gladioli; Burkholderia ambifaria, Burkholderia cenocepacia, Burkholderia cepacia, Burkholderia pyrrocinia, Erwinia persicina, Erwinia rhapontici, Pseudomonas allii, Pseudomonas marginalis pv. marginalis, Pseudomonas viridiflava; Pectobacterium carotovorum; Botrytis aclada, Botrytis allii; Fusarium oxysporum f. sp. cepae, Fusarium proliferatum var. minus, Fusarium solani; and Aspergillus niger.

6. The method according to claim 4, wherein the pathogen is a bacterium that causes at least one disease selected from the group consisting of onion scale rot, onion rot, and onion soft rot.

7. The method according to claim 6, wherein the pathogenic bacterium is at least one bacterium selected from the group consisting of Pantoea ananatis, Burkholderia gladioli; Burkholderia ambifaria, Burkholderia cenocepacia, Burkholderia cepacia, Burkholderia pyrrocinia, Erwinia persicina, Erwinia rhapontici, Pseudomonas allii, Pseudomonas marginalis pv. marginalis, Pseudomonas viridiflava; and Pectobacterium carotovorum.

8. The method according to any one of claims 1 to 7, wherein the plurality of surface stress sensor elements include at least one first surface stress sensor element using a material selected from the group consisting of Poly(2,6-diphenyl-p-phenylene oxide), Poly(4-methylstyrene), metal porphyrin derivatives having the following structure, Polystyrene, Poly(vinylidene fluoride), Cellulose Acetate Butyrate, and octadecyl group-modified silica / titania composite nanoparticles as the sensing film, and a second surface stress sensor element using another material selected from the group as the sensing film. 【Chemistry 1】

9. The method according to claim 8, wherein the sensitive film of the first surface stress sensor element responds to at least one odor molecule selected from the group consisting of organic acids, alcohols, ketones, and aldehydes, and the sensitive film of the second surface stress sensor element responds to at least one odor molecule selected from the group.

10. The method according to claim 9, wherein the group consists of organic acids, alcohols, and ketones, the organic acids being acetic acid, propionic acid, and butyric acid, the alcohols being methanol and ethanol, and the ketones being acetone.

11. The method according to any one of claims 1 to 7, wherein the plurality of surface stress sensor elements are a plurality of film-type surface stress sensor elements.

12. The method according to any one of claims 1 to 7, wherein onion deterioration testing or onion pathogen identification is performed based on the time-varying patterns of the plurality of signals.

13. The method according to any one of claims 1 to 7, wherein a gas obtained by passing a gas substantially free of components that affect the inspection of onion deterioration and / or the identification of onion pathogens through a container containing the target onions is supplied to the odor sensor array as the gas generated from the onions.

14. The method according to any one of claims 1 to 7, wherein the plurality of signals after the start of supplying the odor sensor array with gas generated from the onion are used to perform an onion spoilage test or onion pathogen identification.

15. The method according to any one of claims 1 to 7, wherein the gas generated from the onion and the purge gas are alternately supplied to the odor sensor array, and the plurality of signals corresponding to the gas generated from the onion and the plurality of signals corresponding to the purge gas are used to perform onion deterioration testing or onion pathogen identification.

16. The method according to any one of claims 1 to 7, wherein onion spoilage inspection or onion pathogen identification is performed by machine learning on the aforementioned multiple signals.

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