JP4635921B2 - Odor evaluation method and odor evaluation apparatus - Google Patents

Description

  The present invention relates to an odor evaluation method and apparatus for evaluating the odor (odor, fragrance, etc.) of various substances, and more specifically, an odor suitable for evaluating subtle changes in the odor quality of an arbitrary odor. The present invention relates to an evaluation method and apparatus.

  2. Description of the Related Art An odor measuring apparatus that captures a certain substance or odor in the atmosphere from the viewpoint of its quality and strength, and expresses the quantified value has been known. Specifically, for example, in the odor measuring apparatus described in Patent Document 1, Non-Patent Document 1, etc., a plurality of reference odor species (for example, butyric acid) are included in a multidimensional space formed by detection outputs of a plurality of odor sensors. System, ester type, etc.) are measured in multiple stages, and the measurement results are positioned as the reference axis. Then, the measurement result for the purpose of measurement is positioned in the same space as the measurement point, and the positional relationship with the reference axis, for example, the shortest distance between the measurement point and the reference axis, the line drawn from the origin to the measurement point, and the reference The angle formed with the axis is obtained, and the similarity of odor quality is judged from now on.

  According to the odor measuring apparatus as described above, even if the odor causing substance is not clearly known, the quality of the odor can be accurately expressed. For this reason, use in a wide range of fields such as measurement of bad odors in the environment, quality control and quality evaluation of products in factories for food and drinks, and the like is advancing.

  By the way, in the manufacturing site of foods and drinks, there is a demand for grasping deterioration or deterioration of products by evaluating changes in odor quality due to environmental changes such as temperature and passage of time. In such cases, the change in odor quality of the measurement object is often quite subtle. In the conventional odor measuring apparatus, in principle, such a change in odor quality should be observed in a multidimensional space. However, in practice, the multi-dimensional space formed in the conventional odor measuring apparatus is very wide, and the intervals between the plurality of reference axes positioned therein are also separated. It is difficult to accurately assess subtle odor quality changes.

  On the other hand, instead of standard odor species such as butyric acid or ester, if the user can prepare multiple odors with known odor qualities similar to the purpose of the evaluation target, the measurement results of the odors It is possible to compare the measurement results for the purpose. However, in practice, it is difficult for the user to prepare such an odor, and it is very troublesome even if possible.

JP 2003-315298 A “Odor identification device FF-2A (Fragrance & Flavor Analyzer) that digitizes the strength and quality of odors more easily”, [online], Shimadzu Corporation, [March 16, 2006 search], Internet <URL : http://www.an.shimadzu.co.jp/products/food/ff1.htm>

  The present invention has been made to solve the above-mentioned problems, and its object is to provide an odor evaluation method and apparatus capable of accurately grasping subtle changes in the odor quality of foods and drinks There is to do. Another object of the present invention is to provide an odor evaluation apparatus that can reduce the burden on the user when performing the odor evaluation as described above.

In order to solve the above problems, the first invention is that an odor measuring device having m (m is an integer of 2 or more) odor sensors having different response characteristics is used to detect the odor of a target substance. An odor evaluation method for evaluating quality changes,
a) A mixture of n (n is an integer of 2 or more) kinds of odors whose odor quality is known for the purpose odor is used as a reference, and the concentration of the added odor is set to 1 for each of the n kinds of reference odors. In addition, by measuring the odor measuring apparatus adjusted in a plurality of stages, n evaluation reference axes respectively corresponding to each reference odor in an m-dimensional space formed by detection outputs from the m odor sensors. A reference axis acquisition step for positioning;
b) Measuring an odor to be evaluated whose odor has changed or possibly having the object with the odor measuring device to position a measurement point in the m-dimensional space, and the measurement point and the n evaluation reference axes. An evaluation step for creating information reflecting the change in odor quality from the target odor to the target odor based on the positional relationship;
It is characterized by having.

A second invention made to solve the above-mentioned problem is an odor evaluation apparatus for evaluating a change in odor quality of a target substance, which embodies the odor evaluation method according to the first invention,
a) m (m is an integer of 2 or more) odor sensors having different response characteristics;
b) A standard odor is prepared by selectively selecting the addition odors of n species (n is an integer of 2 or more) having a known odor quality and mixing them for the purpose. A preparation means with a standard capable of adjusting the concentration;
c) The reference odor preparation means adjusts the concentration of the added odor in one to a plurality of stages for each of the n types of reference odors by bringing them into contact with the m odor sensors, thereby measuring the m Reference axis acquisition means for positioning n evaluation reference axes corresponding to each reference odor in an m-dimensional space formed by detection outputs from individual odor sensors, and obtaining and storing data representing the evaluation reference axes When,
d) A measurement point is positioned in the m-dimensional space by measuring an object whose odor is changed or possibly having contact with the m odor sensors, and the measurement point and the n points are measured. An evaluation processing means for creating information reflecting a change in odor quality from the target odor to the odor to be evaluated based on the positional relationship with the evaluation reference axis,
e) display means for displaying information reflecting the change in odor quality created by the evaluation processing means;
It is characterized by having.

  In the first and second inventions, when an m-dimensional space composed of detection outputs of m odor sensors is considered, a result obtained by measuring a reference odor in which an added odor is mixed for the purpose at a certain concentration Is represented by one measurement point. When the concentration of the same kind of added odor is changed, the measurement point moves in a certain direction as the concentration changes, starting from a measurement point of zero concentration (that is, only for the purpose of no addition). Therefore, one line (straight line or curve) connecting the points is considered, and this is used as one evaluation reference axis. Since the evaluation reference axes of n kinds of reference odors with different addition odors usually do not completely overlap in the m-dimensional space, n different evaluation reference axes are created in the m-dimensional space. . Since the starting points of the n evaluation reference axes are the same measurement points corresponding only to the purpose, the space surrounded by the n evaluation reference axes in the m-dimensional space has a difference in smell from the purpose. To represent.

  In the odor evaluation method according to the first aspect of the present invention, n evaluation reference axes as described above are created in the reference axis acquisition step. Then, in the evaluation step, there is a possibility that the quality of the target odor may have changed (it does not necessarily change actually). The detection output by each odor sensor is obtained by making it contact. This detection result is also positioned as one measurement point in the m-dimensional space, and when the evaluation object has not changed at all from the purpose, the measurement point is positioned on a common starting point of n evaluation reference axes. It is a trap. On the other hand, if there is a change in the odor quality, the measurement point is shifted from the starting point, and the direction of the shift reflects the change in the odor quality.

  The direction of deviation can be expressed by a positional relationship with n evaluation reference axes, and specifically expressed by the degree of proximity or distance to each evaluation reference axis (that is, similarity / difference). it can. For example, if the measurement point is on a certain evaluation reference axis that is not the starting point, the change in odor quality can be regarded as the same change as the addition odor contained in the reference from which the reference axis is based. . Note that this is an evaluation taken from the viewpoint of the quality of the odor to the last, and the component of the added odor is not always present in the odor to be evaluated.

  Various methods are conceivable as methods for obtaining the degree of proximity or distance to each evaluation reference axis. For example, the shortest distance between the measurement point and the evaluation reference axis is determined in the m-dimensional space, and depending on the shortest distance. An index value indicating the degree of proximity / distance can be calculated. As another method, an angle formed by a straight line passing through the start point and the measurement point and the evaluation reference axis can be obtained, and an index value indicating the degree of proximity / distance can be calculated according to the angle.

  However, when expressing a change in odor quality, it is difficult to understand intuitively if the expression is close to that with some added odor. Therefore, the sensory expression corresponding to each standard odor is determined by human sensory evaluation, and information that uses the sensory expression is created when creating information reflecting the change in odor quality from the purpose odor to the target odor. You should make it. The sensory expression here is an expression that is generally used when a human sniffs the smell of a substance, such as “smelly smell”, “mold smell”, “sweet smell”, and the like. Using such expressions, for example, the change in odor quality is dominated by the raw odor and has a slight moldy odor. Therefore, the user can intuitively understand the change in odor quality.

  Further, in the odor evaluation apparatus according to the second invention, the odor evaluation method according to the first invention is carried out and information reflecting the change in odor quality of the odor to be evaluated is displayed on the display means. The standard necessary for creating the evaluation reference axis as described above is automatically prepared by the preparation means. As the addition odor mixed for the purpose, an appropriate one can be selected according to the target substance. Therefore, it is not necessary for the user to mix the scent of the desired concentration and the scent of the predetermined concentration to create the reference odor.

  According to the odor evaluation method according to the first invention and the odor evaluation apparatus according to the second invention, since the different odors are added to the purpose before the change as the reference odor, m odor sensors are used. In the m-dimensional space formed by the detection output, an evaluation reference axis appropriate for capturing the change in odor quality from the target odor is created. As a result, it is possible to capture subtle changes in odor quality, create information according to the change, and present it to the user. In addition, if information using sensory expressions is created as a change in odor quality, the change in odor quality can be easily communicated to the user.

  Hereinafter, an embodiment of an odor evaluation apparatus according to the second invention for realizing the odor evaluation method according to the first invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an odor evaluation apparatus according to the present embodiment.

  The odor evaluation apparatus includes an odor gas supply unit 1 that supplies a gas having an odor that is an evaluation object, a reference odor preparation unit 2 that supplies gas according to a predetermined reference, which will be described later, and an odor gas and reference odor that are to be evaluated. A flow path switching unit 3 that switches between gases, a sensor cell 4 that includes m (for example, 10) odor sensors 5 having different response characteristics, and an evaluation target odor gas or a reference odor gas for drawing into the sensor cell 4 Pump 6, A / D converter 7 that digitizes the detection output of each odor sensor 5, data processor 8 that computes the digitized detection data according to a predetermined algorithm, and a display that displays the data processing results Unit 10 and a control unit 11 that comprehensively controls the operation of each unit. Here, the evaluation target odor is an odor in which the odor quality of the target odor (the odor of the target substance) has changed or may have changed.

  The odor sensor 5 can be, for example, an oxide semiconductor sensor whose resistance value changes according to various gas components, but gas adsorption on the surface of other conductive polymer sensors, crystal resonators, and SAW devices. A sensor using another detection method such as a sensor having a film formed thereon may be used.

  The reference odor preparation unit 2 alternatively includes an added odor gas supply unit 21 in which n types (7 types of A to G) of which odor quality is known are prepared, and alternatively these odor gases are added. The target odor gas and the additional odor gas are mixed while adjusting the mixing ratio of the selected odor gas to be added, the odor gas supply section 23 for the purpose of supplying the gas having the odor that is selected, and the mixing ratio of the selected odor gas. A concentration adjusting / mixing unit 24 serving as a reference odor gas.

  The data processing unit 8 and the control unit 11 are mainly configured by a personal computer, and the functions can be achieved by executing a predetermined program on the computer.

  Next, the odor evaluation processing operation using the odor evaluation apparatus having the above configuration will be described. The odor to be evaluated is a food or drink, for example, the odor of milk, and the case where the odor quality of milk changes upon heating is considered. Therefore, the above-mentioned purpose is unheated milk, and the evaluation object is milk after heating.

  First, measurement of the standard is performed to create an evaluation standard. That is, under the control of the control unit 11, the addition odor selection unit 22 first selects the addition odor gas A and sends it to the concentration adjustment / mixing unit 24. The concentration adjusting / mixing unit 24 measures a certain amount of odor (unheated milk odor) gas supplied from the object odor gas supply unit 23, and adds a predetermined amount of odorous gas A and mixes it. A reference odor gas having a predetermined gas concentration (ratio) is created. By changing the sampling amount of the added odor gas in the concentration adjustment / mixing unit 24, it is possible to prepare a reference odor gas having the same components but only different concentrations of the added odor gas components. Here, it is assumed that three kinds of reference odor gases are prepared with respect to one kind of added odor gas, with the component concentrations differing in three stages (for example, the component concentrations are 0.3 ppm, 0.6 ppm, and 1.0 ppm). Since seven kinds of reference odor gases having different concentrations as described above are generated for the seven kinds of additive odor gases A to G, 21 kinds of reference odor gases are produced as a whole. In addition, the odor gas itself is set as one of the odor gases for the purpose of adding no added odor gas.

  When a certain reference odor gas is drawn into the sensor cell 4 via the flow path switching unit 3 and the gas comes into contact with ten odor sensors 5, different detection signals are output from the odor sensors 5 in parallel. This detection signal is digitized and input to the data processing unit 8. Since the data processing unit 8 obtains one detection data for each odor sensor 5 for one reference odor gas, a total of ten detection data DS1 to DS10 are obtained here. Since the ten odor sensors 5 have different response characteristics, a 10-dimensional space can be considered in which the outputs of the ten odor sensors 5 are axes in different directions. The state where the outputs of all the odor sensors 5 are zero is the origin of the 10-dimensional space. In the 10-dimensional space, the 10 detection data can be positioned as one measurement point U (DS1, DS2, DS3, DS4, DS5, DS6, DS7, DS8, DS9, DS10).

As described above, each measurement point in the 10-dimensional space for the same kind of added odor gas, for example, three kinds of reference odor gases having different component concentrations with respect to the added odor gas A and a pure purpose odor gas that does not mix the added odor. Ask for. Then, in general, each measurement point with the measurement point U ₀ for pure desired odor gases increase the concentration of additive odor gas as the starting point is moved away from the starting point. Therefore, a line (straight line or curved line) connecting these measurement points can be drawn in the 10-dimensional space. Since it is difficult and difficult to understand the 10-dimensional space, FIG. 2 shows a simplified diagram of the 2-dimensional space. As shown in FIG. 2, the measurement points U _a1 , U _a2 , U _a3 for three kinds of reference odor gases having different component concentrations of the added odor gas A are positioned in the two-dimensional space starting from the measurement point U _0. A line Sa passing through these four measurement points can be drawn.

For other added odor gases, for example, three reference gases having different component concentrations for the added odor gas B, the measurement points U _b1 , U _b2 , U _b3 are obtained in the same manner and positioned in the 10-dimensional space. A line extending from U ₀ as a starting point in a direction different from the previous line Sa can be drawn. That is, when considered in a two-dimensional space, the line Sb in FIG. 2 is obtained. In general, if the types of added odorous gases A and B are different, the line Sa and the line Sb do not completely overlap. In FIG. 2, the lines Sa and Sb are drawn as straight lines, but this may be curved.

Since it is possible to draw a line starting at the measurement point U ₀ to 10-dimensional space for the other additives smell gas C~G similarly, any seven lines starting at the measurement point U ₀ 10 It will be set in the dimensional space. These lines serve as evaluation reference axes Sa to Sg when evaluating the change in the odor, and data representing them is stored in the reference axis storage unit 81.

  Although any odorous gas can be selected as the additive odor gas, seven types of sulfur, amine, organic acid, ester, aldehyde, aromatic, and hydrocarbon are used here. And

Subsequently, the flow path switching unit 3 is switched to draw the gas to be evaluated (the smell of milk after heating) into the sensor cell 4 and contact the 10 odor sensors 5 to obtain detection signals of the odor sensors 5. Then, detection data obtained by digitizing this is taken into the data processing unit 8. The measurement point P obtained from this detection data is also positioned in the 10-dimensional space described above. Considering a simplified two-dimensional space as in FIG. 2, as shown in FIG. 3, the measurement point P is positioned at any location in the two-dimensional space. If the odor quality of the evaluation target odor is not changed from the initial state, that is, the target odor quality, the measurement point P should overlap the measurement point U ₀ . In other words, the measurement point P deviates from the measurement point U ₀ if any change occurs in the odor quality. This deviation is expressed using seven evaluation reference axes Sa to Sg.

Assuming that the measurement point P is on the evaluation reference axis Sa, the change in odor quality is the same tendency as when the added odor gas A is added (however, the added odor gas component increases as a component). It is not always possible). Therefore, the tendency of the change in odor quality is expressed based on the proximity / distance between the measurement point P and each of the reference axes Sa to Sg. The degree of closeness / distance between the measurement point P and each of the reference axes Sa to Sg can be obtained by various methods. Here, as shown in FIG. 3, the start point (measurement point U ₀ ), the measurement point P, A line Tx passing through is considered, and similarity is obtained according to the angle formed by the line Tx and the evaluation reference axis.

That is, as shown in FIG. 3, when the angle between the line Tx and the evaluation reference axis Sa is θ, the similarity index α at the angle φ when it can be determined that they are completely different types (no similarity). Is 0, and the similarity index α when θ = 0 is 1,
α = (φ−θ) / φ
To obtain the similarity index α. For example, assuming that φ = 50 °, if θ is 20 °, the similarity index α is obtained as 0.6. Similarly, angles formed by the line Tx and the other six evaluation reference axes Sb to Sg are obtained, and a similarity index is calculated from the angles. The data processing unit 8 creates a diagram as shown in FIG. 4 based on the similarity index. In other words, this diagram shows the change in odor quality from the target odor by the similarity index for each of the seven types of odors. For example, when the odor to be evaluated is indicated by a broken line as shown in FIG. 4, it is understood that the change in odor quality is dominated by sulfur, and the influence of organic acid is large.

  However, since the above expression expresses the change in odor quality as a component, it is difficult for the user to understand. Therefore, in this odor evaluation apparatus, the sensory test by a plurality of panelists is used to investigate in advance what kind of sensory expression the purpose of adding each odor is expressed, and the information is expressed as sensory expression. It is stored in the information storage unit 82. For example, the purpose of mixing a sulfur-based added odor is [city gas odor], and the purpose of mixing an amine-based odor is [fish rot]. Then, when creating the diagram as described above, a diagram using the sensory expression as described above is created instead of the components as described in FIG. This makes it easy for the user to intuitively understand what kind of change the odor quality is.

  In general, the odor sensor has a large change with time such as drift. Therefore, when examining the change in odor quality with time, for example, when checking the odor quality of milk after 1 day, 3 days, 5 days,... It is desirable to perform a process for correcting the change.

  Further, the above-described embodiment is an example of the present invention, and it is obvious that any change, correction, or addition as appropriate within the scope of the present invention is included in the scope of the claims of the present application.

BRIEF DESCRIPTION OF THE DRAWINGS The whole block diagram of the odor evaluation apparatus by one Example of this invention. Explanatory drawing of the evaluation method of the change of the odor quality in the odor evaluation apparatus of a present Example. Explanatory drawing of the evaluation method of the change of the odor quality in the odor evaluation apparatus of a present Example. The figure which shows an example of the display of the evaluation result of the change of the smell quality in the smell evaluation apparatus of a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Odor gas supply part 2 ... Reference | standard odor preparation part 21 ... Addition odor gas supply part 22 ... Addition odor gas selection part 23 ... Objective odor gas supply part 24 ... Concentration adjustment / mixing part 3 ... Flow path switching part 4 ... Sensor cell 5 ... Odor sensor 6 ... Pump 7 ... A / D conversion unit 8 ... Data processing unit 81 ... Reference axis storage unit 82 ... Sensory expression information storage unit 9 ... Display unit 10 ... Control unit

Claims (4)

An odor evaluation method for evaluating a change in odor quality of a target substance by using an odor measuring device having m (m is an integer of 2 or more) odor sensors having different response characteristics,
a) A mixture of n (n is an integer of 2 or more) kinds of odors whose odor quality is known for the purpose odor is used as a reference, and the concentration of the added odor is set to 1 for each of the n kinds of reference odors. In addition, by measuring the odor measuring apparatus adjusted in a plurality of stages, n evaluation reference axes respectively corresponding to each reference odor in an m-dimensional space formed by detection outputs from the m odor sensors. A reference axis acquisition step for positioning;
b) Measuring an odor to be evaluated whose odor has changed or possibly having the object with the odor measuring device to position a measurement point in the m-dimensional space, and the measurement point and the n evaluation reference axes. An evaluation step for creating information reflecting the change in odor quality from the target odor to the target odor based on the positional relationship;
An odor evaluation method characterized by comprising:   The sensory expression corresponding to each of the n types of odors is determined by human sensory evaluation, and the sensory expression is used as information reflecting the change in odor quality from the target odor to the target odor in the evaluation step. Information is created, The smell evaluation method of Claim 1 characterized by the above-mentioned. An odor evaluation apparatus for evaluating a change in odor quality of a target substance,
a) m (m is an integer of 2 or more) odor sensors having different response characteristics;
b) A standard odor is prepared by selectively selecting the addition odors of n species (n is an integer of 2 or more) having a known odor quality and mixing them for the purpose. A preparation means with a standard capable of adjusting the concentration;
c) The reference odor preparation means adjusts the concentration of the added odor in one to a plurality of stages for each of the n types of reference odors by bringing them into contact with the m odor sensors, thereby measuring the m Reference axis acquisition means for positioning n evaluation reference axes corresponding to each reference odor in an m-dimensional space formed by detection outputs from individual odor sensors, and obtaining and storing data representing the evaluation reference axes When,
d) A measurement point is positioned in the m-dimensional space by measuring an object whose odor is changed or possibly having contact with the m odor sensors, and the measurement point and the n points are measured. An evaluation processing means for creating information reflecting a change in odor quality from the target odor to the odor to be evaluated based on the positional relationship with the evaluation reference axis,
e) display means for displaying information reflecting the change in odor quality created by the evaluation processing means;
An odor evaluation apparatus comprising: The n-type reference odor is further provided with sensory expression storage means for determining and storing corresponding sensory expressions by human sensory evaluation, and the evaluation processing means has the odor quality from the object smell to the object to be evaluated. The odor evaluation apparatus according to claim 3, wherein information using the sensory expression is created as information reflecting the change of the odor.

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