JP6796248B2 - Freshness estimation method and freshness estimation device for fish - Google Patents

Description

The present invention relates to a method for estimating the freshness of fish as a food material and an apparatus therefor.

Conventionally, a method of objectively estimating the freshness of fish as a food material has been proposed (see, for example, Patent Documents 1 and 2).

In Patent Document 1, light is applied to the crystalline lens of a fish, and the freshness of the fish is determined by spectral analysis of the reflected light. Further, in Patent Document 2, the surface of meat is irradiated with light, and the number of attached bacteria is estimated by using the absorbance thereof.

Japanese Unexamined Patent Publication No. 7-21348 Japanese Unexamined Patent Publication No. 2010-268792

However, since Patent Document 1 does not describe a specific criterion using a spectrum, the effectiveness of freshness estimation is unknown.

Further, in Patent Document 2, although it is effective as a local freshness estimation for the meat to be eaten, it is not possible to estimate the freshness of the whole fish.

Therefore, an object of the present invention is to provide a fish freshness estimation method and a freshness estimation device capable of objectively estimating the freshness of a fish as a whole with higher accuracy than before.

In order to achieve the above object, the fish freshness estimation device according to one embodiment of the present invention is a freshness estimation device that estimates the freshness of fish, and emits light having a plurality of different wavelengths in a wavelength band of 315 nm to 450 nm. A spectrophotometer that detects the intensity of a plurality of reflected light obtained by irradiating a fish eye, and an absorbance spectrum acquisition unit that acquires an absorbance spectrum using the intensity of the plurality of reflected light detected by the spectrophotometer. And a terminal device having a freshness estimation unit that estimates the freshness of the fish based on the absorbance difference obtained by using the absorbances corresponding to the two predetermined wavelengths in the absorbance spectrum .

The general or specific embodiment of the freshness estimation method may be realized by a recording medium such as an apparatus, a system, an integrated circuit, a computer program, or a computer-readable CD-ROM, and the method, the apparatus, the system, and the like. It may be realized by any combination of integrated circuits, computer programs and recording media.

INDUSTRIAL APPLICABILITY The present invention provides a fish freshness estimation method and a freshness estimation device capable of objectively estimating the freshness of a fish as a whole with higher accuracy than before.

The figure which shows the structure of the freshness estimation apparatus in embodiment of this invention. The figure which shows the embodiment of the freshness estimation apparatus in embodiment of this invention. A flowchart showing the basic operation of the freshness estimation device according to the embodiment of the present invention. The figure which shows the absorbance spectrum used in the estimation example of freshness The figure which shows the experimental result about the relationship between the time passage after the death of Japanese dace and the rigidity index which shows the state of putrefaction. A flowchart showing the operation of the freshness estimation unit in the freshness estimation example 1. The figure which shows the example of the threshold value table used in the freshness estimation example 1. A flowchart showing the operation of the freshness estimation unit in another example of freshness estimation example 1. The figure which shows the example of the threshold table in another example of the freshness estimation example 1. Flow chart showing the operation of the terminal device in the freshness estimation example 2 The figure which shows the example of the threshold value table used in the freshness estimation example 2. The figure which shows the structure of the reflection intensity measuring instrument in the modification 1 of the Embodiment of this invention. The figure which shows the apparatus which extracts the biological fluid in the eyeball of a fish, and the processing procedure in the modification 2 of the Embodiment of this invention. The figure which shows the structure of the spectrophotometer in the modification 2 of the Embodiment of this invention. The figure which shows the dropper with a liquid pool part which can be applied to the modification 2 of the Embodiment of this invention. The figure which shows the structure of the spectrophotometer when the spectrophotometric property is obtained using the dropper with a liquid pool part. A flowchart showing the basic operation of the freshness estimation device in the third modification of the embodiment of the present invention. A flowchart showing a detailed procedure of step S60 (pre-classification) in FIG. 17A. A flowchart showing a detailed procedure of step S70 (freshness estimation) in FIG. 17A. The figure which shows the result of freshness estimation in the modification 3 of the Embodiment of this invention. The figure which shows the structure of the freshness estimation apparatus in the modification 4 of the Embodiment of this invention.

(Knowledge that became the basis of the present invention)
Conventionally, in order to estimate the freshness of fish, a sensual method is generally used in which an expert visually checks the appearance and surface condition of the fish and estimates the freshness from the color, luster, and scale condition. Has been adopted. However, this method is largely dependent on the subjectivity of the expert and lacks objectivity.

Therefore, in recent years, as a method of objectively estimating the freshness of fish, an index called "K value" for quantitatively evaluating the freshness of fish has been proposed. Adenosine triphosphate (ATP) in fish muscle is degraded by related enzymes by the following pathways after the death of the fish. That is, from adenosine triphosphate (ATP), through adenosine diphosphate (ADP), adenosine monophosphate (AMP), inosinic acid (IMP), inosine (HxR), and finally hypoxanthine (Hx). It is decomposed into. This decomposition route is constant regardless of the type of fish. Therefore, paying attention to the fact that ATP decreases as the freshness decreases and inosinic acid and hypoxanthine are produced, the ratio of the amount of inosinic acid and hypoxanthine to the total amount of the above substances is defined as the K value, and the K value is defined. Quantitatively estimate the freshness of fish by measuring.

However, in the measurement of the K value, since a chemical reaction is used for measuring the amount of each substance, there is a problem that it takes time to prepare for the measurement and it takes time for the reaction to stabilize. Furthermore, for the chemical reaction, a part of the fish meat must be cut out as a sample, and from the viewpoint of hygiene, a more non-contact and non-invasive method is desired.

Therefore, recently, a method of estimating the freshness of a food material in a short time and without contact has been proposed (see, for example, Patent Documents 1 and 2).

In Patent Document 1, light is applied to the crystalline lens of a fish, and the reflected light is spectrally analyzed. This suggests that the freshness of fish can be estimated by capturing changes that depend on the turbidity of the fish's eyes. Further, in Patent Document 2, the number of bacteria adhering to the surface of fish meat is estimated by shining light on the surface of fish meat and measuring the reflectance (in other words, absorbance) at light having a wavelength of 270 nm. Since none of these methods of Patent Documents 1 and 2 utilize a chemical reaction such as the above-mentioned K value measurement, the measurement can be performed in a short time, and since the measurement is performed by non-contact, it is hygienic. Is also superior.

However, in the method of Patent Document 1, the freshness is estimated by capturing the attenuation of the spectral power depending on the turbidity of the eyes of the fish, but the relationship between the turbidity of the eyes and the freshness, the change state of the spectrum, and the method of capturing the same. There is no specific description about such things, and its effectiveness as a freshness estimation is unknown.

Further, in the method of Patent Document 2, the amount of ATP in the microorganism attached to the surface of the fish meat is observed by irradiating the surface of the fish meat with light and observing the reflectance (in other words, the absorbance) in the wavelength range around 270 nm. The freshness is estimated by indirectly measuring. Basically, this method is superior in observing the edible parts such as meat and vegetables, but in the case of crustaceans and fish, it is necessary to further relate the number of bacteria on the surface to the meat inside. Therefore, it seems that the effectiveness of the whole fish as an estimate of freshness is unknown.

Therefore, the present invention is a method for estimating the freshness of fish in a short time and in a non-contact and non-invasive manner, and can objectively estimate the freshness of fish as a whole with higher accuracy than before. It is an object of the present invention to provide a freshness estimation method and a freshness estimation device.

As a result of intensive studies and examination of the absorbance spectrum in the fisheye, the present inventors found that a characteristic shape appears in the wavelength band of 315 nm to 450 nm depending on the freshness (elapsed time after death) of the whole fish. I found. Therefore, it has been found that the freshness of fish can be estimated with high accuracy by using the characteristic shape in such an absorbance spectrum.

That is, the fish freshness estimation method according to one embodiment of the present invention is a fish freshness estimation method, and obtains an absorbance spectrum obtained by irradiating the fish eye with light containing all or part of the wavelength band of 315 nm to 450 nm. It is a fish freshness estimation method including a freshness estimation step of estimating the freshness of the fish by using the absorbance spectrum acquisition step to be performed and the shape of the acquired absorbance spectrum.

As a result, the freshness of the fish is estimated based on the wavelength band (315 nm to 450 nm) that is highly related to the freshness of the whole fish (elapsed time after death of the fish) and the shape of the absorbance spectrum obtained by using the irradiation target (fisheye). To. Therefore, there is a method for estimating the freshness of fish in a short time and in a non-contact and non-invasive manner, and a method for estimating the freshness of fish that can objectively estimate the freshness of the whole fish with higher accuracy than before. It will be realized.

Further, the fish freshness estimation method according to one embodiment of the present invention is a fish freshness estimation method, which is a method for estimating fish freshness, and is a plurality of absorbances obtained by irradiating a fish eye with light having a plurality of different wavelengths in a wavelength band of 315 nm to 450 nm. This is a method for estimating the freshness of a fish, which includes a step of acquiring the absorbance of the fish and a step of estimating the freshness of the fish using the obtained plurality of absorbances.

As a result, the absorbance (for example, absorbance) obtained by using a plurality of light having different wavelengths in a wavelength band (315 nm to 450 nm) that is highly related to the freshness of the whole fish (elapsed time after death of the fish) and an irradiation target (fish eye). The freshness of the fish is estimated based on the difference, ratio, etc.). Therefore, there is a method for estimating the freshness of fish in a short time and in a non-contact and non-invasive manner, and a method for estimating the freshness of fish that can objectively estimate the freshness of the whole fish with higher accuracy than before. It will be realized.

Here, in the freshness estimation step, the freshness of the fish is estimated based on the fact that the peak value of the absorbance appearing in the wavelength band of 410 nm to 430 nm is higher when the fish is rotten than when the fish is fresh. May be.

As a result, the freshness of the fish is estimated with high accuracy by utilizing the characteristic that the peak value of the absorbance corresponding to 410 nm to 430 nm becomes a small value in the fresh fish and a large value in the non-fresh fish.

Further, in the freshness estimation step, when the first absorbance difference obtained by subtracting the absorbance at an arbitrary wavelength in the wavelength band of 315 nm to 380 nm from the peak value of the absorbance in the wavelength band of 410 nm to 430 nm is smaller than a certain threshold value. It may be presumed that the fish is fresh.

As a result, in the absorbance spectrum of the fish eye, the first absorbance difference obtained by subtracting the absorbance at an arbitrary wavelength in the wavelength band of 315 nm to 380 nm from the peak value of the absorbance in the wavelength band of 410 nm to 430 nm is fresh. The freshness of the fish is estimated with high accuracy by utilizing the characteristic that the value is small for fish and large for non-fresh fish.

Further, in the freshness estimation step, when the second absorbance difference obtained by subtracting the absorbance at an arbitrary wavelength in the wavelength band of 450 nm or more from the peak value of the absorbance in the wavelength band of 410 nm to 430 nm is smaller than a certain threshold value. It may be estimated that the fish is fresh.

Thereby, in the absorbance spectrum of the fish eye, the absorbance at an arbitrary wavelength in the wavelength band of 450 nm or more (for example, 450 nm to 600 nm, etc.) is subtracted from the peak value of the absorbance in the wavelength band of 410 nm to 430 nm. The freshness of the fish is estimated with high accuracy by utilizing the characteristic that the difference in absorbance is small for fresh fish and large for non-fresh fish.

Further, in the absorbance spectrum acquisition step, the absorbance spectrum obtained by irradiating the fish eye with light having a wavelength band of 450 nm or more in addition to the wavelength band of 315 nm to 380 nm is acquired, and in the freshness estimation step, the absorbance is obtained. The freshness of the fish may be estimated based on the third absorbance difference, which is the difference between the absorbance in the wavelength band of 315 nm to 380 nm and the absorbance in the wavelength band of 450 nm or more in the spectrum. At this time, in the freshness estimation step, when the third absorbance difference is equal to or less than a certain threshold value, the fish is fresh, and when the third absorbance difference is greater than or equal to another threshold value larger than the constant threshold value. It may be estimated that the fish is not fresh.

As a result, in the absorbance spectrum of the fish eye, the third absorbance difference obtained by subtracting the absorbance in the wavelength band of 450 nm or more (for example, 450 nm to 600 nm) from the absorbance in the wavelength band of 315 nm to 380 nm is the fresh fish. The freshness of the fish is estimated with high accuracy by utilizing the characteristic that the value becomes small in the case of, and the value becomes large in the case of unfresh fish.

Further, in the absorbance spectrum acquisition step, the absorbance spectrum may be acquired by using a plurality of light sources that emit light having different wavelengths.

As a result, the absorbance spectrum can be easily obtained by switching a plurality of light sources and irradiating the fish eye, and a complicated optical system for sweeping the wavelength of the light irradiating the fish eye or splitting the light into a plurality of wavelengths. Is no longer needed.

Further, in the absorbance spectrum acquisition step, the biological fluid in the eyeball of the fish is extracted, the biological fluid in the extracted eyeball is irradiated with the light, and the light transmitted through the biological fluid in the eyeball is measured. The absorbance spectrum may be obtained.

As a result, it is possible to obtain a more accurate absorbance spectrum by utilizing the light transmission characteristics of the biological fluid in the eyeball of the fish, and to estimate the freshness of the fish with higher accuracy.

Further, the absorbance spectrum acquisition step is a step of acquiring the absorbance spectrum of a plurality of fish including fresh fish and non-fresh fish for classification, and a fish for which freshness is estimated for freshness estimation. Including the step of acquiring the absorbance spectrum for the subject, the freshness estimation step includes a step of classifying a plurality of the absorbance spectra acquired for classification in the absorbance spectrum acquisition step into two classes, and the absorbance. In the spectrum acquisition step, it is determined whether the absorbance spectrum acquired for freshness estimation is similar to the absorbance spectrum belonging to which of the two classes, and the freshness of the fish is estimated based on the result of the determination. May be included.

As a result, a complicated determination process is used by utilizing the characteristic that the absorbance spectrum of the fisheye including the wavelength band of 315 nm to 450 nm is automatically clustered into two types, that of fresh fish and that of non-fresh fish. The freshness of the fish is estimated with high accuracy.

Further, the fish freshness estimation device according to one embodiment of the present invention is a freshness estimation device for estimating the freshness of fish, and is obtained by irradiating the fish's eye with light containing all or part of the wavelength band of 315 nm to 450 nm. It is a freshness estimation device including an absorbance spectrum acquisition unit that acquires an absorbance spectrum and a freshness estimation unit that estimates the freshness of the fish using the shape of the acquired absorbance spectrum.

As a result, the freshness of the fish is estimated based on the wavelength band (315 nm to 450 nm) that is highly related to the freshness of the whole fish (elapsed time after death of the fish) and the shape of the absorbance spectrum obtained by using the irradiation target (fisheye). To. Therefore, the freshness of the fish can be estimated in a short time and in a non-contact and non-invasive manner, and the freshness of the whole fish can be objectively estimated with higher accuracy than before.

Here, further, the fish eye is provided with a spectrophotometer that irradiates the fish eye and detects the intensity of the reflected light or the transmitted light in the eye, and the absorbance spectrum acquisition unit is the reflected light detected by the spectrophotometer. Alternatively, the absorbance spectrum may be obtained by calculating the absorbance spectrum using the intensity of transmitted light.

As a result, the absorbance spectrum can be obtained from the target fish using a spectrophotometer, so that when a fish whose freshness is to be estimated is given, the freshness of the fish can be estimated immediately on the spot.

Further, the spectrophotometer has a removable dropper for sucking up and holding the biological fluid in the eyeball of the fish to be irradiated with the light, and the dropper is the biological fluid in the sucked up eyeball. It may have a liquid pool portion made of quartz for storing the liquid.

As a result, when a fish whose freshness is to be estimated is given, the freshness of the fish can be estimated immediately on the spot by utilizing the light transmission characteristic of the biological fluid in the eyeball of the fish.

Further, it is provided with a reflection intensity measuring device having a plurality of light sources that emit light having different wavelengths, irradiating the fish eye with light from each of the plurality of light sources, and detecting the intensity of the reflected light in the eye. The absorbance spectrum acquisition unit may acquire the absorbance spectrum by calculating the absorbance spectrum using the intensity of the reflected light detected by the reflection intensity measuring device.

As a result, the absorbance spectrum can be easily obtained by switching a plurality of light sources and irradiating the fish eye, and a complicated optical system for sweeping the wavelength of the light irradiating the fish eye or splitting the light into a plurality of wavelengths. Is no longer needed.

Further, the fish freshness estimation method according to one embodiment of the present invention is a fish freshness estimation method, and is an absorbance acquisition step of acquiring the absorbance obtained by irradiating the fish's eye with light of one wavelength in the wavelength band of 410 nm to 430 nm. This is a method for estimating the freshness of a fish, which comprises a freshness estimation step of estimating the freshness of the fish using the obtained absorbance.

As a result, the freshness of the fish is estimated based on the light having a wavelength in the wavelength band (410 nm to 430 nm) that is highly related to the freshness of the whole fish (elapsed time after the death of the fish) and the absorbance obtained by using the irradiation target (fisheye). Will be done. Therefore, a method for estimating the freshness of a fish in a short time and in a non-contact and non-invasive manner, and a method for estimating the freshness of a fish that can objectively estimate the freshness of a fish is realized.

Further, the fish freshness estimation device according to one embodiment of the present invention is a freshness estimation device for estimating the freshness of fish, and obtains the absorbance obtained by irradiating the fish eye with light of one wavelength in the wavelength band of 410 nm to 430 nm. It is a freshness estimation device including an absorbance acquisition unit for estimating the freshness of the fish and a freshness estimation unit for estimating the freshness of the fish using the acquired absorbance.

As a result, the freshness of the fish is estimated based on the wavelength band (410 nm to 430 nm), which is highly related to the freshness of the whole fish (elapsed time after death of the fish), and the absorbance obtained by using the irradiation target (fisheye). Therefore, the freshness of the fish can be estimated in a short time and in a non-contact and non-invasive manner, and the freshness of the whole fish can be objectively estimated.

The general or specific aspects of the freshness estimation method and the freshness estimation device may be realized by a recording medium such as a system, an integrated circuit, a computer program, or a computer-readable CD-ROM. It may be realized by any combination of a system, an integrated circuit, a computer program and a recording medium.

Hereinafter, the fish freshness estimation method and the freshness estimation device according to one aspect of the present invention will be specifically described with reference to the drawings.

The embodiments and modifications thereof described below all show specific examples of the present invention. Numerical values, shapes, materials, components, arrangement positions and connection forms of components, steps, order of steps, etc. shown in the following embodiments and modifications thereof are examples, and are not intended to limit the present invention. .. Further, among the components in the following embodiments, the components not described in the independent claims indicating the highest level concept are described as arbitrary components.

(Embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a fish freshness estimation device 10 according to an embodiment of the present invention. The freshness estimation device 10 is a device for estimating the freshness of fish, and is composed of a spectrophotometer 20 and a terminal device 30. In this figure, the fish 12 for which the freshness is estimated is also shown. The fish 12 is preferably installed on a table (not shown) or the like in which the position of the eyes can be adjusted.

The spectrophotometer 20 is a measuring instrument that irradiates the eyes of the fish 12 with light containing all or part of the wavelength band of 310 nm to 450 nm and measures the spectral characteristics thereof (detects the intensity of reflected light or transmitted light). As an example, the light source 21, the diffraction grating 22, the focusing lens 23, the condensing lens 24, and the receiver 25 are provided. Note that FIG. 1 shows a spectrophotometer 20 of a type that detects reflected light.

The light source 21 is an example of a light source that emits light including all or a part of a wavelength band of 310 nm to 450 nm, and is, for example, a xenon flash lamp that emits light having a wavelength from the ultraviolet region to the visible region. The diffraction grating 22 is a spectroscope that disperses the light emitted from the light source 21 into monochromatic light. The focal lens 23 is a lens that collects the light dispersed by the diffraction grating 22 and irradiates the eyes of the fish 12. The condenser lens 24 is a lens that collects the light reflected by the eyes of the fish 12 and guides it to the receiver 25. The receiver 25 is a sensor that detects the intensity of the reflected light incident through the condenser lens 24 (converts the light into an electric signal), and is, for example, a photomultiplier tube or a photodiode. According to the spectrophotometer 20, the light having a wavelength from the ultraviolet region to the visible region is emitted from the fish 12 by changing (sweeping) the diffraction angle of the diffraction grating 22 by a control signal from a driving device (not shown). It can irradiate the eye and output the intensity of reflected light (that is, spectral characteristics) at each wavelength.

As the spectroscope, a prism may be used instead of the diffraction grating 22. Further, the focal lens 23 and the condenser lens 24 are arbitrary components and may be omitted or replaced with another optical system such as a mirror. Further, instead of irradiating the fish 12 with monochromatic light, the fish 12 is irradiated with light containing all or part of the wavelength band of 310 nm to 450 nm (for example, light having a wavelength from the ultraviolet region to the visible region) and reflected. Alternatively, the intensity of the reflected light or the transmitted light in the above wavelength band may be collectively detected by dispersing and detecting the transmitted light.

The terminal device 30 is a device that estimates the freshness of the fish 12 using the spectral characteristics (intensity of reflected light or transmitted light) obtained by the spectrophotometer 20, and is an absorbance spectrum acquisition unit 31 and a freshness estimation unit 31. 32 and an output unit 33 are provided.

The absorbance spectrum acquisition unit 31 is a processing unit that acquires the absorbance spectrum obtained by irradiating the eyes of the fish 12 with light containing all or part of the wavelength band of 310 nm to 450 nm. In the present embodiment, the absorbance spectrum acquisition unit 31 acquires the spectral light intensity. It is composed of a communication interface that acquires spectral characteristics (intensity of reflected light or transmitted light) from a total of 20, an arithmetic processing unit that calculates an absorbance spectrum from the acquired spectral characteristics, and the like.

More specifically, when the absorbance spectrum acquisition unit 31 receives the intensity of the reflected light or the transmitted light for each wavelength from the spectrophotometer 20, the absorbance spectrum is calculated by calculating the absorbance for each wavelength according to the following formula 1. calculate.

A (r) =-log (I (r) / I ₀ (r)) Equation 1

Here, A (r) is the absorbance at the wavelength r, I (r) is the intensity of the reflected light or the transmitted light at the wavelength r, and I ₀ (r) is the intensity of the incident light at the wavelength r. When the absorbance spectrum acquisition unit 31 calculates the absorbance for each wavelength according to the above formula 1, the intensity I ₀ (r) of the incident light is held inside in advance (the spectrophotometer 20 to be used). (Intensity of incident light) is used.

The freshness estimation unit 32 is a processing unit that estimates the freshness of the fish 12 using the shape of the absorbance spectrum acquired by the absorbance spectrum acquisition unit 31, and is composed of an arithmetic processing unit and the like. Specific examples of estimation will be described later.

The output unit 33 is a processing unit that outputs the estimation result of the freshness estimation unit 32, and is, for example, a liquid crystal display that displays whether the fish 12 is fresh or not. In the display of the estimation result, the output unit 33 may display the estimation result using not only text but also figures, colors, etc., instead of the display output, or in addition to the display output. The estimation result may be output by voice or by data output to the outside.

The absorbance spectrum acquisition unit 31 and the freshness estimation unit 32 may be realized by hardware by a dedicated electronic circuit or the like, or by software by a processor that executes a program. When realized by software, the absorbance spectrum acquisition unit 31 and the freshness estimation unit 32 include a non-volatile memory in which the program is stored, a volatile memory as a working area of the processor, a processor that executes the program, and control by the processor. It is realized by a computer equipped with an input / output interface and the like that exchanges signals with and from peripheral circuits under the above.

FIG. 2 is a diagram showing a realization example of the freshness estimation device 10 shown in FIG. Here, a smartphone (multifunctional mobile phone) 14 is adopted as the terminal device 30 shown in FIG. The absorbance spectrum acquisition unit 31 and the freshness estimation unit 32 are realized by an application (application program) executed on the smartphone 14. The absorbance spectrum acquisition unit 31 acquires the intensity of each wavelength of reflected light or transmitted light in the eyes of the fish 12 from the spectrophotometer 20 via a wired or wireless communication interface. Further, the spectrophotometer 20 shown in FIG. 2 includes a reflector 26 that guides the light that has passed through the condensing lens 24 to the receiver 25, thereby making it compact and portable. By using the smartphone 14 and the compact portable spectrophotometer 20 as shown in this figure, it is possible to objectively know the freshness of fish at a fish store, at home, etc. on the spot with a simple operation. Can be done.

In the freshness estimation device 10 according to the present invention, the spectrophotometer 20 is not an essential component. When the absorbance spectrum calculated by using a spectrophotometer or the like is generated in advance, the absorbance spectrum acquisition unit 31 may acquire the absorbance spectrum thus generated in advance. For example, the absorbance spectrum acquisition unit 31 may acquire the absorbance spectrum by reading the absorbance spectrum stored therein from the auxiliary storage device connected to the terminal device 30.

Similarly, in the fish freshness estimation device 10 according to the present invention, the output unit 33 is not an essential component. Regarding the estimation result by the freshness estimation unit 32, for example, an external device connected to the terminal device 30 may read out the estimation result and utilize it.

FIG. 3 is a flowchart showing the basic operation of the freshness estimation device 10 (that is, the fish freshness estimation method) according to the present embodiment configured as described above.

First, the spectrophotometer 20 irradiates the eyes of the fish 12 with light including all or part of the wavelength band of 310 nm to 450 nm (measurement step S10).

The absorbance spectrum acquisition unit 31 acquires the intensity of the reflected light or transmitted light for each wavelength obtained by the irradiation in the measurement step S10 from the spectrophotometer 20, and acquires the absorbance spectrum by calculating the absorbance spectrum (absorbance). Spectrum acquisition step S11).

Subsequently, the freshness estimation unit 32 estimates the freshness of the fish 12 using the shape of the absorbance spectrum acquired by the absorbance spectrum acquisition unit 31 (freshness estimation step S12). The specific estimation method will be described later.

Finally, the output unit 33 outputs by displaying the estimation result of the freshness estimation unit 32 (output step S13).

In the fish freshness estimation method according to the present invention, the measurement step (S10) by the spectrophotometer 20 is not essential. For example, the absorbance spectrum acquisition unit 31 may acquire the absorbance spectrum by reading the absorbance spectrum stored therein from the auxiliary storage device connected to the terminal device 30.

Similarly, in the fish freshness estimation method according to the present invention, the output step (S13) by the output unit 33 is not essential. For example, the estimation result by the freshness estimation unit 32 may be read out by an external device connected to the terminal device 30 and utilized.

(Estimation example of freshness 1)
Next, as an example 1 of estimating the freshness by the freshness estimation device 10 in the present embodiment, a method of estimating the freshness of a fish based on the fact that the peak of the absorbance spectrum in the wavelength band of 410 nm to 430 nm increases with the passage of time after the death of the fish. Will be explained.

FIG. 4 is a diagram showing an absorbance spectrum (wavelength band of 250 nm to 600 nm) used in estimation example 1 of freshness. The vertical axis (absorbance: units) of the absorbance spectrum shown in FIG. 4 represents the absorbance (the ratio of the intensity of input light to the intensity of transmitted light (or the intensity of reflected light) subtracted from 1) on the logarithmic axis. It is a thing. Here, the absorbance spectrum obtained by actual measurement is shown for a gel-like liquid existing between the cornea and the crystalline lens in the fish eye of Japanese dace (hereinafter, this liquid is referred to as "biofluid in the eyeball"). Dace is a fish classified into the subfamily Cyprinidae, Cyprinidae. Here, the absorbance spectra observed at intervals of about 6 hours (6, 12, 18, 24, 30, 36 hr) from the time after the death of the dace to 36 hours are superimposed. In this experiment, only the biological fluid in the eyeball was extracted from the fish eye of Ugui every 6 hours with a injector, centrifuged at a rotation speed of 5000 rpm for 30 minutes, and then the supernatant was 1 mm × 1 cm. It is placed in a cell, irradiated with light of 250 nm to 600 nm using a spectrophotometer 20, and the absorbance spectrum is calculated from the intensity of transmitted light in the obtained supernatant. It is expected that the same tendency can be obtained even if the fisheye is irradiated with light and the absorbance spectrum is calculated based on the intensity of the reflected light.

As can be seen from the results of this experiment, the absorbance spectrum of the fresh dace (dace from the death of the dace to 18 hours after the death when the dace is expected to rot) shows a low peak at 410 nm to 430 nm, but 24 hours. Subsequent absorbance spectra of Japanese dace show high peaks at 410 nm to 430 nm. Therefore, the difference or ratio between the absorbance at 410 nm to 430 nm and the absorbance at other stable (that is, the absorbance change with respect to the wavelength change) wavelength band (for example, the wavelength band from 315 nm to 380 nm) is calculated. It is possible to compare the size of the calculated value with a constant value (threshold value) and determine whether the fish is fresh or rotten based on the magnitude of the comparison result. As a specific example of the judgment, for example, the difference between the peak value of absorbance (for example, the maximum value) in the wavelength band of 410 nm to 430 nm in which the peak of the absorbance spectrum exists and the maximum value of absorbance in the wavelength band of 315 nm to 380 nm is the threshold value ( For example, if it is less than 0.2), it may be judged that the fish is fresh, and if it is more than the threshold value, it may be judged that the fish is not fresh (that is, the fish is rotten).

The grounds for determining whether or not the dace is in a fresh state based on whether or not it exceeds 18 hours after the death of the dace are as follows.

FIG. 5 is an experimental result showing the relationship between the time lapse (horizontal axis) after death of Japanese dace left in a temperature environment of 20 ° C. and the rigidity index (vertical axis: hardness (N)) indicating the state of putrefaction. A hardness tester was used in this experiment. The hardness tester is a device that measures the degree of rigidity (rigidity index) of a fish from its elasticity by pressing the tip of a cone against the muscle part of the fish body. The unit of the degree of rigidity (rigidity index) obtained by the hardness tester is Newton (N). Non-Patent Document 1 (“Fresheness assessment of cultured seed bleamby chemical and sensory methods” C Alassalver etc. Food Chemistry 72 (2001) It is stated that the stiffness index corresponding to the situation determined to be rotten using the K value is approximately 5N.

In FIG. 5, the average value obtained by examining the rigidity index is plotted for the muscles of three fish in the central part of the fish body. The muscles of fish become stiff as time passes after death, so the stiffness index (hardness (N)) decreases, but the time when the value of the stiffness index 5N, which is said to be empirically decomposed, is 18 It was time. Therefore, it seems that the decay time of Japanese dace at room temperature is around 18 hours after death. Based on the results of this experiment, it was determined that dace up to 18 hours after death was fresh, and dace over 18 hours after death was not fresh.

More specifically, the operation related to the estimation of the freshness of the fish in the freshness estimation device 10 described above is as shown in the flowchart of FIG. FIG. 6 is a flowchart showing the operation of the freshness estimation unit 32 (that is, the method for estimating the freshness of fish) in the freshness estimation example 1.

The freshness estimation unit 32 calculates the maximum value X1 of the absorbance in the wavelength band of 315 nm to 380 nm in the absorbance spectrum (S20). Further, the freshness estimation unit 32 calculates the maximum value X2 as the peak value of the absorbance in the wavelength band of 410 nm to 430 nm in the absorbance spectrum (S21).

Then, the freshness estimation unit 32 compares the first absorbance difference, which is the difference between the two maximum values, with the threshold value (for example, 0.2) (S22), and when the difference is smaller than the threshold value (Yes in S22), the fish It is determined (that is, estimated) that the fish is fresh (S23), while if the difference is equal to or greater than the threshold value (No in S22), the fish is determined (estimated) that it is not fresh (S24). This first absorbance difference is a value obtained by subtracting the absorbance value of 315 nm to 380 nm (for example, the maximum value) from the peak value of the absorbance of 410 nm to 430 nm (for example, the maximum value).

As described above, according to the freshness estimation device 10 and the freshness estimation method in the present embodiment, the absorbance spectrum acquisition unit 31 irradiates the fish eye with light containing all or part of the wavelength band of 315 nm to 450 nm. The obtained absorbance spectrum is acquired, and the freshness estimation unit 32 calculates the difference or ratio between the absorbance in the wavelength band of 410 nm to 430 nm and the absorbance in the other stable wavelength band of 315 nm to 380 nm, for example. If the magnitude of the value is less than a certain value (threshold), the fish is judged to be fresh, and if it is more than the threshold, it is judged to be rotten. The absorbance in the wavelength band from 410 nm to 430 nm is, for example, the maximum value of the absorbance in the wavelength band, and the absorbance in the other stable wavelength band of 315 nm to 380 nm is, for example, the maximum value in the wavelength band. The minimum value, the average value within the wavelength band, and the like may be used instead of the maximum value.

As a result, the freshness of the fish is estimated based on the wavelength band (315 nm to 450 nm) that is highly related to the freshness of the whole fish (elapsed time after death of the fish) and the shape of the absorbance spectrum obtained by using the irradiation target (fisheye). To. Therefore, the freshness of the fish can be estimated in a short time and in a non-contact and non-invasive manner, and the freshness of the fish as a whole can be objectively estimated with higher accuracy than before.

In the freshness estimation example 1, the freshness of the fish is estimated using one type of threshold value (first threshold value), but a plurality of threshold values may be used. For example, each of the above-mentioned wavelength bands (410 to 430 nm, 315) for obtaining the absorbance spectrum as shown in FIG. 4 for each type of fish and the storage state of the fish and distinguishing between fresh fish and non-fresh fish. Threshold values for the difference or ratio for the absorbance (up to 380 nm) are set, and the threshold values are registered as in the threshold table 32a shown in FIG. 7 and held by the freshness estimation unit 32. Then, when the freshness estimation unit 32 receives input from the user about the type of fish to be estimated for freshness and the storage state of the fish, the freshness estimation unit 32 corresponds to the received fish type and storage state by referring to the threshold table 32a. The threshold value to be used is read out, and the freshness of the fish is estimated using the read threshold value. This makes it possible to estimate the freshness with higher accuracy in consideration of the type of fish and the storage state.

In addition to the above-mentioned wavelength band of 315 nm to 380 nm, the stable wavelength band other than 410 nm to 430 nm in which the peak of the spectrum exists (that is, there is not much change in absorbance with respect to the wavelength change) is, for example, 450 nm or more (for example). There is a wavelength band (450 nm to 600 nm). Therefore, the freshness of the fish may be estimated from the magnitude of the difference or ratio between the absorbance in the wavelength band of 410 nm to 430 nm and the absorbance in the wavelength band of 450 nm or more (for example, 450 nm to 600 nm). Further, it may be determined whether or not the fish is fresh based on the magnitude of the comparison result between the value of the difference or the ratio and the predetermined threshold value. In addition, at 450 nm or more, it can be expected to be similarly stable at 600 nm or more (for example, up to 1000 nm in the infrared region beyond the visible region). An operation example using the absorbance in the wavelength band of 450 nm or more is shown in the flowchart of FIG. FIG. 8 is a flowchart showing another operation example of the freshness estimation unit 32 in the freshness estimation example 1. As shown in the figure, the freshness estimation unit 32 calculates the maximum value X1 of the absorbance in the wavelength band of 450 nm or more (for example, 450 nm to 600 nm) in the absorbance spectrum (S20a). In addition, the freshness estimation unit 32 calculates the maximum value X2 of the absorbance in the wavelength band of 410 nm to 430 nm in the absorbance spectrum (S21a). Then, the freshness estimation unit 32 compares the second absorbance difference, which is the difference between the two maximum values, with the threshold value (for example, 0.3) (S22a), and when the difference is smaller than the threshold value (Yes in S22a), the fish It is determined (that is, estimated) that the fish is fresh (S23a), while if the difference is equal to or greater than the threshold value (No in S22a), the fish is determined (estimated) that it is not fresh (S24a). The second absorbance difference in this case is a value obtained by subtracting the absorbance value in the wavelength band of 450 nm or more (for example, the maximum value in 450 nm to 600 nm) from the peak value of the absorbance in the range of 410 nm to 430 nm (for example, the maximum value). Is. In this case, the threshold table held by the freshness estimation unit 32 is, for example, the threshold table 32b shown in FIG.

(Estimation example of freshness 2)
Next, as Example 2 of freshness estimation by the freshness estimation device 10 in the present embodiment, the difference between the absorbance in the wavelength band of 315 nm to 380 nm and the absorbance in the wavelength band of 450 nm or more (for example, 450 nm to 600 nm) in the absorbance spectrum. A method of estimating the freshness of fish based on the third absorbance difference is described.

According to the absorbance spectrum shown in FIG. 4, a comparison between the spectrum before 18 hours before putrefaction (not fresh) and the spectrum after 24 hours beyond the expected putrefaction of 18 hours is compared, and overall. The absorbance after putrefaction is high. In particular, it can be seen that the absorbance in the wavelength band of 315 nm to 380 nm, which is the ultraviolet region, has a larger difference before and after decay than in the wavelength band of 450 nm or more.

Based on the above findings, in the freshness estimation example 2, first, the absorbance spectrum acquisition unit 31 emits light having a wavelength band of 450 nm or more (for example, 450 nm to 600 nm) in addition to the wavelength band of 315 nm to 380 nm. The absorbance spectrum obtained by irradiating the light is obtained. Then, the freshness estimation unit 32 is based on the third absorbance difference, which is the difference between the absorbance in the wavelength band of 315 nm to 380 nm in the absorbance spectrum and the absorbance in the wavelength band of 450 nm or more (for example, 450 nm to 600 nm). Estimate freshness. More specifically, the freshness estimation unit 32 determines that the fish is fresh when the third absorbance difference is equal to or less than a certain threshold value (threshold value A), and another threshold value (threshold value B) in which the third absorbance difference is larger than the constant threshold value. ) If it is above, it is estimated that the fish is not fresh.

More specifically, it is as shown in the flowchart of FIG. FIG. 10 is a flowchart showing an operation example (that is, a method for estimating freshness of fish) of the terminal device 30 in the estimation example 2 of freshness. First, the absorbance spectrum acquisition unit 31 acquires an absorbance spectrum obtained by irradiating a fish eye with light having a wavelength band of 450 nm to 600 nm in addition to a wavelength band of 315 nm to 380 nm (S50).

Then, the freshness estimation unit 32 subtracts the absorbance A (450 to 600) in the wavelength band of 450 nm or more (for example, 450 nm to 600 nm) from the absorbance A (315 to 380) in the wavelength band of 315 nm to 380 nm in the absorbance spectrum. Therefore, the third absorbance difference, which is the difference between the two absorbances A, is calculated (S51).

Further, the freshness estimation unit 32 compares the third absorbance difference with the threshold value A (for example, 0.2) and the threshold value B (for example, 0.25) (S52). As a result, when the third absorbance difference is less than or equal to the threshold value A (for example, 0.2) (third absorbance difference ≤ threshold value A), the fish is fresh (S53), and the third absorbance difference is the threshold value A (for example, 0.2). If it is larger than 0.2) and smaller than the threshold value B (0.25) (threshold value A <third absorbance difference <threshold value B), the fish is suspected to be rotten (S54), and the third absorbance difference is equal to or greater than the threshold value B. In the case (threshold value B ≤ third absorbance difference), it is estimated that the fish is not fresh (S55).

As described above, in the freshness estimation example 2, the freshness estimation unit 32 determines the difference between the absorbance in the wavelength band of 315 nm to 380 nm in the absorbance spectrum and the absorbance in the wavelength band of 450 nm or more (for example, 450 nm to 600 nm). It is estimated that the fish is fresh when a certain third absorbance difference is equal to or less than the threshold value A, and the fish is not fresh when the third absorbance difference is equal to or greater than the threshold value B.

As a result, in the absorbance spectrum of fish eyes, the third absorbance difference, which is the difference between the absorbance in the wavelength band of 315 nm to 380 nm and the absorbance in the wavelength band of 450 nm or more (for example, 450 nm to 600 nm), is small in fresh fish. The freshness of the fish is estimated with high accuracy by taking advantage of the characteristic that it becomes a value, while it becomes a large value for non-fresh fish.

In the freshness estimation example 2, the freshness of the fish was estimated using one set of threshold values (a constant threshold value A and another threshold value B), but a plurality of sets of threshold values were used. May be good. For example, the absorbance spectrum as shown in FIG. 4 is acquired for each type of fish and the storage state of the fish, and a set of a third threshold value for the absorbance difference for distinguishing between fresh fish and non-fresh fish is determined. Then, the plurality of sets of threshold values are registered as in the threshold value table 32c shown in FIG. 11 and held in the freshness estimation unit 32. Then, when the freshness estimation unit 32 receives input from the user about the type of fish to be estimated for freshness and the storage state of the fish, the freshness estimation unit 32 corresponds to the received fish type and storage state by referring to the threshold table 32c. The set of threshold values to be used is read out, and the freshness of the fish is estimated using the set of the read threshold values. This makes it possible to estimate the freshness with higher accuracy in consideration of the type of fish and the storage state.

(Modification example 1)
Next, a modification 1 of the above embodiment will be described. In this modification, the absorbance spectrum is acquired by using a plurality of light sources (a plurality of light sources of monochromatic light) that emit light having different wavelengths.

In the above embodiment, the light from the light source 21 is separated by the diffraction grating 22 while changing the diffraction angle to obtain a continuous absorbance spectrum from the ultraviolet region or the ultraviolet region to the visible region, and the absorbance spectrum of the ultraviolet region is obtained. The shape was used to estimate the freshness of the fish. However, in the freshness estimation examples 1 and 2, if the absorbances in at least two wavelength bands are known, the difference in absorbance or the magnitude of the ratio can be calculated to estimate the freshness of the fish. For example, as in Estimated Example 1 of freshness, the degree of how much the peak protrudes from the other part due to the difference between the peak part of the absorbance and the gentle part (stable part) other than the peak. The freshness of the fish can be estimated by judging. Further, for example, the freshness of the fish is determined by determining the magnitude of the difference in absorbance in the portion stable in each of the two different wavelength bands (that is, the portion where the change in absorbance with respect to the wavelength change is relatively small) as in Example 2 of estimating freshness. Can be estimated.

Therefore, in this modification, by using the reflection intensity measuring device 20a instead of the spectrophotometer 20 described above, a plurality of light sources (a plurality of light sources of monochromatic light) that emit light of different wavelengths can be easily used. The absorbance of the two wavelengths is obtained to estimate the freshness of the fish.

FIG. 12 is a diagram showing the configuration of the reflection intensity measuring device 20a in this modified example. The reflection intensity measuring device 20a is provided with a light source 21a, a light source 21b, and a selector 27 in place of the light source 21 and the diffraction grating 22 of the spectrophotometer 20 in the above embodiment shown in FIG. The reflection intensity measuring device 20a is a modification of the spectrophotometer 20, and the interface with the terminal device 30 is the same as that of the spectrophotometer 20. Hereinafter, in the reflection intensity measuring device 20a, the same components as those of the spectrophotometer 20 described above are designated by the same reference numerals, the description thereof will be omitted, and the differences will be mainly described.

The two light sources 21a and 21b are a plurality of light sources (a plurality of light sources of monochromatic light) that emit light having different wavelengths. The selector 27 is a selection switch that selects and passes only one of the lights emitted from the two light sources 21a and 21b. The selector 27 sequentially irradiates the eyes of the fish 12 with two lights having different wavelengths by sequentially selecting each of the two light sources 21a and 21b by a control signal from a driving device (not shown). ..

In the terminal device 30, the absorbance spectrum acquisition unit 31 receives the intensity of the reflected light or the transmitted light generated by the light emitted from each of the two light sources 21a and 21b from the reflection intensity measuring device 20a, and according to the above formula 1, By calculating the absorbance at the two wavelengths, the absorbance spectrum can be easily calculated. The freshness estimation unit 32 uses the shape of the absorbance spectrum acquired by the absorbance spectrum acquisition unit 31, that is, the absorbance at two wavelengths, and uses the freshness of the fish 12 according to the procedure described in the freshness estimation examples 1 and 2. To estimate.

An example of combining the two light sources 21a and 21b is as follows.

(1) Combination example 1
One light source 21a emits narrow band light having an arbitrary wavelength between 410 nm and 430 nm as the center wavelength (peak wavelength), and the other light source 21b emits light having an arbitrary wavelength between 315 nm and 380 nm as the center wavelength (peak wavelength). ) Is emitted in a narrow band. Thereby, the freshness of the fish can be estimated in the same manner as in the above-mentioned estimation example 1 of freshness.

(2) Combination example 2
One light source 21a emits narrow-band light having an arbitrary wavelength between 410 nm and 430 nm as the center wavelength (peak wavelength), and the other light source 21b emits light having an arbitrary wavelength of 450 nm or more (for example, between 450 nm and 600 nm). Is emitted as a narrow band light having a center wavelength (peak wavelength). Thereby, the freshness of the fish can be estimated in the same manner as the other examples shown in the estimation example 1 of the freshness.

(3) Combination example 3
One light source 21a emits ultraviolet light having a wavelength in the wavelength band of 315 nm to 380 nm, and the other light source 21b emits light having a wavelength band of 450 nm or more (for example, visible light having a wavelength in the wavelength band of 450 nm to 600 nm, or further). Infrared light including wavelengths in the wavelength band up to 1000 nm) is emitted. Thereby, the freshness of the fish can be estimated in the same manner as in the above-mentioned estimation example 2 of freshness.

As described above, according to this modification, the absorbance spectrum can be easily obtained by switching a plurality of light sources and irradiating the fish eye, and the wavelength of the light irradiating the fish eye can be swept or separated into a plurality of wavelengths. There is no need for a complicated optical system to make it. Therefore, it is relatively inexpensive and it is possible to estimate the freshness of fish by a small freshness estimation device.

(Modification 2)
Next, a modification 2 of the above embodiment will be described. In this modification, the absorbance spectrum is acquired by extracting the biological fluid in the eyeball of a fish, irradiating the biological fluid in the extracted eyeball with light, and measuring the light transmitted through the biological fluid in the eyeball.

In the above embodiment, the freshness of the fish is estimated by shining light on the fish eye and using the reflected light. However, in this modified example, the biological fluid in the eyeball is extracted from the fish eye and the biological fluid in the eyeball is lighted. The freshness is estimated using the absorbance (that is, transmitted light) when the light is applied. Compared with the method using reflected light, such a method using transmitted light takes more time and effort to extract the biological fluid in the eyeball from the fish's eye, but its absorbance changes with the time change after the death of the fish. Since the freshness of the fish can be estimated using only the biological fluid in the eyeball that has been confirmed to be used (see the above examples 1 and 2 of estimating the freshness), it is possible to estimate the freshness of the fish with higher accuracy.

Hereinafter, the process of obtaining the absorbance spectrum of the biological fluid in the eyeball will be described. FIG. 13 is a diagram showing an apparatus and a processing procedure for extracting the biological fluid in the eyeball of the fish in this modified example.

First, the biological fluid in the eyeball is extracted from the fish ((a) in FIG. 13). As shown in FIG. 13 (a), the fish 42 is placed on the tray 41. There is a mark on the tray 41 for placing the fisheye in place, and the fish 42 is placed on the tray 41 so that the fisheye is located on the mark. The tray 41 is placed on a table 40 that moves up and down, and a syringe 43 is fixed above the table 40. The needle of the syringe 43 points to the mark indicating the position of the fisheye on the tray 41. After installing the fish 42 on the tray 41, the table 40 is automatically or manually raised, and when the needle of the syringe 43 is stuck in the cornea of the eye of the fish 42, the raising of the table 40 is stopped. At this time, a mechanism may be provided to automatically stop the base 40 by detecting the pressure of the cornea, or the base 40 may be stopped manually. With the needle of the syringe 43 stuck in the fisheye, the biological fluid in the fisheye is extracted into the syringe 43 by pulling up the presser 44 fixed to the piston portion of the syringe 43.

After extracting a certain amount of the biological fluid in the eyeball in this way, the biological fluid in the eyeball is subjected to the centrifuge 46 ((b) in FIG. 13). This is because the absorbance spectrum with less distortion can be obtained by measuring the intensity of the transmitted light of only the supernatant of the biological fluid in the eyeball. Therefore, first, by pulling down the pressing device 44 fixed to the piston portion of the syringe 43, the biological fluid in the eyeball accumulated in the syringe 43 is injected into the centrifuge tube 45 and centrifuged by the centrifuge 46. As the centrifugation time, for example, the absorbance spectrum of the target biological fluid in the eyeball can be obtained by performing the centrifugation at 5000 rpm for 30 minutes, but the rotation speed and time are not limited to this.

As a result of centrifugation, the transparent part with visible light becomes the supernatant liquid, so only this part (supernatant liquid) is sucked up into the empty syringe 43 ((c) in FIG. 13), and this is sucked into the cell 47. Insert ((d) in FIG. 13). The cell 47 needs to be made of a material that transmits light in a wide band from the ultraviolet region to the infrared region, and is preferably made of, for example, quartz.

FIG. 14 is a diagram showing the configuration of the spectrophotometer 20b in this modified example. In this spectrophotometer 20b, the components are the same as those of the spectrophotometer 20 in the embodiment of the above embodiment, but here, the intensity of transmitted light is collected so as to be detected instead of reflected light. An optical lens 24 and a receiver 25 are arranged. That is, the light emitted from the light source 21 is incident on the diffraction grating 22. The light incident on the diffraction grating 22 is separated by the diffraction grating 22, collected by the focusing lens 23, and irradiated to the cell 47. The cell 47 may be placed on a table whose position can be adjusted so that the light collected by the focusing lens 23 is irradiated to an appropriate position of the cell 47.

The light transmitted through the cell 47 is condensed by the condenser lens 24 installed behind the cell 47 and incident on the receiver 25. The position of the condenser lens 24 is adjusted so that the light passing therethrough is focused on the receiver 25.

The processing in the terminal device 30 is basically the same as that of the above embodiment. That is, the absorbance spectrum acquisition unit 31 receives the intensity of transmitted light from such a transmission type spectrophotometer 20b, and calculates the absorbance at each wavelength according to the above formula 1 to calculate the absorbance spectrum. The freshness estimation unit 32 estimates the freshness of the fish 42 by using the shape of the absorbance spectrum calculated by the absorbance spectrum acquisition unit 31.

As described above, according to this modification, a more accurate absorbance spectrum is obtained by utilizing the light transmission characteristics in the supernatant of the biological fluid in the eyeball of the fish, and thereby the fish is more accurately obtained. The freshness can be estimated.

In this modified example, the biological fluid in the eyeball was extracted with the syringe 43, and the supernatant liquid separated by the centrifuge 46 was replaced with the cell 47 to obtain an absorbance spectrum, as shown in FIG. The absorbance spectrum may be obtained by extracting the biological fluid in the eyeball with a dropper 50 with a liquid pool and obtaining spectral characteristics with the spectrophotometer 20b together with the dropper 50 with a liquid pool. FIG. 15 is a diagram showing a dropper 50 with a liquid pool that can be applied to this modification. As shown in FIG. 15, the dropper 50 with a liquid pool portion has a liquid pool portion 51 made of quartz, which stores the biological fluid in the sucked eyeball.

FIG. 16 is a diagram showing a configuration of a spectrophotometer 20b when a spectrophotometer 50 with a liquid pool portion is used to obtain spectroscopic characteristics. Here, the configuration of the spectrophotometer 20b when the spectrophotometer 20b obtains the spectral characteristics together with the dropper 50 with the liquid pool portion is shown. The spectrophotometer 20b is a removable liquid pool for sucking up and holding the biological fluid in the eyeball of the fish to be irradiated with light instead of the cell 47 in the spectrophotometer 20b shown in FIG. A dropper 50 is provided.

According to such a configuration, the biological fluid in the eyeball of the fish is extracted by the dropper 50 with a liquid pool, the dropper 50 with a liquid pool is attached to the spectrophotometer 20b to acquire the spectral characteristics, and the terminal device 30 By performing the processing as described in Examples 1 and 2 of estimating the freshness, the freshness of the fish can be estimated by a simpler method without using the centrifuge 46 and without taking time and effort.

Further, according to the method using the dropper 50 with a liquid pool, it takes time and effort to extract the biological fluid in the eyeball from the fish, but it can be confirmed that the absorbance changes with the time change after death. Since the freshness is determined using only the biological fluid in the eyeball, the freshness of the fish can be estimated with higher accuracy than the method using the reflected light from the fish eye.

(Modification 3)
Next, a modification 3 of the above embodiment will be described. In this modification, the absorbance spectrum of fresh fish and the absorbance spectrum of non-fresh fish are classified by clustering by statistical processing, and it is determined which classification the absorbance spectrum of fish of unknown freshness is similar to. By doing so, the freshness of the fish is estimated.

In the above embodiment, the relationship between the shape of the absorbance spectrum of the fisheye and the freshness of the fish is analyzed, and the freshness of the fish is obtained from the shape of the absorbance spectrum of the fish whose freshness is unknown by using the threshold value obtained as a result of the analysis. Was estimated. However, the present inventors are automatically fresh by clustering (multivariate analysis) by statistical processing on the absorbance spectra of various fish without analyzing the relationship between the shape of the absorbance spectrum and the freshness of the fish. It was discovered that the absorbance spectrum of fish and the absorbance spectrum of fresh fish can be classified. Therefore, it was found that the freshness of the fish can be easily estimated from the absorbance spectrum of the fish whose freshness is unknown by using the classification result.

FIG. 17A is a flowchart showing the basic operation of the freshness estimation device (that is, the method for estimating the freshness of fish) in this modified example. This freshness estimation method is roughly divided into two steps. That is, first, the absorbance spectrum of fresh fish and the absorbance spectrum of non-fresh fish are classified (learned) in advance (S60). Next, by using the classification result, the freshness of the fish is estimated from the absorbance spectrum of the fish whose freshness is unknown (S70).

FIG. 17B is a flowchart showing a detailed procedure of step S60 (pre-classification) in FIG. 17A. The absorbance spectrum acquisition unit 31 of the terminal device 30 uses a spectrophotometer 20 to target a plurality of fish including fresh fish and non-fresh fish for prior classification (learning), and uses an absorbance spectrum (for example, for example). Absorbance spectrum in the wavelength band of 315 nm to 600 nm) is acquired (S61). Then, the freshness estimation unit 32 of the terminal device 30 divides a plurality of absorbance spectra acquired by the absorbance spectrum acquisition unit 31 for prior classification (learning) into two classes by clustering (multivariate analysis) by statistical processing. Classify (S62). In this classification, it is not necessary to teach which absorbance spectrum is for fresh fish and which absorbance spectrum is for non-fresh fish. Statistical clustering (multivariate analysis) is performed so that all absorbance spectra to be classified are classified into two classes with the highest possible resolution. As a result, as described above, the absorbance spectrum of fresh fish and the absorbance spectrum of non-fresh fish are automatically classified.

FIG. 17C is a flowchart showing a detailed procedure of step S70 (freshness estimation) in FIG. 17A. The absorbance spectrum acquisition unit 31 acquires an absorbance spectrum (for example, an absorbance spectrum in a wavelength band of 315 nm to 600 nm) using a spectrophotometer 20 for a fish whose freshness is to be estimated for freshness estimation. (S71). Then, in the freshness estimation unit 32, the absorbance spectra acquired by the absorbance spectrum acquisition unit 31 for freshness estimation are of two classes obtained in the above classification (step S60 in FIG. 17A; steps S61 to S62 in FIG. 17B). It is determined which one is similar to the absorbance spectrum (S72), and the freshness of the fish is estimated based on the result of the determination (S73 to S74). That is, as a result of the determination, if the absorbance spectrum obtained for freshness estimation is more similar to the absorbance spectrum of a fresh fish (in S72, "similar to the fresh fish class"), it is determined that the fish is fresh (S73). ), On the other hand, if the absorbance spectrum obtained for freshness estimation is more similar to the absorbance spectrum of a non-fresh fish (“similar to rotten fish class” in S72), it is determined that the fish is not fresh (S74). As a result, the freshness of the fish can be estimated from the absorbance spectrum of the fish whose freshness is unknown.

Regarding the similarity, the absorbance spectrum may be regarded as a multidimensional vector and may be judged by the distance between the multidimensional vectors. That is, the distance between the average (absorbance spectrum) of the absorbance spectra classified as a class of fresh fish and the absorbance spectrum of a fish of unknown freshness, and the average (absorbance spectrum) and freshness of the absorbance spectra classified as a class of non-fresh fish. The similarity may be judged based on which of the distances from the absorbance spectrum of the unknown fish is smaller.

FIG. 18 is a diagram showing the result of freshness estimation in this modified example. Here, SIMCA (Soft Independent Modeling of), which is one method of multivariate analysis, is used.
A diagram plotting the distance between the two classes created by the Class Analogy method and the absorbance spectra obtained from the fish eyes that were not used to train the classes is shown. The horizontal axis shows the distance to the fresh fish class (fresh fish class), and the vertical axis shows the distance to the non-fresh fish class (rotten fish class). Circled plots are data for fish (rotten fish) over 18 hours after death used for pre-classification (learning), and square plots are 16 hours after death used for pre-classification (learning). The data of fish (fresh fish) up to, the plot of the triangle mark is the data of the fish (rotten fish) used for the test over 18 hours after death, and the plot of the + mark is the data of 16 after death used for the test. It is the data of fish (rotten fish) up to the time. The distance from the class is the distance from the average (absorbance spectrum) of the absorbance spectra belonging to the class.

For prior classification (learning), absorbance spectra were calculated from eight fisheye lenses every hour from 1 hour to 96 hours after death, and these absorbance spectra were used. A large number of obtained absorbance spectra were separated into two classes by the SIMCA method. The SIMCA method is a method of multivariate analysis (see http://www.gls.co.jp/glsoft/chemomet/chemometo/simca/simca.html). The clustering (multivariate analysis) by statistical processing is not limited to the SIMCA method, and may be another clustering method.

As can be seen from the circle and square plots in FIG. 18, according to the SIMCA method, the absorbance spectrum used for the test was a class corresponding to a fresh fish composed of the absorbance spectrum of the fish 1 to 16 hours after death. , Was separated into the class corresponding to the less fresh fish composed of the absorbance spectra of the fish after 18 hours after death.

Then, when the distances between the two already classified classes of the absorbance spectra obtained from the eight fish eyes of the fish that were not used in the prior classification (learning) with time change were calculated, the fresh fish (after death). The absorbance spectrum for fish up to 16 hours is close to the freshness class, and the absorbance spectrum for poorly fresh fish (fish 18 hours after death) is close to the low freshness class. It was close. The correct answer rate for freshness estimation by this method was a high probability of 90% or more. It is considered that the reason why the freshness could be estimated with such high accuracy is that the absorbance spectrum of the biological fluid in the eyeball of the fish has different characteristics between the fish with high freshness and the fish with low freshness.

As described above, according to this modification, the absorbance spectrum of fresh fish and the absorbance spectrum of non-fresh fish are classified by clustering by statistical processing, and the absorbance spectrum of fish of unknown freshness is classified into any of the absorbance spectra. The freshness of the fish was estimated by determining whether it was similar to. As a result, a complicated determination process is used by utilizing the characteristic that the absorbance spectrum of the fisheye including the wavelength band of 315 nm to 450 nm is automatically clustered into two types, that is, a fresh fish and a non-fresh fish. The freshness of the fish is estimated with high accuracy.

(Modification example 4)
Next, a modification 4 of the above embodiment will be described. In this modification, a single light source (monochromatic light source) that emits light of one wavelength in a certain wavelength band (for example, 410 nm to 430 nm) in which the peak of absorbance appears in the above-mentioned absorbance spectrum (see FIG. 4) is used. By doing so, the absorbance is obtained. In this way, it is possible to estimate the freshness of a fish by setting conditions such as the type of fish for which the freshness is to be estimated and the humidity around the fish to some extent even by the absorbance at one wavelength.

Therefore, in this modification, by using the reflection intensity measuring device 20c instead of the reflection intensity measuring device 20a shown in the modification 2 of the above-described embodiment, the absorbance can be easily obtained by using a single light source of monochromatic light. Is obtained, and the freshness of the fish is estimated by comparing the absorbance with a predetermined threshold. Therefore, instead of the terminal device 30 that uses the absorbance spectrum, the terminal device 30a for estimating the freshness of the fish from one absorbance is used. If the absorbance is less than the threshold, it can be estimated that the fish is fresh, and if it is above the threshold, it can be estimated that the fish is not fresh. The threshold value can be set in advance by experiment for each type of fish. For example, based on FIG. 4, the threshold value can be set as the boundary of whether or not the absorbance when the elapsed time after the death of the fish is 18 hours is fresh. .. Specifically, for example, 0.3 ± 0.05 can be set as the threshold value.

Further, for example, in order to keep the humidity around the fish constant, the absorbance may be measured in a state where the fish is covered with a food wrap film and the humidity is maintained at about 90%.

FIG. 19 is a diagram showing the configuration of the freshness estimation device 10a (terminal device 30a and reflection intensity measuring device 20c) in this modified example. The terminal device 30a includes an absorbance acquisition unit 31a instead of the absorbance spectrum acquisition unit 31 of the terminal device 30 shown in FIG. 1, and estimates the freshness of fish by comparing one absorbance with a threshold value instead of the freshness estimation unit 32. The freshness estimation unit 39 is provided. The reflection intensity measuring device 20c is a device in which a support 29 is added except for the light source 21b and the selector 27 of the reflection intensity measuring device 20a shown in FIG. Hereinafter, in the terminal device 30a and the reflection intensity measuring device 20c, the same components as those of the terminal device 30 and the reflection intensity measuring device 20a described above are designated by the same reference numerals, the description thereof will be omitted, and the differences will be mainly described.

The light source 21a is a light source that emits monochromatic light of one wavelength in the wavelength band of 410 nm to 430 nm. The support 29 is a mechanism that supports the light source 21a so that the optical axis of the light source 21a can be moved within a certain range.

The receiver 25a is a sensor that detects the intensity of the reflected light incident through the condenser lens 24 (converts the light into an electric signal), and is, for example, a photomultiplier tube or a photodiode.

In the reflection intensity measuring device 20c, the position where the light emitted from the light source 21a hits the fish's eye via the focal lens 23 is changed by the support 29 to perform a plurality of measurements. By receiving the reflected light from the fish's eye via the condensing lens 24, the receiver 25a sends the maximum intensity of the reflected light detected by the plurality of measurements to the terminal device 30a. ..

The absorbance acquisition unit 31a of the terminal device 30a is a processing unit that acquires the absorbance obtained by irradiating the fish eye with light in the wavelength band of 410 nm to 430 nm, and obtains the intensity of the reflected light or the transmitted light from the reflection intensity measuring device 20c. It is composed of a communication interface to be acquired, an arithmetic processing unit for calculating the absorbance according to the above formula 1, and the like.

The freshness estimation unit 39 is a processing unit that estimates the freshness of the fish 12 (that is, executes a fish freshness estimation method) using the absorbance acquired by the absorbance acquisition unit 31a, and is composed of an arithmetic processing unit and the like.

In the terminal device 30a, the absorbance acquisition unit 31a receives the intensity of the reflected light or the transmitted light generated by the light emitted from the light source 21a from the reflection intensity measuring device 20c, and calculates the absorbance according to the above formula 1. Then, the freshness estimation unit 39 estimates whether the fish is fresh or not by comparing the absorbance with the threshold value, and the output unit 33 outputs the estimation result. For example, the freshness estimation unit 39 determines (estimates) that the fish is fresh when the absorbance is smaller than the threshold value, and determines (estimates) that the fish is rotten when the absorbance is equal to or higher than the threshold value.

As described above, according to this modification, it is possible to estimate the freshness of a fish with a simple configuration in which light is radiated to the fisheye using a single light source. Even if the optical axis of the light source 21a is not changed by the support 29 (that is, without the support 29), the positional relationship between the eyes of the fish 12 and the optical axis of the light emitted from the reflection intensity measuring device 20c. It is possible to estimate the freshness of fish with a certain degree of accuracy by performing a plurality of measurements by changing the above and using the average value, the maximum value, etc. of the absorbance.

The fish freshness estimation method and the freshness estimation device according to one or more aspects of the present invention have been described above based on the embodiments and variations thereof, but the present invention is limited to the embodiments and modifications. It is not something that is done. As long as the gist of the present invention is not deviated, various modifications that can be conceived by those skilled in the art are applied to the present embodiment or the modified examples, and a mode constructed by combining components in different embodiments or modified examples is also the present invention. It may be included in the range of one or more aspects of.

For example, in the embodiments and modifications described above, the freshness estimation unit 32 estimated whether the fish was fresh or not, or whether the fish was fresh, suspected of spoilage, or not fresh. However, the estimation is not limited to such two-step and three-step estimation, and the freshness estimation unit 32 uses the absorbance difference or the difference between the ratio and the threshold value in the absorbance spectrum, or the absorbance spectrum of a fish whose freshness is unknown and the class of fresh fish. Depending on the magnitude of the distance to and, the possibility of being fresh may be estimated with probability.

Further, in the above embodiment, a plurality of freshness estimation examples are shown, and in the above modified example, a freshness estimation example by clustering is shown, but these plurality of estimation examples may be selectively used. It may be used in any combination. Which estimation example is used may be determined by a preset setting in the terminal device 30, or may be determined each time by a dialogue between the terminal device 30 and the user.

Further, the method for estimating the freshness of fish in the above embodiment may be realized by the following program. The program uses an absorbance spectrum acquisition step of irradiating a fish's eye with light containing all or part of the wavelength band of 315 nm to 450 nm to acquire an absorbance spectrum obtained by irradiating a computer with light, and the shape of the acquired absorbance spectrum. Then, the freshness estimation step of estimating the freshness of the fish is executed. With such a program, a fish freshness estimation method capable of objectively estimating the freshness of the whole fish with higher accuracy than before is realized.

Further, in the above embodiment, it is described that light in the wavelength band of 315 nm to 450 nm is used, and the range of 315 nm to 380 nm, the range of 410 nm to 430 nm, and the wavelengths of 600 nm, 1000 nm, etc. are shown. Due to the influence of individual differences in fish and the measurement environment, the wavelength band range or individual wavelengths should actually take into account a margin (error) of about ± 5 nm. Therefore, the range of the wavelength band to be actually used is, for example, 315 nm ± 5 nm to 450 nm ± 5 nm, 315 nm ± 5 nm to 380 nm ± 5 nm, 410 nm ± 5 nm to 430 nm ± 5 nm, and the like.

Further, in the above embodiment, the main processing unit (absorbance spectrum acquisition unit 31, freshness estimation unit 32) of the freshness estimation device 10 is composed of one terminal device 30, and the main processing unit of the freshness estimation device 10a. (Absorbance acquisition unit 31a, freshness estimation unit 39) is composed of one terminal device 30a, but may be composed of a plurality of terminal devices and a computer. That is, a plurality of terminal devices and computers may cooperate to execute a process of estimating the freshness of fish by communicating with each other.

The present invention determines the freshness of fish as a method and device for estimating the freshness of fish, for example, at a site where fish is caught or at a site where fish is distributed, in a short time by a non-contact, non-invasive method. As a result, it can be used as a freshness estimation method and a freshness estimation device that provides a mechanism for efficiently guaranteeing the safety of foodstuffs.

10, 10a Freshness estimation device 12, 42 Fish 14 Smartphone (multifunctional mobile phone)
20, 20b Spectrophotometer 20a, 20c Reflection intensity measuring device 21, 21a, 21b Light source 22 Diffraction grating 23 Focus lens 24 Condensing lens 25, 25a Receiver 26 Reflector 27 Selector 29 Supporter 30, 30a Terminal device 31 Absorbance Spectrum acquisition unit 31a Absorbance acquisition unit 32, 39 Freshness estimation unit 32a, 32b, 32c Threshold table 33 Output unit 40 units 41 Tray 43 Injector 44 Presser 45 Centrifugal tube 46 Centrifugal separator 47 Cell 50 Dropper with liquid pool (spot)
51 Liquid pool

Claims (11)

It is a freshness estimation device that estimates the freshness of fish.
A spectrophotometer that detects the intensity of a plurality of reflected lights obtained by irradiating the fish's eye with light having a plurality of different wavelengths in the wavelength band of 315 nm to 450 nm.
An absorbance spectrum acquisition unit that acquires an absorbance spectrum using the intensities of the plurality of reflected lights detected by the spectrophotometer, and an absorbance spectrum acquisition unit.
A terminal device having a freshness estimation unit that estimates the freshness of the fish based on the absorbance difference obtained by using the absorbances corresponding to the two predetermined wavelengths in the absorbance spectrum.
A freshness estimation device equipped with. It is a freshness estimation device that estimates the freshness of fish.
It has a plurality of light sources that emit light having a plurality of wavelengths different from each other in a wavelength band of 315 nm to 450 nm, and detects the intensity of a plurality of reflected lights obtained by irradiating the fish eye with the light from the plurality of light sources. Reflection intensity measuring device and
An absorbance spectrum acquisition unit that acquires an absorbance spectrum using the intensities of the plurality of reflected lights detected by the reflection intensity measuring device, and an absorbance spectrum acquisition unit.
A terminal device having a freshness estimation unit that estimates the freshness of the fish based on the absorbance difference obtained by using the absorbances corresponding to the two predetermined wavelengths in the absorbance spectrum.
A freshness estimation device equipped with. It is a method of estimating the freshness of fish
An absorbance spectrum acquisition step of acquiring an absorbance spectrum using a plurality of reflected lights obtained by irradiating the fish's eye with light having a plurality of different wavelengths in the wavelength band of 315 nm to 450 nm.
A fish freshness estimation method including a freshness estimation step for estimating the freshness of the fish based on the absorbance difference obtained by using the absorbances corresponding to the two predetermined wavelengths in the absorbance spectrum . It is a method of estimating the freshness of fish
An absorbance acquisition step of acquiring a plurality of absorbances corresponding to a plurality of reflected lights obtained by irradiating the fish eye with a plurality of lights having different wavelengths in the wavelength band of 315 nm to 450 nm.
A method for estimating freshness of a fish, which comprises a freshness estimation step of estimating the freshness of the fish based on the difference in absorbance obtained by using the plurality of absorbances . In the freshness estimating step, the peak value of absorbance appearing in the wavelength band of 410nm~430nm is fish fish when corrupt estimates the freshness of the fish based on the fact that higher than in the case fresh claim 3 or 4. The method for estimating the freshness of fish according to 4 . In the freshness estimation step, when the first absorbance difference obtained by subtracting the absorbance at an arbitrary wavelength in the wavelength band of 315 nm to 380 nm from the peak value of the absorbance in the wavelength band of 410 nm to 430 nm is smaller than a certain threshold value. The method for estimating the freshness of a fish according to claim 3 or 4 , wherein the fish is estimated to be fresh. In the freshness estimation step, the fish is obtained when the second absorbance difference obtained by subtracting the absorbance at an arbitrary wavelength in the wavelength band of 450 nm or more from the peak value of the absorbance in the wavelength band of 410 nm to 430 nm is smaller than a certain threshold value. The method for estimating the freshness of fish according to claim 3 or 4 , wherein the fish is estimated to be fresh. In the absorbance spectrum acquisition step, the absorbance spectrum obtained by irradiating the fish eye with light having a wavelength band of 450 nm or more in addition to the wavelength band of 315 nm to 380 nm is acquired.
In the freshness estimation step, the freshness of the fish is estimated based on the third absorbance difference, which is the difference between the absorbance in the wavelength band of 315 nm to 380 nm and the absorbance in the wavelength band of 450 nm or more in the absorbance spectrum. 3. The method for estimating the freshness of fish according to the above. In the freshness estimation step, the fish is fresh when the third absorbance difference is less than or equal to a certain threshold value, and the fish is greater than or equal to another threshold value larger than the certain threshold value. 8 is the method for estimating the freshness of fish according to claim 8 . The method for estimating freshness of a fish according to claim 3 , wherein in the absorbance spectrum acquisition step, the absorbance spectrum is acquired by using a plurality of light sources that emit light having different wavelengths. A program for estimating the freshness of fish
A program that causes a computer to perform a step included in the method for estimating freshness of fish according to any one of claims 3 to 10 .

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