JP7669017B2 - Freshness evaluation device for fresh produce and freshness evaluation method for fresh produce - Google Patents

Description

The present invention relates to a freshness evaluation device for fresh produce and a freshness evaluation method for fresh produce.

A biochemical indicator of freshness known as the "K value" is known as an index of freshness for fresh produce. The K value is an indicator of the degree of decomposition of ATP (adenosine triphosphate) present in the muscle of an animal.

Patent Document 1 describes a method for evaluating the freshness of fresh produce using the K value, in which the fresh produce and a color-developing medium are enclosed in a transparent container, and the K value is estimated from the color change that accompanies a chemical reaction in the color-developing medium to evaluate the freshness of the fresh produce.

JP 2005-345263 A

However, freshness evaluation methods using the K value, such as the evaluation method described in Patent Document 1, use a chemical reaction to measure the degree of ATP decomposition, so the preparations required to measure the K value are time-consuming, and it takes time for the chemical reaction to stabilize.

The present invention was made in consideration of the above problems, and its purpose is to provide a freshness evaluation device and a freshness evaluation method that can easily and quickly evaluate the freshness of fresh products.

The freshness evaluation device according to the present invention is a device for evaluating the freshness of fresh produce. The freshness evaluation device according to the present invention includes a light source, a fluorescence selection unit, and an electrical signal conversion unit. The light source irradiates the fresh produce with excitation light. The fluorescence selection unit selectively transmits fluorescence from advanced glycation end products in the fresh produce from autofluorescence emitted by the fresh produce in response to irradiation with the excitation light. The electrical signal conversion unit receives the fluorescence that has transmitted through the fluorescence selection unit and converts the fluorescence into an electrical signal.

In one embodiment, the fluorescence selection unit has a cut filter that blocks light with a wavelength of 420 nm or less from the autofluorescence emitted by the fresh produce, and a bandpass filter that selectively transmits light with a wavelength in the range of -50 nm or more to +50 nm from the peak wavelength of the fluorescence from advanced glycation end products from the light that has passed through the cut filter.

In one embodiment, the electrical signal conversion unit is an image sensor.

In one embodiment, the freshness evaluation device further includes an image processing unit that uses the electrical signal converted by the electrical signal conversion unit to map the distribution of advanced glycation end products on an image of the fresh product.

In one embodiment, the fresh produce is fruit or vegetables, meat, or flowers.

The freshness evaluation method according to the present invention is a method for evaluating the freshness of fresh produce. The freshness evaluation method according to the present invention includes an irradiation step and a conversion step. In the irradiation step, excitation light is irradiated onto the fresh produce. In the conversion step, among the autofluorescence emitted by the fresh produce upon irradiation with the excitation light, fluorescence from advanced glycation end products in the fresh produce is selectively converted into an electrical signal.

In one embodiment, the freshness assessment method further includes an image processing step of mapping the distribution of advanced glycation end products on an image of the fresh product using the electrical signal converted by the conversion step.

The present invention provides a freshness evaluation device and a freshness evaluation method that can easily and quickly evaluate the freshness of fresh produce.

1 is a diagram showing an example of the configuration of a freshness evaluation device according to a first embodiment of the present invention. FIG. 10 is a flowchart showing an example of a freshness evaluation method according to a second embodiment of the present invention. 4A and 4B are images after image processing in the first embodiment. 13A and 13B are images after image processing in the second embodiment. 13A and 13B are images after image processing in the third embodiment.

The following describes preferred embodiments of the present invention. However, the present invention is not limited to the following embodiments, and can be implemented in various forms without departing from the spirit of the invention. Note that where explanations overlap, they may be omitted as appropriate.

First, we will explain the terms used in this specification. "Perishables" refers to products that are required to be perishable (fresh). Examples of perishables include fruits and vegetables, meat, and flowers.

"Advanced glycation end products" is a general term for structures that are produced in the later stages of the reaction between sugar and protein (the Maillard reaction). Hereinafter, advanced glycation end products may be referred to as "AGEs."

"Imaging element" refers to an electronic component that converts light into an electrical signal.

<First embodiment: freshness evaluation device>
The freshness evaluation device according to the first embodiment of the present invention will be described below. The freshness evaluation device according to the first embodiment includes a light source, a fluorescence selection unit, and an electrical signal conversion unit. The light source irradiates excitation light onto the fresh product. The fluorescence selection unit selectively transmits fluorescence from AGEs in the fresh product among the autofluorescence emitted by the fresh product when irradiated with the excitation light. The electrical signal conversion unit receives the fluorescence that has transmitted through the fluorescence selection unit and converts the fluorescence into an electrical signal.

The freshness evaluation device according to the first embodiment has the above-mentioned configuration, and can easily and quickly evaluate the freshness of fresh produce. The reason for this is believed to be as follows.

AGEs are the products of biochemical reactions that take place to maintain the vital activities of living organisms. For this reason, as the freshness of fresh produce decreases, the amount of AGEs in the fresh produce tends to increase. In other words, the amount of AGEs in fresh produce is an indicator of the freshness of the fresh produce.

The freshness evaluation device according to the first embodiment includes a light source, a fluorescence selection unit, and an electrical signal conversion unit. The light source irradiates the fresh product with excitation light. The fluorescence selection unit selectively transmits fluorescence from AGEs in the fresh product among the autofluorescence emitted by the fresh product when irradiated with excitation light. The electrical signal conversion unit receives the fluorescence that has transmitted through the fluorescence selection unit and converts the fluorescence into an electrical signal. Thus, according to the freshness evaluation device according to the first embodiment, by irradiating the fresh product with excitation light from the light source, the fluorescence from the AGEs in the fresh product (more specifically, the intensity of the fluorescence) can be selectively converted into an electrical signal, so that the amount of AGEs in the fresh product can be easily and quickly recognized as an electrical signal. Therefore, according to the freshness evaluation device according to the first embodiment, the freshness of the fresh product can be easily and quickly evaluated.

In addition, the freshness evaluation device according to the first embodiment can irradiate fresh produce with excitation light, thereby allowing the amount of AGEs in the fresh produce to be recognized as an electrical signal, making it possible to accurately evaluate the freshness of fresh produce in which changes in freshness are difficult to ascertain from the outside without destroying it.

In the first embodiment, in order to more easily and quickly evaluate the freshness of fresh products, fruits and vegetables, meat, or flowers are preferred as fresh products.

Examples of fresh produce include fruits (more specifically, strawberries, peaches, apples, pears, bananas, figs, pineapples, mangoes, persimmons, cherries, etc.) and vegetables (more specifically, eggplants, cucumbers, tomatoes, cherry tomatoes, spinach, carrots, radishes, cabbage, edamame, corn, bean sprouts, mizuna, broccoli, lettuce, etc.). Examples of meat include beef, lamb, pork, chicken, horse meat, and venison. Examples of flowers include gerberas, roses, chrysanthemums, carnations, lisianthus, statice, stocks, begonias, cyclamen, and sweet peas. In the first embodiment, in order to more easily and quickly evaluate the freshness of fresh produce, strawberries, beef, or gerberas are preferred as fresh produce.

Next, the freshness evaluation device according to the first embodiment will be described in detail with reference to FIG. 1. Note that FIG. 1, which is referred to, shows each component mainly in a schematic manner for ease of understanding, and the size, number, shape, etc. of each component shown in the figure may differ from the actual ones due to the convenience of creating the drawing.

Figure 1 is a diagram showing an example of the configuration of a freshness evaluation device according to the first embodiment. The freshness evaluation device 10 shown in Figure 1 is a device for evaluating the freshness of a fresh product 11. The freshness evaluation device 10 includes a light source 12, a fluorescence selection unit 13, an electrical signal conversion unit 14, and an image processing unit 15. The light source 12 is provided diagonally above the fresh product 11 to be evaluated in Figure 1. The fluorescence selection unit 13 and the electrical signal conversion unit 14 are provided above the fresh product 11 to be evaluated in Figure 1. The fluorescence selection unit 13 is disposed between the fresh product 11 and the electrical signal conversion unit 14. The electrical signal conversion unit 14 and the image processing unit 15 are connected via wiring 16. The freshness evaluation device 10 may include a placement table (not shown) on which the fresh product 11 is placed.

The light source 12 irradiates the fresh product 11 with excitation light L1 from diagonally above in FIG. 1. The light source 12 is not particularly limited as long as it is a light source that can irradiate excitation light L1 that excites the AGEs in the fresh product 11. Specific examples of the light source 12 include an ultraviolet lamp, a mercury lamp, a xenon lamp, a deuterium lamp, a halogen lamp, a tungsten lamp, a laser, a light-emitting diode (LED), and an electroluminescence (EL) element. In order to more easily and quickly evaluate the freshness of the fresh product 11, an LED is preferable as the light source 12, and an LED (LED lamp) with a maximum peak wavelength of 365 nm is more preferable. Note that the excitation light L1 emitted from the light source 12 may contain light other than the light that excites the substances in the fresh product 11.

The fluorescence selection unit 13 selectively transmits fluorescence L4 from AGEs in the fresh product 11 out of the autofluorescence L2 emitted by the fresh product 11 when irradiated with excitation light L1. In the freshness evaluation device 10 shown in FIG. 1, the fluorescence selection unit 13 has a cut filter 20 and a bandpass filter 21. The cut filter 20 blocks light with a wavelength of 420 nm or less out of the autofluorescence L2 emitted by the fresh product 11. The bandpass filter 21 selectively transmits light with a wavelength in the range of the peak wavelength of the fluorescence L4 from the AGEs -50 nm or more and the peak wavelength of the fluorescence L4 from the AGEs +50 nm or less out of the light L3 transmitted through the cut filter 20. In addition, in the freshness evaluation device 10, the fluorescence selection unit 13 (more specifically, the cut filter 20 and the bandpass filter 21) are provided detachably. Hereinafter, the peak wavelength (unit: nm) of the fluorescence L4 from the AGEs may be referred to as "L4W".

The cut filter 20 does not have to completely block light with wavelengths of 420 nm or less. However, in order to more easily evaluate the freshness of the fresh product 11, it is preferable to use a cut filter 20 with a transmittance of 1% or less for light with wavelengths of 420 nm or less. The cut filter 20 may block not only light with wavelengths of 420 nm or less contained in the autofluorescence L2, but also, for example, reflected light from the fresh product 11.

To more easily evaluate the freshness of fresh product 11, it is preferable to use a bandpass filter 21 that has a transmittance of 2.6% or less for light other than light with wavelengths in the range of L4W-50 nm or more and L4W+50 nm or less (L4W±50 nm). Also, to more easily evaluate the freshness of fresh product 11, it is preferable that the peak of the fluorescence L4 used to evaluate the freshness does not overlap with the peaks of other light. Therefore, to more easily evaluate the freshness of fresh product 11, it is preferable to use a bandpass filter 21 that can selectively transmit fluorescence L4 (more specifically, fluorescence L4 from AGEs) whose peak does not overlap with other light.

The bandpass filter 21 that selectively transmits light with wavelengths in the range of L4W ± 50 nm includes a bandpass filter that selectively transmits light of any wavelength range within the range of L4W ± 50 nm. For example, as the bandpass filter 21, a bandpass filter that selectively transmits fluorescence L4 from AGEs (a bandpass filter that selectively transmits light in a wavelength range including L4W) can be selected from commercially available bandpass filters that selectively transmit light with wavelengths in the range of L4W ± 50 nm.

Specific examples of the bandpass filter 21 that selectively transmits light of a wavelength in the range of L4W ±50 nm include a bandpass filter that selectively transmits light of a wavelength in the range of L4W ±50 nm (half-width for L4W is 50 nm), a bandpass filter that selectively transmits light of a wavelength in the range of L4W ±40 nm (half-width for L4W is 40 nm), a bandpass filter that selectively transmits light of a wavelength in the range of L4W ±30 nm (half-width for L4W is 30 nm), a bandpass filter that selectively transmits light of a wavelength in the range of L4W ±20 nm (half-width for L4W is 20 nm), a bandpass filter that selectively transmits light of a wavelength in the range of L4W ±10 nm (half-width for L4W is 10 nm), a bandpass filter that selectively transmits light of a wavelength in the range of L4W -50 nm or more and L4W +40 nm or less, a bandpass filter that selectively transmits light of a wavelength in the range of L4W -40 nm or more and L4W +50 nm or less. , a bandpass filter that selectively transmits light with a wavelength in the range of L4W-40 nm or more and L4W+30 nm or less, a bandpass filter that selectively transmits light with a wavelength in the range of L4W-30 nm or more and L4W+40 nm or less, a bandpass filter that selectively transmits light with a wavelength in the range of L4W-30 nm or more and L4W+20 nm or less, a bandpass filter that selectively transmits light with a wavelength in the range of L4W-20 nm or more and L4W+30 nm or less, a bandpass filter that selectively transmits light with a wavelength in the range of L4W-20 nm or more and L4W+10 nm or less, a bandpass filter that selectively transmits light with a wavelength in the range of L4W-10 nm or more and L4W+20 nm or less, a bandpass filter that selectively transmits light with a wavelength in the range of L4W-13 nm or more and L4W+7 nm or less, and a bandpass filter that selectively transmits light with a wavelength in the range of L4W-7 nm or more and L4W+13 nm or less.

The electrical signal conversion unit 14 receives the fluorescence L4 that has passed through the fluorescence selection unit 13 and converts the fluorescence L4 into an electrical signal. To more easily evaluate the freshness of the perishable product 11, an imaging element is preferable as the electrical signal conversion unit 14. Examples of imaging elements include a charge coupled device (CCD) and a complementary metal oxide semiconductor (CMOS).

The electrical signal conversion unit 14 may also be configured to be able to capture an image of the fresh product 11 when the fluorescence selection unit 13 is removed.

The image processing unit 15 uses the electrical signal converted by the electrical signal conversion unit 14 to map the distribution of AGEs (more specifically, AGEs in the fresh product 11) on the image of the fresh product 11. An example of the image processing unit 15 is a computer on which image processing software is installed. The image processed by the image processing unit 15 is, for example, an image of the fresh product 11 captured using the electrical signal conversion unit 14 with the fluorescence selection unit 13 removed.

The image processing unit 15 uses the electrical signal converted by the electrical signal conversion unit 14 to process the image so that, for example, the stronger the intensity of the fluorescence L4 is in a location on the image of the fresh product 11, the higher the image density of the corresponding pixel becomes. This makes it possible to match the shade of the pixels in the image of the fresh product 11 with the amount of AGEs. As a result, the distribution of AGEs is mapped on the image of the fresh product 11.

When a computer with image processing software installed is used as the image processing unit 15, the image mapped (image processed) by the image processing unit 15 is displayed, for example, on the computer's display.

The freshness evaluation device 10 can selectively convert the fluorescence L4 from the AGEs in the fresh product 11 into an electrical signal by irradiating the fresh product 11 with excitation light L1 from the light source 12, so that the amount of AGEs in the fresh product 11 can be easily and quickly recognized as an electrical signal (more specifically, an image processed using the electrical signal). Therefore, the freshness evaluation device 10 can easily and quickly evaluate the freshness of the fresh product 11.

The above describes the freshness evaluation device according to the first embodiment, but the freshness evaluation device of the present invention is not limited to the above-described first embodiment.

For example, in the first embodiment, a freshness evaluation device equipped with an image processing unit as shown in FIG. 1 has been described as an example, but the freshness evaluation device of the present invention does not have to be equipped with an image processing unit. Also, in the freshness evaluation device of the present invention, for example, the electrical signal conversion unit may also function as the image processing unit.

<Second embodiment: freshness evaluation method>
Next, a freshness evaluation method according to a second embodiment of the present invention will be described with reference to Fig. 1 and Fig. 2. Fig. 2 is a flowchart showing an example of the freshness evaluation method according to the second embodiment. The freshness evaluation method shown in Fig. 2 is, for example, a freshness evaluation method for evaluating fresh products using the freshness evaluation device 10 shown in Fig. 1. Hereinafter, description of contents that overlap with the first embodiment described above may be omitted.

The freshness evaluation method according to the second embodiment shown in FIG. 2 includes an irradiation process S1, a conversion process S2, an image processing process S3, and a display process S4.

In the irradiation step S1, excitation light L1 is irradiated onto the fresh product 11. For example, when using the above-mentioned freshness evaluation device 10, excitation light L1 is irradiated onto the fresh product 11 using the light source 12.

In the conversion step S2, the fluorescence L4 from AGEs in the fresh product 11 is selectively converted into an electrical signal from the autofluorescence L2 emitted by the fresh product 11 when irradiated with the excitation light L1. For example, when the above-mentioned freshness evaluation device 10 is used, the fluorescence selection unit 13 selectively transmits the fluorescence L4 from AGEs in the fresh product 11 from the autofluorescence L2, and the electrical signal conversion unit 14 converts the fluorescence L4 that has transmitted through the fluorescence selection unit 13 into an electrical signal.

To more easily evaluate the freshness of the fresh product 11, it is preferable that the peak of the fluorescence L4 used to evaluate the freshness does not overlap with the peaks of other light. Therefore, to more easily evaluate the freshness of the fresh product 11, it is preferable to use a bandpass filter 21 that can selectively transmit fluorescence L4 (more specifically, fluorescence L4 from AGEs) whose peak does not overlap with other light.

In the image processing step S3, the electrical signal converted in the conversion step S2 is used to map (image process) the distribution of AGEs on an image of the fresh product 11 (e.g., an image of the fresh product 11 captured using the electrical signal conversion unit 14). For example, when the above-mentioned freshness evaluation device 10 is used, the image processing unit 15 maps the distribution of AGEs on the image of the fresh product 11 using the electrical signal converted by the electrical signal conversion unit 14.

In the display step S4, the image processed in the image processing step S3 is displayed. For example, when the above-mentioned freshness evaluation device 10 is used, the image processed by the image processing unit 15 is displayed on the display of the image processing unit 15 (more specifically, a computer, etc.).

According to the freshness evaluation method of the second embodiment, by irradiating the fresh product 11 with excitation light L1, the fluorescence L4 from the AGEs in the fresh product 11 can be selectively converted into an electrical signal, so that the amount of AGEs in the fresh product 11 can be easily and quickly recognized as an electrical signal (more specifically, an image processed using the electrical signal). Therefore, according to the freshness evaluation method of the second embodiment, the freshness of the fresh product 11 can be easily and quickly evaluated.

The above describes the freshness evaluation method according to the second embodiment, but the freshness evaluation method for fresh produce of the present invention is not limited to the second embodiment described above.

For example, in the second embodiment, a freshness evaluation method including an image processing step and a display step as shown in FIG. 2 is described as an example, but the freshness evaluation method of the present invention does not have to include an image processing step and a display step.

The following describes examples of the present invention, but the present invention is not limited to the scope of the examples.

<Preparation of freshness evaluation device>
A freshness evaluation device (hereinafter, sometimes simply referred to as "evaluation device") having the same configuration as the freshness evaluation device 10 shown in FIG. 1 was prepared. Hereinafter, the same components as those shown in FIG. 1 will be described with the same reference numerals as those in FIG. 1. As the light source 12, an LED lamp with a maximum peak wavelength of 365 nm ("ULTRA VIOLET LED Lamp SMD Type NS365L-6SMG" manufactured by Nitride Semiconductor Corporation) was used. As the cut filter 20, a cut filter ("L42" manufactured by HOYA Corporation) that blocks light with a wavelength of 420 nm or less was used. As the bandpass filter 21, a bandpass filter ("HMX0490" manufactured by Asahi Spectroscopic Co., Ltd.) that selectively transmits light with a wavelength of 480 nm or more and 500 nm or less was used. As the electric signal conversion unit 14, a CMOS (more specifically, a CMOS mounted on "EOS (registered trademark) 50D" manufactured by Canon Inc.) was used. A computer in which image processing software ("ImageJ" manufactured by the National Institutes of Health, USA) was installed was used as the image processing unit 15. Note that in the evaluation device, the electrical signal conversion unit 14 was configured to be able to capture an image of the fresh product 11 with the fluorescence selection unit 13 (cut filter 20 and band pass filter 21) removed.

Example 1
Strawberries were selected as the evaluation subject (fresh product 11) in Example 1, and the freshness of the strawberries was evaluated in the following manner. First, commercially available strawberries were stored in a refrigerator set at a temperature of 1° C. for 8 days from the date of purchase to prepare strawberries stored for 8 days (hereinafter, sometimes referred to as "Strawberry ₈ "). Separately, commercially available strawberries were stored in a refrigerator set at a temperature of 1° C. for 16 days from the date of purchase to prepare strawberries stored for 16 days (hereinafter, sometimes referred to as "Strawberry ₁₆ ").

Next, the evaluation device was used to irradiate the evaluation object (either strawberry ₈ or strawberry ₁₆ ) with excitation light L1, and the fluorescence L4 from the AGEs in the evaluation object was selectively converted into an electric signal. The converted electric signal was then used for image processing. More specifically, the converted electric signal was used to map the distribution of AGEs on the image of the evaluation object (image captured by the electric signal conversion unit 14) using image processing software ("ImageJ" manufactured by the National Institutes of Health, USA). Note that in the evaluation object (strawberry) of Example 1, the peak wavelength of the fluorescence L4 transmitted through the bandpass filter 21 was 493 nm.

Fig. 3(a) shows an image of strawberry ₈ after image processing. Fig. 3(b) shows an image of strawberry ₁₆ after image processing. As shown in Figs. 3(a) and (b), strawberry ₁₆ had more areas 100 where AGEs were present (areas with high image density) than strawberry _8. Thus, strawberry ₁₆ was less fresh than strawberry _8. The fact that fluorescence L4 transmitted through bandpass filter 21 is fluorescence from AGEs was inferred by the following inference method.

[Method of inference]
Using a preparative high performance liquid chromatography system (Hitachi, Ltd. "LaChrom System", pump: "L-7100", fluorescence detector: "L-7485", autosampler: "L-7200", column oven: "L-7300"), a fraction of fluorescent substances (more specifically, substances that emit fluorescence at wavelengths of 480 nm or more and 500 nm or less) in strawberry ₁₆ was separated under the following separation conditions.

(Isolation conditions)
Column: Reverse phase column manufactured by Kanto Chemical Co., Ltd. ("Mightysil (registered trademark) RP-18GP", length: 250 mm, inner diameter: 20 mm)
Sample: Acetonitrile solution of mashed strawberry ₁₆ (Strawberry ₁₆ concentration: 2% by mass)
Sample injection volume: 0.1 mL
Excitation wavelength: 365 nm
Solution A: distilled water Solution B: acetonitrile Concentration gradient conditions: Conditions shown in Table 1 below

2 mL of the collected liquid was then dried, and 300 μL of distilled water was added to the dried material to obtain a sample liquid for analysis. 100 μL of the obtained sample liquid was analyzed by competitive ELISA using an antibody ("Anti-CML, Mouse-Mono (2G11)" manufactured by Funakoshi Co., Ltd.) and an enzyme-labeled AGEs preparation ("CML-BSA" manufactured by Nippi Co., Ltd.). As a result, it was inferred that the sample liquid contained AGEs that emitted fluorescence with wavelengths of 480 nm or more and 500 nm or less. From this result, it was inferred that the fluorescence L4 transmitted through the bandpass filter 21 was fluorescence from AGEs.

For the evaluation subjects described below (specifically, beef ₁₆ and Gerbera ₄ ), it was inferred that the fluorescence L4 transmitted through the bandpass filter 21 was fluorescence from AGEs using the same method as the [Inference Method] described above.

Example 2
Beef was selected as the evaluation subject (fresh product 11) in Example 2, and the freshness of the beef was evaluated by the following procedure. First, beef on the market was stored in a refrigerator set at a temperature of 3°C for 24 hours immediately after purchase to prepare beef stored at a temperature of 3°C (hereinafter, sometimes referred to as "beef ₃ "). Separately, beef on the market was stored in an atmosphere set at a temperature of 16°C for 24 hours immediately after purchase to prepare beef stored at a temperature of 16°C (hereinafter, sometimes referred to as "beef ₁₆ ").

Next, the evaluation device was used to irradiate the evaluation object (either beef ₃ or beef ₁₆ ) with excitation light L1, and the fluorescence L4 from the AGEs in the evaluation object was selectively converted into an electric signal. The converted electric signal was then used for image processing. More specifically, the converted electric signal was used to map the distribution of AGEs on the image of the evaluation object (image captured by the electric signal conversion unit 14) using image processing software ("ImageJ" manufactured by the National Institutes of Health, USA). Note that in the evaluation object (beef) of Example 2, the peak wavelength of the fluorescence L4 transmitted through the bandpass filter 21 was 490 nm.

Fig. 4(a) shows an image of beef ₃ after image processing, and Fig. 4(b) shows an image of beef ₁₆ after image processing. As shown in Figs. 4(a) and (b), beef ₁₆ had more areas 100 where AGEs were present (areas with high image density) than beef _3. Therefore, beef ₁₆ was less fresh than beef ₃ .

Example 3
Gerbera daisies were selected as the evaluation subject (fresh product 11) in Example 3, and the freshness of the gerbera daisies was evaluated in the following procedure. First, a commercially available gerbera daisy was stored in an atmosphere at a temperature of 16° C. for one hour immediately after purchase to prepare a gerbera daisy stored for one hour (hereinafter, sometimes referred to as "Gerbera ₁ "). Separately, a commercially available gerbera daisy was stored in an atmosphere at a temperature of 16° C. for four days from the date of purchase to prepare a gerbera daisy stored for four days (hereinafter, sometimes referred to as "Gerbera ₄ ").

Next, the evaluation device was used to irradiate the evaluation object (either Gerbera ₁ or Gerbera ₄ ) with excitation light L1, and the fluorescence L4 from the AGEs in the evaluation object was selectively converted into an electric signal. The converted electric signal was then used for image processing. More specifically, the converted electric signal was used to map the distribution of AGEs on the image of the evaluation object (image captured by the electric signal conversion unit 14) using image processing software ("ImageJ" manufactured by the National Institutes of Health, USA). Note that in the evaluation object (Gerbera 1) of Example 3, the peak wavelength of the fluorescence L4 transmitted through the bandpass filter 21 was 490 nm.

Fig. 5(a) shows an image of Gerbera ₁ after image processing, while Fig. 5(b) shows an image of Gerbera ₄ after image processing. As shown in Figs. 5(a) and (b), Gerbera ₄ had more sites 100 where AGEs were present (sites with high image density) than Gerbera _1. Thus, Gerbera ₄ was less fresh than Gerbera ₁ .

The freshness evaluation device and freshness evaluation method of the present invention can be used to evaluate the freshness of perishable goods (more specifically, fruits and vegetables, meat, flowers, etc.).

10: Freshness evaluation device 11: Fresh product 12: Light source 13: Fluorescence selection unit 14: Electrical signal conversion unit 15: Image processing unit 20: Cut filter 21: Band pass filter

Claims (7)

A freshness evaluation device for fresh products, which are products required to be fresh, comprising:
A light source that irradiates the fresh produce with excitation light;
a fluorescence selecting unit that selectively transmits fluorescence from advanced glycation endproducts in the fresh product from among autofluorescence emitted by the fresh product when irradiated with the excitation light;
an electrical signal conversion unit that receives the fluorescence transmitted through the fluorescence selection unit and converts the fluorescence into an electrical signal;
an image processing unit that maps a distribution of advanced glycation endproducts on an image of the fresh product using the electrical signal converted by the electrical signal conversion unit,
A freshness evaluation device, wherein the image of the fresh product is captured using the electrical signal conversion unit without passing through the fluorescence selection unit. The fluorescence selection unit is
A cut filter that blocks light having a wavelength of 420 nm or less from the autofluorescence emitted by the fresh produce;
The freshness evaluation device according to claim 1, further comprising a bandpass filter that selectively transmits light having a wavelength in the range of -50 nm or more from the peak wavelength of the fluorescence from the advanced glycation end products to +50 nm of the peak wavelength of the fluorescence from the advanced glycation end products among the light transmitted through the cut filter. The freshness evaluation device according to claim 1 or 2, wherein the electrical signal conversion unit is an image sensor. The freshness evaluation device according to any one of claims 1 to 3, wherein the fresh product is fruit or vegetables, meat, or flowers. The freshness evaluation device according to any one of claims 1 to 4, wherein the maximum peak wavelength of the excitation light is 365 nm. A method for evaluating the freshness of a fresh product , which is a product required to be fresh , comprising the steps of:
an irradiation step of irradiating the fresh product with excitation light;
a conversion step of selectively converting fluorescence from advanced glycation endproducts in the fresh product, among the autofluorescence emitted by the fresh product when irradiated with the excitation light, into an electrical signal;
and an image processing step of mapping a distribution of advanced glycation endproducts on an image of the fresh product using the electrical signal converted by the conversion step,
A freshness evaluation method, wherein the image of the fresh product is captured using an electrical signal conversion unit without passing through a fluorescence selection unit. The freshness evaluation method according to claim 6 , wherein the maximum peak wavelength of the excitation light is 365 nm.

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