JP7190103B2 - How to distinguish rice production area - Google Patents

Description

The present invention relates to a method for discriminating rice production regions using an excitation fluorescence matrix.

Under the Law Concerning Standardization and Appropriate Labeling of Agricultural and Forestry Products (JAS Law), all perishable foods must be labeled with the country of origin. In addition, the place of production of food is a matter of great concern to consumers, and in particular, the place of production of rice, which is the staple food of the Japanese, is an important factor that affects the price as well as the variety. Furthermore, rice production areas are expected to gain more and more attention in the future due to the import and export of rice.

By the way, conventionally, as a method for determining the production area of food, a method for determining the production area using an excitation-emission matrix (EEM) is known. There is a description. The excitation fluorescence matrix is the excitation wavelength, fluorescence wavelength, and fluorescence intensity obtained by measuring the fluorescence intensity of the sample while changing the excitation wavelength to be irradiated and the fluorescence wavelength to be observed stepwise within a predetermined range. consists of three-dimensional data of Compared to ordinary fluorescence spectroscopy, which analyzes the fluorescence spectrum obtained by irradiating a sample with one type of excitation light, the amount of information is large and even slight differences in components can be detected. shows a peculiar pattern for

However, Patent Literature 1 does not mention at all how to identify the production area of rice, which is the staple food of the Japanese people. Therefore, the present inventors tried to determine the production area of rice by the method using the excitation fluorescence matrix described in Patent Document 1, but could not obtain a highly accurate excitation fluorescence matrix, and determined the production area of rice. (See Fig. 5(a)).
Therefore, when determining the origin of rice, it was necessary to rely on measurements that require complicated processing such as DNA determination and trace element analysis, rather than methods using excitation fluorescence matrices that do not require complicated processing.

JP 2017-036991 A

Therefore, in view of the above problems, it is a technical object of the present invention to provide a rice production area discriminating method that does not require complicated processing.

In order to solve the above- mentioned problems, the rice production area discrimination method of the present invention comprises the steps of obtaining an excitation fluorescence matrix of rice with a fluorescence spectrophotometer, and analyzing the obtained excitation fluorescence matrix. In the rice production area determination method for determining the rice production area based on the data analyzed in the step, the step of obtaining the excitation fluorescence matrix is preceded by the step of pulverizing rice to obtain pulverized rice, and the pulverized rice. and a moisture homogenization step of leaving the rice to stand still, and the moisture homogenization step adjusts the moisture value of the pulverized rice by humidifying, and reduces the variation of the moisture value to 0.24%. We have taken technical measures to reduce it to the following.

According to the invention of claim 2 , the rice is polished rice.

According to the rice production area determination method of the present invention, the step of obtaining the excitation fluorescence matrix of rice with a fluorescence spectrophotometer and the step of analyzing the obtained excitation fluorescence matrix are provided. In the method for determining the production area of rice for determining the production area of rice based on the processed data, the step of obtaining the excitation fluorescence matrix is preceded by the step of pulverizing the rice to obtain pulverized rice, and allowing the pulverized rice to stand still. Since the pretreatment step including the water homogenization step is provided, the water content of the rice can be made uniform, and an excited fluorescence matrix can be obtained with high precision. Therefore, no complicated pretreatment is required, and the country of origin of rice can be determined with a simple operation.

In addition, a moisture homogenization process is provided to reduce the variation in the moisture content of the pulverized rice to 0.00%. Since it is set to 24 % or less, it is possible to reduce variations in excitation fluorescence matrix due to variations in moisture content of rice. Therefore, it is possible to provide a more accurate locality determination method.

In addition, since the measurement sample contains more fluorescent substances than paddy or brown rice, and the polished rice that produces a strong fluorescence signal is used for the measurement, the characteristics of the excitation fluorescence matrix for each production area can be clearly seen. Therefore, it becomes possible to more easily determine the place of production.
Furthermore, in the case of polished rice, production area discrimination can be used at sites (rice milling factories, etc.) closer to consumers. For this reason, it is possible to provide consumers with timely production area information.

1 is a schematic perspective view of a fluorescence spectrophotometer; FIG. It is the optical part schematic of a fluorescence spectrophotometer. It is a pretreatment device. An example of an excitation fluorescence matrix. It is a production center discrimination|determination result figure. Moisture value of rice before and after the moisture homogenization process (average value, standard deviation, etc.).

A mode for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a schematic perspective view of a fluorescence spectrophotometer, FIG. 2 is a schematic diagram of an optical part of the fluorescence spectrophotometer, FIG. 3 is a pretreatment device, and FIG. 4 is an example of an excitation fluorescence matrix. and FIG. 5 is a diagram showing the result of production area discrimination, and FIG. 6 shows the moisture values of rice before and after the moisture homogenization process (average value, standard deviation, etc.).

FIG. 1 is a fluorescence spectrophotometer 1 used in the present invention. FIG. 1(a) shows the measurement part cover 3 closed, and FIG. 1(b) shows the measurement part cover 3 opened so that the object to be measured (not shown) can be placed on the measurement part 4 be.
The fluorescence spectrophotometer 1 is connected to a computer (not shown in FIG. 1) by a cable (not shown), and through the computer, the setting change of the fluorescence spectrophotometer 1, the measurement command, the result display, etc. are performed.
Note that a general one may be used as the fluorescence spectrophotometer 1 in the present invention.

FIG. 2 is a schematic diagram of the optics of a fluorescence spectrophotometer.
The excitation light emitted from the light source 5 passes only the target wavelength through the excitation side spectroscope 6, and then is separated by the half mirror 7 into the sample box 8 and for reference. The excitation light irradiated to the sample box 8 side is excited by the sample in the sample box 8, and the fluorescence emission of this excitation light is spectroscopically separated by the fluorescence side spectroscope 9, and the fluorescence intensity is measured by the fluorescence detector 10b. The measurement results are output to the computer 11 . On the other hand, the excitation light branched to the reference side by the half mirror 7 is directly measured by the fluorescence detector 10a, output to the computer 11, and used as a reference.
Arrows indicate the flow of excitation light or fluorescence. A reference is not necessarily required, and a fluorescence spectrophotometer that does not use the half mirror 7 may be used. Also, the sample box 8 may use an integrating sphere (not shown).

FIG. 3 shows the state of pretreatment in the present invention.
A key part of the present invention is to reduce the variation in sample moisture. Therefore, the pulverized sample S is placed in a petri dish 13, the sample S is inserted in a constant temperature bath 12 that can maintain constant temperature and humidity, and left to stand for a certain period of time, for example, 48 hours or more (moisture homogenization). do.
For example, a desiccator may be used as the constant temperature bath 12 when it is desired to dry the sample to suppress variations in moisture content.
Conversely, if it is desired to humidify the sample to suppress variations in moisture content, a humidifier may be used as the constant temperature bath 12 .
In either case, the temperature and humidity of the constant temperature bath 12 may be adjusted as appropriate.
Note that even if a humidifier is used, the water content in the rice evaporates during the pulverization, so the water content may not always be higher than the water content of the rice before standing.

FIG. 4 is a three-dimensional fluorescence spectrum diagram obtained when measuring a sample (crushed rice) with a fluorescence spectrophotometer. The vertical axis represents the excitation wavelength (nm), the horizontal axis represents the fluorescence wavelength (nm), and the contour lines indicate the fluorescence intensity.
For example, this three-dimensional fluorescence spectrum shows large peaks at an excitation wavelength of 370 nm and a fluorescence wavelength of 465 nm. As shown in FIG. 4, a fluorescence spectrophotometer can be used to obtain excitation-fluorescence matrix data, ie, three-dimensional enormous data. By analyzing such huge amount of data, it becomes possible to provide a discrimination method with higher accuracy.

An embodiment of the rice production area discrimination method of the present invention will be described.
First, the fluorescence distribution characteristics (excitation fluorescence matrix) of the rice were obtained by using rice from known production areas.
(1) Samples Domestic, Chinese, Thai, and US white rice (yield: about 90%) was prepared, and 4 to 6 types (varieties) of samples were prepared for each country.
(2) Pretreatment After 30 g of each sample was pulverized with a mill for 1 minute, 5 g of each sample was placed in a petri dish 13, and the sample S placed in the petri dish 13 was placed in a constant temperature bath 12 and allowed to stand (moisture homogenization). A plurality of samples S may be put into the constant temperature bath 12 at the same time, and for example, the same sample may be stored as a spare.
In the present example, it was confirmed that the dispersion of the moisture value was reduced by allowing to stand still for 48 hours or longer. On the other hand, if the variation in the moisture content of the original sample is small, the sample may be allowed to stand for a shorter period of time, such as overnight.
In addition, it is not necessary to measure the water content of rice over time in order to determine whether the variation has decreased. For example, the judgment can be made based on the finding that the variation is sufficiently reduced if left to stand for 48 hours or longer.
(3) Measurement of samples Using a commercially available fluorescence spectrophotometer, the three-dimensional fluorescence spectrum of each sample was obtained. Main setting items were that the cell used was a synthetic quartz cell, and the range of excitation wavelength and fluorescence wavelength was set to 200 to 600 nm. However, the wavelength width was 10 nm on the excitation side and 5 nm on the fluorescence side. The measurement time was about 2 minutes per sample, and the measurement mode was three-dimensional.
Note that the above setting is merely an example, and can be changed as appropriate depending on the manufacturer and model of the fluorescence spectrophotometer used.
(4) Analysis and Preparation of Calibration Curves The obtained three-dimensional fluorescence spectra were analyzed by multivariate analysis so that the characteristics between samples in each country would be most conspicuous.
More specifically, data analysis software JMP12 (registered trademark) manufactured by SAS Institute was used to perform stepwise variable selection (F value > 3), and incorporation analysis was performed as variables in descending order of F value.
(5) Preparation of calibration curve (discriminant) By the above analysis, a calibration curve that can best discriminate production areas was prepared.
In the present invention, two types of calibration curves were prepared: one for the case where the sample was dried to suppress variation in moisture content, and the other for the case where the sample was humidified to suppress variation in moisture content.
A more detailed calibration curve may be created for each moisture value. For example, it is possible to create a calibration curve with moisture values in increments of 1%, and use the calibration curve that is closest to the moisture value of the rice when determining the production area of rice whose production area is unknown.
(6) Quality check of calibration curve The quality of the calibration curve was checked.
FIG. 5 is a diagram showing the results of production area discrimination. To make it easier to understand, a two-dimensional scatter diagram shows the distribution of samples from each country.
Fig. 5(a) is a conventional method, and since the variation in moisture content was not adjusted, it was not possible to discriminate by production area except for those produced in the United States. On the other hand, FIGS. 5(b) and 5(c) show that the method of the present invention improves the accuracy of discrimination for each production area because the variation in water content is adjusted. In addition, FIG.5(b) adjusts a moisture value by drying, FIG.5(c) adjusts a moisture value by humidification. Adjusting the moisture content by humidification resulted in less variation in the moisture content, which is thought to have made it possible to more clearly identify the production area.

FIG. 6 is a table showing how the water content of rice changed due to the water homogenization process. In the table, "1 after stationary" is the value when drying with a desiccator, and "2 after stationary" is the value when humidifying with a humidifier.
Although it is natural that the water content of the rice after standing changes due to drying with a desiccator or humidification with a humidifier, it can be seen that the variation (standard deviation) of the water content is reduced. Note that the water content values after standing in FIG. 6 are examples, and it is sufficient if the variation is less than or equal to a certain value. In particular, as in this test, if the concentration is 0.37% or less, it becomes possible to sufficiently distinguish the place of production.
(7) Additional Data for Calibration Curve If necessary, rice from a country of origin not used in the present invention (for example, Korea) may be added. In this case, reexamine the calibration curve as necessary.

In the present invention, uniformity of the moisture content is the essential part, but in this case, the emphasis is placed on reducing variations in moisture content between samples, rather than on the percentage of the moisture content. Therefore, the average moisture content of rice is not particularly important. However, excessive drying or humidification of the sample wastes time and energy, causes damage to the sample, and deteriorates operability.

The average moisture value of the rice after the moisture homogenization process may be the same as before the moisture homogenization process, higher or lower. In other words, it suffices if the variation falls within a certain range.
In this test, the production area was discriminated by country, but it is also possible to subdivide one country, for example, like East Japan production and West Japan production.

It goes without saying that the present invention is not limited to the above-described embodiment, and its configuration can be changed as appropriate without departing from the scope of the invention.

INDUSTRIAL APPLICABILITY The method of the present invention for determining the production area of rice is very useful because it can provide a method for determining the production area of rice that does not require complicated processing.

1 fluorescence spectrophotometer 2 main body 3 measurement part cover 4 measurement part 5 light source 6 excitation side spectroscope 7 half mirror 8 sample box 9 fluorescence side spectroscope 10 fluorescence detector 11 computer 12 constant temperature bath (desiccator/humidifier)
13 Petri dish S Sample (rice, rice flour, brown rice, white rice)

Claims (2)

A step of obtaining an excitation fluorescence matrix of rice with a fluorescence spectrophotometer, and a step of analyzing the obtained excitation fluorescence matrix,
In the rice production area determination method for determining the rice production area based on the data analyzed in the analysis process,
Before the step of obtaining the excitation fluorescence matrix,
a step of pulverizing rice to obtain pulverized rice;
a water homogenization step of leaving the pulverized rice still;
providing a pretreatment step comprising
The water homogenization step adjusts the water content of the pulverized rice by moistening, and suppresses the variation of the water content to 0.24% or less.
2. The method of determining a production area of rice according to claim 1, wherein the rice is milled rice.

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