JP2020038093A - Rice production area discrimination method - Google Patents

Abstract

To provide a rice production area discrimination method dispensing with complicated processing.SOLUTION: A rice production area discrimination method comprises a step of obtaining an excitation fluorescence matrix of rice with a fluorescence spectrophotometer and a step of analyzing the obtained excitation fluorescence matrix, and discriminates a rice production area based on data analyzed in the analyzing process. The rice production area discrimination method is provided with, before the step of obtaining the excitation fluorescent matrix, a pre-processing step comprising a step of crushing rice to obtain crushed rice, and a water homogenization step in which the crushed rice is allowed to stand.SELECTED DRAWING: Figure 5

Description

The present invention relates to a method for judging a rice production area using an excitation fluorescent matrix.

The "Law on Standardization of Agricultural and Forest Products and Appropriate Labeling of Quality (JAS Law)" requires all fresh foods to be labeled with the place of origin. In addition, the origin of food is a major concern of consumers, and especially in rice, which is a staple food for Japanese people, the origin of production is an important factor that affects the price as well as the variety. In addition, rice production is likely to become more and more interested in rice imports and exports in the future.

By the way, conventionally, as a method of judging the production area of food, a production area discrimination method using an excitation fluorescence matrix (Excitation-Emission Matrix: EEM) is known. There is a description. The excitation fluorescence matrix is obtained by measuring the fluorescence intensity of a sample while changing the excitation wavelength to be irradiated and the fluorescence wavelength to be observed stepwise within a predetermined range, the excitation wavelength, the fluorescence wavelength, and the fluorescence intensity. Of three-dimensional data. Compared to ordinary fluorescence spectroscopy, which irradiates a sample with one type of excitation light and analyzes the obtained fluorescence spectrum, the amount of information is large and even a slight difference in components can be detected. Shows a unique pattern for.

However, Patent Literature 1 does not describe at all about the determination of the place of production of rice, which is a staple food of Japanese people. Thus, the present inventors have tried to determine the rice production area by the method using the excitation fluorescence matrix described in Patent Document 1, but could not obtain an accurate excitation fluorescence matrix, and performed the rice production area determination. (See FIG. 5 (a)).
Therefore, when determining the rice production area, it was necessary to rely not on a method using an excitation fluorescent matrix which does not require complicated processing but on a measurement which requires complicated processing such as DNA determination and trace element analysis.

JP 2017-036991 A

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

In order to solve the above-mentioned problems, the rice production area determination method of the present invention
Obtaining a rice excitation fluorescence matrix with a fluorescence spectrophotometer;
Analyzing the obtained excitation fluorescence matrix,
In the rice production area discriminating method for discriminating the rice production area based on the data analyzed in the analysis processing step,
Before the step of obtaining the excitation fluorescent matrix,
A step of crushing rice to obtain crushed rice,
A water homogenization step of allowing the ground rice to stand,
Technical measures were taken to provide a pretreatment step with

According to the invention described in claim 2, the moisture homogenization step is characterized in that the variation in the moisture value of the ground rice is suppressed to 0.37% or less.

According to the invention of claim 3, the rice is polished rice.

According to the rice production area discrimination method of the present invention, the method comprises the steps of obtaining a rice excitation fluorescence matrix with a fluorescence spectrophotometer, and analyzing the obtained excitation fluorescence matrix. In the method for determining the place of production of rice based on the processed data, prior to the step of obtaining the excited fluorescent matrix, a step of crushing the rice to obtain crushed rice, and allowing the crushed 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 a highly accurate excitation fluorescent matrix can be obtained. For this reason, complicated pre-processing is not required, and the production area of rice can be determined by a simple operation.

In addition, since a moisture homogenization step is provided to reduce the variation in the moisture value of the crushed rice to 0.37% or less, it is possible to reduce the variation in the excitation fluorescent matrix due to the variation in the moisture value in the rice. For this reason, it is possible to provide a more accurate production area determination method.

In addition, since the measurement sample contains more fluorescent substance than paddy and brown rice, and at the time of measurement, it is polished rice that shows a strong fluorescence signal, the characteristics of the excitation fluorescence matrix for each production area are remarkably exhibited. For this reason, the place of production can be more easily determined.
Furthermore, in the case of polished rice, it is possible to use the discrimination of the production area at a site closer to the consumer (such as a rice mill). For this reason, the production area information can be provided to consumers in a timely manner.

It is a schematic perspective view of a fluorescence spectrophotometer. FIG. 2 is a schematic diagram of an optical unit of the fluorescence spectrophotometer. It is a pre-processing device. It is an example of an excitation fluorescent matrix. It is a production area discrimination result figure. It is the value of the moisture of rice before and after the moisture homogenization process (average value, standard deviation, etc.).

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

FIG. 1 shows a fluorescence spectrophotometer 1 used in the present invention. FIG. 1A shows a state in which the measuring unit cover 3 is closed, and FIG. 1B shows a state in which the measuring unit cover 3 is opened so that an object to be measured (not shown) can be arranged in the measuring unit 4. is there.
The fluorescence spectrophotometer 1 is connected to a computer (not shown in FIG. 1) by a cable (not shown), and the setting of the fluorescence spectrophotometer 1, a measurement command, a result display, and the like are performed through the computer.
In addition, what is necessary is just to use a general thing as the fluorescence spectrophotometer 1 in this invention.

FIG. 2 is a schematic diagram of an optical unit of the fluorescence spectrophotometer.
The excitation light emitted from the light source 5 passes through only the target wavelength in the excitation-side spectroscope 6, and is then split by the half mirror 7 for the sample box 8 and the reference. The excitation light applied to the sample box 8 is excited by the sample in the sample box 8, and the fluorescence emission of the excitation light is separated by the fluorescence side spectroscope 9, and the fluorescence intensity is measured by the fluorescence detector 10b. The measurement result is 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.
The arrows indicate the flow of excitation light or fluorescence. The reference is not always necessary, and a fluorescence spectrophotometer not using the half mirror 7 may be used. The sample box 8 may use an integrating sphere (not shown).

FIG. 3 shows a state of the pre-processing in the present invention.
An important part of the present invention is to suppress the variation in the moisture content of the sample. Therefore, the crushed sample S is put into a petri dish 13, and the sample S is inserted into a thermostat 12 capable of maintaining a constant temperature and humidity, and left for a certain time, for example, 48 hours or more (water homogenization). I do.
For example, a desiccator may be used as the thermostatic bath 12 when it is desired to dry the sample to suppress variation in moisture.
Conversely, when it is desired to humidify the sample to suppress the variation in moisture, a humidifier may be used as the thermostatic bath 12.
In either case, the temperature and humidity of the thermostat 12 may be adjusted appropriately.
In addition, even if it uses a humidifier, since the water in rice is evaporated by grinding, it does not always become higher than the water value of rice before standing.

FIG. 4 is a three-dimensional fluorescence spectrum diagram obtained when a sample (crushed rice) is measured with a fluorescence spectrophotometer. The vertical axis indicates the excitation wavelength (nm) and the horizontal axis indicates the fluorescence wavelength (nm), and the contour lines indicate the fluorescence intensity.
For example, in this three-dimensional fluorescence spectrum, a large peak is shown at an excitation wavelength of 370 nm and a fluorescence wavelength of 465 nm. As shown in FIG. 4, when a fluorescence spectrophotometer is used, excitation fluorescence matrix data, that is, huge three-dimensional data can be obtained. Then, by analyzing these enormous data, it is possible to provide a more accurate determination method.

An embodiment of the rice production area discriminating method of the present invention will be described.
First, using rice from a known production area, what kind of fluorescence distribution characteristics (excitation fluorescence matrix) the rice exhibited in each production area was determined.
(1) Samples White rice (yield of about 90%) from Japan, China, Thailand and the United States was prepared, and 4 to 6 kinds (varieties) of samples were prepared for each country.
(2) Pretreatment 30 g of each sample was pulverized by a mill for 1 minute, and each sample was placed in a Petri dish 13 by 5 g, and the Sample S put in the Petri dish 13 was put in a thermostat 12 and allowed to stand (water homogenization). Note that a plurality of samples S may be simultaneously placed in the thermostat 12, 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 for 48 hours or more. On the other hand, if the variation in the moisture value of the original sample is small, the sample may be left standing for a shorter time, for example, overnight.
Further, in order to determine whether or not the variation has been reduced, it is not necessary to continuously measure the moisture value of the rice. For example, the determination may be made based on the knowledge that if the sample is left standing for 48 hours or more, the variation becomes sufficiently small.
(3) Measurement of Sample A three-dimensional fluorescence spectrum of each sample was obtained using a commercially available fluorescence spectrophotometer. The main setting items were that a synthetic quartz cell was used as the cell, and both the excitation wavelength and the fluorescence wavelength ranged from 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 can be measured in about 2 minutes per sample, and the measurement mode is three-dimensional.
The above settings are merely examples, and can be changed as appropriate depending on the manufacturer and model of the fluorescence spectrophotometer to be used.
(4) Analysis and preparation of calibration curve The obtained three-dimensional fluorescence spectrum was analyzed by multivariate analysis so that the characteristics between samples in each country were most remarkably exhibited.
More specifically, data analysis software JMP12 (registered trademark) manufactured by SAS Institute was used, and stepwise variable selection (F value> 3) was performed to import and analyze variables in order from the one with the largest F value.
(5) Preparation of calibration curve (discriminant equation) A calibration curve capable of discriminating the production center most was prepared by the above analysis.
In the present invention, two types of calibration curves were prepared, one for drying the sample to reduce the variation in water content and the other for humidifying the sample to reduce the variation in water content.
Note that a more detailed calibration curve may be created for each moisture value. For example, it is also possible to create a calibration curve in 1% increments of the moisture value and determine the production area using the calibration curve closest to the moisture value of the rice when the production area of the unknown rice is determined.
(6) Confirmation of quality of calibration curve The quality of the above calibration curve was confirmed.
FIG. 5 is a drawing showing the results of the production area discrimination. For easy understanding, the distribution of samples from different countries is represented by a two-dimensional scatter diagram.
FIG. 5 (a) shows a conventional method, in which the variation of the moisture value was not adjusted, and therefore, it was not possible to discriminate every production area except for the United States. On the other hand, FIGS. 5B and 5C show the method of the present invention, and show that the accuracy of discrimination for each production area has been increased because the variation in moisture has been adjusted. Note that FIG. 5B shows the case where the moisture value is adjusted by drying, and FIG. 5C shows the case where the moisture value is adjusted by humidification. It is considered that when the moisture value was adjusted by humidification, the variation in the moisture value was smaller, so that it was possible to more clearly determine the production area.

FIG. 6 is a table showing how the moisture value of rice changes in the moisture homogenization step. In the table, "After standing 1" is a value when dried by a desiccator, and "After standing 2" is a value when humidified by a humidifier.
It is obvious that the moisture value of the rice after standing still changes due to the drying by the desiccator or the humidification by the humidifier, but the variation (standard deviation) of the moisture is reduced. Note that the moisture value after standing in FIG. 6 is merely an example, and it is sufficient that the variation is equal to or less than a certain value. In particular, if it is 0.37% or less as in this test, it is possible to sufficiently determine the production area.
(7) Additional Data of Calibration Curve If necessary, rice of a country of origin (for example, Korea) not used in the present invention may be added. In this case, reconsider the calibration curve if necessary.

In the present invention, equalization of the moisture value is an essential part. At that time, the emphasis is on reducing the variation in moisture between samples, rather than the percentage of the moisture value. Therefore, the average value of rice moisture is not particularly important. However, if the sample is dried or humidified too much, time and energy will be wasted, and the sample will cause pain and operability will be deteriorated.

The average moisture value of the rice after the moisture homogenization step may be the same, higher or lower than before the moisture homogenization step. That is, it is only necessary that the variation be within a certain range.
In this test, the production areas were determined on a country-by-country basis, but it is also possible to subdivide one country, for example, from East Japan and West Japan in Japan.

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

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

DESCRIPTION OF SYMBOLS 1 Fluorescence spectrophotometer 2 Main body 3 Measuring unit cover 4 Measuring unit 5 Light source 6 Excitation side spectrometer 7 Half mirror 8 Sample box 9 Fluorescence side spectrometer 10 Fluorescence detector 11 Computer 12 Thermostat (desiccator / humidifier)
13 Petri dish S sample (rice, rice flour, brown rice, white rice)

Claims (3)

Obtaining a rice excitation fluorescence matrix with a fluorescence spectrophotometer;
Analyzing the obtained excitation fluorescence matrix,
In the rice production area discriminating method for discriminating the rice production area based on the data analyzed in the analysis processing step,
Before the step of obtaining the excitation fluorescent matrix,
A step of crushing rice to obtain crushed rice,
A water homogenization step of allowing the ground rice to stand,
A rice production area discriminating method, comprising a pretreatment step provided with: 2. The rice production area judging method according to claim 1, wherein the water homogenization step suppresses a variation in water value of the ground rice to 0.37% or less. 3. The method according to claim 1, wherein the rice is polished rice.

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