JP2745025B2 - Rice quality evaluation method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a rice quality evaluation method which objectively obtains each characteristic value of rice based on the component content of sample rice.

[Conventional technology and its problems]

Conventionally, rice quality evaluations, especially those related to taste, have been evaluated by multiple expert examiners for the appearance, aroma,
Each characteristic item such as taste, stickiness, hardness, etc., is repeatedly tested to see how good or inferior it is compared to those of the standard rice as the evaluation standard, and the average value is taken, by a so-called sensory test It was done. However, since this sensory test is performed based on tastes that differ from person to person, even if the average of multiple evaluation results by multiple examiners is taken, the evaluation Even if changed, it was not universal objective and absolute value.

By the way, the organization and scientific properties of rice are scientifically measured and
Analyzing and examining the correlation between the taste evaluation values obtained in the aforementioned sensory tests, and finally conducting research to evaluate the quality of rice from chemically obtained measurement values have been promoted. As a result, among the ingredients that make up rice, those that are particularly important in evaluating the quality of rice are the amylose and amylopectin content, protein content, and moisture content that make up rice starch. There was found.

From this, it will be described how the magnitude of the content of each component constituting rice affects the quality of rice.

Generally, Koshihikari and Sasanishiki are popular brands with good taste in Japan. For example, Koshihikari and Sasanishiki, including several kinds of rice, have a standard whiteness degree of white rice as compared with the protein content and the amylose content in starch, as shown in Table 1 below. Become. Note that the content of each component is not always the same as shown in the table for the same brand, but also depends on the geological conditions (soil and water quality) of the cultivated production area, and also on the weather conditions (temperature, sunshine hours). , Rainfall, etc.), it goes without saying that the content of each component slightly changes.

(The protein content is the weight ratio and the amylose content is the ratio to 100% starch.) From Table 1 above, the main factor that Koshihikari and Sasanishiki have good taste is compared with other general brand rice. Thus, it can be understood that the protein content is low and the amylose content ratio in the starch is low.

Furthermore, white rice moisture content, quality, especially the viscosity of rice such as rice cooked,
It has a great effect on taste in relation to hardness.
When the white rice has a water content of about 15%, when cooked, even if immersed in water in a kettle, the white rice is cooked into perfect rice grains without moisture cracks, but in the case of rice with a water content of less than 14% Since the water absorption rate during immersion is too fast, cracks occur in the rice grains instantaneously and penetrating cracks soon occur in the inside of the rice grains, so that water is absorbed in the cracks, glue is released from the cracks, and broken rice also absorbs water at a stretch at the same time It is cooked on sticky cooked rice, and it is a low-quality cooked rice that is not chewy or sticky because the cooked rice has collapsed.

In addition, the above ingredients of rice that have a great effect on the quality of rice,
That is, in addition to the protein, starch, and water contents, the size of the fat also affects the quality of the rice such that the lower the content, the better the taste of the rice. Can not be said to be as large as the content of the three components.

Based on the above, it is possible to scientifically measure and analyze the chemical components that make up rice, to conduct an objective evaluation of the quality of rice in general, The theme is to find good quality rice among general brand rice, regardless of famous brands.

[Object of the invention]

Therefore, the present invention provides a method of measuring the content of each component contained in a sample rice in a short time, and objectively determining the quality of rice based on each characteristic value of rice based on the content of each component. For the purpose of providing.

[Means for solving the problem]

According to the present invention, a component conversion coefficient is determined in advance based on the component content of a known sample rice obtained by measurement by a chemical component analysis method and the absorbance measurement value of the known sample rice obtained by near-infrared spectroscopy. Further, a characteristic coefficient is determined in advance based on the component content of the known sample rice and each characteristic value of the known sample rice obtained by a sensory test of the sample rice, and the component conversion coefficient and the near infrared spectroscopy Calculate the component content of amylose, protein, and water contained in the sample rice with the measured absorbance value of the unknown sample rice obtained by the above, and calculate the fragrance, stickiness, This is a means for solving the problem by a rice quality evaluation method that calculates a characteristic value of hardness.

(Operation)

The sample rice is crushed, and the content of amylose, protein, water, etc., which are the main factors in determining the taste of rice contained in the sample rice, are analyzed by a near-infrared spectroscopic analysis method and converted into a predetermined component. By calculating the characteristic values of the flavor, taste, stickiness, and hardness of the sample rice based on the characteristic coefficients determined in advance based on the calculated content of each component, there is no human factor. However, even in the near-infrared spectroscopy with human intervention, the evaluation value obtained by not relying on tastes with individual differences is universal and objective value even when changing time and place. it is obvious.

〔Example〕

Hereinafter, a rice quality evaluation device according to the present invention will be described with reference to the accompanying drawings FIG. 1 to FIG.

FIG. 1 is a schematic view of the rice quality evaluation device 1 according to the present invention when viewed from the front. Inside cabinet 2
The near-infrared spectroscopic analyzer 3 and the control device 4 described in detail with reference to FIG. On the front panel of the cabinet 2, a sample container mounting box 5 for mounting a sample container (sample placement unit) for storing the rice to be measured, a light emitting diode or a CRT format display for visually displaying operation procedures and calculation results of the apparatus. Device 6, operation push button 7
And a printer 8 that enables a hard copy of the operation result
Is arranged. The control device 4 includes a light source of the near-infrared spectroscopic analyzer 3, a detector, a display device 6, an operation push button 7,
An input / output signal processing device 4a connected to the printer 8 and the like for processing various signals, and a component conversion coefficient value for calculating the content of each component, and a rice main component for calculating the quality evaluation value. A storage device 4b for storing individually set specific coefficients, rice prices for each brand or grade, which are input by intervening an input device (keyboard) 9, various corrections and various control procedures, etc .; And an arithmetic unit 4c for calculating rice characteristic values and the like based on the measured values obtained by the external spectroscopic analyzer 3 and the specific coefficient. In addition, the specific coefficient and necessary correction value that are set individually for each main component of rice are
It is stored in a read-only memory (hereinafter referred to as a ROM) in the storage device 4b in advance. Further, the printer 8 is not limited to the built-in type, but may be an external connection type.

By the way, the near-infrared rays irradiated to the sample are absorbed by the sample because the chain of atoms that make up the molecule vibrates due to thermal energy, and the natural frequency differs depending on the type of atom and the state of the chain. In addition, the magnitude of the vibration changes in the near-infrared wavelength region, causing heat absorption. In addition, when the sample initially has a small amount of thermal energy (when the temperature is low), the amount of absorption due to the difference in molecular structure is not accurately measured due to the small vibration, so that it is necessary to correct the temperature. Normally, no correction is required above 20 ° C.

The temperature setting device 77 adjusts the temperature of the near-infrared spectroscopic analyzer 1 to a constant temperature. When the temperature is low, the heating device 78 is operated to set the temperature to 25 ° C. normally. This has the purpose of preventing the sample temperature from changing and eliminating errors due to the temperature of the electric circuit.

FIG. 2 is a cross-sectional view of a main part of an embodiment of the near-infrared spectroscopic analyzer 3 disposed inside the cabinet 2. The illustrated near-infrared spectrometer 3 is of a reflection type, and includes, as main components, a light source 31, a reflector 32, a narrow band-pass filter 33, an integrating sphere 34, and detectors 35a and 35b. Light source 3
The light emitted from 1 and converted into parallel rays through an appropriate optical system (not shown) is converted into near-infrared light of a specific wavelength by passing through a narrow band pass filter 33, and then the inclination angle is changed. The direction can be changed toward a lighting window 36 provided by opening the upper part of the integrating sphere 34 by the reflecting mirror 32 configured to be freely changeable. Light is reflected by the reflector 32 and the lighting window of the integrating sphere 34
The near-infrared light entering the integrating sphere 34 via the
The measuring unit 37 provided with an opening at the bottom of the sample 34, and thus the sample rice 55 in the sample container 52 placed at a predetermined position behind the sample container mounting box 5 is irradiated from directly above. While the diffusely reflected light from the sample rice 55 is reflected inside the integrating sphere 34, finally,
A pair of detectors arranged at target positions around the measurement unit 37
35a and 35b are reached, whereby the intensity of the reflected light is measured. Note that a sensor 79 for measuring the temperature of the sample container is provided in the sample container mounting box 5 below the sample container 52, and the analysis value is corrected by the sample temperature as described in detail for the temperature setting device 77. Further, in the illustrated embodiment, a pair of detectors, that is, two detectors indicated by reference numerals 35a and 35b are provided in order to correct the optical symmetry and efficiently receive the reflected light from the sample rice 55. However, the number is not limited to two, and may be one or three or more detectors.

Here, the light source 31 is provided between the light source 31 and the reflecting mirror 32.
The configuration of the narrow band-pass filter 33 which becomes near-infrared light of a specific wavelength when light emitted from the filter passes therethrough, and physical characteristics required for the filter will be described. The narrow band-pass filter 33 includes an arbitrary number of filters (for example, six filters 33a to 33a) each having a different dominant wavelength pass characteristic.
3f), these are mounted on a rotating disk and rotated by an appropriate angle so that the filter can be sequentially selected and exchanged so that a desired filter is located on a line connecting the light source 31 and the reflecting mirror 32. The dominant wavelength in the transmission characteristics of the filter refers to the maximum transmission wavelength of near infrared rays that are transmitted when the incident optical axis is perpendicular to the surface of the filter. As another specific configuration example of the narrow band pass filter 33, a prismatic reflecting mirror 32 is located inside, and a plurality of filters 33a to 33f are respectively located at positions facing each surface of the reflecting mirror. There is also a configuration in which it is formed in a prism shape and can be rotated. When the narrow band-pass filter 33 is a disk-shaped filter, if the inclination angle of the rotating surface with respect to the incident optical axis can be finely and continuously adjusted by a motor or the like, each filter can be adjusted. Near-infrared light of a different wavelength shifted from the main wavelength of the transmission characteristic of the NIR can be continuously produced. This is a well-known phenomenon.When the angle of the incident optical axis with respect to the filter surface is changed from 90 °, the maximum transmission wavelength shifts in the range of several tens of nm according to the angle change. It depends on the phenomenon.

Next, physical characteristics required for the narrow band pass filter 33 will be described with reference to FIG. FIG. 3 is a graph (absorbance curve) showing the relationship between the irradiation wavelength and the absorbance when near-infrared light whose wavelength continuously changes is irradiated to different material rice. The absorbance log I ₀ / I is a common logarithm of the reciprocal of the ratio of the reflected light amount I from the sample rice to the reference irradiation light amount (total irradiation light amount) I ₀ . It can be easily understood that the content of each of the components is remarkably expressed as a difference in absorbance.
Since the present invention measures the content of a predetermined component contained in the sample rice using this phenomenon, the wavelength of the near-infrared light applied to the sample rice for the measurement has a wavelength range of 19 nm.
Among the 00 to 2500 nm, specific peaks are seen on the absorbance curve for each component (in this example, 1960 nm, 2030 nm, 2100 nm).
nm, 2130 nm, 2270 nm, 2370 nm, etc.). Accordingly, the filters 33a to 33f included in the narrow band pass filter 33 pass the respective wavelengths through a specific pass characteristic, i.e., a main characteristic, in order to generate near-infrared light of the respective wavelengths suitable for measurement of each component contained in the sample rice. It is required to have a wavelength.

Next, the specific operation of the sample rice quality evaluation device of the present invention having the above-described configuration will be described. First, the light source 31 is turned on by operating the operation push button 7, and until the near-infrared light of a specific wavelength reaching the measuring unit 37 based on the light emitted from the light source 31 is stabilized, the near-infrared spectroscopic analyzer 3 Is preheated by a heating device 78 or the like. After a lapse of a predetermined time for preheating, the sample container mounting box 5 is once pulled out of the cabinet 2 of the apparatus, and the sample container 52 filled with the crushed sample rice 55 is placed at a predetermined position, and then inserted into the cabinet 2. To complete the measurement preparation. At this time, the temperature sensor 79 of the sample container device box 5 measures the temperature of the sample container 52. The sample rice 55 is desirably ground to a particle size of about 50 microns or less in order to prevent an error in the measured value, but is not necessarily ground. In addition, in order to reduce light loss due to irregular reflection, the crushed sample rice 55 is filled in the sample container 52 in a state where the surface becomes flat, and further, a pressure is slightly applied by a transparent glass plate. It is preferable to cover the surface while adding.

When the measurement preparation work is completed, first, 1960nm
Is the light source 31 and the reflecting mirror 32
The process starts measuring the reflection absorbance when the sample rice 55 is irradiated with near-infrared light having a wavelength of 1960 nm, which is selected so as to be on the line connecting The measurement operation of the reflection absorbance is performed by measuring the total irradiation amount irradiated to the sample rice 55, that is, the reference light amount, and measuring the sample rice 55 when the sample rice 55 is irradiated with the reference irradiation light amount.
And the measurement of the amount of reflected light that is actually reflected in the measurement. Although one of the two measurements may be performed first for one filter, the following description will be made on the assumption that the measurement of the reference irradiation light amount is performed first. The measurement of the reference irradiation light amount is performed by turning the inclination angle of the reflecting mirror 32 having a variable inclination angle to an angle such that the reflected light directly hits the inner wall of the integrating sphere 34 by using a rotating means using a motor or the like. (Not shown). In this way, the light from the reflecting mirror 32 directly applied to the inner wall of the integrating sphere 34 reaches the detectors 35a and 35b while diffusing and reflecting the inner wall in multiple directions, and is finally detected as the reference irradiation light amount. Is done. On the other hand, the measurement of the amount of reflected light from the sample rice 55 is performed according to the above-described principle after the inclination angle of the reflecting mirror 32 is returned to the original position shown in FIG. It should be noted that the procedure from selection of the first filter after the completion of the preparation for measurement, measurement of the reference irradiation light amount and measurement of the reflected light amount is performed by storing a procedure program in the ROM in the storage device 4b of the control device 4 and automatically executing the program according to the program. Needless to say, it can be done in a specific way. Further, it is also useful to increase the measurement accuracy by performing each of the above-described measurement of the reference irradiation light amount and the reflected light amount for one filter a plurality of times, and taking an average of the measured values. Each measurement value based on the reference irradiation light amount detected by the detectors 35a and 35b and the reflected light amount from the sample rice 55 is an actual measurement for calculating each content rate of amylose, protein, fat, moisture, etc. contained in the sample rice. The data is communicated to the control device 4 as data, and is temporarily stored in a writable memory (hereinafter referred to as a RAM) in the storage device 4b.

When the measurement of the absorbance at the irradiation wavelength of 1960 nm is completed,
The process shifts to the measurement of the absorbance at the next irradiation wavelength, that is, at 2030 nm in this embodiment. Here, the measurement of the reference irradiation light amount and the measurement of the reflected light amount are performed by the same method and procedure as in the case of 1960 nm described above. Each measurement value is communicated to the control device 4 as actual measurement data for calculating the content of each component as in the previous case, and is temporarily stored in the RAM in the storage device 4b. Hereinafter, similarly, the remaining absorbance measurements, that is, wavelengths 2100 nm, 2130 nm, 22
Absorbance measurements at 70 nm and 2370 nm are sequentially performed, and each measured value is communicated to the control device 4 as actual measurement data and stored in the RAM. It should be noted that the operation of exchanging and selecting each of the filters 33a to 33f of the narrow band pass filter 33 accompanying the transition to the absorbance measurement at a specific wavelength after the absorbance measurement at a specific wavelength is completed is usually performed by a storage device of the control device 4. The measurement is automatically performed in accordance with the procedure program pre-written in the ROM in 4b. However, even in the case of this embodiment, it is not always necessary to perform the absorbance measurement for all of the above six wavelengths. Can be arbitrarily selected in consideration of the accuracy required for the desired characteristic value, the required time for measurement, and the like. The selection can be made with the measurement wavelength selection button in the operation push button 7.

The measurement of the absorbance described so far is performed simply by sequentially exchanging the six filters 33a to 33f set in the narrow band pass filter 33, thereby measuring the spot-like absorbance at each main wavelength of each of the filters 33a to 33f. Although it was a method, as described above, if the incident angle of the incident light with respect to the surface of the filter is changed from the reference 90 °, the phenomenon that the maximum transmission wavelength shifts in the range of several tens nm from the main wavelength is used. , Wavelength region where the difference in component content is noticeable in the absorbance difference
Continuous absorbance measurement at 1900 nm to 2500 nm is also possible.
In the case of the first embodiment shown in the figure, the angle of the optical axis incident on the narrow band-pass filter 33 formed in a disc shape is adjusted appropriately by a motor or the like based on a command signal from the controller 4 (not shown). This is possible by finer and continuous changes.

Next, the arithmetic unit 4c of the control device 4 is connected to the RAM of the storage device 4b.
Numerous measured data obtained by the absorbance measurement stored in the storage device 4b, that is, the measured values of the reference irradiation light amount and the reflected light amount at each measurement wavelength, and the content ratio calculation of each component stored in the ROM of the storage device 4b in advance. Based on the component conversion coefficient value for
Calculate the contents of amylose, which is an important component in evaluating the quality of sample rice, and the contents of proteins, fats, moisture, and the like. Note that the component conversion coefficient value previously written in the ROM of the storage device 4b for each component is based on the content of each component measured using, for example, a chemical quantitative analysis method for a large number of sample rices. Is a constant determined by multiple regression analysis after signal processing of the measured absorbance value from.

Here, an example of a multiple regression analysis for obtaining a component conversion coefficient will be described. For example, six filters P ₁ nm, P ₂ nm, P ₃ nm, P ₄ n
When the absorbance of a component A of sample rice is measured by a detector using m, P ₅ nm, and P ₆ nm, the following linear relationship is established.

_{A 1 = F 0 a + F} 1 a · X 11 + F 2 a · X 21 + ... + F 6 a · X 61 + ε 1 this time An: content percentage by atomic absorption spectrometry of the sample rice components A.

F ₀ a~F ₆ a: component conversion coefficient value by multiple regression analysis.

X ₁ ~X _6: P ₁ ~P each filter corresponding absorbance ₆ (IOG value).

εn: error.

It is.

Substituting into n multiple regression equation performs absorbance analysis for the samples in the same _{manner, A 1 = F 0 a +} F 1 a · X 11 · F 2 a · X 21 + ...... + F 6 a · X 61 + ε 1 A 2 _{= F 0 a + F 1 a} · X 12 + F 2 a · X 22 + ...... + F 6 a · X 62 + ε 2 An = F 0 a + F 1 a · X 1 n + F 2 a · X 2 n + ... + F 6 a · X ₆ n + εn, and a multiple regression analysis is performed using the n multiple regression equations described above, and F ₀
to F ₆ seek a component converted coefficient values of the _{A = F 0 a + F 1} a · X 1 + F 2 a · X 2 + ... + F 6 a · X 6 next. A relational expression for measuring the absorbance of the component A with a detector is established.

However, the filter of the filter P ₁ to P ₆ is an illustration of an example, the optimum filter selection of the to ensure accuracy were subdivided the regression analysis in the wavelength range of 1900nm~2500nm All are combined and found in a matrix using the absorbances obtained at wavelength ranges, for example, at 2 nm intervals.

Next, the absorbance of n samples is measured with a detector for one component B of the sample rice using six filters, and the following equation is established similarly to the component A.

_{B = F 0 b + F 1} b · X 1 + F 2 b · X 2 + ... + F 6 in b · X ₆ or more as the components seeking each component conversion factor performs multiple regression analysis. The content of each component is determined by measuring the absorbance of the detector.

Next, the arithmetic unit 4c calculates a characteristic value by a calculation formula based on the respective contents of amylose, protein, fat, water and the like obtained as described above.

Here, components that determine the stickiness, hardness, aroma, taste, etc. of the sample are A and B components. Each component is calculated by the component conversion coefficient obtained by the multiple regression analysis described above.
Here, an example of a regression analysis for obtaining a characteristic coefficient for obtaining each characteristic value will be described.

It is assumed that the specific value (T) is obtained by T = a (A ^x × B ^y ) + b. The above a, b, x, y are the components A, B
Similarly, when the characteristic values obtained by the sensory test and the like of the n sample rice and the respective components A and B of the n sample rice obtained by the detector are obtained by the least square method, a, b, x , y are characteristic coefficients.

For example, assuming that the hardness of rice is determined by amylose and moisture using the hardness as an example of the characteristic values, it is assumed that hardness = a (amylose ^x × moisture ^y ) + b holds, and for each of n samples, (In this example) The values of the characteristic values of the hardness obtained by the contents of amylose and water and the sensory test are substituted into the above equation, and the obtained n relational equations are simultaneously satisfied. A, b, x , y.

Each characteristic value calculated by the above-described each characteristic coefficient and the quality evaluation calculation formula, at the same time as the completion of the calculation in the arithmetic device 4c,
In addition to being visually displayed on the display device 6, it is fed out as a hard copy from the printer 8 automatically or based on a command to the operation push button 7. Further, the respective content rates of the components such as amylose, protein, fat, and moisture determined in the process of obtaining the quality evaluation value may be simultaneously displayed on the display device 6 together with the sensory evaluation value.

The component content and sensory evaluation value of each sampled rice calculated by the present quality evaluation device can be stored as data in an external storage device using a magnetic medium such as a floppy disk. At the time of calculating the mixing ratio of the sample rice or the like, it is also possible to read data from an external storage device into the RAM of the storage device 4b in the present device and perform necessary calculations based on the data.

In the above description, the sampled rice is crushed, but the crushed rice is not necessarily required. However, in this case, it goes without saying that the accuracy of the obtained quality evaluation value is reduced to some extent.

In the quality evaluation device of the above-described embodiment, the absorbance when the sample rice is irradiated with near-infrared light having a specific wavelength is measured by measuring the intensity of the reflected light from the sample rice. Although an analyzer was used, a transmission-type near-infrared spectroscopy analyzer that measures the intensity of transmitted light transmitted through the sample rice can also be used.Furthermore, based on both reflected light and transmitted light, A more accurate near-infrared spectrometer for measuring the absorbance can be provided.

〔The invention's effect〕

As described in detail above, according to the rice quality evaluation method of the present invention, anyone can use a sensory test based on taste with individual differences, or a method that requires time and skill such as chemical quantitative analysis. Accurate rice characteristic values can be obtained easily and in a short time.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a rice quality evaluation device according to the present invention,
FIG. 2 is a side cross-sectional view of a main part of a near-infrared spectroscopy analyzer used in the quality evaluation apparatus of FIG. 1, and FIG. 3 is a graph showing a relationship between near-infrared irradiation wavelength and absorbance of sample rice of different brands ( Absorbance curve). In the figure, 1... Rice quality evaluation device, 2... Cabinet, 3... Near infrared spectroscopy analyzer, 4... Control device, 4a
…… I / O signal processing device, 4b …… Storage device (ROM, RA
M), 4c: arithmetic unit, 5: sample container mounting box, 6:
Display device 7, push button for operation, 8 printer, 9 input device (keyboard), 31 light source, 32
…… Reflector, 33 …… Narrow bandpass filter, 33a-33f…
... Filter, 34 ... Integrating sphere, 35a, 35b ... Detector, 36
… Lighting window, 37… measurement unit, 52… sample container, 55… sample rice, 77… temperature setting device, 78… heating unit, 79… temperature sensor.

Claims (1)

(57) [Claims] 1. A component conversion factor is determined in advance based on the component content of a known sample rice obtained by a chemical component analysis method and the absorbance measurement value of the known sample rice obtained by a near-infrared spectroscopic analysis method. Further, a characteristic coefficient is determined in advance based on the component content of the known sample rice and each characteristic value of the known sample rice obtained by a sensory test of the sample rice, and the component conversion coefficient and the near infrared spectroscopy Calculate the component content of amylose, protein, and water contained in the sample rice with the measured absorbance value of the unknown sample rice obtained by the above, and calculate the fragrance, stickiness, A rice quality evaluation method characterized by calculating a characteristic value of hardness.