JP3047364B2 - Nondestructive quality evaluation method for agricultural products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nondestructive method for evaluating the quality of agricultural products, and particularly relates to the most important factors in quality, such as sugar content as a sweet component constituting taste and organic acidity as a sour component. The present invention relates to a method for evaluating nondestructive quality of agricultural products, in which taste components can be measured by utilizing the NMR (nuclear magnetic resonance) phenomenon.

[0002]

2. Description of the Related Art With respect to the evaluation of the quality of agricultural products such as fruits and vegetables, a method of extracting individuals belonging to each set classified according to the place of origin and brand, performing destructive inspection, and evaluating the quality of the classified set. Is commonly practiced. Evaluation of individual individuals mainly depends on appearance such as shape and size.

Certainly, according to the sampling / destructive inspection, internal factors such as taste can be evaluated, and the characteristics of each set can be extracted by using a statistical method.

[0004] However, agricultural products are different from industrial products, even if they have the same production area and brand, but each individual component such as sugar content, which is a sweet component constituting taste which is an important factor in quality, and organic acid content, which is a sour component. Have different taste components, and as a result, the taste varies greatly among individuals. Therefore, a general evaluation method as a set that is not for individual individuals is not sufficient. In other words, in other words, it is a problem from the viewpoint of quality assurance for consumers if it is difficult to know whether or not it is good without eating it, and a producer cannot obtain an index of efficient production.

[0005] Therefore, there has been a demand for a method for nondestructive quality evaluation of individual fruits or the like in large quantities. recent years,
Non-destructive sorting of fruits by near infrared spectroscopy has been put to practical use for peaches and apples. In this method, a sample is irradiated with near-infrared light, its reflected light is detected, and its spectrum is measured, so that the factors constituting taste can be measured as a whole.

[0006] A nondestructive inspection method by the NMR method is also known. This is to measure the NMR spectrum of various nuclei constituting the substance constituting the taste. C-13NM for Unshu mandarin orange, grape and earthmelon
It is known to determine the sugar content and acid content by R spectrum and H-1 (proton) NMR spectrum (Koichi Akimoto; "Development direction of quality evaluation technology of fruits and vegetables", Agriculture and Horticulture Vol. 60, No. 1) , P9-17, 1985,
Sumino Kono, "Non-destructive Quality Evaluation Method and Apparatus for Agricultural Products," Monthly Food Distribution Technology (Extra Issue), Vol. 19, no. Vol. 11, No. 247, 1990 Agricultural Product Distribution Technology Year Edition, p143
-148, etc.).

[0007]

However, the conventional nondestructive quality evaluation method using near-infrared spectroscopy has a limit from the principle of using reflected light. In other words, according to this, only information on the skin layer of an extremely thin surface can be obtained, and it is limited to some types such as peaches and apples, whose epidermis and internal quality are correlated, in order to estimate the internal state from this. And oranges are difficult and cannot be applied to general agricultural and marine products.

Further, the conventional nondestructive quality evaluation method by the NMR method cannot be used industrially because of the long measurement time. This is due to the C
This is because -13 and proton NMR signals are detected. Agricultural products usually contain water at a high ratio of 80% or more and contain a small amount of substances other than water, and the NMR signal intensity from a trace amount of taste components is weaker than the NMR signal intensity from water, This is because only the error level can be obtained.

[0009] In view of the above, the present invention measures non-destructively, in large quantities and quickly, the information on the taste components of each solid constituting the taste, which is the most important factor in the quality, to obtain general agricultural products. An object of the present invention is to provide a practical nondestructive quality evaluation method for agricultural products that can be widely applied for evaluating quality.

[0010]

In order to achieve the above object, a nondestructive quality evaluation method for agricultural products according to the present invention detects an NMR signal from each individual agricultural product, obtains a T2 value for water, It is characterized in that the taste component inside each individual of the agricultural product is measured based on the correlation between the T2 value and the taste component.

[0011]

An NMR signal from each individual agricultural product is obtained using an MRI apparatus or the like which is mainly used for medical treatment.
In this case, since the agricultural product has a large percentage of water, an NMR signal from the water is detected. From the NMR signal, a T2 value for water is determined. This calculated T2
It can be experimentally confirmed that there is a high correlation between the value and the taste components such as sugar as a sweet component and organic acid as a sour component depending on the kind of the agricultural product. Was. Therefore, the taste component can be measured from the T2 value obtained from the NMR signal from water based on this correlation. In addition, since the NMR signal from water has a high signal intensity, the measurement is easy and can be performed in a short time. In a practical sense, this makes it possible to evaluate the most important taste in the quality evaluation of agricultural products in a non-destructive manner.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the relationship between the sugar content of watermelon and the MRI signal intensity (T2 value) according to the present invention. 2 and 3 show Satsuma mandarin as a sample, and determine the relationship between the sugar content and the MRI signal intensity (T2 value) and the relationship between the acylizer value (acidity) and the MRI signal intensity (T2 value). It is a thing.

As the MRI apparatus, a model MAGNEX50 / HP manufactured by Shimadzu Corporation is used, and five watermelons and five Satsuma mandarins, each of which is expected to have a different taste, and particularly, the watermelon has a cavity therein. The procurement was performed with care taken to mix them, and these were imaged using four types of imaging sequences. That is, a T1-weighted image is imaged by the spin echo method in which both the repetition time TR and the echo time TE are shortened, and a proton density-weighted image is obtained by the spin echo method in which the TR is lengthened and the TE is shortened.
A T2-weighted image is captured by the spin echo method, which is longer for both TR and TE, and is further captured by the field echo method.
A 2 × 512 matrix high resolution image was obtained (the previous three sequences obtained a 256 × 256 matrix image). The average signal intensity is measured for each position inside the fruit as needed. On the other hand, the sugar content of the fruit was measured using a refractometer (Brix), and the acidity of mandarin orange was measured using a cigarette acylizer (Fujihira Industries Co., Ltd., model
15).

The MRI apparatus used will be briefly described with reference to FIG. FIG. 4 is a block diagram showing the configuration of the MRI apparatus. In FIG.
A z-coil 12, a Gy coil 13, and a Gx coil 14 are arranged, and a current is supplied to these coils as indicated by arrows to thereby generate gradient magnetic fields Gx, Gy, and Gx in three directions of X, Y, and Z.
Gz is generated. The main magnet 11 generates a static magnetic field whose magnetic flux is directed in the Z direction. These Gz coil 12, Gy coil 13, Gx coil 14
Is supplied with a current from the gradient magnetic field power supply 22. Those current waveforms are provided by a waveform generator 21.

A subject (test fruit) (not shown) is inserted into a space to which a static magnetic field and a gradient magnetic field are applied, and a transmitting antenna and a receiving antenna (not shown) are attached to the subject. An excitation RF pulse is supplied from the transmission power amplifier 26 to the transmission antenna. This excitation RF pulse
The modulation circuit 25 modulates the RF signal from the signal generator 23 with the signal from the waveform generator 24. The NMR signal received by the receiving antenna is sent to a detection circuit 28 through a preamplifier 27, phase-detected using the signal from the signal generator 23 as a reference signal, and further sampled by an A / D converter 29 and converted into digital data. Then, it is taken into the computer 20.

The computer 20 reconstructs an image by performing a two-dimensional Fourier transform on the data to obtain an MR image. The computer 20 controls the waveform of each gradient magnetic field generated from the waveform generator 21 and its timing, controls the RF pulse waveform from the waveform generator 24 and its timing, and further controls the signal generator 23. Then, by making the frequency of the RF pulse coincide with the resonance frequency, each pulse sequence such as the above spin echo method is performed.

To explain the results obtained by the experiment, first, for the watermelon containing "su", the cavity (density difference) inside the watermelon can be clearly imaged by any of the sequences, and non-destructive "water entering" can be obtained. It was very clear whether or not it was a fruit. In addition, when the inside of the fruit was scratched by artificial stabbing, it was possible to discriminate the old and new states of the scratch inside the fruit in any of the images.

The sugar content of the watermelon was procured so that there was a difference in the sugar content of the fruit of the test material, but the difference was hardly recognized in the measurement result due to destruction. So 5
For the pericarp layer of the fruit, the perimeter of the pulp,
That is, MRI data and sugar content meter data were compared and examined for 15 points. On average, the sugar content of each part is 9.9% (Brix) in the central portion of the pulp, and 8.
It was 7% and the pericarp layer was 5.1%. When the correlation between the sugar content and the MRI data was obtained, the simple correlation coefficient was as follows:
T2 calculated value 0.845, T2 emphasized value 0.764, T1 emphasized value 0.669, T1 calculated value -0.558, proton density emphasized value 0.483, proton density calculated value -0.091
Met. The single correlation coefficient between the product of the sugar content and the water content and the MRI data was calculated as T2 0.859 and T2 weighted value 0.79.
It was 6. Here, T1, T2, and the proton density emphasized value are data (pixel values) obtained in the above-described T1, T2, proton density emphasized image imaging sequence, and the data and the proton density emphasized image imaging sequence are obtained. T1, T2, and the calculated value of proton density are obtained using the data obtained in step (1).

FIG. 1 shows the T2 weighted value and the calculated T2 value, which have a high correlation with the sugar content, with some abnormal values removed. Solid circles and thin lines relate to T2 enhancement values, open circles and thin lines
2 Regarding the calculated value. Since the abnormal value has been removed, the single correlation coefficient between the calculated T2 value and the T2 calculated value is as high as 0.90.

From the above, for watermelon, the MRI image and the value obtained by calculating the T2 relaxation time are given by
It has been found that the state of "contained" and the sugar content can be evaluated with high accuracy. With the MRI apparatus, data for their identification and selection can be obtained in a short time in a non-destructive manner.

With respect to the test material of Satsuma mandarin orange, the sugar content distribution was 0.68 at the minimum and 10.9 at the maximum. The simple correlation coefficient between the sugar content and the MRI data is, in descending order, the calculated T2 value 0.978, the T2 weighted value 0.757, and the calculated T1 value 0.5.
14, proton density emphasis value 0.445, T1 emphasis value-
0.398, and the calculated proton density was 0.195.
FIG. 2 shows the T2 weighted value and the calculated T2 value having a high correlation with the sugar content. As shown in this figure, a high correlation of 0.978 is recognized between the calculated T2 value and the sugar content.

Regarding the acidity of Unshu mandarin orange, the single correlation coefficient between the measured acylizer value and the NMR data is as follows:
T2 calculation value 0.652, T2 emphasis value 0.64 in descending order
6, T1 emphasis value -0.577, T1 calculated value 0.226,
Proton density emphasis value 0.132, proton density calculation value-
0.101. T2 highly correlated with the acylizer value
FIG. 3 shows the emphasized value and the calculated T2 value.

As described above, it has become clear that it is effective to evaluate the sugar content and acidity of Satsuma mandarin orange by MRI data. Further, when the taste was examined by five testers, a result which was in good agreement with the MRI data was obtained.

In addition, when it is sufficient to evaluate only the quality based on taste, and when it is not necessary to evaluate the internal structure such as the internal cavity (s),
The image data becomes unnecessary, and if the sequence for detecting the NMR signal is performed, the sequence for acquiring the image data does not need to be performed.

[0025]

According to the method for evaluating nondestructive quality of agricultural products of the present invention, T2 having a correlation with taste by detecting an NMR signal.
Since the taste component such as sugar or organic acid constituting the taste is measured by obtaining the value, it is possible to evaluate the taste which is the most important factor in the quality. Since the T2 value having a correlation with the taste is obtained by detecting an NMR signal from water contained in a large amount in agricultural products, the signal intensity is large, so that the measurement is easy and can be performed in a short time. As a result, at a practical speed, the quality of a large amount of solids can be evaluated and sorted by taste, which is the most important factor in quality, in a nondestructive manner. Also,
If image data is also obtained, the internal structure such as a cavity can be simultaneously evaluated with a single measurement together with the measurement of the taste component, so that the versatility is high and the application range is wide. Therefore, in addition to the evaluation of tastes that could not be accurately evaluated conventionally,
This will pave the way for a practical evaluation of the quality of the internal structure, provide guidelines for suitable sites and suitable crops for producers, and realize quality assurance for consumers. Furthermore, in the case of quality evaluation and sorting in large quantities, it is sufficient to provide a relatively inexpensive and simple supply mechanism for sequentially supplying samples such as fruits to a normal MRI apparatus, so that the apparatus can be easily constructed. Can be introduced to most production areas.

[Brief description of the drawings]

FIG. 1 is a graph showing data obtained in one embodiment of the present invention.

FIG. 2 is a graph showing other data obtained in the example.

FIG. 3 is a graph showing still another data obtained in the example.

FIG. 4 is a block diagram of the MRI apparatus used in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Main magnet 12-14 Gradient magnetic field generating coil 20 Computer 21 Gradient magnetic field waveform generator 22 Gradient magnetic field power supply 23 Signal generator 24 RF excitation waveform generator 25 Modulation circuit 26 Transmission power amplifier 27 Preamplifier 28 Detection circuit 29 A / D converter

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-110360 (JP, A) JP-A-2-110359 (JP, A) JP-A-2-110358 (JP, A) New Food Industry, Vol. 27, No. 5, pp. 22-26 (1985)

Claims (1)

(57) [Claims] 1. An NMR signal from each individual agricultural product is detected, a T2 value for water is obtained, and a taste component inside each individual agricultural product is measured based on a correlation between the T2 value and a taste component. A non-destructive quality evaluation method for agricultural products, characterized in that: