JP2010256302A - Method for determining cultivation country or area of agricultural product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for conveniently and correctly determining a cultivation country or an area of an agricultural product, for example, tea leaves cultivated in Japan or a foreign country such as China. <P>SOLUTION: The cultivation country or the area is identified by measuring a sulfur stable isotope ratio δ<SP>34</SP>S of the agricultural product. The sulfur stable isotope ratio δ<SP>34</SP>S of the agricultural product whose cultivation country or area is clear is analyzed. The cultivation country or the area of the agricultural product whose cultivation country or area is unclear is determined by a means for establishing a database. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a method for determining a farming country or region of an agricultural product. Specifically, the present invention relates to a method for measuring a stable isotope ratio δ ³⁴ S of sulfur contained in agricultural crops and determining a farming country or region of agricultural products based on the isotope ratio.

  In recent years, imports of crops that are raw materials for vegetables and processed foods have increased rapidly. Along with this, there have been many cases in which the origin of the food material is camouflaged, but no technology has been established to determine the origin of the food material simply and with high accuracy. In addition, the development of a technology that can accurately determine the production area of agricultural products due to the effects of food accidents caused by residual agricultural chemicals and hazardous substances is particularly desirable.

  It was not until the second half of the 1990s that technology for discriminating cultivation areas for crops used as plants and food ingredients in Japan began to be fully studied. As an analysis method, development research on a discrimination method using inorganic element composition analysis has been advanced in advance. For example, it has been reported that tea leaves can be distinguished from foreign (Chinese) and Japanese by inorganic element composition analysis if the sample is unified to the most tea (Non-patent Documents 1 and 2).

  In addition, many techniques for discriminating localities using stable isotope ratios in plants and food crops have been reported. Since a continuous flow type stable isotope ratio mass spectrometer has been developed in recent years, it has become possible to analyze the stable isotope ratios of many kinds of elements relatively easily.

Utilizing these technologies, by combining multiple stable isotope ratios selected from δ ¹³ C, δ ² H, and δ ¹⁸ O, it is possible to identify plant species and foods, especially fermented alcohol raw material species and cultivation areas Has been proposed (Patent Document 1). In addition, a method for identifying a rice production site by analyzing stable isotope ratios of water extracted from rice, specifically, δ ² H and δ ¹⁸ O has been proposed (Patent Document 2). In these prior arts, analysis of oxygen or hydrogen stable isotope ratios has been shown to be effective for identifying fermented alcohol or rice growing areas.

  On the other hand, compared to other light elements, the usefulness of sulfur stable isotope ratio analysis is less known and there are not many scientific papers or patent-pending technologies, but it is related to sulfur stable isotope ratios related to agricultural products. The following reports can be cited.

  In order to investigate the effects of sulfur dioxide in the environment, sulfur stable isotope ratios of mosses, lichens and pine tree leaves have been investigated, and it is known that the sulfur stable isotope ratio varies from region to region (non- Patent Documents 3, 4 and 5).

  Although there are few attempts to distinguish the origin of crops using the stable isotope ratio of sulfur, there have been reports of cases examined with butter and cheese. However, there is no example in which a sample is directly analyzed, and a method of separating and analyzing a fraction having a high sulfur content such as casein contained in the sample is employed (Non-Patent Documents 6, 7, 8, 9). .

JP 2005-130755 A JP 2006-189351 A

Katsunori Kiso (2005): Present status and future prospects of tea origin, TechnoInnovation, 15 (2), 32-37. Katsunori Kiso (2008): Identification of locality based on inorganic element composition ratio and variety identification of green tea, Agriculture, Forestry and Fisheries Research Journal, 31 (4), 28-31. Trust B. A. and Fry B. (1992) Stable sulfur isotpopes in plants: a review.Plant, Cell and Environment, 15, 1105-1110. Nakai Nobuyuki (1984): Sulfur Circulation and Human Life, Modern Science, 165, 39-44. Krouse H. (1977): Sulfur isotope abundance elucidate uptake of atmospheric sulphur emissions by vegetation. Nature, 265, 45-46. Simon K., Karl H. and Jurian H. (2005) Tracing the geographical origin of food: The application of multi-element and multi-isotope analysis.Trends in Food Science & Technology, 16, 555-567. Rossmann A., Haberhauer G., Holzl S., Horn P., Pichlmayer F., Voerkelius S. (2000) The potential of multielement stable isotope analysis for regional origin assignment of butter.Eur. Food Res. Technol., 211, 32-40. Camin F., Wietzerbin K., Cortes AB, Haberhauer G., Lees M., Versini G. (2004) Application of multielement stable isotope ratio analysis to the characterization of French, Italian and Spanish cheeses. J. Agric Food Chem., 52, 6592-6601. Manca G., Franco M., Versini G., Camin F., Rossmann A., Tola A. (2006) Correlation between multielement stable isotope ratio and geographical origin in peretta cows' milk cheese.J. Dairy Sci., 89, 831-839.

  An object of this invention is to discriminate | determine the cultivation country or area of agricultural products, for example, a tea leaf simply and with high precision. In particular, it is to provide a technique for easily and accurately discriminating crops grown in Japan and foreign countries such as China.

In order to solve the above-mentioned problems, the present inventors collect crops whose cultivation country or region is clear, and use a combustion and pyrolysis-type stable isotope ratio mass spectrometer, and use a stable carbon isotope ratio δ ¹³ C, Nitrogen stable isotope ratio δ ¹⁵ N, sulfur stable isotope ratio δ ³⁴ S, and oxygen stable isotope ratio δ ¹⁸ O were measured. When the crop is a tea leaf, it can be confirmed that it is a C3 plant by analyzing the δ ¹³ C value, but even when combined with the δ ¹⁵ N or δ ¹⁸ O value, the origin of the Chinese and Japanese tea leaves is completely discriminated. It was difficult to do. However, when the sulfur stable isotope ratio δ ³⁴ S was measured and subjected to discriminant analysis by statistical analysis, it was surprisingly found that the difference in tea leaf cultivation country or region could be clearly discriminated, and the present invention was completed. It came to do.

That is, the present invention includes the following [1] to [8].
[1] A method for determining a crop-cultivating country or region, the step of measuring a stable isotope ratio δ ³⁴ S of sulfur contained in a crop known to the growing country or region; Measuring the stable isotope ratio of the contained sulfur; and comparing the data to identify a cultivated country or region that exhibits a sulfur stable isotope ratio similar to the sulfur stable isotope ratio of the test sample; Including the determination method.
[2] The determination method according to [1], wherein the crop is tea leaves.
[3] The determination method according to [2], wherein the tea leaves are made in Japan or China.
[4] A method for determining a tea leaf cultivation country or region, the following steps:
Measuring a stable isotope ratio δ ³⁴ S of sulfur contained in Chinese and Japanese tea leaves;
Using the average value and standard deviation of the measured sulfur stable isotope ratio, the boundary value (assuming X) that the Mahalanobis's general distance from the average value in China and Japan is equal to each other is (X-Japanese tea leaves Average value of stable isotope ratio of sulfur contained) / Standard deviation of stable isotope ratio of sulfur contained in Japanese tea leaves = (Average value of stable isotope ratio of sulfur contained in Chinese tea leaves−X ) / Step of calculating by a calculation formula represented by the standard deviation of the stable isotope ratio of sulfur contained in Chinese tea leaves;
A step of measuring the stable isotope ratio of sulfur contained in a test sample of Chinese or Japanese tea leaves; and if the sulfur stable isotope ratio of the test sample is X ‰ or higher, the country of cultivation is China And
Determining that the country of cultivation is Japan if the sulfur stable isotope ratio of the test sample is less than X ‰;
Said method.
[5] A method for determining a farming country or region of a crop, the step of measuring a stable isotope ratio δ ³⁴ S of sulfur contained in a crop known to the growing country or region; Establishing a database of local and sulfur stable isotope ratio δ ³⁴ S; measuring a stable isotope ratio of sulfur contained in a test sample of the same type of crop; and using the database to stabilize sulfur of the test sample Determining the cultivated country or region from the isotope ratio.
[6] The determination method according to [5], wherein the crop is tea leaves.
[7] The determination method according to [6], wherein the tea leaves are made in Japan or China.
[8] The determination method according to any one of [1] to [7], wherein the determination is further made by combining the measured values of the carbon stable isotope ratio δ ¹³ C.

The present invention, by the value of only crop sulfur isotopic [delta] ^{34 S,} or by combining isotopic sulfur isotopic [delta] ^{34 S} and other elements, the cultivated country or region crops A determination method can be provided, and according to the present invention, it is possible to accurately discriminate between foreign and domestic (Japanese) crops.

FIG. 1 is a graph plotting nitrogen stable isotope ratio δ ¹⁵ N value (unit: ‰) and carbon stable isotope ratio δ ¹³ C value (unit: ‰) of green tea leaves whose country of origin is clear. FIG. 2 is a graph in which the oxygen stable isotope ratio δ ¹⁸ O value (unit: ‰) and the carbon stable isotope ratio δ ¹³ C value (unit: ‰) of green tea leaves with a clear country of origin are plotted. FIG. 3 is a graph plotting the sulfur stable isotope ratio δ ³⁴ S value (unit: ‰) and the carbon stable isotope ratio δ ¹³ C value (unit: ‰) of green tea leaves whose country of origin is clear. FIG. 4 is a graph plotting the sulfur stable isotope ratio δ ³⁴ S value (unit: ‰) and nitrogen stable isotope ratio δ ¹⁵ N value (unit: ‰) of green tea leaves whose country of origin is clear. FIG. 5 is a graph plotting the sulfur stable isotope ratio δ ³⁴ S value (unit: ‰) and oxygen stable isotope ratio δ ¹⁸ O value (unit: ‰) of green tea leaves whose country of origin is clear.

Hereinafter, embodiments of the present invention will be described in detail.
Agricultural crops As used herein, crops are raw materials for plants and foods, and are the whole of various crops themselves, the products that plants accumulate as seeds and fruits, or the leaves, roots and stems of plants and crops. And so on. Preferably, it refers to crop seeds, fruits, leaves, roots and stems. Preferably, tea leaves containing green tea, semi-fermented tea or fermented tea are used. Further, in the present invention, a sample obtained by drying these into a fine powder is preferably used.
There are no particular restrictions on the country or region where the crop is grown or the local crop is grown. The agricultural product may be an agricultural product of any region because it exhibits a sulfur stable isotope ratio δ ³⁴ S specific to the country or region of cultivation.

If a specific example is given, in the case of tea leaves, it may originate from any country or region that produces tea leaves. For example, according to the present invention, the cultivation country or region of Chinese or Japanese tea leaves can be specified.
Measurement of stable isotope ratio In the present invention, the cultivated country or region is specified based on the sulfur stable isotope ratio δ ³⁴ S of agricultural products.

  The stable isotope ratio can be measured using, for example, a combustion type or pyrolysis type stable isotope ratio mass spectrometer. When analyzing the stable sulfur isotope ratio of agricultural products such as tea leaves, the present inventors generally set the weight of the sample to be introduced into the elemental analyzer, preferably from 4 of the conditions for analyzing the stable carbon isotope ratio. It has been found that by increasing the amount to about 6 times, it is possible to analyze the sulfur stable isotope ratio contained in the sample without fractionating and purifying the sample.

The stable isotope ratio is expressed as a deviation from a standard substance, and is represented by a δ value in (Equation 1).
δX (‰) = (R _sample / R _standard -1) x 1000 (Equation 1)
Here, X represents ¹³ C, ¹⁵ N, ¹⁸ O, and ³⁴ S with respect to carbon, nitrogen, oxygen, and sulfur, respectively, and the R _sample and the R _standard are stable isotope ratios of the sample and the standard substance, that is, ¹³ C / ¹² C, ¹⁵ N / ¹⁴ N, ¹⁸ O / ¹⁶ O, ³⁴ S / ³² S. Permill (‰) is a thousandths deviation. As a standard substance, an international standard substance (international standard) is used so that data can be compared internationally. A typical international standard sample is shown in Table 1. Vienna Standard Mean Ocean Water (VSMOW) as the oxygen reference material, Palmy fossil (Pee Dee Belemnite: PDB) excavated from the PeeDee Formation in South Carolina as the carbon reference material, and the atmosphere in nitrogen As a nitrogen gas and sulfur standard substance, trolite (iron sulfide) in Diablo gorge meteorite represented as CDT (Canion Diablo Troilite) or CDM (Canyon Diablo Meteorite) is used. However, since international standard substances are rare, a working standard having a known stable isotope ratio relative to the international standard substance can be used in the present invention. As the working standard, L-α-alanine, benzoic acid, sulfanilide and the like can be used, and the analytical value of the sample is obtained from the analytical value of these working standards.

In the present invention, the cultivated country or region can be identified based on the sulfur stable isotope ratio δ ³⁴ S of agricultural products. In addition, in combination with a stable isotope ratio selected from carbon, oxygen, and nitrogen, the cultivated country or region can be specified with higher accuracy.
Judgment Method of Crop Country or Region of Crop Cultivate the country or region of the unknown sample by measuring the stable isotope ratio of the obvious crop in the country or region and comparing the measurement results of the stable isotope ratio of the unknown sample. The area can be determined.

  As an example of a specific method, a stable isotope ratio of an apparent crop in a cultivated country or region is analyzed, a statistical analysis of the analysis value is performed, and a discriminant that can determine the cultivated country or region of the sample is obtained. If an analytical value of an unknown sample is introduced into the equation, it is possible to determine the cultivating country or region of the sample. For the discriminant analysis, “linear discriminant analysis” or “method of comparing Mahalanobis generalized distances” is generally used.

Using only the analysis value δ ³⁴ S of the sulfur stable isotope ratio as a variable, for example, by comparing “Mahalanobis general distance”, it is possible to determine the crop cultivation area. Mahalanobis's generalized distance can be easily calculated using statistical analysis software (Tomoro Tsuji: “Practice of Multivariate Analysis” (Contemporary Mathematics)).

Specifically, when discriminating between Chinese tea leaves and Japanese tea leaves, the sulfur stable isotope ratio δ ³⁴ S contained in Chinese and Japanese tea leaves was measured in advance, and the measured sulfur stable isotope ratio Using the average value and standard deviation, calculate the boundary value (X) that equals the Mahalanobis's general distance from the above average values for Chinese and Japanese products, and include them in Chinese or Japanese tea leaf test samples. The stable isotope ratio of sulfur is measured, and if the sulfur stable isotope ratio is X ‰ or higher, it can be judged that it is made in China, and if it is less than X ‰, it is judged that it is made in Japan.

When a sulfur stable isotope ratio δ ³⁴ S is used in combination with a stable isotope ratio selected from carbon, oxygen, and nitrogen, for example, the δ ³⁴ S value measured for each sample is expressed as δ ¹³ A scatter diagram combined with a C value, a δ ¹⁸ O value, or δ ¹⁵ N can be created and determined from a relative positional relationship on the scatter diagram.

  The present invention will be described more specifically with reference to the following examples, but the present invention is not limited thereto.

In the following, items necessary for carrying out the present invention, such as sample preparation methods and analyzer setting conditions, will be described in detail. However, the present invention is not limited to these conditions.
Sample preparation Chinese and Japanese green tea leaves with a clear country of origin were pulverized using a machine such as a pulverizer and dried, and used as a sample for analysis. When analyzing sulfur stable isotope ratios, weigh 6 to 9 mg, and when analyzing carbon and nitrogen stable isotope ratios, weigh 0.5 to 4 mg and each sample is tin foil (Universal Tin container light, Thermo Fisher Scientific Samples for analysis were used. Further, when analyzing the oxygen stable isotope ratio, a sample of 0.1 to 0.4 mg was weighed and wrapped in silver foil (Silver capsules for solids, manufactured by Thermo Fisher Scientific Co., Ltd.) as an analysis sample.
Analytical instrument setting conditions For analysis of stable isotope ratios of carbon, nitrogen and sulfur, an element analyzer (FlashEA, Thermo Fisher Scientific Co., Ltd.) connected via a gas control device (ConFloIII, manufactured by Thermo Fisher Scientific Co., Ltd.) And a stable isotope ratio mass spectrometer (Delta V advantage, manufactured by Thermo Fisher Scientific Co., Ltd.). Table 2 shows the measurement conditions using the element analyzer in the present invention. In the sulfur stable isotope ratio analysis, a Teflon (registered trademark) separation column for sulfur stable isotope ratio analysis was used.

  For analysis of oxygen stable isotope ratio, pyrolysis element analyzer (TC / EA, Thermo Fisher Scientific Co., Ltd.) connected via a gas control device (ConFlo III, Thermo Fisher Scientific Co., Ltd.) and A stable isotope ratio mass spectrometer (Delta V advantage, manufactured by Thermo Fisher Scientific Co., Ltd.) was used. Table 3 shows the measurement conditions using the pyrolysis element analyzer in the present invention.

Analytical conditions Stable isotope ratio analysis of any element Measures standard gas and sample-derived gas in one analysis and determines stable isotope ratio in sample by comparing with standard gas did.

Carbon and nitrogen stable isotope ratios were analyzed simultaneously. Standard gases are nitrogen and carbon dioxide.
The analysis of the sulfur stable isotope ratio was performed under the condition of measuring only the sulfur stable isotope ratio. The standard gas is sulfur dioxide. In order to suppress the influence of carbon dioxide, dilution with helium was performed until just before the detection of the sample-derived sulfur dioxide gas.

The oxygen stable isotope ratio was also analyzed under the condition that only the oxygen stable isotope ratio was measured. The standard gas is carbon monoxide.
Analytical value correction The analytical value of the stable isotope ratio was determined by comparison with a standard gas to be analyzed each time. Although the stable isotope ratio of the standard gas can be determined using an international standard sample, there are many samples that are difficult to obtain. Therefore, in the present invention, the working standard value is determined using a standard material that is easily available, and this working standard is used. Analysis was carried out. As working standards, L-α-alanine (Shokko Tsusho Co., Ltd .: δ ¹³ C-PDB (‰) = -19.9, δ ¹⁵ N-Air (‰) = -1.21), benzoic acid (Indiana University) : Δ ¹⁸ O (‰) = 23.2), sulfaanilide (Wako Co., Ltd .: δ ³⁴ S (‰) = 2.6), sulfaanilide (Thermo Fisher Scientific Inc.): δ ³⁴ S (‰) ) = 17.0) and the like, and the analytical value of the sample was obtained indirectly from these analytical values.

Stable isotope ratios were measured using dried and finely pulverized samples of green tea leaves (from Japan: 15 points, from China: 24 points) apparent in the country of origin in Table 4. The obtained values are shown in Table 4. Scatter plots in which the δ ¹³ C values in Table 4 are combined with δ ¹⁵ N, δ ¹⁸ O values, or δ ³⁴ S values are shown in FIGS. Also shows a scatter plot of the [delta] ³⁴ S values in Table 4, in combination with [delta] ¹⁵ N or [delta] ¹⁸ O value 4, Figure 5. From FIG. 1, it can be seen that in the combination of nitrogen and carbon stable isotope ratios, Japanese green tea leaves and Chinese green tea leaves are mixed on the scatter diagram, and it is difficult to distinguish the country of origin. In addition, FIG. 2 shows that in the combination of oxygen and carbon stable isotope ratios, Japanese green tea leaves and Chinese green tea leaves are mixed on the scatter diagram, and it is difficult to distinguish the country of origin. However, it can be seen from FIG. 3 that the combination of sulfur and carbon stable isotope ratios allows Japanese green tea leaves and Chinese green tea leaves to be separated and clearly distinguished on the scatter diagram. Similarly, it can be seen from FIG. 4 that it is possible to discriminate between Japanese green tea leaves and Chinese green tea leaves using either a combination of sulfur and nitrogen stable isotope ratios or a combination of sulfur and oxygen stable isotope ratios. Among the above combinations, it was confirmed that a combination of sulfur and carbon stable isotope ratios with small variations in analysis values of Japanese green tea leaves is suitable for discrimination of the origin. Furthermore, it can be seen from FIGS. 3 to 5 that even with a stable sulfur isotope ratio alone, it is possible to discriminate between Japanese green tea leaves and Chinese green tea leaves.

In the sample used in Example 1, since it was confirmed that the production area of green tea leaves can be determined even with the sulfur stable isotope ratio alone, the analysis value δ ³⁴ S of the sulfur stable isotope ratio (unit: Using only ‰) as a variable, an attempt was made to determine the cultivation area of green tea leaves from Japan and China by comparison of the “distance of Mahalanobis”.

Procedure 1: With respect to 29 samples for constructing a discriminant model (Japanese green tea leaves: 10 points, Chinese green tea leaves: 19 points), the sulfur stable isotope ratio δ ³⁴ S (unit: Chinese green tea leaves and Japanese green tea leaves) The average value and standard deviation of ‰) were determined. As shown in Table 5, the average value (B) of sulfur stable isotope ratio of Japanese green tea leaves was 0.94 ‰, and the standard deviation was 0.68 ‰. The average value (D) of sulfur stable isotope ratio of Chinese green tea leaves was 5.76 ‰, and the standard deviation was 1.67 ‰.

Procedure 2: If the value of the sulfur stable isotope ratio at the boundary between Japanese green tea leaves and Chinese green tea leaves is X, the difference (deviation) from the average sulfur stable isotope ratio of Japanese green tea leaves is , X-0.94. Moreover, the difference (deviation) from the average value of the sulfur stable isotope ratio of Chinese green tea leaves is 5.76-X. Mahalanobis' general distance was obtained by dividing the difference between the mean value and the boundary value by the standard deviation. The boundary value X is
(X-0.94) /0.68 = (5.67-X) /1.67
From the above formula, it was confirmed that it was 2.31 ‰.

  Procedure 3: If the sulfur stable isotope ratio was 2.31 ‰ or more, it was judged as Chinese tea leaf if it was made in China and less than 2.31 ‰. Regarding the samples used in the examples, 29 models for discriminant model construction (Japanese green tea leaves: 10 points, Chinese green tea leaves: 19 points), all Japanese green tea leaves are from Japan, all Chinese green tea leaves are from It could be judged that it was made in China. In addition, with regard to 10 test samples (Japanese green tea leaves: 5 points (sample numbers: J1 to J5), Chinese green tea leaves: 5 points (sample numbers: C1 to C5)), all Japanese green tea leaves are from Japan. All the green tea leaves from China were correctly judged to be from China.

  Of the 39 green tea leaves of Example 1 (Japan: 15 points, China: 24 points), 10 points (Japan: 5 points, China: 5 points) are test samples, and the remaining 29 points are discriminating models. A sample for construction was used. Comparing the general distance of Mahalanobis of 29 samples for constructing the discrimination model, it was possible to determine that all Japanese green tea leaves were from Japan and all Chinese green tea leaves were from China. Furthermore, as a result of determining the country of origin of the test sample using the discriminant calculated from the model building sample, it was possible to determine that all Japanese green tea leaves were from Japan and all Chinese green tea leaves were from China. It was.

Hereinafter, by using the analytical values δ ³⁴ S and δ ¹³ C (unit: ‰) of sulfur and carbon stable isotope ratios as variables, determination of the cultivation area of green tea leaves was made by comparison of “general distance of Mahalanobis”. The specific procedure was based on Sadao Ishimura: “Procedure for Multivariate Data Analysis Using SPSS” (Tokyo Book). As statistical analysis software, commercially available products such as Excel 2003 (manufactured by Microsoft Corporation) and SPSS Statics 17.0 (manufactured by SPSS Corporation) were used.

Procedure 1: With respect to 29 samples for constructing a discriminant model (Japanese green tea leaves: 10 points, Chinese green tea leaves: 19 points), the sulfur stable isotope ratio δ ³⁴ S (unit: Chinese green tea leaves and Japanese green tea leaves) The average value of ‰) and stable carbon isotope ratio δ ¹³ C (unit: ‰) was determined. As shown in Table 5, the average value (A) of carbon stable isotope ratio of Japanese green tea leaves was -27.16 ‰, and the average value (B) of sulfur stable isotope ratio was 0.94 ‰. In addition, the average value (C) of carbon stable isotope ratio of Chinese green tea leaves was -25.95 ‰, and the average value (D) of sulfur stable isotope ratio was 5.76 ‰.

  Procedure 2: The difference (deviation) from the average value of each data was calculated, and the variance and covariance values of each group were calculated from those values. The variance and covariance values were calculated by inputting the analysis values into statistical analysis software such as Excel and SPSS Statics 17.0. Table 6 shows the results calculated with the statistical analysis software SPSS Statics 17.0. The dispersion of carbon stable isotope ratio of Japanese green tea leaves was calculated as 0.142, the dispersion of sulfur stable isotope ratio was 0.466, and the covariance of carbon stable isotope ratio and sulfur stable isotope ratio was calculated as 0.024. In addition, the dispersion of carbon stable isotope ratio of Chinese green tea leaves was 1.846, the dispersion of sulfur stable isotope ratio was 2.799, and the covariance of carbon stable isotope ratio and sulfur stable isotope ratio was 1.663.

Step 3: The inverse matrix was calculated by using the variance and covariance values calculated from the analysis values of Japanese and Chinese green tea leaves in Step 2 as determinants. For the calculation of the determinant, Excel and statistical analysis software using its function were used. Table 7 shows the results of calculating inverse matrices S1 ^-1 and S2 ^-1 from the dispersion covariance matrices S1 and S2 of Japanese green tea leaves and Chinese green tea leaves.

Step 4: The average carbon stable isotope ratio A and sulfur stable isotope ratio B of Japanese green tea leaves, the average carbon stable isotope ratio C and sulfur of Chinese green tea leaves calculated in step 1 Mean value D of stable isotope ratio, inverse matrix S1 ^-1 of the covariance matrix of carbon stable isotope ratio and sulfur stable isotope ratio of Japanese green tea leaves calculated in step 3, and carbon of Chinese green tea leaves The Mahalanobis generalized distance was calculated using the inverse matrix S2 ^-1 of the dispersion covariance matrix of stable isotope ratio and sulfur stable isotope ratio.
The X-ray stable isotope ratio (unit: ‰) of the green tea leaf to be judged from Japan or China is X, and the stable sulfur isotope ratio (unit: ‰) is Y. ) And (Equation 3).
In other words, the Mahalanobis generalized distance M1 to the center of gravity of the analysis value of Japanese green tea leaves is
M1 = (X−A, Y−B) × S1 ⁻¹ × (X−A, Y−B) (Formula 2)
The Mahalanobis pan-distance M2 to the center of gravity of the analysis value of Chinese green tea leaves,
M2 = (X−C, Y−D) × S2 ⁻¹ × (X−C, Y−D) (Formula 3)
Sought by. The determinant was calculated using Excel and statistical analysis software using its function. Table 8 shows the calculation results of 29 samples for discriminant model construction (Japanese green tea leaves: 10 points, Chinese green tea leaves: 19 points).
Step 5: Comparing the Mahalanobis's general distance M1 to the center of gravity of the analysis value of Japanese green tea leaf calculated in Step 4 with the Mahalanobis's general distance M2 to the center of gravity of the analysis value of Chinese green tea leaf,
M1 <M2
In the case of, it was determined that it was a Japanese green tea leaf.
In addition, we compared the Mahalanobis pan distance M1 to the center of gravity of the analysis value of Japanese green tea leaves and the Mahalanobis pan distance M2 to the center of gravity of the analysis value of Chinese green tea leaves,
M1> M2
In the case of Chinese green tea leaves. As shown in Table 8, with regard to 29 samples for constructing discriminant models (Japanese green tea leaves: 10 points, Chinese green tea leaves: 19 points), all Japanese green tea leaves are "Japan" and Chinese green tea leaves are All were confirmed to be correctly judged as “Chinese” (correct answer rate: 100%).

  Step 6: About 10 test samples (Japanese green tea: 5 points, Chinese green tea: 5 points), it was confirmed whether the country of origin could be judged by the discriminant calculated from the analysis value of the sample for constructing the discriminant model . From the analysis value of the test sample, according to the procedure 4 and procedure 5, calculate the Mahalanobis general distance to the center of gravity of the analysis value of Japanese green tea leaves and the Mahalanobis distance to the center of gravity of the analysis value of Chinese green tea leaves. The country of origin was determined. As a result, as shown in Table 9, it was confirmed that all Japanese green tea leaves could be correctly judged as “Japanese” and all Chinese green tea leaves could be correctly judged as “Chinese”.

  The present invention provides a simple and highly accurate method for discriminating the cultivated country or region of agricultural crops, particularly tea leaves, and can be widely applied in the fields of agricultural chemistry and food chemistry.

Claims (8)

A method for determining a farming country or region of a crop, which includes the following steps:
Measuring the stable isotope ratio δ ³⁴ S of sulfur contained in crops known to the country or region of cultivation;
Measuring the stable isotope ratio of sulfur in the test sample of the same type of crop; and comparing the data and showing the sulfur stable isotope ratio of the test sample and the approximate sulfur stable isotope ratio Or identifying the region;
Including the determination method.   The determination method according to claim 1, wherein the crop is a tea leaf.   The determination method according to claim 2, wherein the tea leaves are from Japan or China. A method for determining a tea leaf cultivation country or region, comprising the following steps:
Measuring a stable isotope ratio δ ³⁴ S of sulfur contained in tea leaves produced in China and Japan;
Using the average value and standard deviation of the measured sulfur stable isotope ratio, the boundary value (assuming X) that the Mahalanobis's general distance from the average value in China and Japan is equal to each other is (X-Japanese tea leaves Average value of stable isotope ratio of sulfur contained) / Standard deviation of stable isotope ratio of sulfur contained in Japanese tea leaves = (Average value of stable isotope ratio of sulfur contained in Chinese tea leaves−X ) / Step of calculating by a calculation formula represented by the standard deviation of the stable isotope ratio of sulfur contained in Chinese tea leaves;
A step of measuring a stable isotope ratio of sulfur contained in a test sample of Chinese or Japanese tea leaves; and if the sulfur stable isotope ratio of the test sample is X ‰ or more, the growing country is China Judgment,
Determining that the country of cultivation is Japan if the sulfur stable isotope ratio of the test sample is less than X ‰;
Said method. A method for determining a farming country or region of a crop, which includes the following steps:
Measuring the stable isotope ratio δ ³⁴ S of sulfur contained in crops known to the country or region of cultivation;
Constructing a database of the sulfur stable isotope ratio δ ³⁴ S with the cultivated country or region from the obtained data;
Measuring a stable isotope ratio of sulfur contained in a test sample of the same type of agricultural product; and determining a cultivated country or region from the sulfur stable isotope ratio of the test sample using the database;
Including the determination method.   The determination method according to claim 5, wherein the crop is tea leaves.   The determination method according to claim 6, wherein the tea leaves are from Japan or China. Furthermore, the determination method as described in any one of Claims 1-7 which determines combining the measured value of carbon stable isotope ratio (delta) ^13C .