KR20150008292A - A method for quality test of wheat using near-infrared spectroscopy - Google Patents

Abstract

The present invention relates to a method for evaluating the quality of wheat, which comprises: a step of measuring a reflectance spectrum for the specimen of the wheat using a near-infrared (NIR) spectroscopy; a step of determining the water content, the ash content, the protein content, and the sedimentation value content of the specimen of the wheat by applying a spectrum value, which is derived from the measured reflectance spectrum, to the water content calibration curve, the ash content calibration curve, the protein content calibration curve, and the sedimentation value content calibration curve of the wheat. According to the present invention, the method for evaluating the quality of the wheat using the NIR spectroscopy is a non-destructive analysis method capable of using raw wheat as the specimen. In addition, the method for evaluating the quality of the wheat is capable of simultaneously analyzing water, ash, protein, and a sedimentation value as the indices of the quality of the wheat by measuring the water, the ash, the protein, and the sedimentation value once, thereby quickly and conveniently evaluating the quality of the wheat when harvesting the wheat.

Description

Technical Field [0001] The present invention relates to a method for quality inspection of wheat using near-infrared spectroscopy,

The present invention relates to a method for measuring a reflection spectrum of a wheat flour using a near-infrared (NIR) spectrometer; Determining the moisture, ash, protein, and precipitation content of the whey sample by substituting the spectral value derived from the measured spectrum into the moisture, ash, protein, and precipitation content calibration curves of the wheat to determine the quality of the wheat ≪ / RTI >

Wheat is one of the three major food crops on the planet. It is a perennial plant of the paddy field and it is about 1 meter in height and it is also called wheat. It produces about 600 million tons of grain each year along with rice and corn from world grain production. It is used as an auxiliary food in the Orient, but it is the main food in the West. The grain is also used as a raw material for beer, and it is used to make bread, cookies and noodles by grinding the grain and making flour.

Wheat is excellent in calories and contains about twice as much protein as rice. The wheat protein contains protein components not found in other grains, and also has higher lipid, calcium, phosphorus and iron contents than rice.

Wheat is suitable for making bread because it contains a protein called gluten which softens the dough. In addition, protein, starch, vitamin E, niacin, riboflavin, thiamine and vitamin B complex, such as essential minerals such as iron and phosphorus are rich in nutrients. In addition to bread, there are many foods that use wheat, such as noodles, household flour, macaroni, spaghetti, cakes, cookies, biscuits, puddings, and various cereals.

In the United States, Canada, and Australia, which are major mill exporters in the world, wheat quality grades are classified and sold. However, in Korea, wheat quality standards have not been established yet. Quality control has not been achieved. The quality of the wheat can be distinguished by considering the quality of the product related to the flour yield and grade, ie, the physicochemical properties of the wheat flour, such as protein and sedimentation, the dough characteristics and the final processability.

As a result of intensive research to find a method for evaluating the quality of wheat quickly and easily in the harvesting stage, the present inventors measured the reflection spectrum of the Wheatland using a near-infrared spectroscope and measured moisture, ash, protein, And the present invention has been completed.

SUMMARY OF THE INVENTION The object of the present invention is to provide a method of measuring a reflectance spectrum for a wheat sample using a near-infrared (NIR) spectroscope; Determining the moisture, ash, protein, and precipitation content of the whey sample by substituting the spectral value derived from the measured spectrum into the moisture, ash, protein, and precipitation content calibration curves of the wheat to determine the quality of the wheat Method.

According to an aspect of the present invention, there is provided a method for measuring a reflection spectrum of a wheat flour using a near-infrared (NIR) spectroscope. Determining the moisture, ash, protein, and precipitation content of the whey sample by substituting the spectral value derived from the measured spectrum into the moisture, ash, protein, and precipitation content calibration curves of the wheat to determine the quality of the wheat ≪ / RTI >

The method for evaluating the quality of wheat according to the present invention is characterized by being a non-destructive method capable of measuring the content of components from the state of the wheat rather than the sample processed into powder. Therefore, by using the near-infrared spectroscope, it is possible to analyze the content of the four components immediately upon harvesting, so that it can be classified according to quality and / or processing use.

Wheat should be analyzed for its quality in order to be used for various processing purposes such as bread, cookies, noodles, etc. In the case of conventional quality analysis methods of wheat, analysis of moisture, ash, protein, As a general method, it has been done through separate experiments. However, this method has a disadvantage in that it is difficult to analyze the wheat quality in a timely manner in the field because it requires a lot of effort and time and complicated sample processing. In addition, in the case of protein content analysis, there is a disadvantage in that it is necessary to perform analysis using a wheat in powder state rather than a grain.

Accordingly, the present inventors have sought to develop a wheat quality analysis method capable of analyzing in a timely manner in order to solve such disadvantages, and using the near-infrared spectroscopy method of the present invention, In addition, it was confirmed that only a single NIR spectroscopy can analyze various factors affecting wheat quality such as moisture, ash, protein and sediment content.

As a test material, the contents of the wheat resources held by the National Institute of Food Science and Technology (RDA) of the Rural Development Administration were used to quantify the content based on the peaks of the graphs formed by the wavelengths using the 2011 product purchase, the 2012 product purchase, The second calibration equation was used for statistical analysis to optimize the calibration curve.

Therefore, the evaluation method of the present invention is characterized in that moisture, ash, protein, and precipitation content can be simultaneously determined by a single measurement.

In the present invention, the "moisture content of wheat" is a characteristic of wheat, which is defined as a percentage of the weight of water to the total weight of the wheat sample. The moisture content of the wheat may affect the storage state. If the moisture content is high in storing the wheat, it may be corrupted during the storage period. Therefore, it is preferable to purchase and store the wheat having a water content of 14% or less. Therefore, wheat having moisture content of more than 14% is preferably separated and stored separately. If necessary, additional drying process or the like can be carried out or processed immediately.

In the present invention, the "ash content of wheat" is expressed as a percentage of the ash content relative to the total weight of the wheat sample, and the ash weight is measured by the amount of the remaining material, for example, ash after the sample is completely burnt. The ash content is defined as the amount of minerals. Since the husk of wheat seeds has more inorganic components than the husked part, the ash content increases when the shell is thicker. Therefore, the ash content is closely related to the milling performance and milling technology of the wheat. In general, as the ash content increases, the color of the flour becomes darker and affects consumer preference.

In the present invention, the "protein content of wheat" is expressed as a percentage of the protein weight with respect to the total weight of the wheat sample. Specifically, the amount of nitrogen contained is measured and converted into the amount of the protein. The protein content of wheat is an important factor that determines wheat quality both quantitatively and qualitatively. When flour is added with water and kneaded, gluten is formed and becomes viscous. They form a tangled network structure, wrapping starch particles and making various doughs. The gluten is composed of gliadin and glutenin as a storage protein which occupies about 80% of total protein, and has an absolute effect on stretchability and elasticity. As such, the protein content of the wheat has a significant influence on the viscosity and elasticity of the resulting dough, which can serve as a reference for distinguishing the processing purpose of wheat flour. The so-called flour, called flour, contains about 8% protein and is used for confectionery such as soft and crispy cookies, sponge cake, and shoe dough with low viscosity of the dough. The strong powder contains 11 to 13% of protein and is highly viscous and is used for general baking such as pie. The gravity powder having a gluten strength midway between the powder and the strong powder can be used for noodles such as noodles and udon noodles.

In the present invention, the "amount of precipitation of wheat" is one of the measurement values indicating the qualitative characteristics of the protein. Specifically, a solution in which wheat flour is uniformly dissolved is prepared, and the solution is allowed to stand for a sufficient time to precipitate, and then the volume of the resulting precipitate is measured. Based on the protein solubility of wheat flour, the precipitate is a value measured based on the fact that the amount of the eluted protein varies depending on the content of the protein or the qualitative characteristics thereof, and thus the sedimentation rate varies, and thus the sedimentation volume varies. Therefore, it is possible to identify the characteristics of wheat flour protein based on the characteristics of the protein, and in general, the higher the settling value, the better the protein content and qualitative characteristics are for baking. Thus, the settling of the measured mill can serve as another factor in determining the milling application.

The moisture content calibration curve of the wheat used to determine the moisture content of the wheat from the near infrared spectrum value according to the present invention is preferably 1) a value derived by applying a first derivative and a linear subtraction method to the NIR spectrum of a standard wheat sample, ) Standard wheat samples were compared with the moisture content measured by a wet moisture analysis method selected from the group consisting of the AACC Method 44-15 method and the AOAC official method 925.10. In one embodiment of the present invention, a value obtained by performing a series of mathematical operations on the NIR spectrum for the same sample on the basis of the moisture content measured by the wet moisture analysis method on a standard wheat sample is measured by the wet method To optimize the error in the direction of minimizing the error so as to obtain a moisture content calibration curve optimized for the wheat. The wet moisture analysis method for measuring the moisture content with respect to the standard wheat flour as the reference value is not limited to the above-mentioned method, and the moisture analysis method known in the art can be used without limitation.

The moisture content calibration curve of the wheat may be y = (0.922 0.005) x + (0.911 0.01), and preferably the moisture content calibration curve of the wheat may be y = 0.922x + 0.911. Here, when x is the spectral value of the wheat sample, the water content measurement value y (%) of the wheat sample can be determined.

The ash ash content calibration curve used to determine the ash content of the wheat from the near infrared spectrum values according to the present invention is preferably 1) the values derived by applying the first order differential and vector normalization to the NIR spectra of the standard wheat samples, ) Standard wheat samples compared to the ash content measured by a wet batch analysis method selected from the group consisting of the AACC Method 08-01 method and the AOAC official method 923.03. In one embodiment of the present invention, a value obtained by performing a series of mathematical operations on the NIR spectrum for the same sample on the basis of the ash content measured by the wet ash analysis method for a standard wheat sample is measured by the wet method To optimize the error in the direction of minimizing the error to yield a wheat optimized ash content calibration curve. The wet ash analysis method for measuring the ash content of the standard wheat flour as the reference value is not limited to the above-mentioned method, and the ash analysis method known in the art can be used without limitation.

The ash content calibration curve of the wheat may be y '= (0.933 0.005) x' + (0.08 0.01), and preferably the ash content calibration curve of the wheat may be y '= 0.933x' + 0.08. Here, when x 'is the spectral value of the wheat sample, the ash content measurement value y' (%) of the wheat sample can be determined.

The protein content calibration curve of the wheat used to determine the protein content of the wheat from the near infrared spectrum according to the present invention is preferably 1) a value derived by applying a first derivative and a multiplication method to the NIR spectrum of a standard wheat sample, 2) Standard wheat samples were optimized by comparing with the protein content measured by a wet protein assay method selected from the group consisting of AACC Method 44-15 method, AACC Method 46-08, AACC Method 46-16 method and AOAC official method 920.87 . In an embodiment of the present invention, a value obtained by a series of mathematical operations of the NIR spectrum for the same sample on the basis of the protein content measured by the wet protein analysis method for a standard wheat sample is measured by the wet method To optimize the error in the direction that minimizes the error so as to derive the protein content calibration curve optimized for wheat. The wet protein analysis method for measuring the protein content of the standard wheat flour as the reference value is not limited to the above-mentioned method, and any protein analysis method known in the art can be used without limitation.

The protein content calibration curve of the wheat may be y "= (0.937 ± 0.005) x" + (0.786 ± 0.01), and preferably the protein content calibration curve of the wheat may be y "= 0.937x" have. Here, when x "is the spectral value of the wheat sample, the protein content measurement value y" (%) of the wheat sample can be determined.

The calibration curve for the precipitation content of the wheat used to determine the precipitation amount of the wheat from the near infrared spectrum value according to the present invention is preferably 1) a value derived by applying a first derivative to the NIR spectrum of a standard wheat sample, 2) The sample may be one that has been optimized by comparing the sedimentation amount measured by a wet precipitation assay method selected from the group consisting of the Dodecyl sulfate of sodium (SDS) sedimentation test method and the AACC method 56-61A have. In an embodiment of the present invention, a value obtained by a series of mathematical operations of the NIR spectrum for the same sample on the basis of the precipitation amount measured by the wet precipitation analysis method for a standard wheat sample is measured by the wet method To optimize the error in the direction of minimizing the error so as to obtain a precipitation content calibration curve optimized for the wheat. The wet sedimentation analysis method for measuring the sedimentation amount with respect to the standard wheat sample as the reference value is not limited to the above-mentioned method, and the sedimentation analysis method known in the art can be used without limitation.

The precipitation content calibration curve of the wheat may be y''' = (0.947 ± 0.005) x '''+ (2.150 ± 0.01), preferably the precipitation content calibration curve of the wheat is y''' = 0.947x '''Lt; / RTI > Here, when x '''is the spectral value of the wheat sample, the measurement value y''' (ml) of the precipitation content of the wheat sample can be determined.

In the present invention, the quality of the wheat can be evaluated by analyzing the wheat, preferably the unmachined wheat, by the near-infrared spectroscopic method, and simultaneously determining the moisture content, the ash content, the protein content and the precipitation content.

In one embodiment of the present invention, the contents of moisture, ash, protein, and sediment obtained by substituting the spectrum of the Wheatmeal measured by NIR spectroscopy into the optimized calibration curve were compared with those of the same sample, (NIR) of the wheat nets according to the present invention was compared with the conventional analytical values, and it was confirmed that the error range was within ± 0.5 (% or ㎖) for all the components (Table 1).

The method of evaluating the quality of wheat using the near-infrared spectroscopic method of the present invention is a non-destructive analysis method which can use the wheat itself as a sample. Since moisture, ash, protein and precipitation value which are indicators of the quality of wheat can be analyzed simultaneously by a single measurement, The quality of the wheat can be evaluated quickly and easily.

FIG. 1 is a graph showing the NIR spectrum and the wavelength region band for each component of a wheat field sample.
Fig. 2 is a graph showing a calibration curve optimized for each component. Fig.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are for further illustrating the present invention, and the scope of the present invention is not limited to these examples.

Example  1: Test material

As the test materials, we used the wheat resources held by the National Institute of Food Science and Technology, the 2011 product purchase, the 2012 product purchase, and the 2012 annual production line.

The samples used were the products of Jeollanam - do and Gyeongsangnam - do (Gimje, Jangseong, Sacheon and Hapcheon) and the parts of the whole country (150 farmhouses in North and South Korea, 48 farmhouses in North and South Kyungsang provinces, 57 farmhouses in Chungcheongnambuk province and 27 farmhouses in Gangwon province in Gyeonggi province). The products were collected at 500 grams at the place where the products were bought, and the oranges were collected from the cultivation sites throughout the country.

The overall test schedule is as follows: Moisture, ash, protein, and sedimentation value were measured using NIR immediately after harvesting products from farms and harvesting farms in June. In July and August, general analysis was performed on the same samples to measure moisture, ash, protein and sedimentation value. In September and October, the NIR data was compared with the data obtained from the general analysis. In November, the calibration curve was optimized by adding data to the existing calibration curve.

Example  2: Conventional wheat quality analysis method

Moisture, ash, protein, and sedimentation value were measured by the conventional wet method for comparison with the nondestructive quality analysis result using the near-infrared spectroscopic method according to the present invention. Moisture analysis was performed according to AACC Method 44-15 method, ash analysis was performed using AACC Method 44-15 method using a furnace, and protein analysis was performed using the American Association of Cereal Chemists (AACC) Method 46-30 using Elementar Analysensester And sedimentation analysis was performed by the SDS-sedimentation test method. The above general analytical methods use powder samples obtained by pulverizing wheat.

2.1. Moisture analysis

It is heated for 1 to 2 hours with the lid of the weighing bottle kept open at 105 ° C (± 1 ° C), and the lid of the weighing bottle is covered. After transferring to a desiccator and cooling, Respectively. The above procedure was repeated until the weight of the weighing bottle became constant (W ₀ , when the weight became constant) with a heating time of about 30 minutes. 3 to 5 g of a sample was placed in a weighing bottle having reached a constant weight and weighed (W ₁ ). The lid of the weighing bottle was opened and dried for 2 to 3 hours, and the lid was closed and transferred to a desiccator and allowed to cool. When the temperature reached room temperature, it was weighed quickly. The lid was then opened and placed in a drier, dried for one hour in the same manner as described above, weighed, and repeated until the weight became constant (W ₂ ).

2.2. Ash analysis

The weighed container was placed in an electric furnace at 600 ° C or higher for several hours, transferred to a desiccator, allowed to cool, and immediately weighed (W ₀ ) when it reached room temperature. A well-dried sample was crushed finely in a crucible reaching the constant weight, and 2 to 5 g of the sample were weighed and weighed (W ₁ ). The above painting crucible was directly transferred to a painting furnace and heated at 550 to 600 ° C until a white or off-white ash was obtained. When the painting was completed, it was left to cool in the painting furnace. When the temperature reached about 200 ° C, it was transferred to a desiccator, cooled, and then weighed quickly (W ₂ ) when it reached room temperature.

2.3. Protein analysis

The Kjeldahl method proceeds in the following four-step reaction.

Decomposition reaction: nitrogen (N) + H ₂ SO ₄ → (NH ₄ ) ₂ SO ₄ + SO ₂ ↑ + CO ₂ ↑ + CO ↑ + H ₂ O ↑

Distilling the _{reaction: (NH 4) 2 SO 4} + 2NaOH → 2NH 3 + Na 2 SO 4 + 2H 2 O

Neutralization reaction: 2 NH ₃ + H ₂ SO ₄ → (NH ₄ ) ₂ SO ₄

Appropriate reaction: H ₂ SO ₄ + ₂ NaOH → Na ₂ SO ₄ + 2H ₂ O

0.5 to 1 g of a powder sample was precisely weighed, the weighed sample was placed in a dissolution tube, and 2 kinds of catalysts (CuSO ₄ + K ₂ SO ₄ ) and 12 to 15 ml of concentrated sulfuric acid were added in order. The decomposition tube was placed in a decomposer preheated to 420 DEG C by using a stand and decomposed by burning for about 50 minutes. When the decomposition was completed, the decomposition tube was taken out and cooled to room temperature. 40% NaOH was added to the decomposed solution, and when the ammonia was distilled by steam, it was absorbed into a saturated solution. The sample was collected in a boric acid solution containing the indicator and titrated with 0.1 N hydrochloric acid standard solution. The protein content was calculated by the following formula.

In the above equation, V is the 0.1N HCl specific concentration of the analytical sample, ml; V ₀ is the 0.1N HCl specific constant for the blank, ml; F is the factor of a 0.1 N HCl standard solution; D is the dilution factor; 0.001401 represents the amount of nitrogen corresponding to 1 ml of 0.1 N HCl solution, g; N is the nitrogen conversion factor; S is the sample weight, g.

The calculated protein content was used as a laboratory value based on the measured moisture content based on a moisture content of 14%.

2.4. Precipitant  analysis

A 2% SDS solution was prepared by dissolving 20 g of SDS (sodium dodecyl sulfate) in 1 L of distilled water. Lactic acid solution was prepared by mixing 1: 8 of lactic acid and distilled water. To 1 L of the 2% SDS solution prepared above, 20 mL of a lactic acid solution was added to prepare an SDS-lactic acid solution. 5 g of wheat flour with a water content of 14% was placed in a 100 ml cylinder, and 50 ml of distilled water was added thereto, followed by shaking for 15 seconds to mix well. After 2 minutes and 4 minutes, they were shaken again for 15 seconds. To the cylinder containing the flour solution was added 50 ml of the previously prepared SDS-lactic acid solution. The cylinder was shaken up and down about 4 times. After 2 minutes, 4 minutes and 6 minutes, the cylinder was shaken up and down about 4 times. After standing for 40 minutes, the settling amount was determined by reading the value of the interface between the precipitated wheat and the solution.

Example  3: Near infrared  Analysis method of wheat quality by spectroscopy

The wheat grain samples were selected, and 50 grains (or 3 g) of good grape were taken and placed in a measuring bottle. The measurement bottle was placed on the optical measurement position of a near-infrared (NIR) spectrometer, irradiated near-infrared, and the reflected light was received to obtain a spectrum. The intensity of the reflected light corresponds to the intensity of the irradiated light minus the intensity of the transmitted light. The spectrum was repeated three times and the procedure was repeated for each sample after replacing the sample. In order to create the calibration curve, the spectrum of all the samples was called up and the optimal calibration curve was created by statistical analysis of the first and second derivatives. The calibration curves were optimized to minimize errors compared to general analytical data.

The wavelength band of each component is shown in Fig.

In order to establish the calibration curve by quantifying the content around the peak of the graph formed according to the wavelength, statistical analysis was performed using the first and second calculus methods. Moisture content curves were calculated by first order differential and straight line substraction. The ash content curves were subjected to first order differential and vector normalization. The protein content curves were multiplicative scatter correction method (MSC ), And the precipitation content curve was mainly applied to the first derivative. The data obtained from the NIR spectra were optimized to minimize the error range by examining the accuracy of the content measurement for each component. The calibration curves for each component thus obtained showed R ² values exceeding 90. Specifically, the protein content is 93.6 calibration curve, calibration curve moisture content 91.6, 94.3 and chimjeonga calibration curve ash calibration curve exhibited a R ² value of 93.4.

The calibration formula for the content of each component thus obtained is as follows:

Moisture content: y = 0.922x + 0.911;

Ash content: y '= 0.933x' + 0.08;

Protein content: y " = 0.937x " + 0.786; And

Precipitation content: y '' '= 0.947x' '' + 2.150.

In the above equations, x to x '''are spectral values for moisture, ash, protein, and sedimentation, respectively. After spectrum measurement for individual samples is performed, the spectrum of the wavelength region band is quantified by the least squares method, Quot; content y) to y '''can be quantified and obtained in a content. An optimized calibration curve for each component is shown in Fig.

The contents of moisture, ash, protein, and sediment obtained by substituting the spectrum of the Wheatmeal measured by NIR spectroscopy into the above optimized calibration curve and the general analytical values for the same samples are shown in Table 1 below. It was confirmed that the values measured using the NIR from wheat gills according to the present invention can be measured at an error range level within ± 0.5 (% or ㎖) for all the components compared with the conventional analytical values.

Claims (9)

Measuring a reflection spectrum for the wheat sample using a near-infrared (NIR) spectroscope;
Determining the moisture, ash, protein, and precipitation content of the whey sample by substituting the spectral value derived from the measured spectrum into the moisture, ash, protein, and precipitation content calibration curves of the wheat to determine the quality of the wheat Way.
The method according to claim 1,
The moisture content calibration curves of the wheat were 1) values obtained by applying first order differential and linear subtraction to the NIR spectra of standard wheat samples, 2) standard wheat samples were composed of AACC Method 44-15 method and AOAC official method 925.10 Wherein the moisture content is measured by a wet moisture analysis method selected from the group consisting of:
3. The method of claim 2,
Wherein the moisture content calibration curve of the wheat is y = (0.922 0.005) x + (0.911 0.01), and when the x is the spectral value of the wheat sample, the moisture content measurement value y (%) of the wheat sample is determined.
The method according to claim 1,
The ash content of the wheat was determined by 1) the first derivative and vector normalization applied to the NIR spectrum of the standard wheat samples, 2) the standard wheat samples were composed of the AACC Method 08-01 method and the AOAC official method 923.03 Wherein the ash content is determined by optimization with respect to the ash content measured by a wet ash analysis method selected from the following:
5. The method of claim 4,
The ash content calibration curve of the wheat is determined as y '= (0.933 ± 0.005) x' + (0.08 ± 0.01), where x 'is the spectral value of the wheat sample, Lt; / RTI >
The method according to claim 1,
2) standard wheat samples were analyzed by AACC Method 44-15 method, AACC Method 46-08, and AACC Method 46-08, respectively. AACC Method 46-16 method, and AOAC official method 920.87. ≪ Desc / Clms Page number 26 >
The method according to claim 6,
The protein content calibration curve of the optimized wheat is y '' = (0.937 ± 0.005) x '' + (0.786 ± 0.01), and when x '' is the spectral value of the wheat sample, (%) ≪ / RTI > is determined.
The method according to claim 1,
The calibration curve of the amount of precipitation of the wheat was determined by 1) a value derived by applying a first differential to the NIR spectrum of a standard wheat sample, 2) a standard wheat sample using a SDS-sedimentation test (SDS) And AACC method 56-61A. ≪ RTI ID = 0.0 > A < / RTI >
9. The method of claim 8,
The calibration curve of the amount of precipitation of the wheat is y '''= (0.947 ± 0.005) x''' + (2.150 ± 0.01), where x '''is the spectral value of the wheat sample, (&Quot;)< / RTI > is determined.

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