JP6861015B2 - Meat fat measurement method - Google Patents

Description

The invention of this application relates to a technique for evaluating the quality of fat in meat.

Techniques for evaluating an object based on optical properties such as absorbance have been conventionally known as one of the main fields of optical measurement. In recent years, near-infrared spectroscopy technology for evaluating the properties of an object by irradiating the object with light containing near-infrared rays and measuring its spectral absorption characteristics has been actively studied and its application is advancing. For example, in Patent Document 1, in order to evaluate the quality of fat in meat, the meat is irradiated with near infrared rays of about 700 to 1000 nm, and reflected light and / or scattered light from the inside of the meat (hereinafter referred to as reflected scattered light) is emitted. The fatty acid content of the meat is measured by catching it.

As is well known, fat in meat is mainly composed of triacylglycerol, and triacylglycerol is an ester bond of glycerol and three fatty acids. Fatty acids are classified according to the length of the carbon chain and the number of carbon double bonds, and are roughly classified into saturated fatty acids and unsaturated fatty acids. Saturated fatty acids such as palmitic acid are known to form hard fats that are difficult to oxidize due to the lack of carbon double bonds.

In terms of meat quality, fats high in saturated fatty acids have a high melting point and give the unpleasant sensation of eating wax when eaten. On the other hand, since unsaturated fatty acids have a low melting point, fats containing a large amount of unsaturated fatty acids are soft and easy to eat. On the other hand, unsaturated fatty acids are more likely to oxidize as the number of carbon double bonds increases. Oxidation produces an odor (oxidizing odor), so even if there are too many unsaturated fatty acids, it cannot be said to be a good fat.
Among unsaturated fatty acids, monovalent unsaturated fatty acids such as oleic acid are said to be less likely to be oxidized than divalent or higher unsaturated fatty acids, and to give appropriate softness and good flavor. Therefore, how much monovalent unsaturated fatty acid such as oleic acid is contained in fat is often referred to in evaluating the quality of fat.

For these reasons, when the meat fat is evaluated by using near-infrared spectroscopy, the ratio (composition value) of fatty acids forming the fat is measured. Specifically, for example, the ratio of oleic acid, which is a monovalent unsaturated fatty acid, to the whole (total fatty acid) is measured by near-infrared spectroscopy.
At the time of measurement, a near-infrared spectroscopic measuring apparatus as disclosed in Patent Document 1 is used. The device includes a probe that irradiates near-infrared light and captures reflected scattered light from the sample. A probe is applied to the surface of the meat to be evaluated, the meat is irradiated with near-infrared light, and the reflected light scattered light is taken in for spectroscopic measurement. By analyzing the obtained spectral spectrum waveform, the fatty acid composition value in the sample (meat fat) can be obtained.

FIG. 8 is a diagram showing a measurement example of a near-infrared absorption spectrum of a certain pork fat. The horizontal axis of FIG. 8 is the wavelength, and the vertical axis is the absorbance. Absorbances vary in many samples, but there are several peaks of absorbance at approximately the same wavelength in each spectrum. These peaks indicate the light absorption of fatty acids.
In the actual measurement, the near-infrared absorption spectrum is measured by a measuring device (spectral measuring device) for a large number of reference samples (samples having a known fatty acid composition value) whose fatty acid composition values are measured using, for example, gas chromatography. Then, the calibration curve data is created by analyzing the relationship between the known fatty acid composition value and the measured near-infrared absorption spectrum using a statistical method (chemometrics). That is, for each data (each absorption spectrum) obtained from a large number of reference samples, calibration curve data for each fatty acid is obtained. At this time, the measured near-infrared absorption spectrum is appropriately subjected to preprocessing such as smoothing, noise removal such as second derivative, and waveform conversion.

Then, the prepared calibration curve data is applied to a near-infrared absorption spectrum obtained by measuring a sample having an unknown fatty acid composition value to estimate the fatty acid composition value of each meat fat and use it as an evaluation of lipid. .. Since the meat evaluation is performed at various places such as the shipping inspection line of each meat factory, the measuring device is used at each place. Therefore, the measuring device that obtained the calibration curve data as described above is regarded as the master device (master unit), and another measuring device (slave unit) that incorporates the calibration curve obtained by the master unit for measurement at each location. Is used. Although the slave unit is a measuring device with the same specifications that uses exactly the same parts as the master unit, there is a difference in optical performance due to slight variations in each part used and slight variations in adjustment when assembled as a device. Come on. Therefore, even if the same sample is measured, the measurement result of each slave unit is slightly different from that of the master unit. Therefore, a value for correcting the deviation of the measurement result is set for each slave unit. Setting this correction value is called relocation of the calibration curve. By applying this correction to the fatty acid composition value estimated by the slave unit, the same fatty acid composition value as that of the master unit can be obtained.

Japanese Patent No. 5676588

Journal of the Illuminating Engineering Institute, Vol. 93, No. 8A, pp. 492-500

As described above, the evaluation of meat lipids is performed by applying near-infrared spectroscopy, and a measuring device of the slave unit that has been priced (relocation of the calibration curve) to the master unit is used. The fatty acid composition value of each sample is measured.
In the evaluation and measurement of meat fat using such a measuring device at each site, the characteristics of each slave unit inevitably change slightly during use, so calibration is required. Factors of characteristic change are deterioration of the light source, change in sensitivity of the light receiver, slight foreign matter adhering to the optical element, and the like. Due to these changes in characteristics, the measuring device needs to be calibrated on a regular basis.

In particular, in the measurement of meat lipids by near-infrared spectroscopy, the difference in absorption of each fatty acid with respect to light in the near-infrared region is often slight, and the fatty acid composition value is obtained by capturing the slight difference in the absorption spectrum waveform. There are many. Therefore, usually, the absorption spectrum is secondarily differentiated, a calibration curve is created based on the second derivative, and the prepared calibration curve is applied to obtain the composition value. Since the fatty acid composition value is obtained by capturing the slight difference in the absorption spectrum in this way, changes in the characteristics of the measuring device have a large effect on the accuracy of lipid measurement, and slight output fluctuations of the light source and adhesion to the optical system Even a slight change in the characteristics of the measuring device, such as noise caused by foreign matter such as dust, has a great influence on the measurement accuracy. Therefore, calibration is a very important factor for highly reliable evaluation.

For calibration, a reference sample (fat) is required as in the case of preparing a calibration curve, but there is no practical reference sample that can be used in the field of meat lipid evaluation. When obtaining a reference sample, a part of the fat block used as the reference sample is collected, and the fatty acid composition value is precisely measured using a gas chromatography device or the like. The reference sample prepared in this way is brought to the site of meat lipid evaluation and calibrated, but there are some problems.

One is the deterioration of the reference sample. Since the reference sample is a block of fat collected from meat, it is easily oxidized. In particular, in order to measure the composition value of unsaturated fatty acids such as oleic acid, the reference sample must also contain such unsaturated fatty acids and is therefore prone to oxidation. Since optical properties such as absorbance change significantly due to oxidation, there is a risk that the sample cannot be used as a reference sample in a short period of time.

In addition, most unsaturated fatty acids have a low melting point and are easily softened. For example, the melting point of oleic acid is 13.4 ° C., and fat containing oleic acid to some extent softens considerably at room temperature of about 20 ° C. The degree of softening depends on the temperature, but the softening greatly changes optical characteristics such as absorbance. Therefore, when calibrating, it is necessary to perform the calibration at a temperature at which the fat does not soften, and this temperature is often below the freezing point. However, if there is no space below freezing (freezing room) at the site, calibration cannot be performed, and even if there is, it is complicated to bring in a measuring device for calibration.

Even if the reference sample is stored in a frozen state, deterioration such as oxidation occurs. Even if fat is not oxidized, impurities such as blood are likely to be oxidized or deteriorated.
Furthermore, when calibrating, it is necessary to apply a probe to the reference sample to irradiate light and capture reflected scattered light. However, if the reference sample is repeatedly used for calibration, it is likely to wear and dents, which is used for optical measurement. There is a problem in terms of reproducibility. This point becomes more remarkable in the reference sample having a large amount of unsaturated fatty acids.

It is conceivable to give up on-site calibration using the reference sample, return the measuring device to the manufacturer, and calibrate based on the master unit, but even in the case of the master unit, calibrate regularly in consideration of changes over time. There is a need and basically the same problem. That is, it is necessary to calibrate using the reference sample when the master calibration curve data is acquired, but it is difficult to store the reference sample without deterioration. Therefore, it is a very troublesome work to measure a part of the sample again by a gas chromatography device or the like to measure the composition value of each fatty acid and use it as a reference sample, measure it again using it, and then price it to the slave unit. It is necessary for highly accurate calibration.

In this way, although near-infrared spectroscopy has come to be widely used for evaluating the quality of meat fat, calibration of measuring devices is required for stable and long-term evaluation with high accuracy. A reference sample with stable properties is required. Nevertheless, the current situation is that no practical and satisfactory reference sample has been provided.
The invention of the present application has been made in view of such a situation, and an object of the present invention is to enable highly accurate and stable evaluation of the quality of meat fat by near-infrared spectroscopy for a long period of time .

In order to solve the above problems, the invention according to claim 1 of this application is a reference sample for near-infrared spectroscopic measurement of a meat fatty acid composition value obtained by saponifying the fat of meat of the same type as the meat for which the fatty acid composition value is to be measured. Is a meat fat measuring method for measuring the fatty acid composition value of meat fat using
A light source that emits light containing near infrared rays, an optical system that irradiates a sample that is fat of meat with light from the light source, a spectroscope that disperses reflected light and / or scattered light from the light-irradiated sample, and a spectroscope. The absorption spectrum of the sample is calculated from the detector that detects the light dispersed in the above and the spectral intensity distribution obtained by the detector, and the composition value of the specific fatty acid of the sample is calculated based on the calculated absorption spectrum. It is a method of measuring meat fat using a measuring device equipped with a computer in which the program is installed.
The composition value of a specific type of fatty acid obtained for the sample and the composition value of the same type of fatty acid obtained by the same program for the reference sample for near-infrared spectroscopic measurement of the meat fatty acid composition value using the same measuring device. It has a configuration in which a value is compared and calibration is performed based on the difference.
Further, in order to solve the above problems, the invention according to claim 2 is a method in which a plurality of reference samples for near-infrared spectroscopic measurement of meat fatty acid composition value are used in the configuration of claim 1, and each meat fatty acid. Composition values The reference samples for near-infrared spectroscopy have different composition values for the same type of fatty acids.
This is a method of calibrating these meat fatty acid composition values of reference samples for near-infrared spectroscopic measurement by comparing them with the composition values of the same type of fatty acids obtained by the same program using the same measuring device.
The storage unit of the computer stores calibration curve data for obtaining the composition value of the specific type of fatty acid, and the program is a program for obtaining the composition value from the calibration curve data.
Each meat fatty acid composition value has a configuration in which the composition value of the fatty acid obtained from the reference sample for near-infrared spectroscopic measurement is statistically processed and the calibration curve data is updated.

As described below, the reference sample used in the invention of claim 1, wherein the application is easy to handle because the fatty acid is solidified as a fatty acid salt, the deformation is small repeated use and also dents There is no problem of deterioration of measurement reproducibility due to. In addition, by removing impurities, the accuracy as a measurement standard can be improved, the usable temperature range is widened to raise the melting point, and it is an extremely practical reference sample that can be used at room temperature. ..
Further , according to the invention of claim 2 , in addition to the above effects, when measuring the composition value of the same type of fatty acid, calibration is performed using a plurality of standard samples, and thus more accurate in this respect. It is calibrated. Then, since the calibration curve data referred to by the program is updated in the calibration, this point is also convenient.

It is a front sectional schematic which showed the structure of the reference sample kit containing the reference sample for measuring meat fatty acid used in embodiment. It is a figure which shows the absorption spectrum of a plurality of beef tallow soap which can be a reference sample. It is a figure which shows the result of the experiment which confirmed the characteristic stability of the reference sample used in an embodiment. It is a figure which shows the result of the experiment which investigated the temperature characteristic of a certain beef tallow soap which can be a reference sample used in an embodiment. It is the schematic of the meat lipid measuring apparatus used in the meat lipid measuring method of embodiment. FIG. 5 is a schematic front cross-sectional view of the probe 42 shown in FIG. It is a diagram showing the updating of the calibration curve data using a reference sample in the embodiment. It is a figure which showed the measurement example of the near-infrared absorption spectrum of a certain pork fat.

Next, a mode for carrying out the applied invention (hereinafter referred to as an embodiment) will be described.
FIG. 1 is a schematic front sectional view showing the structure of a reference sample kit including a reference sample for measuring meat fatty acids used in the embodiment.
As shown in FIG. 1, the reference sample kit includes a reference sample for measuring meat fatty acids (hereinafter, abbreviated as a reference sample) 1, a sample case 2, and an antioxidant 3.
The reference sample 1 is formed by saponifying the fat of the same kind of meat as the meat for which the lipid is to be measured. In this embodiment, the reference sample 1 is a block having a substantially rectangular parallelepiped shape, but may have a columnar shape or other shape.

The sample case 2 contains the reference sample 1. The sample case 2 includes an upper lid 21 and a case body 22. The upper lid 21 is in close contact with the case body 22, and the reference sample 1 is enclosed in the sample case 2.
The sample case 2 has a translucent portion that at least transmits light in the near-infrared region used for measurement. In this example, the upper lid 21 is made of a translucent material such as acrylic resin, and the upper lid 21 is a translucent portion. The inner surface of the case body 22 may be black to reduce reflected light. The entire sample case 2 may be translucent.
The antioxidant 3 is enclosed in the sample case 2 together with the reference sample 1. Ascorbic acid, for example, is used as the antioxidant 3.
The sample kit includes a display that displays information that allows the composition value of a specific type of fatty acid in the reference sample 1 to be known. In this embodiment, the sample case 2 also serves as a display unit, and information is described at a position (for example, the bottom surface) that does not interfere with the measurement of the sample case 2. In this embodiment, this information is the sample ID.

Next, the reference sample 1 will be described more specifically. In this embodiment, it is assumed that beef lipids in meat are evaluated. Therefore, the reference sample 1 is for near-infrared spectroscopic measurement of beef fat, and is made by saponifying beef fat (beef fat soap). More specifically, the reference sample 1 is a soap made by saponifying meat fat (beef tallow soap in this embodiment), and the composition value of at least one type of fatty acid is known for the soap. become. This known fatty acid composition value is a reference composition value indicated by the reference sample 1. Hereinafter, this value is referred to as a display value.
There are roughly two methods for obtaining such a reference sample 1. One is to separate a part from the fat mass from beef for meat in advance, measure each fatty acid composition value with a gas chromatography device or the like to obtain a displayed value, and saponify the rest as described above. The method. The other is a method of measuring each fatty acid composition value of the saponified beef tallow (beef tallow soap) as described above using a master unit and using the measured value as a displayed value (the acquisition of the displayed value will be described later). To do).

When preparing the beef tallow soap used as the reference sample 1 used in the embodiment, first, a lump of fat is put in water with a little salt and heated. Then, after confirming that the fat is completely melted, cool it. Since fat is lighter than water, it hardens on the upper side. Then, by removing the liquid in the lower layer, impurities such as blood are removed together with water.
The fat thus purified is heated again to melt it into a liquid state. Then, caustic soda is dissolved in purified water to make caustic soda water, and the melted fat is poured into the caustic soda water and stirred uniformly with a stirrer. When the whole becomes cloudy evenly and becomes thick like custard cream, pour it into a container (mold) prepared in advance. This is left to dry and solidify. Since no solidifying agent is used, it usually takes several weeks to solidify.

According to the inventor's experiment, it was found that the fat saponified in this way has exactly the same spectrum as the absorption spectrum of the fat before saponification and can be used as the reference sample 1. Hereinafter, a more specific example will be described.
FIG. 2 is a diagram showing absorption spectra of a plurality of beef tallow soaps that can serve as reference samples. In the example shown in FIG. 2, 12 beef tallow soaps were made from fats separated from 12 different meats. Specifically, 6.3 g of caustic soda was dissolved in 17.5 g of purified water to prepare caustic soda water. 50 g of each fat purified by the above-mentioned method was put into caustic soda water and stirred. Since caustic soda generates heat when dissolved in water, the periphery of the container was cooled with ice, and each fat was added at about 42 ° C. After stirring sufficiently uniformly, each was left to solidify to obtain each beef tallow soap.

FIG. 2 shows the absorption spectra of the 12 beef tallow soaps (Nos. 1 to 12) thus obtained. It has been confirmed that these beef tallow soaps have exactly the same absorption spectra as those measured in the state of beef tallow before saponification. In addition, when the composition value of each fatty acid was measured by applying the calibration curve data already acquired for the measuring device used in the experiment, the composition value of each fatty acid in the state of beef tallow and the composition value of each fatty acid in the saponified state were obtained. It has also been confirmed that there is no particular change. Such results indicate that beef tallow soap obtained by saponifying meat of the same type as the meat for which lipids are to be measured can be used as a reference sample 1 in the evaluation of lipids by near-infrared spectroscopy.

Such a reference sample 1 has many advantages as follows.
First, since the fatty acid is solidified as a fatty acid salt, it is easy to handle. Further, since it is a solid sample, it is less deformed, and even if it is used repeatedly, there is no problem of deterioration in measurement reproducibility due to dents and the like.
Furthermore, the accuracy as a measurement standard can be further improved by removing impurities during saponification. That is, if impurities are mixed, there is a possibility that a value deviating from the fatty acid composition value measured by another method such as gas chromatography may occur due to the influence, but by sufficiently removing the impurities, the value may be different. Such a possibility can be virtually eliminated.

Further, since it is solidified, it can be put in a case together with the antioxidant 3 and sealed, so that antioxidant is easy. Therefore, it can be stably used for a long period of time as a standard for calibration.
Since each fatty acid is a fatty acid salt, it has a high melting point. Therefore, the usable temperature range is widened. It can also be used at room temperature, eliminating the need for calibration work at low temperatures such as below freezing.

More specifically, for example, the melting point of oleic acid, which is a monounsaturated fatty acid, is 13.4 ° C., but the melting point of sodium oleate is 232 to 235 ° C. The melting point of linoleic acid, which is a polyunsaturated fatty acid, is −5.1 ° C., while that of sodium linoleate is 192 ° C. As described above, since the fatty acid has a high melting point due to the bond with sodium, it does not melt or soften even at room temperature and can be used as a standard for calibration.

Next, the results of an experiment confirming the characteristic stability of the reference sample 1 will be described. FIG. 3 is a diagram showing the results of an experiment confirming the characteristic stability of the reference sample used in the embodiment. In this experiment, 12 beef tallow soaps whose absorption spectra are shown in FIG. 2 were examined for fluctuations in measured values over a 5-month period.
Measurements were made for several different fatty acids, but as an example, the results for palmitoleic acid, oleic acid and palmitic acid are shown in FIG. That is, for each of the 12 beef tallow soaps, one month, two months, three months, four months, and five months after preparation, each calibration curve was applied to palmitoleic acid, oleic acid, and palmitic acid. The composition value of was measured. In FIG. 3, (1) shows the composition value of palmitoleic acid, (2) shows the composition value of oleic acid, and (3) shows the composition value of palmitic acid. Each vertical axis of FIGS. 3 (1) to 3 (3) shows the fluctuation with respect to the measured value immediately after production as a percentage. Each horizontal axis is the number of each beef tallow soap.

As shown in FIGS. 3 (1) to 3 (3), the measured fluctuations in the fatty acid composition values of all the beef tallow soaps Nos. 1 to 12 were within the range of only about 0.5%. It was confirmed that the characteristics were maintained extremely stably. Although illustration and description are omitted, when the composition values of other unsaturated fatty acids and saturated fatty acids were measured, the fluctuations in the composition values were also very small, about 0.5% or less.

Next, the temperature characteristics of each beef tallow soap were also investigated in experiments, so they will be explained. FIG. 4 is a diagram showing the results of an experiment investigating the temperature characteristics of a certain beef tallow soap that can be a reference sample used in the embodiment. In this experiment, the fatty acid composition value of a specific beef tallow soap among Nos. 1 to 12 was measured in each temperature environment of 4 ° C., 20 ° C. and 30 ° C. Further, as a comparative example, the unsaponified beef tallow in a normal state was also measured in the same manner under the temperature conditions of 4 ° C., 20 ° C. and 30 ° C. Of these, FIG. 4 also shows the measurement results of palmitoleic acid, oleic acid, and palmitic acid in the sample as beef tallow.

As shown in FIGS. 4 (1) to 4 (3), in the measurement of each fatty acid composition value, when normal unsaponified beef tallow is measured, each fatty acid measurement value changes greatly depending on the temperature. That is, the composition value of palmitoleic acid fluctuates by about 2%, and that of oleic acid fluctuates by about 4%. In addition, palmitic acid fluctuates by about 3%. On the other hand, in the case of beef tallow soap, the fluctuation of the composition value of any fatty acid is less than 1%, and the fluctuation of the measurement result depending on the temperature is extremely small.

In addition, each beef tallow soap becomes the reference sample 1 by obtaining the displayed value as described above. As described above, the displayed value may be measured in advance with a gas chromatography device or the like, or the saponified product may be measured with the master unit, but it is easier to measure with the master unit. Since a calibration curve (hereinafter referred to as a reference calibration curve) has been obtained from a large number of reference samples (reference samples of beef tallow as they are) whose fatty acid composition values have been measured by a gas chromatography device or the like on the master unit. If the produced beef tallow soap is measured with a master unit and the composition value of each fatty acid of the beef tallow soap is measured by applying a reference calibration curve, it becomes the displayed value of the beef tallow soap. At the stage before saponification, a sample collected from the same sample may be subjected to a gas chromatography device or the like to obtain the composition value of each fatty acid and used as each display value, but it is troublesome considering the preparation of a large number of reference samples. .. Therefore, it is preferable to measure it with the master unit and use it as the displayed value.

Next, an embodiment of the invention of the method for measuring meat fatty acid using such a reference sample 1 will be described.
First, the measuring device used will be described. FIG. 5 is a schematic view of a meat lipid measuring device used in the meat lipid measuring method of the embodiment.
As shown in FIG. 5, the meat lipid measuring device (hereinafter, simply referred to as a measuring device) 4 includes a device main body 41 and a probe 42. A flexible cable 43 is provided so as to connect the apparatus main body 41 and the probe 42, and the optical fiber 431 is housed in the flexible cable 43. In addition to the spectroscope 44, the detector 45, and the computer 46, a data processing circuit 471, an interface 472, and the like are provided in the apparatus main body 41.

FIG. 6 is a schematic front sectional view of the probe 42 shown in FIG. As shown in FIG. 6, the probe 42 is provided with a light source 421 and a holder 422 that holds the light source 421 so that the sample is irradiated with the light from the light source 421. The light source 421 emits light having a wavelength in the range of at least 700 nm to 1000 nm, and for example, a halogen lamp is used. In the probe 42, the incident end of the optical fiber 431 is arranged at a position where the reflected scattered light from the sample irradiated with the light from the light source 421 is incident. Further, the measuring device includes an output unit 47 that outputs a measurement result.

As shown in FIG. 6, the probe 42 has a measurement opening 423, and a right-angle prism 424 is provided at a position facing the measurement opening 423. The incident end of the optical fiber 3 is provided at the same height as the right-angle prism 424. An optical window is fitted in the measurement opening 423 in order to prevent contamination inside the housing 92.

Inside the housing 92, an optical axis (hereinafter, irradiation optical axis) A1 for irradiating the sample with light and an optical axis for capturing the reflected scattered light from the light-irradiated sample (hereinafter, captured light). Axis) A2 is set. The capture optical axis A2 is an axis that passes through the center of the total reflection surface of the right-angle prism 424, is bent at a right angle on the total reflection surface, and reaches the center of the incident end of the optical fiber 431. The irradiation optical axis A1 is 30 to 35 ° with respect to the capture optical axis A2.
A condenser lens 425 is provided on the capture optical axis A2. The condenser lens 425 collects the light from the sample and causes it to enter the optical fiber 431.

A power supply circuit 48 for each light source 421 is provided in the apparatus main body 41. The power supply circuit 48 and each light source 421 are connected by a power supply cable 481. The optical fiber 431 and the power supply cable 481 are bundled as one flexible cable 43.
The spectroscope 44 can decompose light with a required resolution for each wavelength in the wavelength range used. As the spectroscope 44, one using a diffraction grating, a Fourier transform spectroscope, or all other spectroscopes can be adopted.

The detector 45 receives the light dispersed by the spectroscope 44 and converts it into an electric signal. In the apparatus shown in FIG. 5, a linear array sensor is used for the detector 45, and photoelectric conversion is performed in the wavelength range used without sweeping the diffraction grating.
The detector 45 and the computer 46 are connected via a data processing circuit 471 and an interface 472. The data processing circuit 471 is for taking the processed data into the computer 46 in addition to the processing such as amplification and A / D conversion, and a USB interface or the like is adopted.

The computer 46 is provided with a microprocessor as an arithmetic processing unit, a memory such as a ROM or a RAM, and the like. In the present embodiment, the output unit 47 is a display included in the computer 46. Further, measurement software is installed in a storage unit (for example, a memory) of the computer 46. This software includes a program that calculates an absorption spectrum from the obtained spectral data (spectral intensity distribution) and calculates a composition value of a specific fatty acid from the calculated absorption spectrum.

The measuring device has an input unit for selecting which fatty acid composition value to measure. For example, the display is a touch panel type input unit, and the software includes an input program. The input program is configured so that a screen for selecting one of the fatty acids is displayed on the display 47, and each argument is set in the program so that the composition value is calculated for the selected fatty acid.

When measuring the lipid of meat using the measuring devices shown in FIGS. 5 and 6, the probe 42 is held in the hand with the light source 421 turned on, and the front plate portion 921 of the housing 92 is in contact with the surface of the sample. Get in touch. The light from the light source 421 is reflected or scattered on the surface or inside of the sample and returned, and is emitted through the surface of the sample. This reflected scattered light reaches the incident end of the optical fiber 431 and is guided by the optical fiber 431 to reach the spectroscope 44. Then, after being separated into light of each wavelength by the spectroscope 44, it reaches the detector 45 and is photoelectrically converted, and the output data is sent from the detector 45 to the computer 46. The reflected scattered light may be referred to as interactivity reflected light in the sense that it is reflected light from the inside of the sample.

A measurement program is activated in the computer 46, and the measurement program processes the sent output data to calculate the spectral intensity distribution, reads out the reference spectral intensity stored in the memory, and compares it with the reference spectral intensity. The absorption spectrum (spectral absorption rate) of the sample is calculated by. Then, the calculated absorption spectrum is statistically processed, and the calibration curve data is applied to calculate the composition value of a specific fatty acid. For example, when measuring the composition value of oleic acid, after performing statistical processing in which the absorption wavelength of oleic acid is weighted by a coefficient, the calibration curve data of oleic acid is applied to obtain the composition value of oleic acid. obtain. The composition value of the obtained oleic acid is displayed on the display, and the value is used as an evaluation of the lipid of the meat.

When the meat lipid measurement is repeated in this way, the measuring device is calibrated as necessary. Calibration is performed on a regular basis, such as once a day, or when a value that seems to be abnormal is obtained. When calibrating, prepare a reference sample kit. The sample ID is written on the bottom surface of the sample case 2. Then, a list showing each display value of the reference sample 1 specified by the sample ID is separately provided. The operator makes measurements using the sample kit while selecting fatty acids at the input section. That is, with the reference sample 1 still contained in the sample case 2, the probe 42 is brought into contact with the transparent upper lid of the sample case 2 to perform measurement. Then, it is determined whether or not the composition value of the fatty acid displayed on the display 47 sufficiently matches the display value of the sample ID described in the list. If they match, it is considered that there is no particular problem with the measuring instrument, and the value obtained for each sample is used as it is as the fatty acid composition value.

If they do not match, the difference is taken into consideration when evaluating the lipid. For example, when the composition value of the fatty acid measured using the reference sample 1 is 30% and the displayed value of the fatty acid is 27%, the composition of each fatty acid subsequently performed using the measuring device. The value shall be the measured value minus 3%.

In the above calibration work, it is judged that the measured value of each fatty acid is uniformly increased by 3% due to an internal factor in the measuring device, but when calibrating more finely, each fatty acid should be calibrated. It may be done. That is, the difference from the displayed value of the measured value of fatty acid A in the reference sample 1 is used for calibration of fatty acid A, and the difference from the displayed value of the measured value of fatty acid B is used for calibration of fatty acid B.・ ・ It is like that.

In addition, a plurality of reference samples 1 may be used to perform calibration for one type of fatty acid. In this case, the calibration curve data stored in the measuring device may be updated according to the measured values obtained from the plurality of reference samples 1. This point will be described with reference to FIG. Figure 7 is a diagram showing the updating of the calibration curve data using a reference sample in the embodiment.
In FIG. 7, the calibration curve of a certain type of fatty acid in the master unit is shown by a solid line. This calibration curve is a reference calibration curve as described above, and is obtained by measuring a large number of reference samples whose composition values have been measured in advance with an analyzer such as a gas chromatography apparatus and performing statistical processing.

Further, the alternate long and short dash line in FIG. 7 indicates a calibration curve at the time of shipment of a certain slave unit (calibration line of the slave unit at the time of shipment). As described above, the calibration curve of the slave unit at the time of shipment is slightly deviated from the reference calibration curve created by the master unit, and therefore is corrected at the time of shipment. The correction is a work of setting a coefficient (correction value) to be multiplied so that the factory calibration curve becomes the reference calibration curve. The set correction value is stored in the storage unit of the slave unit and is used when actually measuring the fat sample and measuring the fatty acid composition value. The correction value may be uniform for each fatty acid, but is often set for each fatty acid.

When the evaluation of fat quality is repeated using the measuring device of the handset shipped with the correction value set in this way, the calibration work is performed as described above. In this case, multiple reference samples are used for calibration of the same type of fatty acid. In this example, three reference samples 1a, 1b, and 1c are used, and an example of the obtained composition value is shown in FIG. For these reference samples 1a, 1b, 1c, each display value is obtained by applying a reference calibration curve using a master unit, and straight lines obtained by regression processing of three reference samples 1a, 1b, 1c. (Two-dot chain line) should be the same as the factory calibration curve (single-dot chain line) under normal conditions, but it will not be the same due to changes in the characteristics of the measuring device over time. In this case, the correction value for making the deviated calibration curve the reference calibration curve is recalculated, and the corrected value is updated and stored in the storage unit of the measuring device. This makes it possible to measure the fatty acid composition value with the same accuracy as that of the master unit. When a program for recalculating the correction value is installed in the measuring device and calibration is performed using a plurality of reference samples 1, the program is executed. In this case, it is preferable to use three or more reference samples 1 having different display values.

When calibration was performed using a plurality of reference samples 1, if the deviation between the displayed value and the measured value was uniform, for example, the measured value of all three reference samples 1 was -3% from the displayed value. In some cases, the calibration may be performed by simply increasing the correction value by + 3% without recalculating the correction value.
In any case, more reliable lipid evaluation can be performed by measuring the composition value of each fatty acid with a near-infrared spectrophotometer while appropriately calibrating using the reference sample 1. Since the reference sample 1 is solid, easy to handle, and maintains stable characteristics for a long period of time, highly reliable meat lipid evaluation can be performed stably and easily for a long period of time.

The fact that the sample case 2 has a translucent portion has an advantage that the measurement can be performed without opening the sample case 2. The sample case 2 may be opened during the calibration work, and the reference sample 1 may be taken out for measurement. However, in this configuration, the reference sample 1 is exposed to the outside air and is easily oxidized. The structure having a translucent portion has a significance of further preventing oxidation so that it can be stably used as a measurement standard for a longer period of time. The upper lid 21 may be completely fixed to the case body 22 by a method such as adhesion, or may be detached when a certain amount of force is applied. In addition, a sealing label or the like may be attached so that it can be seen that the package has been opened.

In addition, the fact that the reference sample kit includes a display object is significant in simplifying the calibration work. If the reference sample kit does not include a display object, it will take time and effort for the operator to know the display value of the reference sample 1, for example, by accessing the manufacturer's website, but in the embodiment, There is no such trouble.
In this case, the displayed material may be a separately provided material such as an instruction manual, but it is necessary to have such a material at hand at the time of calibration. In the configuration in which the sample case 2 also serves as a display object, it is not necessary and it is convenient.
When the information displayed on the displayed object is the displayed value itself, it is necessary to display a plurality of displayed values when measuring and calibrating a plurality of types of fatty acids with one reference sample 1. In this case, if the sample case 2 also serves as a display object, the space for displaying may be insufficient. In this case, it is preferable to display the sample ID and provide a separate list.

The advantage of the reference sample 1 used in the embodiment is derived from the feature of the saponification treatment that the characteristics of the light absorption spectrum in the near infrared region are stably maintained for a long period of time. Therefore, it can be adopted as long as the absorption spectrum can be stably specified for a long period of time without obtaining the reference sample 1 by saponifying the fat derived from meat. For example, in the extreme, it may be an absorption filter such as a colored glass filter.

However, it needs to have an absorption spectrum that is fairly consistent with the meat fat being evaluated and that it is stable for a long period of time. The fact that they match to a considerable extent means that they match to the extent that they can be adjusted by setting a correction value with respect to the absorption spectrum of fat derived from meat obtained from the reference calibration curve. It is almost impossible to make a filter in which the absorption spectra of meat-derived fat match to that extent, according to the research of the inventor. In addition, fat materials containing various fatty acids such as oleic acid are also industrially produced, and it is conceivable to saponify such industrially produced fat materials as a reference sample, but the invention According to one's research, saponified solidified products of such industrially produced fat materials were also produced to have an absorption spectrum that was sufficiently consistent with the absorption spectrum derived from meat obtained from the reference calibration curve. Very difficult to do.

On the other hand, according to the reference sample 1 formed by saponifying a fat of the same type as the meat fat to be evaluated as in the embodiment, the absorption spectrum does not change due to saponification, so that it is suitably used as a reference sample. can do. In this case, the "homogeneous" means beef-derived fat if the beef lipid is to be evaluated, and pork-derived fat if the pork lipid is to be evaluated. However, since there are various varieties of beef, for example, if you are trying to evaluate the qualities of Wagyu beef, it is more preferable to saponify the fat derived from Wagyu beef. As for pork, for example, if the fat of black pig is to be evaluated, the one obtained by saponifying the fat derived from black pig is more preferable.
Although it has been explained that the absorption spectrum does not change due to saponification, even if it does change, it can be used without any problem as long as it can be adjusted to the reference calibration curve by setting the above correction value.

In the above embodiment, the saponification is to produce sodium fatty acid using caustic soda, but it may be saponification to produce potassium fatty acid using potassium hydroxide.
Moreover, although beef fat was taken as an example of lipid evaluation, the same can be applied to the qualities of other meats such as pork and chicken. When evaluating fat, a more accurate fatty acid composition value can be obtained by measuring the part where only fat is agglomerated than the part where lean meat and fat are mixed (marbling, etc.). Therefore, it is more preferable as a lipid evaluation.
In the above embodiment, the sample ID is displayed on the sample case 2, but the displayed value of a specific type of fatty acid of the reference sample may be displayed. In this case, a reference sample is prepared and used for each type of fatty acid whose composition value is to be measured.

1 Reference sample 2 Sample case 3 Antioxidant 4 Meat fat measuring device 41 Device body 42 Probe

Claims (2)

Meat fatty acid composition value obtained by saponifying the fat of meat of the same type as the meat for which the fatty acid composition value is to be measured Meat fat measurement method for measuring the fatty acid composition value of meat fat using a reference sample for near-infrared spectroscopic measurement And
A light source that emits light containing near infrared rays, an optical system that irradiates a sample that is fat of meat with light from the light source, a spectroscope that disperses reflected light and / or scattered light from the light-irradiated sample, and a spectroscope. The absorption spectrum of the sample is calculated from the detector that detects the light dispersed in the above and the spectral intensity distribution obtained by the detector, and the composition value of the specific fatty acid of the sample is calculated based on the calculated absorption spectrum. It is a method of measuring meat fat using a measuring device equipped with a computer in which the program is installed.
The composition value of a specific type of fatty acid obtained for the sample and the composition value of the same type of fatty acid obtained by the same program for the reference sample for near-infrared spectroscopic measurement of the meat fatty acid composition value using the same measuring device. A method for measuring meat fat, which comprises comparing with a value and calibrating based on the difference. A method of using a plurality of reference samples for near-infrared spectroscopic measurement of the meat fatty acid composition value, and each of the reference samples for near-infrared spectroscopic measurement of the meat fatty acid composition value has different composition values for the same type of fatty acid. It is a thing
This is a method of calibrating these meat fatty acid composition values of reference samples for near-infrared spectroscopic measurement by comparing them with the composition values of the same type of fatty acids obtained by the same program using the same measuring device.
The storage unit of the computer stores calibration curve data for obtaining the composition value of the specific type of fatty acid, and the program is a program for obtaining the composition value from the calibration curve data.
Meat fat measuring method according to claim 1, wherein the composition of the obtained fatty acid by the meat fatty acid composition values near infrared spectroscopy measurement reference sample by statistically processing for updating the calibration curve data.

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