JP2017191099A - Food inspection device and food inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and a method for inspecting the state of food non-destructively.SOLUTION: A food inspection device 100 according to the present invention includes: a resonance unit 40 having a pair of electrodes 7 and a coil 6; a transmission unit 5(5a) for generating a first AC signal to the resonance unit 40; a reception unit 5(5b) for receiving at least one type of a second AC signal selected from a group of an AC signal reflected from the resonance unit 40, an AC signal passing through the resonance unit 40, an AC signal made of a current flowing in the resonance unit 40, and an AC signal made of a voltage generated in the resonance unit 40 when a food (10) is arranged between the electrodes (7); and a measuring unit 8 for measuring at least one selected from a group of the center frequency of the resonance spectral characteristics based on the second AC signal, the band width of the resonance spectral characteristics based on the second AC signal, and the signal intensity of a specific frequency in the resonance spectral characteristic based on the second AC signal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a food inspection apparatus and a food inspection method for food.

  For a food product, the state of water, the concentration of salinity, or the proportion of lipid in the food product can affect the finished state of the processed or cooked food product. In particular, in the case of frozen foods, the state of water contained in the food (whether it is ice or water), the concentration of salinity, or the proportion of lipid is the finished state of the processed or cooked food (the state of the final product). As well as the quality of the food. In addition, various indicators such as water content, salt concentration, or lipid ratio that can be included in the food also relate to the finished state of the processed or cooked food and the quality of the food. Therefore, for producers, those involved in logistics, and consumers (consumers), such an indicator that affects the quality of food is based on the current situation in which “food safety and security” is particularly attracting attention. This is a very important concern.

  For example, in the case of frozen food, the assumed temperature and quality may not be achieved depending on the conditions of ice and / or water contained in the food. Specifically, the food that should be heated after full thawing may not be sufficiently heated by heating it in the half-thawed stage. Conversely, if the food that should be processed at low temperature after it has been half-thawed is completely thawed, the food cannot be kept at a low temperature for a certain period of time, and the quality of the food is maintained. Sometimes it is difficult to do. Moreover, regardless of whether it is frozen food or not, the assumed quality may not be achieved depending on the salt concentration or the lipid ratio.

  So far, several devices or methods have been disclosed for examining food temperature and frozen / thawed state, or food quality deterioration state, focusing on the electrical conductivity or capacitance of the food (Patent Documents 1 to 3). 4, and Non-Patent Document 1).

  As an example, since the state of water contained in food varies depending on the temperature of the food, monitoring the temperature and / or temperature change is a main method for quality control of food that has been conventionally employed. is there. Typically, the temperature and / or temperature change of the food is monitored by a direct monitoring method using a thermometer, a non-destructive monitoring method using thermography, or, in some cases, human touch. Ambiguous indicators are also adopted.

International Publication No. WO00 / 14522 JP 2005-337986 A JP-A-8-75806 JP-A-4-73582

Narumiya and 1 other, “Quality evaluation of foods using non-contact capacitive sensors”, Japan Society of Refrigeration and Air Conditioning, 1999, Vol. 16, no. 1, p23-25

  However, in a direct monitoring method using a thermometer, the thermometer is inserted into the food to be measured and used. As a result, the food cannot be sold as a product, and the food must be disposed of. Moreover, when thermography is used, even if the surface (surface layer) of food can be measured, it is difficult to measure the inside thereof. In addition, the ambiguous indicator of human tactile sensation is a personal indicator and lacks versatility and permanence.

  Even if the temperature and / or temperature change of the food can be monitored, the state of water contained in the food is not correctly grasped. In particular, taking frozen food as an example, the state of water in a food during the process from a frozen state to a thawed state, or vice versa, is usually an indicator of the temperature of the food. Often does not appear. This is because, when thawing, the temperature becomes constant at the melting point where water and ice exist at the same time, and the state of water cannot be measured even if the temperature is measured. In addition, during freezing, water is once subcooled below the melting point and then frozen, so that the temperature of the water cannot be measured as in the case of thawing. Therefore, it is very difficult to grasp the state of water contained in food by an index called temperature.

  For example, when the frozen food is uniformly heated to the inside, it is desirable to thaw it in advance. Moreover, in the low-temperature processing of food, a semi-thawed state with an appropriate hardness may be desirable. Therefore, it can be said that evaluating a frozen state or a thawed state of water without using an index of temperature is one of the important technical problems in food inspection.

  On the other hand, although some prior arts for managing the quality of food based on an index other than temperature are disclosed, even if each of the above-mentioned patent documents or non-patent documents is adopted, the state of water contained in the food An apparatus or method for accurately grasping the above has not yet been realized.

  The development of a means for measuring the concentration of salt or the proportion of lipid in food with high accuracy without contact is still halfway.

  The present invention provides an inspection apparatus and an inspection method capable of measuring or inspecting a food state exemplified by a moisture state, a salt concentration, or a lipid ratio with high accuracy and non-destructiveness. It contributes greatly.

  The present inventors pay attention to the relationship between water and ice contained in foods, the salt concentration, or the ratio of lipids, with different complex permittivity including dielectric constant and electrical conductivity. We worked hard on research and analysis for realization. For example, water and ice differ in dielectric constant by about 20 times and electrical conductivity by about 100 times. If these physical quantities can be measured at a time, it becomes possible to evaluate the state of water, the salinity concentration, or the ratio of lipids in the food from various perspectives.

  By the way, in general, in measuring electrical conductivity (or electrical resistivity), a current is measured by applying a constant voltage in a state where a plurality of metal electrodes are in contact with an object to be measured (food in the present invention). Alternatively, the electrical conductivity (or electrical resistivity) is derived by measuring a voltage difference between the electrodes by applying a constant current. However, when food is an object to be measured, since the contact resistance between the metal electrode and the food is large, it is difficult to measure electrical conductivity (or electrical resistivity) due to the food alone. Furthermore, when the electrode is not contacted, only the electrical conductivity (or electrical resistivity) near the surface of the food can be measured.

  Therefore, the present inventors have overcome such problems unique to foods and can measure the index based on both the dielectric constant and the electrical conductivity at one time to measure the water and / or ice contained in the food. We thought that this would lead to a more accurate understanding of the situation, salinity, or lipid ratio, and further research. As a result, the present inventors will be able to inspect the state of food in a multifaceted and more accurate manner by paying attention to the complex dielectric constant including both components of dielectric constant and electrical conductivity. Obtained knowledge. The present invention was created based on the above-described viewpoints.

  A typical example of the above knowledge will be described in detail using the following formula.

In general, the center frequency (fr) and bandwidth (Δfr) of the resonance spectrum in a resonance circuit composed of an inductance (L), an electric capacitance (C), and a resistance (R) are the same as those when the resonance circuit is a parallel RLC resonance circuit. Are represented by the following equations (1) and (2).

Here, when a food, which is a measurement target in the present application, is disposed between a pair of electrodes as if it were a dielectric, the pair of electrodes can be regarded as a capacitor. Consider a resonant LC circuit in which an inductance (L) is connected in parallel with this capacitor. At this time, the food disposed between the electrodes not only accumulates electrical energy but also causes a loss of energy. Therefore, the dielectric constant of the food is represented by a complex dielectric constant ε using an imaginary unit j as shown in Equation (3).

In the above equation, the real part of the first term contributes to energy storage, and the imaginary part of the second term contributes to energy loss. Considering the complex dielectric constant, the capacitance (C) of the capacitor is expressed as the following equation (4).

In that case, the admittance Y is expressed as the following equation (5).

  Here, the first term on the right side of Equation (5) corresponds to the resistance component (R) of the food and is a component that contributes to energy loss (conduction loss). The second term corresponds to the electric capacity (C ′) in the food and is a component that contributes to energy storage. Further, ω is an angular frequency. Therefore, a pair of electrodes on which food is arranged can be regarded as a circuit in which a capacitor and a resistor are connected in parallel. As a result, the resonant LC circuit can be regarded as a resonant LC′R circuit.

  Based on the above, the resistance R in Equation (2) for a general resonant circuit corresponds to the resistance R of the food appearing on the right side of Equation (5). When the applied voltage is constant, the conduction loss increases as the resistance value decreases, and the bandwidth (Δfr) increases from Equation (2).

  The electric capacity C in the formula (2) for a general resonance circuit corresponds to the electric capacity C ′ of the food appearing on the right side of the formula (5). Therefore, when the capacitance C ′ increases, the center frequency (fr) in the resonance spectrum decreases and the bandwidth (Δfr) also decreases according to the equation (1).

  Accordingly, by measuring both the center frequency and the bandwidth in the resonance spectrum of the resonance circuit, the resistance R and the capacitance C ′ are derived, and the real part and the imaginary part in the complex dielectric constant are obtained from the equation (5). It becomes possible.

  For example, when fitting the state of water and ice, when the center frequency is 1 MHz, when comparing the state of water and ice, the real part ε ′ of the complex dielectric constant of the water state is Bigger than that. Therefore, C ′ in the water state increases. As a result, the center frequency (fr) and the bandwidth (Δfr) are smaller in the water state than in the ice state. On the other hand, ε ″ in the water state is smaller than that in ice. Therefore, the resistance R in the water state increases, and the bandwidth (Δfr) decreases.

  Moreover, the complex dielectric constant in the whole food changes depending on the content of water in the food. Furthermore, it has been confirmed that the complex dielectric constant of food can be changed depending on the concentration of salt contained in the food or the ratio of lipid (typically, the ratio of water to oil). Therefore, the present invention can perform inspection or evaluation related to the quality of food as well as the state of water.

  Based on the above-described principle or the theory that takes into account the assumed correction point described later, the food inspection apparatus and the food inspection method of the present invention can realize the inspection of the state of food with non-destructive and high accuracy. it can.

  One food inspection apparatus of the present invention for producing the above-described technical effect includes a resonance unit including a pair of electrodes and a coil, a transmission unit that generates a first AC signal for the resonance unit, and a food product. The AC signal reflected on the resonance part, the AC signal transmitted through the resonance part, the AC signal consisting of the current flowing through the resonance part, and the voltage generated at the resonance part A receiver that receives at least one second AC signal selected from the group of AC signals, a center frequency of resonance spectrum characteristics based on the second AC signal, and a bandwidth of resonance spectrum characteristics based on the second AC signal And a measurement unit that measures at least one selected from a group of signal intensities at a specific frequency in a resonance spectrum characteristic based on the second AC signal.

  According to this food inspection apparatus, when the first AC signal including the center frequency is applied to the above-described resonance unit, the reception unit receives the second AC signal described above when food is disposed between the pair of electrodes in the resonance unit. Receive. In addition, the measurement unit of the food inspection apparatus has a resonance frequency characteristic center frequency based on the second AC signal, a resonance spectrum characteristic bandwidth based on the second AC signal, and a resonance spectrum based on the second AC signal. By measuring at least one selected from a group of signal strengths at a certain frequency in a characteristic, it is possible to obtain a change in dielectric constant and / or electrical conductivity (or resistivity) of the food Become. As a result, the state of the food represented by the state of moisture, the concentration of salt contained in the food, or the ratio of lipid (typically, the ratio of water to oil) is measured with high accuracy and nondestructively. Can be inspected.

  Note that the measurement unit described above measures at least the center frequency and the bandwidth of the resonance spectrum characteristic based on the second AC signal to change the dielectric constant and the electrical conductivity (or resistivity) of the food. Since it becomes possible to acquire, it is a suitable one aspect | mode.

  Further, one food inspection method of the present invention includes an arrangement step of arranging a food between the electrodes of a resonance part including a pair of electrodes and a coil, and transmission for generating a first AC signal to the resonance part. And when the food is placed between the electrodes, the AC signal reflected on the resonance part, the AC signal transmitted through the resonance part, the AC signal composed of the current flowing through the resonance part, and the resonance part A reception step of receiving at least one second AC signal selected from a group of AC signals composed of generated voltages, a center frequency of resonance spectrum characteristics based on the second AC signal, and resonance based on the second AC signal Measuring at least one selected from a group of signal strengths of a specific frequency in a resonance spectral characteristic based on a bandwidth of the spectral characteristic and a resonance spectral characteristic based on the second alternating signal.

  According to this food inspection method, when the first AC signal including the center frequency is applied to the above-described resonance unit, the above-described second AC signal when the food is disposed between the pair of electrodes in the resonance unit is received. become. Furthermore, according to this food inspection method, in the center frequency of the resonance spectrum characteristic based on the second AC signal, the bandwidth of the resonance spectrum characteristic based on the second AC signal, and the resonance spectrum characteristic based on the second AC signal A measurement step of measuring at least one selected from a group of signal strengths at a specific frequency makes it possible to obtain a change in dielectric constant and / or electrical conductivity (or resistivity) of the food. . As a result, the state of the food represented by the state of moisture, the concentration of salt contained in the food, or the ratio of lipid (typically, the ratio of water to oil) is measured with high accuracy and nondestructively. Can be inspected.

  In the measurement step described above, at least measuring the center frequency and the bandwidth of the resonance spectrum characteristic based on the second AC signal is to change the dielectric constant and the electrical conductivity (or resistivity) of the food. Since it becomes possible to acquire, it is a suitable one aspect | mode.

  In the present application, “signal intensity” is a concept including “standardized intensity”, “non-standardized intensity”, and “reflection intensity” in an embodiment described later.

  According to one food inspection apparatus of the present invention and one food inspection method of the present invention, it is possible to obtain a change in dielectric constant and electrical conductivity (or resistivity) of the food. As a result, the state of the food represented by the state of moisture, the concentration of salt contained in the food, or the ratio of lipid (typically, the ratio of water to oil) is measured with high accuracy and nondestructively. Can be inspected.

It is a lineblock diagram of the food inspection device of a 1st embodiment. It is a graph which shows the resonance spectrum in 1st Embodiment. 2A is a graph in which the vertical axis of the resonance spectrum is not normalized. The graph which investigated the change of the intensity | strength when the salmon was changed temporally from the frozen state to the thawed state in the frequency 1.93MHz using the food inspection apparatus of 1st Embodiment. It is. It is a graph which shows the elapsed time dependence of the center frequency and temperature in 1st Embodiment. It is a graph which shows the elapsed time dependence of a bandwidth and temperature in 1st Embodiment. It is an equivalent circuit of the resonance part of the food inspection apparatus of 1st Embodiment. It is a figure explaining the difference of the equivalent circuit of the resonance part by the state change of a foodstuff about the food inspection apparatus of 1st Embodiment. It is a block diagram of the food inspection apparatus of 2nd Embodiment. It is a graph which shows the resonance spectrum which paid its attention only to the change of the state of water in 2nd Embodiment. It is a graph which shows the resonance spectrum when changing the ratio of the lipid in case water and lipid (oil) coexist. It is a graph which shows the change of the resonant frequency (MHz) by a mixing ratio in case water and lipid (oil) coexist. It is a graph which shows the change of a bandwidth (kHz) when the ratio of a lipid is changed when water and lipid (oil) are mixed. It is a side view which shows the structure of the electrode in the modification of 1st or 2nd embodiment. It is a side view which shows the modification of the removal means which removes the water droplet which exists in the surface of a foodstuff in the modification of 1st or 2nd embodiment. It is a block diagram of the food inspection apparatus in other embodiment. It is a block diagram of the food inspection apparatus in other embodiment. It is a block diagram of the food inspection apparatus in other embodiment. It is a block diagram of the food inspection apparatus in other embodiment.

  As an embodiment of the present invention, a food inspection apparatus and a food inspection method will be described in detail with reference to the accompanying drawings. In this description, common parts are denoted by common reference symbols throughout the drawings unless otherwise specified. In the drawings, elements of the present embodiment are not necessarily described with each other kept to scale. Further, some symbols may be omitted to make each drawing easier to see.

<First Embodiment>
The food inspection apparatus 100 of this embodiment is demonstrated. FIG. 1 is a configuration diagram of a food inspection apparatus 100 for food according to the present embodiment. In the present embodiment, the aspect and effect of the food inspection apparatus 100 and the food inspection method using the food inspection apparatus 100 are the foods to be measured (for example, seafood, more specific examples). , Fish) 10 will be described.

  As shown in FIG. 1, the food inspection apparatus 100 according to the present embodiment includes a resonance unit 40 including a pair of electrodes 7 and a coil 6, a network analyzer 5, and a resonance spectrum based on an AC signal received by the network analyzer 5. And a measurement unit 8 that measures the center frequency and / or bandwidth of the characteristic. Hereinafter, “inspecting or measuring” the food 10 may be collectively referred to as “inspecting”, and “measuring or inspection” of the food 10 may be collectively referred to as “inspection”.

  The network analyzer 5 according to the present embodiment will be described more specifically. The network analyzer 5 arranges the food 10 between the electrode 7 and the transmitter 5 a that generates the first AC signal including the center frequency with respect to the resonance unit 40. Selected from the group of an AC signal reflected to the resonance unit 40, an AC signal transmitted through the resonance unit 40, an AC signal consisting of current flowing through the resonance unit 40, and an AC signal consisting of the voltage generated in the resonance unit 40. A receiving unit 5b for receiving at least one second AC signal.

  Here, in the present embodiment, the network analyzer 5 having a transmission function and a reception function is employed, but the present embodiment is not limited to such an aspect. For example, even when the transmitting unit 5a and the receiving unit 5b are provided as different components, the same effect as that of the present embodiment can be achieved. Other known transmitting devices (for example, function generators) or receiving devices (oscilloscopes, lock-in amplifiers, spectrum analyzers) are other modes that can be employed as long as the resonance spectrum described later can be acquired. .

  Next, the resonance unit 40 of the present embodiment will be described more specifically. The resonance unit 40 includes at least a pair of electrodes 7 and a coil 6 as described above. In the present embodiment, the resonance unit 40 is formed by connecting a coil (Bourm, model number RLB0912-101KL, 100 μH) 6 having a commercially available ferrite core and a capacitor including a pair of electrodes 7 in series. It is a series resonant circuit. Note that, when the food inspection apparatus 100 is inspected, the food 10 is disposed between the pair of electrodes 7, so that the state is regarded as a capacitor.

  In the present embodiment, an insulating layer or an insulator (in this embodiment, an acrylic plate) 9 is provided between the pair of electrodes 7. On this insulator 9, a fish (for example, salmon) which is the object to be measured 10 is arranged. Therefore, in the present embodiment, the acrylic plate and the food 10 (for example, salmon) to be measured are disposed between the pair of electrodes 7. When the food 10 to be measured is salmon, the salmon may be stored in a thin bag so that water (including water droplets) does not flow out of the resonance part (particularly, the electrode 7). This is a preferred example. Further, in the present embodiment, one electrode 7 is arranged such that the distance between the electrodes 7 facing the food 10 is shorter than the distance between the electrodes 7 facing the food 10. The side surface 7s of the electrode is formed by bending the part.

  Note that the food inspection apparatus 100 does not necessarily include the insulating layer or the insulator (hereinafter collectively referred to as “insulator”) 9. However, for example, during the inspection of the present embodiment, water (including water droplets) existing by adhering to the food 10 and water (including water droplets) existing when the water content of the food 10 appears on the outer periphery or surface thereof. ), And / or water (including water droplets) present on the outer periphery or surface of the food 10 from the beginning to directly contact the electrode 7 or to intervene between the electrode 7 and the food 10 with high accuracy. The provision of the insulator 9 is a preferable aspect from the viewpoint of improving the inspection accuracy. Examples of foods 10 that may have water on their perimeters are foods 10 where moisture will appear around or on the surface when exposed to outside air, or in contact with water (or existed in water before the test) ) A food that does not remove its water or performs insufficient water removal.

  Further, in the food inspection apparatus 100 of the present embodiment, the network analyzer 5 and a known temperature measuring device 12 that acquires information of the thermocouple 11 including the temperature of the food 10 (in this embodiment, model NR, manufactured by KEYENCE Corporation). -1000) and a computer 8 connected thereto. The computer 8 of this embodiment controls each process (hereinafter also referred to as “inspection process”) for inspecting the state of the food 10. The computer 8 also obtains information obtained from the network analyzer 5 or the temperature measuring device 12 (for example, temperature, resonance spectrum characteristics, center frequency (fr) of the resonance spectrum characteristics, and bandwidth (Δfr) of the resonance spectrum characteristics). It can also be used to store, display the information and / or analyze the information.

  In addition, the computer 8 of this embodiment can monitor the said process by the inspection program for test | inspecting the state of the above-mentioned food 10, for example, or can control it integrally. For example, in the present embodiment, the inspection program is stored in a known recording medium such as an optical disk inserted into a hard disk drive in the computer 8 or an optical disk drive provided in the computer 8. The storage destination is not limited to this. The inspection program can also monitor or control the above-described processing via a known technique such as a local area network or an Internet line.

  If the food inspection apparatus 100 having the above-described configuration is used, the state of the food 10 disposed between the pair of electrodes 7 (for example, a frozen / thawed state) by measuring the center frequency and bandwidth of the resonance unit 40. It becomes possible to investigate.

  More specifically, first, in the food inspection method according to the present embodiment, an arrangement step of arranging the food 10 between the electrodes 7 of the resonance unit 40 including the pair of electrodes 7 and the coil 6 is performed. After the food 10 is arranged, the food inspection apparatus 100 performs a transmission process of generating a first AC signal including the center frequency with respect to the resonance unit 40 using the transmission unit 5a.

  The receiving unit 5b receives the second AC signal that reflects the state of the food 10. Specifically, when the food 10 is disposed between the electrodes 7, an AC signal reflected on the resonance unit 40, an AC signal transmitted through the resonance unit 40, an AC signal composed of a current flowing through the resonance unit 40, and the resonance unit 40 A receiving step of receiving at least one second AC signal selected from a group of AC signals composed of voltages generated at the same time is performed. Thereafter, the measurement unit 8 performs a measurement process of measuring the center frequency and / or the bandwidth of the resonance spectrum characteristic based on the received second AC signal.

  The range of the center frequency of the resonance unit 40 is not particularly limited. However, for reasons that will be described later, the range of the center frequency of the resonance unit 40 is preferably 10 kHz or more and less than 100 MHz.

  If the frequency is 100 MHz or more, the stray capacitance of the device becomes a problem, and it becomes difficult to produce an appropriate resonance circuit. In addition, there is a problem that the cost of the inspection apparatus increases. Furthermore, when 1 kHz or 10 MHz is adopted as the center frequency of the resonance part 40, there arises a problem that the electric conductivity of ice and water becomes substantially equal. Therefore, it is a preferable aspect that a frequency range of 10 kHz or more and less than 100 MHz is adopted as the range of the center frequency of the resonance unit 40.

  The second AC signal is an AC signal reflected from the resonance unit 40, an AC signal transmitted through the resonance unit 40, an AC signal composed of current flowing through the resonance unit 40, and an AC signal composed of voltage generated in the resonance unit 40. At least one selected from the group. Further, the network analyzer 5 that can also serve as a measurement unit of the food inspection apparatus 100 of the present embodiment acquires the resonance spectrum characteristic based on the second AC signal, and the center frequency and / or band of the resonance spectrum characteristic. Measure the width.

<Inspection result by food inspection apparatus 100>
An example of the result of inspection by the food inspection apparatus 100 having the above-described configuration will be described below with reference to FIGS. 2A to 4. In this example, the measurement unit of the food inspection apparatus 100 measures the center frequency and / or the bandwidth of the resonance spectrum characteristic based on the moisture state change of the food 10 accompanying the time change of the food 10. Here, the temperature is measured by inserting a thermocouple into the food 10 for reference.

  FIG. 2A is a resonance spectrum of salmon in a frozen state and salmon in a fully thawed state in the present embodiment, and the specified numerical value represents a bandwidth. Moreover, in FIG. 2A, the vertical axis of the resonance spectrum before and after thawing of the food 10 is normalized in order to make the drawing easier to see. On the other hand, FIG. 2B is a graph in which the vertical axis of the resonance spectrum in FIG. 2A is not normalized. In FIG. 2A and FIG. 2B, the vertical axis represents the degree of resonance intensity as reflection intensity (the unit is “arbitrary unit”, abbreviated “a.u.”). Moreover, FIG. 2C investigated the change of the intensity | strength when the salmon was changed temporally from the frozen state to the thawed state in the frequency of 1.93 MHz using the food inspection apparatus 100. It is a graph.

  FIG. 3 is a graph showing the elapsed time dependence of the center frequency (solid line in FIG. 3) and temperature (dotted line in FIG. 3) in the present embodiment. In addition, FIG. 4 is a graph showing the elapsed time dependence of the bandwidth (solid line in FIG. 4) and temperature (dotted line in FIG. 4) in the present embodiment. 3 and 4, the vertical axis represents the degree of resonance intensity (hereinafter also referred to as “resonance intensity” for convenience). In each graph of the present application, “resonance strength” can be expressed as “strength”.

  The food 10 in this example is a frozen fish (specifically, a frozen salmon) at the stage before the start of the inspection. In this example, the process (removal process) which removes the water which exists on the outer periphery or surface of the foodstuff 10 observed with progress of time during a test | inspection is not performed.

  As shown in FIG. 3 and FIG. 4, the temperature of the food 10 initially shows a temperature rise, but does not change much while about 100 minutes to about 280 minutes have passed. This is considered to be because heat from the outside air given to the food 10 is consumed as latent heat as the food 10 is thawed during that time period.

  On the other hand, very interestingly, in the time zone (about 100 minutes to about 280 minutes) in which there is not much temperature change, a noticeable change is observed in the center frequency and a noticeable change in the bandwidth (kHz). confirmed. The bandwidth in this example is the full width at half maximum when the spectrum of the reflected wave with respect to the resonance circuit is displayed in power.

  Based on the above, the present inventors have found that the center frequency and / or bandwidth is an index that makes it easy to confirm the state of fluctuation in a time zone (about 100 minutes to about 280 minutes) in which there is not much temperature change. The knowledge that it is. Therefore, it became clear that the state of the food 10 (in this example, ice thawing condition) can be inspected based on the center frequency and / or the bandwidth.

  Here, the resonance part 40 which has arrange | positioned the foodstuff between the electrodes 7 can be represented using the equivalent circuit shown to FIG. 5A. The electric capacity (Ca) of the air layer is an electric capacity generated between the electrode 7 on the upper surface and the food 10 to be measured. Further, the electric capacity (Ci) of the insulating layer is an electric capacity generated between the electrode 7 on the bottom surface and the food 10 to be measured (that is, the insulator 9 in the present embodiment). Both are ingredients that do not depend on the thawing / frozen status of the food. Therefore, by measuring at least one (more preferably both) of the center frequency and the bandwidth in the resonance spectrum of this resonance circuit, the resistance R and the capacitance C of the food 10 to be measured, that is, the complex It becomes possible to obtain the real part and the imaginary part in the dielectric constant. From this, by examining the center frequency and / or bandwidth, the state of water in food (eg, ice thawing status), salinity, or lipid percentage can be evaluated, and the thawing / freezing status can be ascertained. It becomes possible to do.

  In order to make it easier to understand, a state where the equivalent circuit of the resonance part is substantially different depending on the state change of the food will be described with reference to FIGS. 5B (a) to (c). However, since FIGS. 5B (a) to 5 (c) are equivalent circuit diagrams adopted for convenience in explaining the case where the balance of the impedance of the resistor R and the capacitance C is greatly changed, the “frozen / thawed state” is particularly selected. Is not intended to explain.

  The equivalent circuit shown in FIG. 5B (a) is the same as that shown in FIG. 5A. Like this equivalent circuit, a current flows through both the resistance R and the electric capacity C of the food 10 to be measured, which means that the impedance of either the resistance R or the electric capacity C is extremely high. The state is not large (or not small). On the other hand, when the resistance R of the food 10 to be measured is extremely large with respect to the impedance of the electric capacity C of the food 10, the equivalent circuit shown in FIG. 5B (b) is obtained. On the other hand, when the resistance R of the food 10 to be measured is extremely small with respect to the impedance of the electric capacity C of the food 10, the equivalent circuit shown in FIG.

  That is, regarding the resistance R and electric capacity C of the food 10 to be measured, the change in the relationship between the accumulation of electrical energy according to the state of the food 10 and the loss of the energy (the accumulation of electrical energy). In this embodiment, it is possible to inspect the state of the food 10 in a non-destructive manner by paying attention to the difference in how the energy is lost.

  As described above, by using the food inspection apparatus 100 and the food inspection method of the present embodiment, it becomes possible to inspect the state of the food 10 in a non-destructive manner, which greatly contributes to “food safety and security”. .

  In this example, the center frequency and / or the bandwidth is examined in the process of changing the food 10 to be measured from the frozen state to the thawed state, so that it is difficult to identify the seafood ( For example, it is possible to grasp the preferable cutting timing of fish) with higher accuracy. As a result, the yield when cutting marine foods (for example, fish) as primary processing, particularly in the manufacture of processed fishery products, is increased.

  Further, in this example, the process of change from the frozen state to the thawed state was examined, but the reverse, that is, the process of change from the thawed state to the frozen state was also performed by the food inspection apparatus 100 using the center frequency and / or It is possible to inspect the food 10 by examining the bandwidth.

  For example, when there is a cavity in the food 10 to be measured, the change in the capacitance value can be detected by using the food inspection apparatus 100 and the food inspection method of the present embodiment. As a result, the presence or absence of a defect in the food 10 can be identified. This can contribute to ease or certainty of quality control of the food 10. Moreover, even if a foreign substance is mixed in the food 10, a change in capacitance value can be detected. This can contribute to facilitation or certainty of hygiene management in addition to facilitation or certainty of quality control of the food 10.

  In addition, according to the present embodiment, when a substance having a dielectric constant or resistivity significantly different from that of water or ice is included, the present invention can be applied to inspecting or evaluating the ratio of water and / or ice to the different substance. Can do.

<Second Embodiment>
Below, the inspection method using the food inspection apparatus 200 of this embodiment shown in FIG. 6 and the food inspection apparatus 200 is demonstrated.

  In the present embodiment, first, a pulse is generated by the transmission unit 5a and is incident on the resonance unit. Next, an oscilloscope 14 is used to measure the real time waveform of the voltage generated in the resonator. Then, a Fourier transform process is performed on the real-time waveform by an arithmetic means that performs a Fourier transform process to obtain a resonance spectrum. In addition, the coil 6, the electrode 7, and the insulator 9 in this embodiment are the same as those of the food inspection apparatus 100 of 1st Embodiment. The frequency of the pulse incident on the resonance part by the transmission part 5a is 5 kHz, and the pulse width is 200 nsec (nanoseconds). Note that a known calculation means can be adopted as the calculation means.

<Inspection result by food inspection apparatus 200 (1)>
FIG. 7A is a graph showing a resonance spectrum focusing on only a change in the state of water, which is a test result of the present embodiment. The same results as those in the first embodiment are obtained in the behavior of the center frequency and / or the bandwidth before and after the decompression. In the second embodiment, since a resonance spectrum can be acquired with one pulse, measurement can be performed at high speed. In addition, measurement can be performed with a relatively inexpensive apparatus.

<Inspection result by food inspection apparatus 200 (2)>
In addition, when the present inventors investigated the change in the resonance spectrum and the bandwidth when the ratio of lipid in the case where water and lipid (oil) are mixed, the following interesting results were obtained. 7B to 7D were all mixed liquids (hereinafter referred to as “mixed liquids” in the present embodiment) in PET (polyethylene terephthalate) containers prepared for each investigation. Thus, the ratio of the mixed liquid in the actual food 10 is not changed. Accordingly, the PET container serves as the insulator 9 provided between the pair of electrodes 7 in FIG. In addition, the frequency of the pulse incident on the resonance unit by the transmission unit 5a is 910 Hz, and the pulse width is 200 nsec.

  Specifically, since water and lipid (oil) with different specific gravity are mixed, the mixing ratio of water and lipid (oil) is changed so that the volume of the liquid mixture to be measured in the same container is the same. Each measurement sample was prepared. In addition, although the emulsifier and the antifoamer were utilized in order to mix water and oil, since both are less than 1% by weight ratio, the influence which it has on a dielectric constant is very small. In addition, since both the emulsifier and the antifoaming agent are difficult to ionize, the influence on the conductivity or resistance is small. Therefore, the center frequency or bandwidth is not substantially affected. In addition, the lipid (oil) employ | adopted in this liquid mixture is canola oil.

  FIG. 7B is a graph showing a resonance spectrum when the ratio of lipid in the case where water and lipid (oil) are mixed is changed. Moreover, FIG. 7C is a graph which shows the change of the resonant frequency (MHz) by a mixing ratio in case water and lipid (oil) coexist. Furthermore, FIG. 7D is a graph showing a change in bandwidth (kHz) when the ratio of lipid is changed when water and lipid (oil) coexist.

  As shown in FIGS. 7B and 7C, it was confirmed that the center frequency increases as the ratio of lipid (oil) increases. This is thought to be because the dielectric constant of lipid (oil) decreases more than the dielectric constant of water. On the other hand, as shown in FIG. 7D, the bandwidth increases as the ratio of lipid (oil) increases until the ratio of lipid (oil) reaches 80%, but the ratio of lipid (oil) increases to 100. %, The bandwidth value greatly decreased. Accordingly, it has been clarified that the center frequency and / or the bandwidth fluctuate when the mixing ratio of water and lipid (oil) is different, so that the change of the mixing ratio of water and lipid (oil) in the food 10 is changed. By using the food inspection apparatus 100 and the food inspection method of the present embodiment, it has been found that non-destructive inspection can be performed.

  In addition, the present inventors investigated the change of the resonance spectrum and the bandwidth when the salinity concentration in the water is changed. As a result, the center frequency and / or the bandwidth varies depending on the salinity concentration in the water. Became clear. Therefore, it has been found that the change in the salt concentration in the food 10 can be inspected nondestructively by using the food inspection apparatus 100 and the food inspection method of the present embodiment. “Salt concentration” means the concentration of sodium chloride.

<Modification (1) of the first or second embodiment>
By the way, in each above-mentioned embodiment, although transmitting part 5a has generated the 1st exchange signal containing a center frequency, each above-mentioned embodiment is not limited to such a mode. For example, the transmitter 5a may generate a first AC signal that does not include the center frequency. In addition, in each of the above-described embodiments, the measurement unit 8 measures the center frequency and / or bandwidth of the resonance spectrum characteristic based on the received second AC signal. It is not limited to such an embodiment. For example, the measurement unit 8 measures the signal strength of a specific frequency in the resonance spectrum characteristic based on the second AC signal without measuring the center frequency and / or the bandwidth of the resonance spectrum characteristic based on the second AC signal. This is another aspect that can be adopted. Hereinafter, a food inspection apparatus and a food inspection method based on generation of a first AC signal that does not include a center frequency and measurement of a signal intensity of a specific frequency in a resonance spectrum characteristic based on the second AC signal will be described.

  FIG. 2B is a resonance spectrum of a frozen salmon and a fully thawed salmon using the food inspection apparatus 100 of the first embodiment as described above, and the vertical axis of the resonance spectrum is not normalized. It is a graph.

  Here, focusing on the difference in strength (vertical axis) due to the difference between the frozen salmon and the fully thawed salmon at a frequency of 1.93 MHz in FIG. 2B, before and after thawing, that is, the frozen state (solid line) and the thawing. It can be seen that the difference (P in FIG. 2B) from the state (dotted line) clearly appears.

  Therefore, by generating a first AC signal that does not include the center frequency and measuring the signal strength of a specific frequency (for example, frequency 1.93 MHz in FIG. 2B) in the resonance spectrum characteristic based on the second AC signal, It can be seen that the difference between the frozen state (solid line) and the thawed state (dotted line) in the food 10 can be inspected nondestructively.

  2C, as already described, the salmon was changed in time from the frozen state to the thawed state at the frequency of 1.93 MHz using the food inspection apparatus 100 of the first embodiment (that is, the salmon). It is the graph which investigated the change of the intensity | strength (when the temperature of this changes temporally).

  As shown in FIG. 2C, the intensity change range is 0.043 to 0.415, which is a change of 9 times or more, and the intensity is also increased between 100 minutes and 200 minutes when the temperature is substantially constant. Since the change from 0.415 to 0.372 was confirmed, the state change from freezing to thawing, which was difficult to confirm with a change in temperature, is a signal of a specific frequency in the resonance spectrum characteristic based on the second AC signal. It was confirmed that the strength can be evaluated.

  According to the analysis of the inventors of the present application, for example, in FIG. 2A or FIG. 2B, the numerical value obtained by differentiating the intensity with respect to the frequency, or the center frequency derived using the differentiated numerical value (for example, the differential value is 0). (A frequency that becomes zero) is recognized as a center frequency) and / or a bandwidth (for example, a frequency width that maximizes the absolute value of a differential value, etc.) as a reference, more prominently from freezing to thawing. There is knowledge that it is possible to evaluate the state change.

  According to another analysis by the inventors, the change in the mixing ratio of water and lipid (oil) is also measured by measuring the signal intensity at a specific frequency in the resonance spectrum characteristic based on the second AC signal. We have obtained knowledge that non-destructive inspection is possible.

  In addition, after generating the first AC signal including the center frequency, the resonance spectrum based on the second AC signal is measured without measuring the center frequency and / or the bandwidth of the resonance spectrum characteristic based on the second AC signal. Measuring the signal strength of a particular frequency in the characteristic is another aspect that can be employed.

<Modification (1) of the first or second embodiment>
By the way, for example, when a food 10 having a complicated shape is used as a measurement object, such as a fishery product represented by fish, it is extremely difficult to measure an average electric conductivity or electric resistance inside the food 10. It is. Moreover, since it has a complicated shape, it is preferable to devise the shape of the electrode 7 in order to realize measurement with higher accuracy. FIGS. 8A to 8C show examples of the shape of the electrode 7 corresponding to the food 10 having such a complicated shape.

  Although not limited to the example illustrated in FIG. 8, for example, as illustrated in FIG. 8, the distance between the electrodes 7 of the portion facing each other without the food 10 (for example, “d1” in FIG. 8A) is A part of the electrode 7 is bent or bent, or a part of the electrode 7 is curved so as to be shorter than the distance (“D” in FIG. 8A) between the electrodes 7 opposed to each other. It can be realized to prevent or suppress leakage of the electric field formed by the electrodes, or to be less susceptible to the influence of the surroundings. Therefore, it is a preferable aspect to adopt such a configuration. As described above, the food inspection apparatus 100 or 200 described in the first or second embodiment further includes a shielding unit that prevents or suppresses leakage of the electric field formed by the pair of electrodes 7. It is preferable from the viewpoint of realizing high measurement.

  Therefore, the food 10 is not covered only with the pair of side surfaces (7s in FIG. 1) as shown in FIG. 8, but the food 10 is added with another pair of side surfaces in the same manner as the pair of side surfaces (7s). It is possible to realize that the covering is more preferable, or the influence of the surroundings is less likely to be caused. Another example of the shield means is to install the electrode inside a metal box (or metal mesh). Further, for example, as compared with FIG. 8A, FIG. 8B or FIG. 8C has a curved surface substantially along the outer shape of the food 10 to be measured, so that the food under inspection The position of 10 can be stabilized with high accuracy. Increasing the stability of the position of the food 10 during the inspection, in other words, suppressing movement or movement of the food 10 during the inspection contributes to a more accurate inspection.

<Modification (3) of the first or second embodiment>
In the food inspection apparatuses 100 and 200 described in the first or second embodiment, it is also possible to employ a moving mechanism that allows the food 10 to be measured and the pair of electrodes 7 to move relatively. This is a preferred embodiment. For example, by adopting a configuration in which the food 10 to be measured is fed between a pair of electrodes 7 using a belt conveyor, a large number of foods can be inspected continuously, thereby realizing a very efficient inspection. obtain.

<Modification (1) of the first or second embodiment>
In addition, when the food 10 in which water is present on the outer periphery or the surface or the food 10 in which the contained water appears on the outer periphery or the surface as time passes is measured, after removing the water with high accuracy Alternatively, the food 10 is preferably inspected under the condition that the water is removed during the measurement. The food inspection apparatus 100, 200 described in the first or second embodiment removes water (including water droplets) present on the outer periphery or the surface of the food 10 without damaging the food 10 as much as possible. As an example of the means for achieving this, the following configurations (A) to (C) may be employed.
(A) By using a known member for hanging the food 10 (for example, a hook for hanging or a member sandwiched so as to hang down), the gravity or the surface of the food 10 is used. (B) A pair of electrodes 7 shown in FIG. 1 (at least an arrangement part (food arrangement part) on which food 10 is arranged or placed, or an insulator 9 side as an example of the placement part) A structure in which the water on the outer periphery or surface of the food 10 is washed off by using the gravity by tilting the electrode 7). (C) Before or after being placed between the pair of electrodes 7, it is almost uniform. A structure that blows away water existing on the outer periphery or the surface by sending sheet-like air strongly toward the food 10 (typically, an air knife device)

  In addition, Fig.9 (a)-(c) has each shown an example of the means (removal means which removes the water droplet which exists on the surface of the foodstuff 10) shown in the above-mentioned (A)-(C), and a structure. . In the example of FIGS. 9A to 9C, an example using the moving mechanism that can move the food 10 and the pair of electrodes 7 relatively, as described in the modification (3) of the first embodiment. It is shown. X in each figure indicates a moving direction (advancing direction of the food 10).

  For example, in Fig.9 (a), the hook 21 for hanging the foodstuff 10 hangs down from the rail 22 for moving the hook 21. FIG. A configuration is shown in which water on the outer periphery or the surface of the food 10 suspended by the hook 21 is dropped using gravity. Moreover, in FIG.9 (b), the water on the outer periphery or surface of the foodstuff 10 is poured off using gravity by using the belt conveyor 25 inclined by angle (theta) (for example, about 15 degrees) from the horizontal surface ( The configuration to be removed is shown. In addition, in FIG. 9C, sheet-like air shown as air (1) and / or air (2) is applied to the food 10 moving substantially along a horizontal plane using a belt conveyor. The structure which blows off the water which exists on the outer periphery or the surface by being sent strongly toward the foodstuff 10 is shown. In FIG. 9A, the rail 22 for positioning between the pair of electrodes 7 corresponds to the placement portion (food placement portion) where the food 10 is placed. In FIG. 9B and FIG. 9C, the placement portion (food placement portion) or placement portion on which the food 10 is placed or placed is a belt conveyor 25. In addition, in FIG.9 (b) and FIG.9 (c), an arrangement | positioning part or a mounting part is not limited only to the belt conveyor 25. FIG. For example, when the food 10 is placed on a tray or the like, the tray or the like on the belt conveyor 25 becomes the placement unit or the placement unit.

  Note that the means and configurations shown in the above (A) to (C) are not limited to the means and configurations shown in FIGS. A person skilled in the art can apply other known means by knowing the means and configurations shown in the above (A) to (C).

  Since the water on the outer periphery or the surface of the food 10 can be removed with high accuracy by performing the removal step employing the means and configurations shown in the above examples (A) to (C), the state of the food 10 is inspected. It is possible to greatly improve the inspection accuracy.

<Other embodiment (1)>
By the way, as a structure which can have an effect similar to the food inspection apparatus 100,200 demonstrated in 1st or 2nd embodiment, the modification (implementation) of FIG. 10 thru | or FIG. Form).

  FIG. 10 is a configuration diagram of one food inspection apparatus 300 in the present embodiment. In this configuration, the first AC signal is applied to the resonance unit 40 by the transmission unit 5a which is an AC signal source, and the voltage applied to the resonance unit 40 is measured by the measurement unit which the oscilloscope, the voltmeter 14 and the computer 8 serve. At the time of resonance, the impedance (electric resistance) of the resonance unit 40 is reduced, and the voltage applied to the resonance unit 40 is reduced. Therefore, the characteristics of the resonance unit 40 can be measured. The measurable frequency band depends on the performance of the measuring device, but when a commercially available oscilloscope is used, the frequency band is several GHz or less.

<Other embodiment (2)>
FIG. 11 is a configuration diagram of one food inspection apparatus 310 in the present embodiment. In this configuration, a first AC signal is given to the resonance unit 40 by the transmission unit 5a that is an AC signal source, and the voltage applied to the resonance unit 40 is measured using the measurement unit that the lock-in amplifier 16 and the computer 8 serve. . At the time of resonance, since the impedance (electric resistance) of the resonance unit 40 becomes small, the voltage applied to the resonance unit 40 decreases, and the characteristics of the resonance unit 40 can be measured. The measurable frequency band depends on the performance of the measuring device, but when a commercially available lock-in amplifier is employed, the frequency band is generally 1 MHz or less.

<Other embodiment (3)>
FIG. 12 is a configuration diagram of one food inspection apparatus 400 in the present embodiment. In this configuration, a first AC signal is given to the resonance unit 40 by the transmission unit 5a which is an AC signal source, and a magnetic field generated by the current flowing in the coil 6 of the resonance unit 40 is coupled to another coil 6x by mutual inductance. . As a result, a voltage is generated in the coil 6x, and the voltage is measured using a measurement unit that the oscilloscope and the voltmeter 14 and the computer 8 serve. In the example shown in FIG. 12, the electrode 7 (9) and the coil 6 form a parallel circuit, but the present embodiment is not limited to such a circuit structure. For example, it is another aspect in which the electrode 7 (9) and the coil 6 form a series circuit.

<Other embodiment (4)>
FIG. 13 is a configuration diagram of one food inspection apparatus 410 in the present embodiment. In this configuration, a first AC signal is given to the resonance unit 40 by the transmission unit 5a which is an AC signal source, and a magnetic field generated by the current flowing in the coil 6 of the resonance unit 40 is coupled to another coil 6x by mutual inductance. . As a result, a voltage is generated in the coil 6x, and the voltage is measured using a measurement unit that the lock-in amplifier 16 and the computer 8 serve.
In the example shown in FIG. 13, the electrode 7 (9) and the coil 6 form a parallel circuit, but the present embodiment is not limited to such a circuit structure. For example, it is another aspect in which the electrode 7 (9) and the coil 6 form a series circuit.

<Other embodiment (5)>
Incidentally, for example, in FIGS. 10 and 12 described above, an AC signal including a broadband frequency component such as a pulse can be used as the first AC signal from the AC signal source. Further, the resonance signal can be obtained by receiving the second AC signal using, for example, an oscilloscope, and decomposing the intensity for each frequency using the Fourier transform process by an arithmetic means for calculating the Fourier transform process. Furthermore, by analyzing the resonance spectrum, it is possible to measure the center frequency and / or bandwidth of the resonance spectrum characteristic, or the signal intensity of a specific frequency in the resonance spectrum characteristic based on the second AC signal.

<Other embodiment (6)>
Moreover, in the food inspection apparatus of any of the above-described embodiments, it is another aspect that can be adopted to further include a recording unit that records the center frequency of the resonance spectrum characteristic measured in advance and / or its bandwidth. is there. Specifically, the food inspection apparatus measures the center frequency and / or bandwidth in the resonance spectrum characteristics of food samples (for example, fish) of various sizes and weights for reference in advance. It is a preferable aspect to provide a recording unit or database in which results are registered. By providing such a recording unit or database, results relating to samples of various sizes and weights can be set as known information. In addition, when an unknown sample is newly measured, it is compared with the measurement results of the same size and weight among the data (measurement result samples) registered in the recording unit or database. By doing so, it is possible to facilitate the inspection of an unknown sample (food) that is the new measurement object. In addition, the above-mentioned recording part or the above-mentioned database is an aspect which can also be employ | adopted, for example connecting to this food inspection apparatus via a well-known communication network.

Therefore, in one aspect, the food inspection apparatus of each embodiment described above further includes a recording unit or a database, and the measurement unit compares and determines any of the following (x1) to (x3).
(X1) Based on the center frequency recorded in the recording unit or the database (that is, the reference center frequency registered in the recording unit or the database) and the second AC signal newly received by the receiving unit Center frequency of resonance spectrum characteristic (x2) The bandwidth recorded in the recording unit or the database (that is, the reference bandwidth registered in the recording unit or the database) and the reception unit newly received Resonance spectral characteristic bandwidth based on second AC signal (x3) Resonance spectral characteristic based on second AC signal newly received by receiving unit and center frequency and bandwidth recorded in recording unit or database Center frequency and bandwidth

Moreover, in another one aspect | mode, the food inspection apparatus of each above-mentioned embodiment is provided with at least some resonance part instead of the above-mentioned recording part or database, The measurement part is the following (y1)-(y3) It is also possible to employ any one of the comparison and determination steps.
(Y1) Comparison between the center frequency of the resonance spectrum characteristic based on the second AC signal when one resonance part is used and the center frequency of the resonance spectrum characteristic based on the second AC signal when another resonance part is used Determination step (y2) The bandwidth of the resonance spectrum characteristic based on the second AC signal when one resonance part is used, and the bandwidth of the resonance spectrum characteristic based on the second AC signal when another resonance part is used (Y3) The center frequency and bandwidth of the resonance spectrum characteristic based on the second AC signal when one resonance part is used, and the resonance spectrum based on the second AC signal when another resonance part is used Step of comparing and determining the center frequency and bandwidth of the characteristic In each of the above-described examples, the resonance conditions of the above-described one resonance part and the other resonance part are different from each other, and thus the measurement target. It is possible to change the pair of the electrodes and / or coils conditions for placing the goods.

  In addition, for example, in the process of freezing and thawing food, the center frequency and / or bandwidth of the resonance spectral characteristics can change over time. Therefore, once the food to be measured is measured, and after some time interval, the center frequency and / or the bandwidth is measured again and the values are compared. It is. By measuring by such a method, the progress of freezing or thawing can be known with higher accuracy. In this thawing, if the food is, for example, a fish, accelerating the thawing by immersing the fish in water or applying a wind can achieve multiple measurements in a shorter time.

  On the other hand, in the same manner as described above, instead of a recording unit or database that records the center frequency and / or the bandwidth of the resonance spectrum characteristic measured in advance, the signal intensity of a specific frequency in the resonance spectrum characteristic measured in advance is calculated. Providing a recording unit or database for recording is another aspect that can be adopted.

  Therefore, in one aspect, the food inspection apparatus according to each of the above embodiments further includes a recording unit or a database, and the measurement unit is a resonance spectrum based on the second AC signal recorded in the recording unit or the database. A specific frequency signal strength of a specific frequency (that is, a reference signal strength registered in the recording unit or the database) and a specific resonance frequency characteristic based on a second AC signal newly received by the receiving unit. Compare and determine the signal strength of the frequency.

  Moreover, in another one aspect | mode, the food inspection apparatus of each above-mentioned embodiment is provided with at least some resonance part instead of the above-mentioned database, and when the measurement part uses one resonance part, it is 2nd. Comparison of comparing and determining the signal intensity of a specific frequency in the resonance spectrum characteristic based on the AC signal and the signal intensity of the specific frequency in the resonance spectrum characteristic based on the second AC signal when using another resonance unit It is also possible to employ a determination step. In this example, the conditions of the pair of electrodes and / or coils for arranging the food to be measured are changed in order to make the resonance conditions of the one resonance part and the other resonance part different from each other. can do.

<Other embodiment (7)>
On the other hand, in the food inspection apparatus of any of the above-described embodiments, it is another aspect that can be adopted to further include a recording unit that records the signal intensity of a specific frequency in the resonance spectrum characteristic measured in advance. . Specifically, the food inspection apparatus measures the signal intensity of a specific frequency in the resonance spectrum characteristics of food samples (for example, fish) of various sizes and weights for reference in advance, and the measurement It is a preferable aspect to provide a recording unit or database in which results are registered. By providing such a recording unit or database, results relating to samples of various sizes and weights can be set as known information. In addition, when an unknown sample is newly measured, it is compared with the measurement results of the same size and weight among the data (measurement result samples) registered in the recording unit or database. By doing so, it is possible to facilitate the inspection of an unknown sample (food) that is the new measurement object. In addition, the above-mentioned recording part or the above-mentioned database is an aspect which can also be employ | adopted, for example connecting to this food inspection apparatus via a well-known communication network.

  Therefore, in one aspect, the food inspection apparatus according to each of the above embodiments further includes a recording unit or a database, and the measurement unit records the signal intensity recorded in the recording unit (that is, the recording unit or the database). And the signal strength of a specific frequency in the resonance spectrum characteristic based on the second AC signal newly received by the receiving unit.

  Moreover, in another one aspect | mode, the food inspection apparatus of each above-mentioned embodiment is provided with at least some resonance part instead of the above-mentioned database, and when the measurement part uses one resonance part, it is 2nd. It is also possible to employ a comparison and determination step for comparing and determining the signal intensity of the resonance spectrum characteristic based on the AC signal and the signal intensity of the resonance spectrum characteristic based on the second AC signal when using another resonance unit. . In this example, the conditions of the pair of electrodes and / or coils for arranging the food to be measured are changed in order to make the resonance conditions of the one resonance part and the other resonance part different from each other. can do.

  Further, for example, in the process of freezing and thawing food, the signal intensity of the resonance spectrum characteristic can change with time. Therefore, once the food to be measured is measured, and after some time interval, the signal intensity is measured again and the values are compared. By measuring by such a method, the progress of freezing or thawing can be known with higher accuracy. In this thawing, if the food is, for example, a fish, accelerating the thawing by immersing the fish in water or applying a wind can achieve multiple measurements in a shorter time.

  As described above, the disclosure of each of the embodiments described above is described for explaining the embodiments, and is not described for limiting the present invention. In addition, modifications that exist within the scope of the present invention including other combinations of the embodiments are also included in the scope of the claims.

  One food inspection apparatus and one food inspection method of the present invention are extremely useful in current and future industries that handle food or industries that inspect food.

5 network analyzer 5a transmitter 5b receiver 6 coil 7, 7a, 7b electrode 7s side of electrode 8 computer 9 insulating layer or insulator (acrylic plate)
DESCRIPTION OF SYMBOLS 10 Food 11 Thermocouple 12 Temperature measuring instrument 14 Oscilloscope and voltmeter 16 Lock-in amplifier 21 Rail 22 Hook 25 Belt conveyor 40 Resonance part 100,200,300,310,400,410 Food inspection apparatus

Claims (17)

A resonating part including a pair of electrodes and a coil;
A transmitter for generating a first AC signal to the resonance unit;
When a food is placed between the electrodes, the AC signal is reflected from the resonance unit, the AC signal is transmitted through the resonance unit, the AC signal is a current flowing through the resonance unit, and the voltage is generated in the resonance unit. A receiver for receiving at least one second AC signal selected from the group of AC signals;
From the group of the center frequency of the resonance spectrum characteristic based on the second AC signal, the bandwidth of the resonance spectrum characteristic based on the second AC signal, and the signal intensity of a specific frequency in the resonance spectrum characteristic based on the second AC signal A measurement unit that measures at least one selected
Food inspection device. The measurement unit measures the center frequency and / or the bandwidth based on a lipid ratio of the food, a salt concentration of the food, or a change in the state of moisture accompanying a time change of the food;
The food inspection apparatus according to claim 1. The first AC signal is a broadband AC signal,
An arithmetic means for calculating the center frequency and / or the bandwidth by Fourier transform processing is further provided.
The food inspection apparatus according to claim 1 or 2. A recording unit for recording the center frequency and / or the bandwidth measured in advance;
The measurement unit includes the center frequency of the resonance spectrum characteristic based on the center frequency recorded in the recording unit and the second AC signal newly received by the receiving unit, and the bandwidth recorded in the recording unit. The bandwidth of the resonance spectrum characteristic based on the second AC signal newly received by the receiving unit, or the center frequency and the bandwidth recorded in the recording unit and the receiving unit newly received Comparing and determining the center frequency and the bandwidth of the resonant spectral characteristic based on the second AC signal;
The food inspection apparatus according to any one of claims 1 to 3. A recording unit that records the signal intensity of the specific frequency measured in advance;
The measurement unit compares and determines the signal strength recorded in the recording unit and the signal strength of a specific frequency in the resonance spectrum characteristic based on the second AC signal newly received by the receiving unit. To
The food inspection apparatus according to any one of claims 1 to 4. The measurement unit measures at least the center frequency and the bandwidth of the resonance spectrum characteristic based on the second AC signal;
The food inspection apparatus according to any one of claims 1 to 4. A removal means for removing water present on the surface of the food disposed between the electrodes;
The food inspection apparatus according to any one of claims 1 to 6. The resonance unit includes an insulator between the electrodes,
The receiving unit receives the second AC signal when the insulator and the food are disposed between the electrodes.
The food inspection apparatus according to any one of claims 1 to 7. Shielding means for preventing or suppressing leakage of the electric field formed by the electrodes is further provided,
The food inspection apparatus according to any one of claims 1 to 8. A portion of the electrodes is curved or bent so that the distance between the electrodes in the portion facing without food is shorter than the distance between the electrodes in the portion facing through the food; or A part of the electrode has a curved surface;
The food inspection apparatus according to any one of claims 1 to 9. An arrangement part for arranging the food;
The placement portion is disposed between the electrodes, and further includes a moving mechanism that relatively moves the placement portion and the electrode.
The food inspection apparatus according to any one of claims 1 to 10. An arrangement step of arranging a food item between the electrodes of a resonance part including a pair of electrodes and a coil;
A transmitting step for generating a first AC signal to the resonating unit;
When the food is disposed between the electrodes, an AC signal reflected on the resonance unit, an AC signal transmitted through the resonance unit, an AC signal including a current flowing through the resonance unit, and a voltage generated in the resonance unit A receiving step of receiving at least one second AC signal selected from the group of AC signals;
From the group of the center frequency of the resonance spectrum characteristic based on the second AC signal, the bandwidth of the resonance spectrum characteristic based on the second AC signal, and the signal intensity of a specific frequency in the resonance spectrum characteristic based on the second AC signal Measuring at least one selected, and
Food inspection method. In the measurement step, the center frequency and / or the bandwidth based on the lipid ratio of the food, the salt concentration of the food, or the change in the state of moisture accompanying the time change of the food is measured.
The food inspection method according to claim 12. One measured center frequency and the other measured center frequency, one measured bandwidth and the other measured bandwidth, or one measured center frequency and the bandwidth And comparing and determining the other measured center frequency and the bandwidth.
The food inspection method according to claim 12 or claim 13. A comparison and determination step of comparing and determining the measured signal strength of one particular frequency and the measured signal strength of the other particular frequency;
The food inspection method according to any one of claims 12 to 14. In the measurement step, at least the center frequency and the bandwidth of the resonance spectrum characteristic based on the second AC signal are measured.
The food inspection method according to any one of claims 12 to 14. A removal step of removing water present on the surface of the food disposed between the electrodes is performed before the reception step.
The food inspection method according to any one of claims 12 to 16.