JP2017205066A - Measurement apparatus, measurement method, and measurement program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring apparatus capable of highly accurately measuring the active state of a microorganism by using a thermoelectric element.SOLUTION: According to the present invention, there is provided a measurement apparatus 1 for measuring the active state of a microorganism contained in a sample. Here, the apparatus comprises: a thermostat bath 2; a thermostat member 23 arranged in the thermostat bath 2 and maintained at a constant temperature; first to third thermoelectric elements S1 to S3 installed in the thermostat member 23; and an arithmetic device 4. Here, on the thermoelectric element S1, a container C1 containing a sample is placed. On the thermoelectric elements S2 and S3, the containers C2 and C3 respectively containing the first and second reference samples are respectively placed. The arithmetic device determines the active state of the microorganism based on a first primary difference between a first electromotive force and a second electromotive force and a secondary difference, which is a first primary difference between a second electromotive force and a third electromotive force.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for measuring the activity state of microorganisms contained in a sample, and particularly to a technique for measuring the number of microorganisms from the heat generated by the microorganisms.

  In order to detect the presence or absence of microorganisms contained in samples such as foods, conventionally, there has been a technology for measuring the heat generated with the metabolic activity of microorganisms with a thermoelectric element and detecting the presence or absence of microorganisms based on the measured heat. It is used (for example, Patent Document 1). In patent document 1, the heat | fever which the microorganisms contained in a sample generate | occur | produce is measured by comparing the temperature of the sample in a thermostat with the temperature of the sterilized reference. Specifically, the presence or absence of microorganisms contained in the sample is detected by analyzing the electromotive force generated by the thermoelectric element with a computer.

JP 2003-125797

  In Patent Document 1, the thermostatic chamber is provided in a heat sink having heat insulation properties. However, since the heat generated by microorganisms is very small, a change in the ambient temperature of the thermostatic chamber greatly affects the detection result. For this reason, it is difficult for the technique of Patent Document 1 to detect the active state of the microorganism with high accuracy based on the minute electromotive force of the thermoelectric element.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a measuring apparatus capable of measuring the active state of microorganisms with high accuracy using a thermoelectric element.

  As a result of extensive research, the present inventor has found that the active state of microorganisms can be measured with high accuracy by removing fluctuation components generated in the electromotive force of the thermoelectric element due to changes in the ambient temperature of the thermostatic chamber. It was.

The present invention has been completed based on such findings and has the following aspects.
Item 1.
A measuring device for measuring the active state of microorganisms contained in a sample,
A thermostat,
A thermostatic member disposed in the thermostat and maintained at a constant temperature;
A first thermoelectric element, a second thermoelectric element, and a third thermoelectric element that are installed on the thermostatic member and generate an electromotive force according to a temperature difference between the first surface and the second surface opposite to the first surface. Thermoelectric elements of
The first primary difference, which is the difference between the first electromotive force generated by the first thermoelectric element and the second electromotive force generated by the second thermoelectric element, and the third generated by the third thermoelectric element A primary difference output unit that outputs a second primary difference that is a difference between the electromotive force of the second electromotive force and the second electromotive force;
An analysis unit for analyzing the output of the primary difference output unit;
With
The temperature of the sample is conducted to the first surface of the first thermoelectric element,
The first surface of the second thermoelectric element is conducted with the temperature of the first reference sample not containing microorganisms,
The first surface of the third thermoelectric element conducts the temperature of the second reference sample that does not contain microorganisms,
The temperature of the thermostatic member is conducted to each second surface of the first thermoelectric element, the second thermoelectric element, and the third thermoelectric element,
The analysis unit
Secondary difference output means for outputting a secondary difference that is a difference between the first primary difference and the second primary difference;
An active state measuring means for measuring an active state of the microorganism based on the second order difference;
A measuring apparatus comprising:
Item 2.
Item 2. The measuring device according to Item 1, wherein the second reference sample is a sample having a cooling constant equal to that of the sample.
Item 3.
The analysis unit
Item 3. The measuring device according to Item 1 or 2, further comprising zero correction means for correcting the secondary difference to zero.
Item 4.
The zero correction means includes
A value of 0 or less of the secondary difference is regarded as 0, and an integrated value of zero correction values of the secondary difference is calculated.
Item 4. The measuring device according to Item 3, wherein the secondary difference is zero-corrected based on the integrated value.
Item 5.
The zero correction means includes
Using a plurality of time points within a predetermined time range from the start of measurement as a reference point, the integrated value of the zero correction value of the secondary difference at each reference point is calculated,
Item 5. The measuring device according to Item 4, wherein the second-order difference is zero-corrected based on an average of the integrated values of the zero correction values.
Item 6.
The analysis unit
Item 6. The measuring apparatus according to any one of Items 1 to 5, further comprising virtual adiabatic correction means that corrects the difference on the assumption that the heat of the sample is in a virtual adiabatic state in which the heat does not move around.
Item 7.
Item 7. The measuring apparatus according to Item 6, wherein the virtual adiabatic correction unit obtains a cooling constant in Newton's cooling law of the sample from a temperature change of the sample, and corrects the secondary difference based on the Newton's cooling law.
Item 8.
Item 8. The measuring device according to any one of Items 1 to 7, wherein the first reference sample is a sample having the same cooling constant as the sample.
Item 9.
Item 9. The measuring apparatus according to any one of Items 1 to 8, wherein the sample is food.
Item 10.
A thermostatic member maintained at a constant temperature;
A first thermoelectric element, a second thermoelectric element, and a third thermoelectric element that are installed on the thermostatic member and generate an electromotive force according to a temperature difference between the first surface and the second surface opposite to the first surface. Thermoelectric elements of
Is a measurement method for measuring the activity state of microorganisms contained in a sample, using a thermostat equipped with,
The temperature of the sample is conducted to the first surface of the first thermoelectric element, and the temperature of the first reference sample that does not contain microorganisms is formed on the first surface of the second thermoelectric element. Conducting and conducting the temperature of the second reference sample not containing microorganisms to the first surface of the third thermoelectric element, the first thermoelectric element, the second thermoelectric element, and the third A conduction step of conducting the temperature of the thermostatic member to each of the second surfaces of the thermoelectric element;
The first primary difference, which is the difference between the first electromotive force generated by the first thermoelectric element and the second electromotive force generated by the second thermoelectric element, and the third generated by the third thermoelectric element A primary difference output step of outputting a second primary difference that is a difference between the electromotive force of the second electromotive force and the second electromotive force;
An analysis step of analyzing the output in the primary difference output step;
With
The analysis step includes
A secondary difference output step of outputting a secondary difference that is a difference between the first primary difference and the second primary difference;
An active state measuring step of measuring an active state of the microorganism based on the second order difference;
A measurement method comprising:
Item 11.
Item 10. A measurement program that causes a computer to function as each of the means according to any one of Items 1 to 9.

  ADVANTAGE OF THE INVENTION According to this invention, the measuring apparatus which can measure the active state of microorganisms with a high precision using a thermoelectric element can be provided.

It is the schematic which shows the whole structure of the measuring apparatus which concerns on the 1st Embodiment of this invention, (a) has shown the state which the cover part opened, (b) has shown the state in which the cover part was closed. Show. It is a top view of the thermostat in the measuring apparatus shown in FIG. (A) is a block diagram which shows the hardware constitutions of the arithmetic unit in the measuring apparatus shown in FIG. 1, (b) is a functional block diagram of the said arithmetic unit. (A) and (b) show examples of waveforms of the first primary difference Vd1 and the second primary difference Vd2 in the first embodiment, respectively, and (c) shows the first primary difference Vd1. 2 shows a waveform of the secondary difference VD between the second primary difference Vd2 and (d) shows a common logarithmic value of the secondary difference VD. It is the schematic which shows the whole structure of the measuring apparatus which concerns on the example of improvement of 1st Embodiment. An example of the waveform of the secondary difference VD before correction in the improved example is shown. (A)-(d) is a graph which shows the waveform of the secondary difference VD in each step | level of the zero correction | amendment with respect to the secondary difference VD. It is explanatory drawing of the principle of virtual adiabatic correction. The secondary difference VD corrected by the virtual adiabatic correction unit is shown. It is the schematic which shows the whole structure of the measuring apparatus which concerns on the 1st modification of 1st Embodiment. It is the schematic which shows the whole structure of the measuring apparatus which concerns on the 2nd modification of 1st Embodiment. It is the schematic which shows the whole structure of the measuring apparatus which concerns on the 2nd Embodiment of this invention. It is the schematic which shows the whole structure of the measuring apparatus which concerns on the modification of 2nd Embodiment. In Example 1, it is a graph which shows the measurement result by a measuring apparatus and a preservation | save test at the time of using egg-baking as a sample. In Example 1, it is a graph which shows the measurement result by a measuring device and a preservation | save test at the time of using an insulator as a sample. In Example 1, it is a graph which shows the measurement result by a measuring apparatus and a preservation | save test at the time of using a white sauce as a sample. 6 is a graph showing a waveform of a difference Vd measured in Example 2.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In addition, this invention is not limited to the following embodiment.

[First Embodiment]
Overall Configuration FIG. 1 is a schematic view showing the overall configuration of a measuring apparatus 1 according to the first embodiment of the present invention, and FIG. 2 is a plan view of a thermostatic chamber 2 in the measuring apparatus 1.

  The measuring apparatus 1 is a measuring apparatus that measures the activity state of microorganisms contained in a sample. In this embodiment, the number of microorganisms (the number of bacteria) can be measured as the activity state of microorganisms. As shown in FIG. 1, the measuring device 1 includes a constant temperature bath 2, an output unit 3, and a calculation device 4.

As shown in FIGS. 1 and 2, the thermostat 2 is a device that keeps the internal temperature constant. In the present embodiment, the lid 21, the box 22, the thermostat 23, and the thermoelectric element S1. To S9. The lid 21 and the box 22 are formed of a heat insulating material. A liquid whose temperature is adjusted circulates in the internal space of the box 22, and the lid 21 seals the box 22, whereby the inside of the thermostatic chamber 2 can be kept at a desired temperature. 1A shows a state in which the lid 21 is opened, and FIG. 1B shows a state in which the lid 21 is closed.

  The constant temperature member 23 is made of a material having high thermal conductivity, and is provided in the internal space of the box 22. In addition, nine concave portions are formed on the inner surfaces of the thermostatic member 23 and the lid portion 21. As shown in FIG. 1B, the thermostatic member 23 and the lid 21 are in contact with each other when the lid 21 is closed. Nine divided spaces (cells) are formed by overlapping the concave portions of the thermostatic member 23 and the lid portion 21.

  The structure of the thermostatic chamber 2 is not limited to the above, and is not particularly limited as long as the temperature of the thermostatic member 23 can be kept constant.

  As shown in FIG. 2, thermoelectric elements S <b> 1 to S <b> 9 are provided in the concave portion of the thermostatic member 23. The thermostat 2 shown in FIG. 1 is shown as an AA cross section in FIG. 2. In FIG. 1, three thermoelectric elements S <b> 1 to S <b> 3 of the thermoelectric elements S are shown. In addition, since the structure of thermoelectric element S1-S9 is the same, in this specification, these may be named the thermoelectric element S generically.

  The thermoelectric element S is an element that generates an electromotive force according to a temperature difference between the front surface (first surface) and the back surface (second surface) due to the Seebeck effect. The shape of the thermoelectric element S is not particularly limited, but is a disk shape in the present embodiment. Further, the back surface of the thermoelectric element S is in contact with the constant temperature member 23, and the temperature of the constant temperature member 23 is conducted to the reverse surface. If the temperature of the thermostatic member 23 is conducted to the back surface of the thermoelectric element S, the back surface is not necessarily in contact with the thermostatic member 23, and the thermal conductivity is between the back surface and the thermostatic member 23. A high sheet or the like may be provided.

  Each thermoelectric element S is connected to a wiring for extracting an electromotive force. In FIG. 1, wirings L1 to L3 are connected to the thermoelectric elements S1 to S3, respectively, the electromotive force V1 of the thermoelectric element S1 is taken out by the wiring L1, and the electromotive force V2 of the thermoelectric element S2 is taken out by the wiring L2. The electromotive force V3 of the thermoelectric element S3 is taken out by the wiring L3.

  The output unit 3 converts the electromotive force of each thermoelectric element S into a digital signal, and the electromotive forces V1, V3-V9 of the thermoelectric elements S1, S3 to S9 other than the thermoelectric element S2, and the electromotive force of the thermoelectric element S2. This is a device that outputs the primary difference from V2 to the outside of the thermostat 2. For example, it is provided in the housing of the thermostat 2. The output unit 3 is an amplifier that amplifies the electromotive force of each thermoelectric element S, an analog-digital conversion circuit (hereinafter referred to as ADC) that converts the amplified electromotive force into a digital signal, and a primary that outputs a primary difference of the digital signal. A differential output unit is provided. For convenience, in FIG. 1, an amplifier 31a that amplifies the electromotive force V1, an amplifier 31b that amplifies the electromotive force V2, an amplifier 31c that amplifies the electromotive force V3, an ADC 32a that digitally converts the amplified electromotive force V1, and an amplification ADC 32b for digitally converting the generated electromotive force V2, ADC 32c for digitally converting the amplified electromotive force V3, and a first primary difference Vd1 (= V1) that is a difference between the digitally converted electromotive force V1 and the electromotive force V2. -V2), and a primary difference output unit 33b that outputs a second primary difference Vd2 (= V3-V2) that is a difference between the digitally converted electromotive force V3 and the electromotive force V2. Is shown. The first primary difference Vd1 and the second primary difference Vd2 are input to the arithmetic device 4.

  When the thermostat 2 is used, a container that can store a sample or the like is placed on the surface of the thermoelectric element S, and the lid 21 is closed. In this embodiment, as shown in FIG.1 (b), container C1-C3 is each mounted on each surface of thermoelectric element S1-S3. The containers C1 to C3 are stainless containers having high thermal conductivity such as a petri dish, and a sample containing microorganisms is accommodated in the container C1. The container C2 contains a first reference sample that does not contain microorganisms, and the container C3 contains a second reference sample that does not contain microorganisms.

  In this embodiment, the sample accommodated in the container C1 is food. The temperature of the sample is conducted to the surface of the thermoelectric element S1 through the container C1, and the thermoelectric element S1 generates an electromotive force V1 corresponding to the temperature difference between the thermostatic member 23 and the sample.

  The first reference sample stored in the container C2 is not particularly limited as long as it is a sterile sample that has been subjected to a treatment that does not allow microorganisms to grow even if left for a long period of time. The second reference sample stored in the container C3 is preferably a sample having the same cooling constant as that of the sample stored in the container C1. In the present embodiment, the second reference sample is the same type of food and the same weight as the sample, and is subjected to a treatment that does not allow microorganisms to propagate. The temperature of the first reference sample is conducted to the surface of the thermoelectric element S2 via the container C2, and the thermoelectric element S2 has an electromotive force V2 corresponding to the temperature difference between the thermostatic member 23 and the first reference sample. Is generated. Similarly, the temperature of the second reference sample is conducted to the surface of the thermoelectric element S3 via the container C3, and the thermoelectric element S3 corresponds to the temperature difference between the thermostatic member 23 and the second reference sample. An electromotive force V3 is generated.

  Note that it is not essential to use the container C1 as long as the temperature of the sample is conducted to the surface of the thermoelectric element S1. For example, the sample may be wrapped with a packaging material such as a wrap, and the packaging material may be placed on the surface of the thermoelectric element S1, or the sample may be placed directly on the surface of the thermoelectric element S1. Similarly, the first reference sample and the second reference sample may be wrapped with a packaging material, and the packaging material may be placed on each surface of the thermoelectric elements S2 and S3, or the first reference sample. The second reference sample may be placed directly on the surfaces of the thermoelectric elements S2 and S3.

  When the container C1 is placed on the surface of the thermoelectric element S1, the temperature of the container C1 and the sample inside becomes equal to the temperature of the thermostatic member 23 after several tens of minutes. Thereafter, as the microorganisms grow, the metabolic heat released by the microorganisms increases, and the temperature difference between the thermostatic member 23 and the sample increases. Thereby, the electromotive force V1 of the thermoelectric element S1 increases in accordance with the number of microorganisms grown.

  Similarly, when containers C2 and C3 are placed on the surfaces of thermoelectric elements S2 and S3, after several tens of minutes, the temperatures of containers C2 and C3, the first reference sample, and the second reference sample are constant. An equilibrium state equal to the temperature of the member 23 is obtained. Since the first reference sample and the second reference sample do not contain microorganisms, the temperature does not increase even after reaching the equilibrium state, and the electromotive forces V2 and V3 of the thermoelectric elements S2 and S3 are Theoretically it is zero.

  Here, since the electromotive force generated by the thermoelectric element S is an analog signal, it is susceptible to noise before being converted into a digital signal. Therefore, noise components are likely to be mixed into the electromotive force of the thermoelectric element S. On the other hand, in the measuring apparatus 1, the output unit 3 subtracts the electromotive force V2 of the thermoelectric element S2 from the electromotive forces V1 and V3 to V9 of the thermoelectric elements S1 and S3 to S9. Thereby, noise components are removed from the electromotive forces V1, V3 to V9.

  However, since the heat generated by the microorganism is very small, a change in the ambient temperature of the thermostatic chamber 2 greatly affects the measurement result. Although the thermostatic member 23 of the thermostat 2 is insulated from the outside, it is actually difficult to maintain the insulated state from the outside for a long time at the level of temperature change caused by the heat generated by the microorganisms. Therefore, the sample in the container C1 and the second reference sample in the container C3 are affected by the ambient temperature of the constant temperature bath 2, and the first primary difference Vd1 and the second primary difference output from the output unit 3 Vd2 includes an error component due to the ambient temperature of the thermostat 2.

  Therefore, in the present invention, the error component is removed by taking a secondary difference that is a difference between the first primary difference Vd1 and the second primary difference Vd2 output from the output unit 3. The error component is removed by processing in the arithmetic unit 4.

Arrangement of Arithmetic Unit FIG. 3A is a block diagram showing a hardware configuration of the arithmetic unit 4, and FIG. 3B is a functional block diagram of the arithmetic unit 4. The arithmetic device 4 is, for example, a general-purpose personal computer, and includes a CPU 101, a memory 102, and a hard disk 103 as shown in FIG. The CPU 101 executes various arithmetic processes by reading a program stored in the hard disk 103 into the memory 102 and executing it. The memory 102 temporarily stores programs and data read by the CPU 101 from the hard disk 103. The hard disk 103 stores various programs including the measurement program according to the present embodiment and various data generated by executing the program.

  The measurement program according to the present embodiment may be recorded on a non-transitory computer-readable recording medium such as a CD-ROM, and the measurement program is stored in the hard disk 103 by causing the arithmetic device 4 to read the recording medium. Stored. Alternatively, the arithmetic device 4 may be connected to a communication network, and the program code of the measurement program may be downloaded via the communication network.

  Further, an input device 5 and a display device 6 are connected to the arithmetic device 4 as necessary. The input device 5 includes a keyboard and a mouse, and mainly accepts input from the user. The display device 6 is composed of a liquid crystal display or the like, and displays a calculation processing result by the CPU 101.

  When the CPU 101 executes the measurement program stored in the hard disk 103, the arithmetic device 4 having a function as shown in FIG. The arithmetic device 4 includes a secondary difference output unit 41 and a bacteria count measurement unit 42 as functional blocks. Note that at least one of the secondary difference output unit 41 and the bacteria count measurement unit 42 may be realized in hardware by a logic circuit or the like.

  The first primary difference Vd1 and the second primary difference Vd2 are input to the secondary difference output unit 41 from the output unit 3 illustrated in FIG. The secondary difference output unit 41 outputs a secondary difference VD = Vd1−Vd2 that is a difference between the first primary difference Vd1 and the second primary difference Vd2 to the bacterial count measuring unit 42.

  The bacterial count measuring unit 42 measures the bacterial count contained in the sample based on the secondary difference VD. Specifically, table data indicating the relationship between the electromotive force of the thermoelectric element and the number of bacteria is stored in the hard disk 103 of the arithmetic device 4 for each type of microorganism, and the bacteria count measuring unit 42 stores this table data. The number of bacteria is calculated with reference.

The secondary difference VD output by the calculation secondary difference output unit 41 of the number of bacteria is expressed by a mathematical expression:
VD = Vd1-Vd2 = (V1-V2)-(V3-V2) = V1-V3
Theoretically, since V3 = 0, VD = V1.

  FIGS. 4A and 4B show examples of waveforms of the first primary difference Vd1 and the second primary difference Vd2 in the present embodiment, respectively. The first primary difference Vd1 corresponds to a value obtained by removing a noise component from the electromotive force V1 of the thermoelectric element S1 on which the container C1 containing the sample is placed (Vd1 = V1−V2), but FIG. As shown in FIG. 4, fluctuations occur according to changes in the ambient temperature of the thermostatic chamber 2. On the other hand, the second primary difference Vd2 is theoretically 0 (Vd2 = V3−V2). However, as shown in FIG. A fluctuation similar to that in the primary difference Vd1 occurs.

  FIG. 4C shows a waveform of the secondary difference VD between the first primary difference Vd1 and the second primary difference Vd2. In the present embodiment, the second reference sample stored in the container C3 is a sample having the same cooling constant as the sample stored in the container C1. Therefore, the temperature change due to the ambient temperature of the thermostat 2 is equal between the sample and the second reference sample, and is included in the fluctuation component (error component) included in the first primary difference Vd1 and the second primary difference Vd2. The fluctuation components (error components) to be transmitted are almost the same. Therefore, the fluctuation component can be removed from the first primary difference Vd1 by taking the secondary difference VD between the first primary difference Vd1 and the second primary difference Vd2. Therefore, the fluctuation component is hardly included in the secondary difference VD, and the bacterial count measuring unit 42 can accurately calculate the bacterial count based on the secondary difference VD.

  FIG. 4D is a graph showing the common logarithm of the secondary difference VD, and the vertical axis on the right side shows the number of bacteria corresponding to the secondary difference VD. The electromotive force corresponding to the heat generated by the number of microorganisms that can safely ingest samples as food (approximately 5 log cfu / g, hereinafter referred to as safe bacteria count) depends on the type of microorganism and the storage conditions. In general, if the food has a expiration date of 1 to 2 days, it is about 100 μV as shown by the broken lines in FIGS. 4 (a), (b) and (d).

  As shown in FIG. 4A, the fluctuation component is included in the first primary difference Vd1, and therefore it cannot be accurately determined at which point the bacterial count exceeds the safe bacterial count. On the other hand, since the secondary difference VD contains almost no fluctuation component, as shown in FIGS. 4C and 4D, it can be determined that the number of safe bacteria has been exceeded after about 2000 minutes.

  As described above, in this embodiment, the container C1 containing the sample is placed in the thermoelectric element S1, and the container C2 containing the first reference sample that does not contain microorganisms is placed in the thermoelectric element S2. The container C3 containing the second reference sample that does not contain microorganisms is placed in the thermoelectric element S3, and the output unit 3 generates the electromotive force V1 generated by the thermoelectric element S1 and the electromotive force generated by the thermoelectric element S2. Output a first primary difference Vd1 from V2 and a second primary difference Vd2 between the electromotive force V3 generated by the thermoelectric element S3 and the electromotive force V2 generated by the thermoelectric element S2, and The secondary difference output unit 41 outputs a secondary difference VD that is a difference between the first primary difference Vd1 and the second primary difference Vd2, and the bacterial count measuring unit 42 is based on the secondary difference VD, The number is being measured. By taking the secondary difference, the fluctuation component included in the first primary difference Vd1 can be removed, so that the activity state of the microorganism can be measured with higher accuracy than in the prior art that does not remove the fluctuation component. Can do.

  In addition, when the temperature of the sample becomes higher than the environmental temperature (internal temperature of the thermostat 2 = temperature of the thermostatic member 23) with the growth of microorganisms, the sample is cooled by moving the heat of the sample to the surroundings. . Thereby, since electromotive force V1 falls by cooling of a sample, the measurement result of a microbe count becomes smaller than an actual microbe count.

  Therefore, it is desirable to suppress the amount of heat that moves from the sample in the container C1 to the surroundings as much as possible. For example, by forming the container C1 other than the bottom surface in contact with the thermoelectric element S1 with a heat insulating material or covering the inner surface of the cell containing the container C1 with a heat insulating material, it approximates a virtual heat insulating state in which the heat of the sample does not move around. Can be made.

  Moreover, although the position in which each container C1-C3 is mounted is not specifically limited, It is preferable to mount the containers C1 and C3 in the thermoelectric element located in the mutually equal distance from the inner surface of the box 22 in FIG. . Thereby, the influence which the sample in the container C1 and the 2nd reference sample in the container C3 receive from the ambient temperature of the thermostat 2 can mutually be made equal. As a combination of the thermoelectric elements on which the containers C1 and C3 are placed, the thermoelectric elements S1 and S3, the thermoelectric elements S5 and S8, the thermoelectric elements S6 and S7, the thermoelectric elements S4 and S9, and the thermoelectric element S4 as in this embodiment. And S6, thermoelectric elements S6 and S9, thermoelectric elements S7 and S9, and thermoelectric elements S4 and S7.

  In addition to the second reference sample, the first reference sample preferably has the same cooling constant as the sample.

Modified Example In the above-described form, the secondary difference VD output from the secondary difference output unit 41 does not include a fluctuation component. However, when the cooling constant of the sample and the cooling constant of the second reference sample are different, the fluctuation component remains. Further, when the temperature of the sample becomes higher than the environmental temperature (internal temperature of the thermostatic chamber 2 = temperature of the thermostatic member 23) as the microorganisms grow, the sample is cooled by the heat of the sample moving to the surroundings. . Thereby, since electromotive force V1 falls by cooling of a sample, the measurement result of a microbe count becomes smaller than an actual microbe count.

  Therefore, in the following improvement example, the fluctuation component remains in the secondary difference VD, and the configuration in which the activity state of the microorganism can be measured with high accuracy even when the heat of the sample moves to the surroundings. explain.

FIG. 5 is a schematic diagram showing the overall configuration of the measuring apparatus 1a according to this improved example. The measuring device 1a includes a constant temperature bath 2, an output unit 3, and an arithmetic device 4a. That is, the measuring device 1a has a configuration in which the arithmetic device 4 is replaced with the arithmetic device 4a in the measuring device 1 shown in FIG. In addition, about the member which has the same function as the thing in the measuring apparatus 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
The hardware configuration of the arithmetic device 4a is the same as that shown in FIG. As shown in FIG. 5, the arithmetic device 4 a includes a secondary difference output unit 41, a bacterial count measurement unit 42, a zero correction unit 43, and a virtual adiabatic correction unit 44. These functional blocks may be realized by the CPU of the arithmetic device 4a executing the measurement program according to this improved example, or may be realized in hardware by a logic circuit or the like. The secondary difference output unit 41 and the bacteria count measurement unit 42 are the same as those in the arithmetic device 4 described above. On the other hand, each of the zero correction unit 43 and the virtual adiabatic correction unit 44 has a function of correcting the secondary difference VD output from the secondary difference output unit 41. The number of bacteria is calculated based on the next difference VD.

Zero Correction Unit FIG. 6 shows an example of the waveform of the secondary difference VD before correction in this improved example. Due to the difference between the cooling constant of the sample and the cooling constant of the second reference sample, a fluctuation component remains in the secondary difference VD.

  Therefore, in the present improved example, the zero-order correction unit 43 corrects the secondary difference VD as follows. First, the zero correction unit 43 determines a point in time in the temporal change of the secondary difference VD, regards the value at that point as 0, and integrates the values after that point. For example, the solid line, the broken line, and the alternate long and short dash line shown in FIG. 7A indicate the time change of the integrated value of the secondary difference VD corrected by setting the value of the difference Vd at the measurement start time 172 minutes, 171 minutes, and 170 minutes to 0. Show.

  Further, the zero correction unit 43 performs correction to set a value equal to or less than 0 to 0 in the integrated value shown in FIG. 7A (minus correction). Thereby, the integrated value of the zero correction value of the secondary difference VD shown in FIG. 7B is obtained.

  Further, the zero correction unit 43 calculates the integrated value of the zero correction value of the secondary difference at each reference point using a plurality of time points in a predetermined time range from the start of measurement as the reference point, and the integrated value of the zero correction value The secondary difference is zero-corrected based on the average of. In this improved example, a plurality of time points (151 minutes, 152 minutes, 153 minutes,..., 190 minutes, 191 minutes) in the range of 151 minutes to 191 minutes from the start of measurement are used as reference points, and the secondary at each reference point. The zero correction value 41 of the difference VD is calculated, and the average of the 41 zero correction values is calculated.

  FIG. 7 (c) shows an average integrated value (one-dot chain line) of zero correction values of secondary difference VD with each time point from 150 minutes to 190 minutes from the start of measurement being 0, each of 151 minutes to 191 minutes from the start of measurement. The average integrated value (broken line) of the zero correction value of the secondary difference VD with the time point set to 0, and the average of the zero correction value of the secondary difference VD with the time points of the 152 to 192 minutes from the measurement start being set to 0 The integrated value (solid line) is shown. From FIG. 7C, the average integrated value of the correction values of the secondary difference VD is substantially the same regardless of the above-described time range serving as the reference for zero correction. The time range is such that the temperature of each of the containers C1 to C3 and the temperature of the thermostatic member 23 are in an equilibrium state so that the sample microorganism in the container C1 generates an electromotive force in the thermoelectric element S1. It is preferably included in the period until the metabolic fever is generated.

  In this improved example, as shown in FIG. 7 (d), the zero correction unit 43, for example, of the integrated value of the zero correction value of the secondary difference VD with each time point of 151 minutes to 191 minutes from the start of measurement as 0. Calculate the average. Thereby, the zero correction | amendment part 43 can carry out zero correction | amendment of the secondary difference VD based on the average of this integrated value.

Virtual Adiabatic Correction Unit Further, in this improved example, the virtual adiabatic correction unit 44 corrects the above-described zero-corrected secondary difference VD on the assumption that the heat of the sample is in a virtual adiabatic state in which it does not move to the surroundings (virtual adiabatic correction unit 44) Adiabatic correction). First, the principle of virtual adiabatic correction will be described with reference to FIG.

  An actual measurement value 1 shown in FIG. 8 is an actual measurement value of the sample temperature at a certain point in time, and an actual measurement value 2 is an actual measurement value of the sample temperature after a predetermined time has elapsed from that point in time. When the temperature of the sample is higher than the environmental temperature (internal temperature of the thermostat 2 = temperature of the thermostatic member 23), the sample is cooled by moving the heat of the sample to the surroundings. Therefore, the difference between the actual measurement value 1 and the actual measurement value 2 is obtained by subtracting the electromotive force decrease due to cooling of the sample from the electromotive force increase due to microorganism growth. Therefore, when the number of bacteria is measured based on the actual measurement value 2, the amount of decrease in electromotive force due to cooling of the sample becomes an error, and the measurement result becomes smaller than the actual number of bacteria.

Therefore, in the present embodiment, the virtual adiabatic correction is performed by adding the electromotive force decrease due to the cooling of the sample to the actual measurement value 2. Specifically, the decrease in electromotive force due to cooling of the sample is calculated based on Newton's cooling law. Newton's cooling law is expressed by the following equation.
t: Time T: Sample temperature C: Environmental temperature r: Cooling constant

  In this improved example, the virtual adiabatic correction unit 44 obtains the cooling constant r in Newton's cooling law from the temperature change of the sample in the container C1 placed on the thermoelectric element S1. More specifically, the virtual adiabatic correction unit 44 determines the temperature of the sample during a period (for example, 30 minutes) from when the container C1 is placed on the thermoelectric element S1 until the temperature of the sample and the constant temperature member 23 becomes equal. The cooling constant r is obtained from the change. Thereby, the virtual heat insulation correction | amendment part 44 can calculate the calorie | heat amount which moved to the circumference | surroundings from the sample based on Newton's cooling law, and can obtain | require the correction value of the secondary difference VD in a virtual heat insulation state.

  FIG. 9 shows the secondary difference VD corrected by the virtual adiabatic correction unit 44. The secondary difference VD after the virtual adiabatic correction corresponds to the electromotive force V1 in a virtual adiabatic state in which the fluctuation component is removed and the heat of the sample does not move to the surroundings. The bacterial count measuring unit 42 measures the bacterial count of microorganisms contained in the sample based on the secondary difference VD from the virtual adiabatic correction unit 44. Therefore, in this improved example, even if a fluctuation component remains in the secondary difference VD, the number of bacteria can be measured with high accuracy.

  Even when the cooling constant of the sample and the cooling constant of the second reference sample are the same, the influence of the ambient temperature of the thermostat 2 differs between the sample and the second reference sample, etc. For the reason, a fluctuation component may remain in the secondary difference VD. Therefore, it is preferable to correct the secondary difference VD as in this improved example.

In the present embodiment, the output unit 3 outputs the first primary difference Vd1 and the second primary difference Vd2, and the arithmetic device 4 outputs the secondary difference VD and the number of bacteria based on the secondary difference VD. Was measured. That is, the output unit 3 includes the primary difference output unit described in the claims, and the arithmetic device 4 includes the analysis unit described in the claims. However, the present invention is not limited to this. Hereinafter, modifications of the present embodiment will be described.

  FIG. 10 is a schematic diagram showing an overall configuration of a measuring apparatus 1b according to a first modification of the present embodiment. The measuring device 1b includes a constant temperature bath 2, an output unit 3b, and an arithmetic device 4b. That is, the measuring device 1b has a configuration in which the output unit 3 and the arithmetic device 4 are replaced with the output unit 3b and the arithmetic device 4b in the measuring device 1 shown in FIG.

  The output unit 3b includes an amplifier 31a, an amplifier 31b, an amplifier 31c, an ADC 32a, an ADC 32b, an ADC 32c, a primary difference output unit 33a, a primary difference output unit 33b, and a secondary difference output unit 34. In other words, the output unit 3b is configured to further include a secondary difference output unit 34 in the output unit 3 shown in FIG. The secondary difference output unit 34 outputs a secondary difference VD between the first primary difference Vd1 input from the primary difference output unit 33a and the second primary difference Vd2 input from the primary difference output unit 33b. The secondary difference VD output from the secondary difference output unit 34 is input to the arithmetic device 4b.

  The arithmetic device 4b includes a bacterial count measuring unit 42. The bacterial count measurement unit 42 measures the bacterial count based on the secondary difference VD received from the secondary difference output unit 34.

  Thus, in the first modification, the output unit 3b includes the primary difference output unit described in the claims and the secondary difference output means of the analysis unit, and the arithmetic device 4b analyzes the claims described in the claims. Part activity state measuring means.

  FIG. 11 is a schematic diagram showing an overall configuration of a measuring apparatus 1c according to a second modification of the present embodiment. The measuring device 1c includes a constant temperature bath 2, an output unit 3c, and an arithmetic device 4c. That is, the measuring device 1c has a configuration in which the output unit 3 and the arithmetic device 4 are replaced with the output unit 3c and the arithmetic device 4c in the measuring device 1 shown in FIG.

  The output unit 3c includes an amplifier 31a, an amplifier 31b, an amplifier 31c, an ADC 32a, an ADC 32b, and an ADC 32c. That is, the output unit 3c has a configuration in which the primary difference output units 33a and 33b are omitted from the output unit 3 illustrated in FIG. The electromotive forces V1, V2, and V3 of the digital signals output from the ADCs 32a, 32b, and 32c are input to the arithmetic device 4c.

  The arithmetic device 4c includes a primary difference output unit 40a, a primary difference output unit 40b, a secondary difference output unit 41, and a bacteria count measurement unit 42 as functional blocks. That is, the arithmetic device 4c has a configuration further including a primary difference output unit 40a and a primary difference output unit 40b in the arithmetic device 4 shown in FIG.

  The primary difference output unit 40a outputs a first primary difference Vd1 that is a difference between the electromotive force V1 and the electromotive force V2, and the primary difference output unit 40b is a second that is a difference between the electromotive force V3 and the electromotive force V2. The primary difference Vd2 is output. The secondary difference output unit 41 and the bacteria count measurement unit 42 have the same functions as the secondary difference output unit 41 and the bacteria count measurement unit 42 shown in FIG.

  Thus, in the second modification, the arithmetic device 4c includes the primary difference output unit and the analysis unit described in the claims.

[Second Embodiment]
Subsequently, a second embodiment of the present invention will be described.

  FIG. 12 is a schematic diagram showing the overall configuration of a measuring apparatus 1d according to the second embodiment of the present invention. The measuring device 1d includes a constant temperature bath 2, an output unit 3d, and an arithmetic device 4d. That is, the measuring device 1d has a configuration in which the output unit 3 and the arithmetic device 4 are replaced with the output unit 3d and the arithmetic device 4d in the measuring device 1 shown in FIG. In addition, about the member which has the same function as the thing in the measuring apparatus 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  The thermostat 2 in this embodiment has the same configuration as the thermostat 2 shown in FIG. As shown in FIG. 12, the container C1 is placed on the surface of the thermoelectric element S1, and the container C2 is placed on the surface of the thermoelectric element S2. The container C1 contains a sample containing microorganisms. When the temperature of the sample is conducted to the surface of the thermoelectric element S1 via the container C1, the thermoelectric element S1 generates an electromotive force V1. The electromotive force V1 of the thermoelectric element S1 increases according to the number of microorganisms grown.

  The container C2 contains a reference sample that does not contain microorganisms. The temperature of the reference sample is conducted to the surface of the thermoelectric element S2 via the container C2, so that the thermoelectric element S2 generates an electromotive force V2. Since the reference sample does not contain microorganisms, the electromotive force V2 of the thermoelectric element S2 is theoretically zero.

  The sample stored in the container C1 is the same as in the first embodiment and is a food. In addition, the reference sample stored in the container C2 is a sterile sample that has been subjected to a process in which microorganisms do not propagate even when left for a long period of time, like the first reference sample in the first embodiment. In the present embodiment, the first reference sample stored in the container C2 uses a sample having the same cooling constant as that of the sample stored in the container C1, for example, an aqueous solution adjusted in weight or the like, Similar to the second reference sample in the embodiment, a sample having the same type of food and the same weight as the sample stored in the container C1 can be used.

  The output unit 3d includes an amplifier 31a, an amplifier 31b, an ADC 32a, and an ADC 32b. The electromotive force V1 and electromotive force V2 of the digital signals output from the ADC 32a and the ADC 32b are input to the arithmetic device 4d.

  The arithmetic device 4d includes a difference output unit 40 and a bacteria count measurement unit 42. These functional blocks may be realized in software by the CPU of the arithmetic device 4d executing a program, or may be realized in hardware by a logic circuit or the like.

  The difference output unit 40 outputs a difference Vd between the electromotive force V1 and the electromotive force V2. That is, the difference output unit 40 has the same function as the primary difference output units 33a and 40a in the first embodiment.

  The bacterial count measuring unit 42 measures the bacterial count based on the difference Vd received from the differential output unit 40. Unlike the first embodiment, the measurement apparatus 1d according to the present embodiment does not have a function corresponding to the secondary difference output unit 41 illustrated in FIG. 3B, and the electromotive force V1 and the electromotive force V2 The number of bacteria can be measured based on the primary difference.

  As described above, in this embodiment, the cooling constant of the sample stored in the container C1 is equal to the cooling constant of the reference sample stored in the container C2. For this reason, the temperature change of the sample due to the ambient temperature of the thermostat 2 is equal to the temperature change of the reference sample, whereby the fluctuation component included in the electromotive force V1 is equal to the fluctuation component included in the electromotive force V2. Become. Therefore, in the difference output part 40, the fluctuation component contained in the electromotive force V1 is removed by taking the difference of the electromotive force V1 and the electromotive force V2, and the microbe count measurement part 42 measures microbe count with high precision. be able to.

  FIG. 13 is a schematic diagram illustrating the overall configuration of a measurement apparatus 1e according to a modification of the present embodiment. The measuring device 1e includes a constant temperature bath 2, an output unit 3e, and an arithmetic device 4b. That is, the measuring device 1e has a configuration in which the output unit 3d and the calculation device 4d are replaced with the output unit 3e and the calculation device 4b in the measurement device 1d shown in FIG. In addition, about the member which has the same function as what is in the measuring apparatus 1d, the same code | symbol is attached | subjected and the description is abbreviate | omitted. For example, the configuration of the thermostatic chamber 2 and the contents contained in the containers C1 and C2 are the same as those in the measuring device 1d.

  The output unit 3e includes an amplifier 31a, an amplifier 31b, an ADC 32a, an ADC 32b, and a differential output unit 33. The difference output unit 33 has the same function as the difference output unit 40 shown in FIG. 12 and outputs a difference Vd between the electromotive force V1 and the electromotive force V2. The difference Vd is input to the arithmetic device 4b.

  The arithmetic device 4b includes a bacterial count measuring unit 42 as in the arithmetic device 4b shown in FIG. The bacterial count measuring unit 42 measures the bacterial count based on the difference Vd received from the differential output unit 40.

  Thus, in the measuring apparatus 1e, the difference output unit 33 is provided in the output unit 3e.

  In the present embodiment, the cooling constant of the sample and the cooling constant of the reference sample may be slightly different. The allowable difference between the cooling constants depends on the level of the electromotive force generated by the metabolic heat of the microorganism. For example, the ratio of the cooling constant of the sample to the cooling constant of the reference sample is 0.95 to 1.05. Preferably there is.

  In this case, since some fluctuation components remain in the difference Vd, the zero correction unit 43 and the virtual heat insulation shown in FIG. 5 are provided downstream of the difference output unit 40 shown in FIG. 12 or the difference output unit 33 shown in FIG. It is preferable to correct the difference Vd by providing the correction unit 44 and measure the number of bacteria based on the corrected difference Vd.

[Additional Notes]
The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical matters disclosed in the embodiments are also included in the present invention. Is included in the technical scope.

  For example, in the above embodiment, the number of bacteria is measured as the active state of the microorganism. However, the calorific value of the microorganism may be measured, or the electromotive force (that is, the difference Vd) of the thermoelectric element S1 due to the heat generation is measured. May be. Alternatively, it may be determined whether or not the number of bacteria in the sample exceeds the number of safe bacteria.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. In the following, “%” means “% by mass” and “parts” means “parts by mass” unless otherwise specified. Also, the “*” mark in the text means that it is a registered trademark of San-Eigen FFI Corporation.

[Example 1]
In Example 1, the measuring device 1a according to the modified example of the first embodiment shown in FIG. 5 is used. As the thermostatic chamber 2 of the measuring device 1a, the microorganism activity measuring system “Leonis” manufactured by ULVAC-RIKO Co., Ltd. is used. A thermostatic bath was used. In addition, stainless steel dishes were used as the containers C1 to C3.

1. Fried egg
1-1. Preparation of sample Egg solution in which 72 parts of whole egg (behind), 3.5 parts of super white sugar, 2 parts of potato starch, sun-like * Japanese-style dashi 6402L * 2 parts, Sansugen ** 0.25 parts, 16.25 parts of water Then, Bacillus cereus (Cereus bacterium) was inoculated to 50 cfu / g and then baked in a frying pan to obtain a fried egg. The fried egg was put in a bag and heated at 90 ° C. for 30 minutes to kill bacteria other than Bacillus cereus. Thereby, a plurality of fried eggs samples were prepared.

1-2. Production of second reference sample A second reference sample having the same cooling constant as that of the above sample was produced. Specifically, a second reference sample for fried eggs is prepared by adding a natural keeper * that has a bacteriostatic effect to an egg solution not inoculated with Bacillus cereus so as to be 0.2%. did.

1-3. Measurement of the number of bacteria using a measuring device In advance, 20 g of a 5% aqueous solution of sansgen * 5% was placed in the container C2 as a first reference sample and placed on the thermoelectric element S2. Thereafter, the lid portion 21 was closed and left for 2 hours to stabilize the temperature of the thermostatic member 23 at 30 ° C.

  Subsequently, 20 g of the sample prepared in “1-1. Preparation of sample” is put in the container C1, and the second reference sample 20g prepared in “1-2. Preparation of reference sample” is put in the container C3. Containers C1 and C3 were simultaneously placed on thermoelectric elements S1 and S3, respectively. And in the same way as the said improvement example, in the arithmetic unit 4a, the microbe count was measured based on the corrected secondary difference VD. Specifically, the output unit 3 outputs the primary differences Vd1 and Vd2, the secondary difference output unit 41 outputs the secondary difference VD, and the zero correction unit 43 and the virtual adiabatic correction unit 44 correct the secondary difference VD. Then, based on the secondary difference VD corrected by the bacterial count measuring unit 42, the bacterial count of the sample was measured.

1-4. Measurement of Bacterial Count by Storage Test With respect to the rest of the sample prepared in “1-1. Preparation of Sample”, the actual bacterial count was measured over time by a storage test without using a measuring device. The bacteria were measured by culturing the bacteria at 30 ° C. based on the food hygiene inspection guidelines.

1-5. FIG. 14 shows the measurement results of the measurement result comparison measurement apparatus and the storage test. In FIG. 14, the solid line is the number of bacteria measured by the measuring device, and the Δ mark is the number of bacteria measured by the storage test. Since the measurement result by the measurement device almost coincided with the measurement result by the storage test, it was found that the number of bacteria can be measured with high accuracy by the measurement device according to the present invention.

2. Bean paste
2-1. Preparation of Samples A plurality of eggplant samples were prepared by inoculating a commercially available canned eggplant (water activity 0.93) with Hansenula anomala at 30 cfu / g.

2-2. Production of second reference sample The above-mentioned aseptic canned eggplant was used as a second reference sample.

2-3. Measurement of the number of bacteria using a measuring device In advance, 20 g of a 5% aqueous solution of sansgen * 5% was placed in the container C2 as a first reference sample and placed on the thermoelectric element S2. Thereafter, the lid portion 21 was closed and left for 2 hours to stabilize the temperature of the thermostatic member 23 at 30 ° C.

  Subsequently, 20 g of the sample prepared in “2-1. Preparation of sample” is put in the container C1, and the second reference sample 20g prepared in “2-2. Preparation of reference sample” is put in the container C3. Containers C1 and C3 were simultaneously placed on thermoelectric elements S1 and S3, respectively. And in the same way as the said improvement example, in the arithmetic unit 4a, the microbe count of the sample was measured based on the corrected secondary difference VD.

2-4. Measurement of the number of bacteria by a storage test With respect to the remainder of the sample prepared in “2-1. Preparation of sample”, the actual number of bacteria was measured over time by a storage test without using a measuring device. The bacteria were measured by culturing the bacteria at 30 ° C. based on the food hygiene inspection guidelines.

2-5. FIG. 15 shows the measurement results obtained by the comparative measurement device and the storage test. In FIG. 15, the solid line is the number of bacteria measured by the measuring device, and the mark ● is the number of bacteria measured by the storage test. The measurement result obtained by the measuring device almost coincides with the measurement result obtained by the storage test. In particular, even when the number of bacteria is less than 3 log cfu / g, the measurement result by the measuring device almost coincides with the measurement result by the storage test. Therefore, it was found that the number of bacteria can be measured with high accuracy by the measuring apparatus according to the present invention.

3. White sauce
3-1. Preparation of sample Commercial white sauce and milk were mixed at a ratio of 1: 1, and Bacillus cereus (Bacillus cereus) was inoculated to 50 cfu / g. Then, it heated at 90 degreeC for 20 minute (s), and bacteria other than Bacillus cereus were killed. Thus, a plurality of white source samples were prepared.

3-2. Production of second reference sample A second reference sample having the same cooling constant as that of the above sample was produced. Specifically, a second reference sample of white sauce is prepared by adding and adjusting the natural keeper * to 0.2% to the commercial white sauce not inoculated with Bacillus cereus. did.

3-3. Measurement of the number of bacteria using a measuring device In advance, 20 g of a 5% aqueous solution of sansgen * 5% was placed in the container C2 as a first reference sample and placed on the thermoelectric element S2. Thereafter, the lid portion 21 was closed and left for 2 hours to stabilize the temperature of the constant temperature member 23 at 25 ° C.

  Subsequently, 20 g of the sample prepared in “3-1. Preparation of sample” is put in the container C1, and the second reference sample 20g prepared in “3-2. Preparation of reference sample” is put in the container C3. Containers C1 and C3 were simultaneously placed on thermoelectric elements S1 and S3, respectively. And in the same way as the said improvement example, in the arithmetic unit 4a, the microbe count of the sample was measured based on the corrected secondary difference VD.

3-4. Measurement of Bacterial Count by Storage Test For the rest of the sample prepared in “3-1. Preparation of Sample”, the actual bacterial count was measured over time by a storage test without using a measuring device. The bacteria were measured by culturing the bacteria at 25 ° C. based on food hygiene inspection guidelines.

3-5. FIG. 16 shows the measurement results of the measurement result comparison measurement apparatus and the storage test. In FIG. 16, the solid line is the number of bacteria measured by the measuring device, and the mark ● is the number of bacteria measured by the storage test. The measurement result obtained by the measuring device almost coincides with the measurement result obtained by the storage test. In particular, even when the number of bacteria is 3 to 5 log cfu / g, the measurement result by the measurement device almost coincides with the measurement result by the storage test. Therefore, it was found that the number of bacteria can be measured with high accuracy by the measuring apparatus according to the present invention.

[Example 2]
In Example 2, the measuring device 1e according to the modification of the second embodiment shown in FIG. 13 is used, and as a thermostat 2 of the measuring device 1e, a microorganism activity measuring system “Leonis” manufactured by ULVAC-RIKO Inc. is used. A thermostatic bath was used. Further, stainless steel dishes were used as the containers C1 and C2. In this example, the measurement of the number of bacteria was not performed, and the waveform of the difference Vd output from the difference output unit 33 was measured as the microbial activity state.

  Potage soup was used as a sample. Specifically, a sample was prepared by inoculating a potage soup with Bacillus cereus at 50 cfu / g and heating at 90 ° C. for 30 minutes to kill bacteria other than Bacillus cereus. As a reference sample, a 5% aqueous solution of sangsugen * was used.

  In the measurement of the active state of the microorganism, 20 g of the reference sample was placed in the container C2 and placed on the thermoelectric element S2. Thereafter, the lid portion 21 was closed and left for 2 hours to stabilize the temperature of the thermostatic member 23 at 30 ° C.

  Subsequently, 21.0 g of the sample was placed in the container C1, and the container C1 was placed on the thermoelectric element S1. The cooling constant of the sample 21.0 g is equal to the cooling constant of the reference sample 20.0 g. And the waveform of the difference Vd from the difference output part 33 was measured in the same way as 2nd Embodiment.

  As a comparative example, 23.1 g of a sample was placed in the container C1, and the container C1 was placed on the thermoelectric element S1. The cooling constant of the sample 23.1 g is 1.1 times the cooling constant of the reference sample 20.0 g. And the waveform of the difference Vd from the difference output part 33 was measured in the same way as 2nd Embodiment.

  A waveform of the measured difference Vd is shown in FIG. In FIG. 17, the waveform when the cooling constant of the sample is equal to the cooling constant of the reference sample is shown by a solid line, and the waveform when the cooling constant of the sample is 1.1 times the cooling constant of the reference sample is shown by a broken line. ing. Since the amplitude of the solid line is smaller than the amplitude of the broken line, it was found that the fluctuation component included in the difference Vd can be significantly reduced by making the cooling constants of the sample and the reference sample equal.

  When the sample is fried rice, the cooling constant of the sample can be made equal to the cooling constant of 20.0 g of the reference sample by adjusting the weight of the sample to 17.3 g. Similarly, when the sample is a parent and child bowl, the cooling constant of the sample can be made equal to the cooling constant of 20.0 g of the reference sample by adjusting the weight of the sample to 22.9 g.

DESCRIPTION OF SYMBOLS 1 Measuring apparatus 1a Measuring apparatus 1b Measuring apparatus 1c Measuring apparatus 1d Measuring apparatus 1e Measuring apparatus 2 Thermostatic bath 3 Output part 3a Output part 3b Output part 3c Output part 3d Output part 3e Output part 4 Arithmetic apparatus 4a Arithmetic apparatus 4b Arithmetic apparatus 4c Arithmetic Device 4d Arithmetic device 21 Lid 22 Box 23 Constant temperature member 31a Amplifier 31b Amplifier 31c Amplifier 32a ADC
32b ADC
32c ADC
33 Difference output unit 33a Primary difference output unit 33b Primary difference output unit 34 Secondary difference output unit 40 Difference output unit 40a Primary difference output unit 40b Primary difference output unit 41 Secondary difference output unit (secondary difference output means)
42 Bacteria count measurement unit (active state measurement means)
43 Zero correction part (zero correction means)
44 Virtual insulation correction part (virtual insulation correction means)
C1 container C2 container C3 container L1 wiring L2 wiring L3 wiring S thermoelectric element S1 thermoelectric element (first thermoelectric element)
S2 Thermoelectric element (second thermoelectric element)
S3 Thermoelectric element (third thermoelectric element)
V1 First electromotive force V2 Second electromotive force V3 Third electromotive force Vd1 First primary difference Vd2 Second primary difference VD Secondary difference

Claims (11)

A measuring device for measuring the active state of microorganisms contained in a sample,
A thermostat,
A thermostatic member disposed in the thermostat and maintained at a constant temperature;
A first thermoelectric element, a second thermoelectric element, and a third thermoelectric element that are installed on the thermostatic member and generate an electromotive force according to a temperature difference between the first surface and the second surface opposite to the first surface. Thermoelectric elements of
The first primary difference, which is the difference between the first electromotive force generated by the first thermoelectric element and the second electromotive force generated by the second thermoelectric element, and the third generated by the third thermoelectric element A primary difference output unit that outputs a second primary difference that is a difference between the electromotive force of the second electromotive force and the second electromotive force;
An analysis unit for analyzing the output of the primary difference output unit;
With
The temperature of the sample is conducted to the first surface of the first thermoelectric element,
The first surface of the second thermoelectric element is conducted with the temperature of the first reference sample not containing microorganisms,
The first surface of the third thermoelectric element conducts the temperature of the second reference sample that does not contain microorganisms,
The temperature of the thermostatic member is conducted to each second surface of the first thermoelectric element, the second thermoelectric element, and the third thermoelectric element,
The analysis unit
Secondary difference output means for outputting a secondary difference that is a difference between the first primary difference and the second primary difference;
An active state measuring means for measuring an active state of the microorganism based on the second order difference;
A measuring apparatus comprising:   The measurement apparatus according to claim 1, wherein the second reference sample is a sample having a cooling constant equal to that of the sample. The analysis unit
The measuring apparatus according to claim 1, further comprising a zero correction unit that zero-corrects the secondary difference. The zero correction means includes
A value of 0 or less of the secondary difference is regarded as 0, and an integrated value of zero correction values of the secondary difference is calculated.
The measurement apparatus according to claim 3, wherein the secondary difference is zero-corrected based on the integrated value. The zero correction means includes
Using a plurality of time points within a predetermined time range from the start of measurement as a reference point, the integrated value of the zero correction value of the secondary difference at each reference point is calculated,
The measurement apparatus according to claim 4, wherein the secondary difference is zero-corrected based on an average of the integrated values of the zero correction values. The analysis unit
The measurement apparatus according to claim 1, further comprising virtual adiabatic correction means that corrects the difference on the assumption that the heat of the sample is in a virtual adiabatic state in which the heat does not move around.   The measurement apparatus according to claim 6, wherein the virtual adiabatic correction unit obtains a cooling constant in Newton's cooling law of the sample from a temperature change of the sample, and corrects the secondary difference based on the Newton's cooling law. .   The measurement apparatus according to claim 1, wherein the first reference sample is a sample having a cooling constant equal to that of the sample.   The measuring apparatus according to claim 1, wherein the sample is food. A thermostatic member maintained at a constant temperature;
A first thermoelectric element, a second thermoelectric element, and a third thermoelectric element that are installed on the thermostatic member and generate an electromotive force according to a temperature difference between the first surface and the second surface opposite to the first surface. Thermoelectric elements of
Is a measurement method for measuring the activity state of microorganisms contained in a sample, using a thermostat equipped with,
The temperature of the sample is conducted to the first surface of the first thermoelectric element, and the temperature of the first reference sample that does not contain microorganisms is formed on the first surface of the second thermoelectric element. Conducting and conducting the temperature of the second reference sample not containing microorganisms to the first surface of the third thermoelectric element, the first thermoelectric element, the second thermoelectric element, and the third A conduction step of conducting the temperature of the thermostatic member to each of the second surfaces of the thermoelectric element;
The first primary difference, which is the difference between the first electromotive force generated by the first thermoelectric element and the second electromotive force generated by the second thermoelectric element, and the third generated by the third thermoelectric element A primary difference output step of outputting a second primary difference that is a difference between the electromotive force of the second electromotive force and the second electromotive force;
An analysis step of analyzing the output in the primary difference output step;
With
The analysis step includes
A secondary difference output step of outputting a secondary difference that is a difference between the first primary difference and the second primary difference;
An active state measuring step of measuring an active state of the microorganism based on the second order difference;
A measurement method comprising:   A measurement program for causing a computer to function as each of the means according to claim 1.