Edible oil quality control device and edible oil quality control method

Abstract

To provide a new technique related to evaluating the quality of cooking oil.SOLUTION: The present invention relates to a quality managing device for evaluating the degradation index of a cooking oil 3, and the device includes a conduction unit 1 which can be set in an oil tank 2 storing the cooking oil 3. The conduction unit 1 has a parallel flat electrode 11 arranged across a space 15 which thermally convecting cooking oil 3 can pass through. The present invention also relates to a method for evaluating a quality for evaluating the degradation index of the cooking oil 3, and the method includes a step of measuring a parameter selected from a group including the dielectric constant and the conductance related to the cooking oil 3 by using the parallel flat electrode 11 arranged across a space 15 which thermally convecting cooking oil 3 can pass through.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an apparatus and a method for controlling the quality of edible oil. [Background technology]

[0002] The edible oils used in deep-fried foods can deteriorate due to reactions such as thermal oxidation, thermal polymerization, thermal decomposition, and hydrolysis, so daily quality control is important. The quality of edible oils is directly related to the quality of fried foods, so their quality should be appropriately controlled to ensure the safety of fried foods.

[0003] One of the deterioration indicators used for quality control of edible oil is the amount of polar compounds in the edible oil. Because the degradation products such as free fatty acids that are generated during deterioration of edible oil have polarity, the amount of polar compounds in edible oil is sometimes used as one of the deterioration indicators for edible oil.

[0004] It is desirable to evaluate the deterioration index based on the amount of polar compounds in edible oil non-destructively in order to reduce the cost of evaluation and testing. Non-destructive methods for evaluating the quality of edible oil include, for example, electrical measurements of parameters such as capacitance, conductance, and dielectric constant of edible oil.

[0005] Patent Document 1 discloses, as an example of a technology for evaluating the electrical properties of edible oil, a method for evaluating the degree of deterioration of edible oil, which is based on the finding that there is a good correlation between the slope of the temperature dependence of the electrical conductivity of the test oil and indicators related to the degree of deterioration of the edible oil (acid value, weight, color, amount of polar compounds).The method for evaluating the degree of deterioration of edible oil of the present invention discloses an invention that includes a step of calculating at least one of the acid value, weight, color and amount of polar compounds from the slope of the temperature dependence of the electrical conductivity of the test oil, or a step of determining that the test oil cannot be used as edible oil when the slope of the temperature dependence of the electrical conductivity of the test oil is equal to or greater than a predetermined value.

[0006] The invention described in Patent Document 1 can evaluate the degree of deterioration of edible oil by capturing all (or several) of the indicators related to the deterioration level of edible oil (acid value, weight, color, amount of polar compounds), and can evaluate the degree of deterioration of edible oil without considering the conditions of the use time of the edible oil and the measurement temperature. However, the device configuration of the invention is immersed in edible oil and is not easy to remove from the edible oil, and is not easy to install in an oil tank containing edible oil, so there is room for improvement in terms of handling. In addition, the invention is not easy to combine cooking fried foods using edible oil and evaluating the edible oil, so there is room for improvement.

[0007] Patent Document 2 discloses an invention that is an oil deterioration detection device comprising a sensor for measuring the electrical properties of oil, a main body having the sensor at one end of its length facing sideways, a base attached to the main body, a tip head disposed with an arc-shaped or annular shape that protrudes further toward the tip side than the sensor and is large in the radial direction, and a sensor cover having a connecting portion including a first connecting column connecting the base and the tip head and a second connecting column narrower than the first connecting column. Here, the sensor cover is characterized in that the connecting portion is located at a first circumferential position that covers at least a portion of the sensor.

[0008] The invention described in Patent Document 2 provides an oil deterioration detection device with a sensor that is durable and easy to clean, addressing the problems of reduced measurement accuracy due to other types of oil remaining on the surface from the previous measurement, and the difficulty of cleaning the electrode surface. However, in a method such as this invention in which a rod-shaped detection device is installed in an oil tank to evaluate edible oil, the electrical measurement of the edible oil is localized, and therefore the results of the electrical measurement are prone to fluctuate and vary.

[0009] The invention described in Patent Document 2, for example, requires stirring of cooking oil with a rod-shaped detector. In addition, it can be understood that the invention requires consideration of the fact that, even in cooking oil where thermal convection occurs, the measurement results may vary depending on the spot where the rod-shaped detector is immersed. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2006-226735 A [Patent Document 2] JP 2019-191140 A Summary of the Invention [Problem to be solved by the invention]

[0011] In consideration of the above circumstances, an object of the present invention is to provide a novel technology for quality control of edible oils for evaluating the deterioration index of edible oils. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention provides a quality control device for evaluating a deterioration index of edible oil, comprising an electric current unit that can be installed in an oil tank that contains the edible oil, and the electric current unit comprises parallel plate electrodes arranged across a gap through which the edible oil undergoing thermal convection can pass. With this configuration, the present invention can achieve both cooking of fried foods accompanied by thermal convection of the edible oil and evaluation of the deterioration index of the edible oil. Also, with this configuration, the present invention can perform electrical measurement of the edible oil that flows through the gap due to thermal convection, thereby realizing non-local electrical measurement of the edible oil.

[0013] In a preferred embodiment of the present invention, the current-carrying unit includes a comb-shaped electrode formed by adjacently disposing a plurality of the parallel plate electrodes. With this configuration, the present invention can realize highly accurate quality control of edible oil by performing electrical measurement of edible oil flowing through each of the plurality of gaps due to thermal convection.

[0014] In a preferred embodiment of the present invention, the current-carrying unit further includes a mounting fixture that can be hooked onto the outer edge of the oil vat. With this configuration, the current-carrying unit including the parallel plate electrodes for electrical measurement can be easily installed in the oil vat. As a result, the present invention can reduce the workload of a cooker in evaluating the deterioration index of an edible oil, and can more easily evaluate cooking of fried foods and the deterioration index of an edible oil.

[0015] In a preferred embodiment of the present invention, the apparatus further includes an evaluation unit capable of evaluating the deterioration index, the current supply unit being capable of measuring a parameter selected from a group including a dielectric constant and a conductance of the edible oil placed in the oil tank, and the evaluation unit being capable of evaluating the deterioration index based on the parameter. With this configuration, the present invention can realize a non-local, highly accurate and non-destructive evaluation of the deterioration index of the edible oil.

[0016] In a preferred embodiment of the present invention, the apparatus further includes a temperature measuring unit capable of measuring the temperature of the edible oil placed in the oil tank simultaneously with the measurement of the parameter by the current supply unit, and the evaluation unit is capable of determining the temperature dependency of the parameter and evaluating the deterioration index based on the temperature dependency. With this configuration, the deterioration index of the edible oil can be evaluated with higher accuracy based on temperature information.

[0017] In a preferred embodiment of the present invention, the deterioration indicator is selected from the group consisting of acid value, peroxide value, carbonyl value, anisidine value, amount of polar compounds, amount of polymers and color.

[0018] In a preferred embodiment of the present invention, the current supply unit is capable of applying an AC electric field to the edible oil, the evaluation unit is capable of determining whether the edible oil in the oil vat is in a deteriorated state based on the deterioration index and a predetermined threshold value corresponding to the deterioration index, and the current supply unit applies the AC electric field to the edible oil in the oil vat when the evaluation unit determines that the edible oil in the oil vat is in a deteriorated state. With this configuration, the present invention can realize quality control that extends the life of edible oil in accordance with the deterioration index of the edible oil.

[0019] Furthermore, by adopting such a configuration, the present invention can suppress the formation of a hydrophobic-hydrophilic interface of water in contact with edible oil, reduce the volume of each water droplet in the oil, and improve the heat conduction from the oil to the food. As a result, the present invention can achieve the effects of reducing bumping caused by the release of water from food in edible oil during deep frying, reducing oil splashes caused by bumping, reducing oil mist, reducing the amount of edible oil absorbed by food, and shortening the frying time by improving the thermal efficiency due to the increase in the surface area of ​​the water, thereby extending the life of the edible oil and contributing to suitable quality control of the edible oil.

[0020] In a preferred embodiment of the present invention, the current supply unit applies the AC electric field to the edible oil using a measurement frequency at which the parameter takes an extreme value as a frequency of the AC electric field. With this configuration, the present invention can improve the effect of the electric field treatment on the edible oil.

[0021] In order to solve the above problems, the present invention provides a quality control method for evaluating a deterioration index of edible oil, comprising a step of measuring a parameter selected from a group including a relative dielectric constant and a conductance of the edible oil using parallel plate electrodes arranged on either side of a gap through which the edible oil undergoing thermal convection can pass. With this configuration, the present invention can realize electrical measurement of the edible oil flowing through the gap due to thermal convection, and therefore can measure the electrical parameters of the edible oil non-locally.

[0022] In a preferred embodiment of the present invention, the method further includes a step of measuring the temperature of the edible oil simultaneously with the measurement of the parameter, and a step of evaluating the deterioration index based on the temperature dependency of the parameter. With this configuration, the deterioration index of the edible oil can be evaluated with higher accuracy based on temperature information that can be collected as data during the cooking process of deep-fried foods.

[0023] In a preferred embodiment of the present invention, the deterioration index is selected from the group including acid value, peroxide value, carbonyl value, anisidine value, amount of polar compounds, amount of polymers, and color. With this configuration, the present invention can evaluate the degree of deterioration of edible oil used for cooking fried foods based on the deterioration index that is correlated with the electrical measurement results of the edible oil.

[0024] In a preferred embodiment of the present invention, the method further includes a step of determining whether or not the edible oil is in a deteriorated state based on the deterioration index and a predetermined threshold value corresponding to the deterioration index, and a step of applying the AC electric field to the edible oil if it is determined that the edible oil is in a deteriorated state.

[0025] In a preferred embodiment of the present invention, the method further includes the steps of determining a measurement frequency at which the parameter takes an extreme value, and applying the AC electric field to the edible oil at the measurement frequency. With this configuration, the present invention can improve the effect of the electric field treatment on the edible oil.

[0026] In a preferred embodiment of the present invention, the method further includes a step of measuring the parameters of the edible oil to which the AC electric field has been applied. With this configuration, the present invention can similarly evaluate the deterioration index of edible oil whose life has been extended by electric field treatment, and therefore can cyclically evaluate the deterioration index and modify the edible oil by electric field treatment, thereby contributing to suitable quality control. Effect of the Invention

[0027] According to the present invention, a novel technology for quality control of edible oil can be provided. Also, according to the present invention, it is possible to realize evaluation of deterioration index of edible oil nondestructively, highly accurately, and nonlocally by electrical measurement of edible oil flowing through the gap due to thermal convection.

[0028] Furthermore, according to the present invention, it is possible to routinely monitor the deterioration state of cooking oil using a device (corresponding to an electrically conductive part) permanently installed in the oil tank, thereby providing a solution that makes it easier to manage the timing of changing cooking oil, which has previously been unclear in deep-frying cooking sites. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a schematic diagram of an edible oil quality control device according to one embodiment. [Diagram 2] FIG. 2 is a schematic diagram of a current-carrying unit according to one embodiment. [Diagram 3] FIG. 2 is a schematic diagram of a current-carrying unit according to one embodiment. [Figure 4] FIG. 2 is a schematic diagram of a current-carrying unit according to one embodiment. [Diagram 5] FIG. 2 is a schematic diagram of an electric current conductor installed in an oil tank according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] <Embodiment> An embodiment of the present invention will be described below. The embodiment of the edible oil quality control device and the edible oil quality control method are not limited to the configuration of the following embodiment, and can be modified as appropriate based on known technology. The configuration of the edible oil quality control method corresponds to the configuration of the edible oil quality control device as appropriate.

[0031] As illustrated in FIG. 1, the electric field treatment device for edible oil 3 includes a heating unit 5, a current-carrying unit 1 that can be installed in an oil tank 2 that contains edible oil 3, and has a gap 15 through which the edible oil 3 undergoing thermal convection can pass. Here, the oil tank 2 is connected to earth. Here, the heating unit 5 can heat the side and / or bottom of the oil tank 2, and can form thermal convection of the edible oil 3 in both directions between the side area 10A in the oil tank 2 including the current-carrying unit 1 and the central area 10B in the oil tank 2. Here, the heating unit 5 may be provided outside the oil tank 2, for example, and based on an electric heating mechanism. Note that thermal convection of the edible oil 3 in the oil tank 2 is preferably performed in both directions (corresponding to the direction X) between the above-mentioned side area 10A including the current-carrying unit 1 and the central area 10B. Note that each part and each device constituting one embodiment of the present invention are interconnected via a network, and transmission and reception of information such as measurement data and control instructions are appropriately performed.

[0032] As illustrated in FIG. 2 and FIG. 3, the current-carrying unit 1 includes parallel plate electrodes 11 (electrodes 11a and 11b) arranged across a gap 15 along a direction (for example, direction Z) perpendicular to the thermal convection direction (direction X) of the edible oil 3. Here, the electrodes 11a and 11b are treated as a positive electrode and a negative electrode, respectively. The current-carrying unit 1 is provided on the side wall of the oil vat 2 or in its vicinity (corresponding to the side region 10A). The parallel plate electrodes 11 may be arranged across a gap 15 along direction Y instead of / in addition to direction Z. Here, the separation distance d between the parallel plate electrodes 11 is, for example, 2 mm, and is not limited within a range corresponding to the dimensions of the oil vat 2. Here, the electrode area A (not shown) of the parallel plate electrodes 11 is not limited within a range corresponding to the dimensions of the oil vat 2.

[0033] The current-carrying unit 1 may include a comb-shaped electrode (corresponding to electrodes 11a and 11b) formed by adjacent parallel plate electrodes 11. Here, in electrodes 11a and 11b, the extension direction of the tooth-like portions of the comb corresponds to direction Y and / or direction Z. Note that "direction Y and direction Z" correspond to, for example, an oblique direction, and correspond to a combined direction of direction Y and direction Z.

[0034] The current-carrying unit 1 can measure a parameter selected from a group including the relative permittivity (ε) and conductance (G) of the edible oil 3 placed in the oil tank 2. The parameter is any parameter obtained by electrical measurement of the edible oil 3, and may be, for example, the capacitance (C), electrical resistance (R), resistivity, or conductivity (ρ) of the edible oil 3. The current-carrying unit 1 may obtain a statistical indicator of the parameter, such as an average value or a median value, based on the results of measurement at each of one or more parallel plate electrodes 11. The current-carrying unit 1 may also obtain a statistical indicator of the parameter, such as an average value or a median value, based on the results of measurement at a predetermined time interval under conditions of uniform temperature.

[0035] When measuring the parameters, the current-carrying unit 1 may determine a measurement frequency that is within a frequency band in which the frequency dependence of capacitance (C) or conductance (G) does not appear. The measurement frequency adopted by the current-carrying unit 1 may be, for example, 50 Hz to 10 kHz, or may be 1 kHz. When measuring the relative dielectric constant, the current-carrying unit 1 may determine, for example, the capacitance (C r ) may be measured and used as a reference, and the capacitance of the newly stored edible oil 3 (C r ) may be measured and used as a reference.

[0036] The current-carrying unit 1 may include a protective cover 12 that covers a part of the parallel plate electrodes 11 (for example, a part where no gaps or the like are present). The two protective covers 12 that sandwich the parallel plate electrodes 11 from the left and right may be fastened by bolts or the like via fastening units 13. There are no limitations on the electrode material and coating material of the parallel plate electrodes 11, and an example of such a material is a copper material having electrical conductivity. The protective cover 12 may include an insulating material.

[0037] The current-carrying unit 1 may be immersed in the cooking oil 3 by being installed on the outer edge 21 constituting the oil tank 2, or may be immersed in the cooking oil 3 by being installed by being held by a mounting fixture 14, and there is no limitation on the manner of installation. In addition, there is no limitation on the number of current-carrying units 1 that can be installed in the oil tank 2.

[0038] 4 and 5, the current-carrying unit 1 includes a mounting fixture 14 that can be hooked onto the outer edge 21. The mounting fixture 14 has, for example, a torsion spring structure, and can realize the installation of the current-carrying unit 1 regardless of the dimensions of the outer edge 21, etc.

[0039] The evaluation unit 6 can evaluate the deterioration index of the edible oil 3. The evaluation unit 6 can evaluate the deterioration index based on the parameters measured by the current supply unit 1. Here, the deterioration index is an index selected from a group including acid value, peroxide value, carbonyl value, anisidine value, polar compound amount (corresponding to TPM value), polymer amount, and color. Here, the index corresponds to an index measured based on the standard oil and fat analysis test method, for example. Here, the acid value is an index based on the amount of free fatty acid generated by hydrolysis of water constituting the food material to be cooked in the edible oil 3. Here, the amount of polar compound is an index based on the amount of low molecular decomposition products generated by decomposition of peroxide in the edible oil 3, the amount of polymerized products generated by thermal polymerization of peroxide in the edible oil 3, the amount of free fatty acid in the edible oil 3, etc. Note that the deterioration index of the edible oil 3 employed in one embodiment of the present invention is not limited as long as it is correlated with the parameters measured by the current supply unit 1.

[0040] The temperature measuring unit 7 can measure the temperature (T) of the edible oil 3 placed in the oil tank 2 at the same time as the measurement of the parameters by the current carrying unit 1. The temperature measuring unit 7 can measure the temperature based on a known method, and for example uses a thermocouple or the like.

[0041] The temperature measuring unit 7 can measure the temperature (T) simultaneously with the measurement of parameters by the current conducting unit 1 under high temperature conditions, such as when deep-fried food is being cooked, and under low temperature conditions when deep-fried food is not being cooked. The temperature measuring unit 7 can measure the temperature (T) simultaneously with the measurement of parameters by the current conducting unit 1 while sweeping the temperature zone in cooperation with the heating unit 5. Here, it is desirable that the measurement of temperatures and parameters under a plurality of temperature conditions is performed within a predetermined time. The functions of the temperature measuring unit 7 may be realized by the current conducting unit 1.

[0042] The evaluation unit 6 is capable of determining the temperature dependence of the parameter measured by the current supply unit 1, and evaluating the deterioration index based on the temperature dependence. Here, the temperature dependence may be, for example, the slope (dG / dT) of the temperature dependence of the conductance (G), and the slope of the temperature dependence of another parameter may be used instead of the conductance (G) as long as it is correlated with the deterioration index of the edible oil.

[0043] The current-carrying unit 1 can apply an AC electric field to the edible oil 3 using the electrode 1a and the electrode 1b as one pole or two poles. The voltage of the AC electric field applied to the edible oil 3 is, for example, in the range of 5 to 600 V. The frequency of the AC electric field applied to the edible oil 3 is not limited and is in the range of 25 kHz to 150 kHz. The current of the AC electric field applied to the edible oil 3 is, for example, in the range of 500 mA or less. The field strength of the AC electric field applied to the edible oil 3 is, for example, 10 2 ~10 5 The range is V / m.

[0044] The current supplying unit 1 may appropriately adopt, as the frequency of the AC electric field, a measurement frequency at which the above-mentioned parameters take extreme values ​​in the frequency dependence. The current supplying unit 1 may also appropriately adopt, as the frequency of the AC electric field, a measurement frequency at which the electrostatic quantity (C) is maximized in the frequency dependence. The current supplying unit 1 may also appropriately adopt, as the frequency of the AC electric field, a measurement frequency at which the conductance (G) is minimized in the frequency dependence.

[0045] With this configuration, the current-carrying unit 1 can generate cavitation vibration in the edible oil 3, and the generation of cavitation vibration breaks down and emulsifies the water in the edible oil 3, thereby contributing to extending the life of the edible oil 3. Here, the target edible oil 3 is, for example, deteriorated edible oil 3 whose polar compound amount is in the range of 1 to 24%, and which can be determined based on the deterioration index.

[0046] The evaluation unit 6 can determine whether the edible oil 3 in the oil vat 2 is in a deteriorated state based on the deterioration index and a predetermined threshold value corresponding to the deterioration index. Here, the evaluation unit 6 determines that the edible oil 3 is in a deteriorated state, for example, when the deterioration index corresponding to the amount of polar compounds measured and determined exceeds a predetermined threshold value. Here, the predetermined threshold value may be stored in a database constituting the control unit 8 described below in a referable manner.

[0047] When the evaluation unit 6 determines that the edible oil 3 in the oil tank 2 is in a deteriorated state, the current supply unit 1 applies an AC electric field to the edible oil 3 placed in the oil tank 2. With this configuration, the present invention can eliminate the need to replace the deteriorated edible oil 3 with new oil, extend the life of the edible oil 3 by the electric field treatment, and reduce the economic costs associated with cooking fried foods.

[0048] The control unit 8 can control the current supply unit 1 and can communicate with the evaluation unit 6. The control unit 8 may, for example, be provided with an LCR meter for measuring the parameter and contribute to the measurement of the above-mentioned electrical parameter, or may contribute to the measurement of the thermal parameter. Here, the evaluation unit 6 is a known computer device in which at least an arithmetic unit such as a processor, a main memory such as a RAM, an auxiliary memory which is a data storage constituting a database, and a communication device which is a network interface are connected via a bus interface. Here, the evaluation of the deterioration index of the edible oil 3 by the evaluation unit 6 may be performed on an edge basis or on a cloud basis, and there is no restriction on the data storage location. Note that the measurement data and deterioration index obtained in one embodiment of the present invention may be configured to be appropriately transmittable to an external server or the like via a network.

[0049] In one embodiment of the present invention, electrical measurement and evaluation of the deterioration indicator of the edible oil 3 may be realized by appropriately adopting part of the configuration according to known technology such as that disclosed in Japanese Patent Application Laid-Open No. 2006-226735. [Explanation of symbols]

[0050] 1: Current carrying part 2: Oil tank 3: Edible oil 5: Heating part 6: Evaluation section 7:Temperature measurement part 8: Control section 11:Parallel plate electrode 12: Protective cover 13: Fastening part 14: Mounting fixture 15 :Void

Claims

1. A quality control device for evaluating a deterioration index of edible oil, comprising: A current-carrying unit that can be installed in an oil tank that contains the edible oil and includes parallel plate electrodes arranged across a gap through which the edible oil undergoing thermal convection can pass; An evaluation unit capable of evaluating the deterioration index, The current passing unit measures a parameter selected from a group including a relative dielectric constant and a conductance of the edible oil placed in the oil tank by applying an AC electric field with a measurement frequency of 50 Hz to 10 kHz; The evaluation unit is capable of evaluating the deterioration index based on the parameter, and is capable of determining whether or not the edible oil in the oil vat is in a deteriorated state based on the deterioration index and a predetermined threshold value corresponding to the deterioration index; The edible oil quality control device, wherein when the evaluation unit determines that the edible oil in the oil tank is in a deteriorated state, the electrical current supply unit applies an AC electric field at a frequency higher than the measurement frequency to the edible oil in the oil tank.

2. The edible oil quality control device according to claim 1 , wherein the current-carrying unit includes a comb-shaped electrode formed by adjacently disposing a plurality of the parallel plate electrodes.

3. The edible oil quality control device according to claim 1 or 2, wherein the current-carrying unit further comprises a mounting fixture capable of being hooked onto an outer edge of the oil tank.

4. The temperature measuring unit may further include a temperature measuring unit capable of measuring the temperature of the edible oil in the oil tank simultaneously with the measurement of the parameter by the current passing unit; The edible oil quality control device according to claim 1 , wherein the evaluation unit is capable of determining a temperature dependency of the parameter and evaluating the deterioration index based on the temperature dependency.

5. 5. The quality control device for edible oil according to claim 1, wherein the deterioration indicator is selected from the group consisting of acid value, peroxide value, carbonyl value, anisidine value, amount of polar compounds, amount of polymers and color.

6. A quality control method for evaluating a deterioration index of an edible oil, comprising: measuring a parameter selected from a group including a dielectric constant and a conductance of the edible oil by applying an AC electric field having a measurement frequency of 50 Hz to 10 kHz using parallel plate electrodes arranged on either side of a gap through which the edible oil undergoes thermal convection; A step of determining whether the edible oil is in a deteriorated state based on the deterioration index that can be evaluated based on the parameters and a predetermined threshold value corresponding to the deterioration index; If the edible oil is determined to be in a deteriorated state, applying an AC electric field to the edible oil placed in an oil tank at a frequency higher than the measurement frequency.

7. The method for quality control of edible oil according to claim 6, further comprising the steps of: measuring the temperature of the edible oil simultaneously with measuring the parameter; and evaluating the deterioration index based on the temperature dependency of the parameter.

8. The method for controlling the quality of edible oil according to claim 6 or 7, wherein the deterioration indicator is selected from the group consisting of acid value, peroxide value, carbonyl value, anisidine value, amount of polar compounds, amount of polymers and color.

9. A method for quality control of edible oil, further comprising a step of measuring parameters of the edible oil to which the AC electric field at a frequency higher than the measurement frequency has been applied by the method described in claim 6.

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