JP2008288095A - Heating device for food and drink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain food and drink by subjecting each of them to a high-quality heating treatment as a heating object. <P>SOLUTION: This heating device uses food/drink having fluidity as a heating object and heats the heating object by Joule heat. A passage 18 for running the heating object therethrough is formed in a heating machine body 10, electrodes 11 and 12 are exposed in the passage 18 by forming a pair, and a current is supplied to the electrodes 11 and 12 from a power unit 31. The current value thereof is controlled by a control signal transmitted from a current control part 41 to the power unit 31 to be set at a set current value based on a detection signal from a product temperature sensor 44 sensing the temperature of the heating object heated by carrying the current, and the value of the current flowing to the electrodes 11 and 12. By controlling the current value supplied to the electrodes 11 and 12, the high-quality heating treatment can be executed without even locally causing overheating in the heating object. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a food and drink heating apparatus that heats food and drink having fluidity such as juice and mayonnaise with Joule heat as a heated object.

  Foods and drinks having fluidity such as juice and mayonnaise are heat-treated in order to sterilize or kill microorganisms such as bacteria contained therein. As this heat treatment method, boiling is generally used, and the boiling treatment is performed by holding food and drink at a temperature of, for example, about 120 ° C. for several minutes.

  A method of heating a food or drink having fluidity as an object to be heated is a method in which an electric current is passed through the object to be heated and Joule heat is generated in the object to be heated as described in Patent Document 1. According to this heating method, the object to be heated can be continuously heated while flowing in the flow path. As described in Patent Document 1, there is an annular electrode as an electrode type for passing an electric current to an object to be heated, and the annular electrode is disposed at both ends of an insulating cylinder. In a heating apparatus using this type of electrode, a current flows in the direction in which the object to be heated flows. On the other hand, there is a plate type as an electrode type, and in this case, since the flow path is formed between the plate electrodes facing each other in pairs, heating using this type of electrode is possible. In the apparatus, an object to be heated flows along between the plate-like electrodes, and a current flows in a direction crossing the flow. In any type, the object to be heated can be continuously heat-treated by flowing the object to be heated in the flow path, but the object to be heated needs to be held at the above-described temperature and flows out of the heating device. The heated object is held for a predetermined time by a temperature holder, that is, a hold unit.

In recent years, a heating technique for applying a high electric field to an electrode pair as described in Patent Document 2 has been developed for such heat treatment. In this technique, when an external electric field is applied to microorganism cells floating in the object to be heated, the Coulomb force acts on the microorganism cells, and when the applied electric field is increased, the cell membrane is damaged by the Coulomb force, and the surface is microscopic. It is a technology that utilizes the phenomenon of opening a hole, that is, the phenomenon of electroporation, and if the object to be heated is Joule-heated while applying a high electric field to the microorganism to such an extent that electroporation is not repaired, the cells are destroyed and bacteria etc. The microorganisms can be killed in a short time.
Japanese Patent No. 2821087 JP 2000-107261 A

  As described above, the method of heating the object to be heated by Joule heat includes heating the object to be heated to a predetermined sterilization temperature and holding it for a predetermined time, heating the object to be heated, and applying a high electric field to the object to be heated. There is a method that destroys the cells of microorganisms in the object to be heated, and the latter heating method applies a high voltage to the electrode, so that the object to be heated passes through the flow path in a short time. become. In any method, conventionally, the temperature of the heated object after heating is detected, and the heating temperature of the heated object is set to a predetermined temperature by adjusting the voltage supplied to the electrode pair according to the temperature of the heated object. It is controlled to become.

  The object to be heated flowing in the flow path becomes higher in temperature toward the downstream side, and the electric resistance of the object to be heated tends to decrease as the temperature increases. For this reason, in a heating apparatus using plate-like electrodes as described above, if the electrical resistance of the heated object on the downstream side decreases as it flows along the flow path between the plate-like electrodes, Since the heated object has a higher current than the heated object on the upstream side, the rate of temperature increase is higher on the downstream side. This temperature change is not a linear change but changes geometrically so that the temperature rapidly increases at the downstream end. For this reason, even if a constant voltage is applied to the electrode pair, the current value flowing through the object to be heated is different between the upstream side and the downstream side of the flow path, and the rate of heating by the current flowing through the downstream end is extremely high. It will be expensive.

  Therefore, even if the voltage applied to the electrode pair is adjusted according to the temperature of the heated object as in the conventional case, the current value is different in each part in the flow direction of the flow path, To be heated is included. If an object to be heated is included, even if the object of sterilization is achieved, the object to be heated is partially included, and the quality of the object to be heated after heating is deteriorated. It will be.

  On the other hand, when the object to be heated is caused to flow through the flow path at a high speed, the object to be heated becomes a turbulent flow. On the other hand, if it flows at a relatively low speed, the heated object will flow in the channel as a laminar flow, and the flow velocity distribution will draw a parabola. The flow rate is slower. In particular, an object to be heated that adheres to the inner wall surface of the flow path has the slowest flow velocity due to viscosity, and the object to be heated may adhere to the inner peripheral surface of the flow path as a scale. Therefore, the flow rate becomes slow, or the heated object attached as a scale on the inner peripheral surface of the flow path is energized longer than the other portions, and may be heated excessively to increase the temperature.

  As described above, when the object to be heated attached to the inner peripheral surface of the flow path is heated more excessively than the other part, even if the sterilization treatment is achieved for the overheated object, the flavor is impaired. Will be. If the object to be heated whose flavor is impaired is partially included, the heating quality may be deteriorated in the entire object to be heated. Furthermore, if the portion adhering to the scale is excessively heated, the heated object in that portion may cause a bumping phenomenon, and the electrode in that portion may spark and deteriorate the electrode.

  An object of the present invention is to enable food and drink to be heated and to be heat-treated with high quality.

  The food and drink heating device of the present invention is a food and drink heating device that heats food and drink having fluidity as a heated object by Joule heat, and is provided with an inlet and an outlet of the heated object, A heater body in which a flow path is formed from the inlet to the outlet and is exposed to the flow path and an electrode pair is provided; a rectifier that converts current from an AC power source into direct current; and direct current from the rectifier An inverter for converting to a high frequency, a power supply unit having a transformer for boosting and supplying a high-frequency current from the inverter to the electrode pair, and provided in the heater body, while flowing in the flow path, the electrode pair from the transformer A product temperature detector for detecting the temperature of a heated object energized and heated by a current supplied to the electrode, a current detector for detecting a current value supplied to the electrode pair, and the product temperature detector Characterized in that on the basis of signals with the signal from the current detector and a current control means for controlling the current supplied to the electrode pair from the power supply unit.

  The food and drink heating device according to the present invention is further provided with an electrode temperature detector for detecting the temperature of the electrode pair and a refrigerant flow path for cooling the heater body, and cooling the heater body to heat the heater. A cooling unit that cools the inner peripheral surface of the flow channel of the machine main body by heat conduction, and a cooling control unit that controls a cooling amount of the heater main body by the cooling unit based on a signal of the electrode temperature detector. Features.

  The food and drink heating apparatus of the present invention further applies a voltage of 0.2 kV / mm or more per 1 mm distance between the electrodes to the electrode pair, destroys the cell membrane of microorganisms by Joule heat and electric field effect, and sterilizes the object to be heated. It is characterized by heating.

  According to the present invention, when the object to be heated is sterilized by passing an electric current through the object to be heated by Joule heat, the temperature of the object to be heated after heating is detected and the object to be heated is set to a set temperature. Thus, since the value of the current flowing through the heated object between the electrodes is controlled, it is possible to prevent an excessive current from flowing even at the end of the flow path through which the heated object flows. Since overheating of the object to be heated is prevented, the heating quality of the object to be heated can be improved without impairing the flavor of the food or drink that is the object to be heated.

  According to the present invention, the inner peripheral surface of the flow path formed in the heater main body can be cooled by cooling the heater main body with the cooling unit, and the portion of the object to be heated that is in contact with the inner peripheral surface is Excessive heating can be prevented. Thereby, the heating quality of a to-be-heated object can be improved, without impairing the flavor of the food and drink which are to-be-heated objects.

  According to the present invention, by setting the voltage supplied to the electrode pair to 0.2 kV / mm or more per 1 mm distance between the electrodes, the cells of microorganisms contained in the heated object are heated while the heated object is heated by Joule heat. Since it can be destroyed by the electric field effect, heat-resistant bacteria can be instantly sterilized. Moreover, since the sterilization can be performed only by instantaneously heating to the heating temperature, the sterilization can be performed without destroying active ingredients such as vitamins contained in the object to be processed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a food and drink heating apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view showing a main body of the heater shown in FIG. 1, and FIG. FIG. 4 is a block diagram showing a power supply unit and a current control unit shown in FIG.

  As shown in FIGS. 1 and 2, the heater body 10 has two electrodes 11 and 12 made of a rectangular titanium plate, and a resin that is an insulating material between the electrodes 11 and 12. A spacer 13 made of metal is sandwiched between the two electrodes 11, 12 and the spacer 13 between them are fastened by a plurality of bolts 14. One electrode 11 is attached to one side in the longitudinal direction and an inflow side joint 15 is attached as an inlet, and the other electrode 12 is attached to the other side in the longitudinal direction and an outflow side joint 16 is attached as an outlet. Yes.

  As shown by a broken line in FIG. 3, the spacer 13 is provided with a long hole 17 penetrating from the inlet to the outlet, and overlapped on both sides of the spacer 13 as shown in FIG. 2. The long holes 17 are covered with the electrodes 11 and 12, and a flow path 18 is formed by the long holes 17 and the electrodes 11 and 12. In the electrode 11, a communication hole 21 communicating with the inflow end of the flow path 18 is formed, and a connection block 22 having a through hole communicating with the communication hole 21 is incorporated in the fastening holder 23. It is fastened to the electrode 11 by a bolt 24 that penetrates the fastening holder 23. On the other hand, a communication hole 25 communicating with the outflow end of the flow path 18 is formed in the electrode 12, and a connection block 26 formed with a through hole communicating with the communication hole 25 is incorporated in the fastening holder 27, and the outflow side joint is formed. 16 is fastened to the electrode 12 by a bolt 28 penetrating the fastening holder 27.

  A supply pipe (not shown) is connected to the inflow side joint 15 so that a heated object accommodated in the hopper is supplied to the inflow side joint 15 via a supply pipe by a pump (not shown). It has become. When preheating the object to be heated supplied to the inflow side joint 15, a preheating unit is arranged between the hopper and the inflow side joint 15. A discharge pipe (not shown) is connected to the outflow side joint 16, and the heated object to be heated is guided to a recovery tank (not shown) through the discharge pipe. When the heated object to be heated is cooled, a cooling unit (not shown) is disposed between the outflow side joint 16 and the recovery tank. Furthermore, when the heated object to be heated is held at a predetermined temperature, a hold unit (not shown) is disposed between the cooling unit and the outflow side joint 16.

  When a fluid heated object such as juice or mayonnaise is supplied as an object to be heated from the inflow side joint 15 into the channel 18, the object to be heated is a channel between the electrodes 11 and 12 that are opposed to each other. 18 flows toward the outflow side joint 16 as indicated by an arrow. A current flows through the object to be heated by the electric power applied to the electrodes 11 and 12, and the object to be heated is heated by Joule heat while flowing through the flow path 18. Since the object to be heated flows between the electrodes 11 and 12, a current flows through the object to be heated in a direction crossing the flow direction from the electrodes 11 and 12.

  As shown in FIG. 4, the electrodes 11 and 12 are connected to the power supply unit 31. The power supply unit 31 has a thyristor stack 33 connected to the AC power supply terminal 32. The AC current supplied from the AC power supply terminal 32 is rectified into a DC current by the thyristor stack 33 and the voltage is adjusted. In the illustrated case, a three-phase 200 V current is supplied from the AC power supply terminal 32 to the thyristor stack 33. The output terminal of the thyristor stack 33 is connected to the inverter 34, and the direct current is converted into a high-frequency current of 20 kHz, for example, by the inverter 34. The inverter 34 is connected to the output transformer 35, the output terminal on the secondary side of the output transformer 35 is connected to the electrodes 11 and 12, and the power boosted by the output transformer 35 is supplied to the electrodes 11 and 12. It has become.

  In order to control the current value supplied to the electrodes 11, 12, a current control unit 41 is connected to the power supply unit 31 as current control means. The current controller 41 has a programmable controller 42, and an operation panel 43 having input keys and the like is connected to the programmable controller 42, and a product temperature detector 44 provided at the outflow side joint 16 as shown in FIG. 1. Are connected, and the detection signal of the product temperature detector 44 is sent to the programmable controller 42. The current control unit 41 sets a current flowing between the electrodes 11 and 12 by a signal from the programmable controller 42 and a thyristor that sends a control signal to the thyristor stack 33 based on the signal from the current setting unit 45 And a control unit 46. The operation panel 43 is provided with an input unit composed of keys, dials, and the like for setting the current value supplied to the electrodes 11 and 12, and the current is set so that the maximum current value is set by operating the input unit. A control signal is sent from the programmable controller 42 to the setting unit 45. The maximum current value is set by the voltage value between the electrodes 11 and 12, and the voltage value supplied from the thyristor stack 33 to the inverter 34 is adjusted by a signal from the thyristor control unit 46, so that the voltage between the electrodes 11 and 12 is adjusted. Current value is controlled. A current value flowing from the thyristor stack 33 to the inverter 34 is sent to the current setting unit 45 as a feedback signal, and a voltage value is sent to the thyristor control unit 46 as a feedback signal.

  The electrodes 11 and 12 are connected to the secondary side of the output transformer 35. By controlling the current value on the primary side of the output transformer 35 using the current value supplied to the primary side of the output transformer 35 as a feedback signal, A predetermined current corresponding to the winding ratio is supplied to the electrodes 11 and 12, and the secondary current value can be set with high accuracy by controlling the primary current value.

  The current control unit 41 has an inverter control unit 47 that sends a control signal to the inverter 34. The operation panel 43 is provided with an input unit for setting the frequency of the current supplied to the electrodes 11 and 12 so that a high-frequency current having a frequency set by the input unit is supplied to the electrodes 11 and 12. A control signal is sent from the inverter control unit 47 to the inverter 34.

  FIG. 5 is a characteristic diagram showing a current distribution in the flow path 18 between the paired electrodes 11 and 12. The current flowing through the object to be heated in the flow path 18 is determined based on the resistance of the object to be heated and the potential difference, that is, the voltage between the electrodes 11 and 12, but as shown in FIG. Observe the current distribution at the temperature of the object to be heated. The temperature of the object to be heated is increased by Joule heat from the inlet side to the outlet side, and the resistance value of the object to be heated decreases as the temperature increases. The temperature suddenly increases in the section and the resistance value decreases, and the current flowing in the direction crossing the flow of the object to be heated increases intensively and rapidly at the outlet side end. In other words, the final heating temperature for the object to be heated greatly depends on the current value at the outlet side end.

  Therefore, when the current value flowing between the electrodes 11 and 12, that is, the average current value is set to be a predetermined value, it is possible to suppress the maximum current value that becomes higher at the outlet side end from becoming an excessive current value. Therefore, it can suppress that a to-be-heated material is overheated in the outflow end part of channel 18, can prevent a flavor of a to-be-heated material from falling, and can heat-treat a to-be-heated material with high quality. .

  When the flow rate of the heated object in the flow path 18 is increased, the heated object flows in a turbulent state, so that the flow rate distribution of the heated object does not greatly differ between the central portion and the peripheral portion of the flow path 18. . On the other hand, if the flow velocity is lowered, the heated object flows in a laminar flow state, and therefore the flow velocity distribution of the heated object becomes slower in the peripheral portion than the central portion of the flow path 18 and is exposed to the flow path 18. Thus, the flow rate of the heated object in contact with the electrodes 11 and 12 for forming the flow path 18 is the slowest due to viscosity. For this reason, the to-be-heated object which flows through a peripheral part may be overheated and energized over a longer time than the to-be-heated object which flows through a center part. The overheated portion of the object to be heated may cause a bumping phenomenon, and the electrodes 11 and 12 may spark. If sparked, the electrodes 11 and 12 are deteriorated.

  As shown in FIG. 2, the heater main body 10 is covered with a case body 51 fixed to the electrode 11 and a case body 52 fixed to the electrode 12, and each case body 51, 52 has a cover 53, 54 is attached. The electrode 11, the case body 51, and the cover 53 form a cooling unit 56 having a cooling chamber 55, and the inflow side joint 15 is incorporated in the cooling chamber 55. The electrode 12, the case body 52, and the cover 54 form a cooling unit 58 having a cooling chamber 57, and the outflow side joint 16 is incorporated in the cooling chamber 57. A ventilation duct 61 is attached to the outer surface of the electrode 11, and the air blown from the outlet 63 of the air supply pipe 62 attached to the cooling unit 56 is supplied to the refrigerant flow path 64 in the ventilation duct 61. ing. A ventilation duct 65 is attached to the outer surface of the electrode 12, and the air blown from the outlet 67 of the air supply pipe 66 attached to the cooling unit 58 is supplied to the refrigerant flow path 68 in the ventilation duct 65. ing.

  When cooling air flows through the refrigerant flow paths 64 and 68, the cooling air flows along the outer surfaces of the electrodes 11 and 12, and the electrodes 11 and 12 are radiated from the outer surfaces. When the electrodes 11 and 12 are radiated from the outer surface, the temperature of the inner surfaces of the electrodes 11 and 12 forming the flow path 18 is also cooled by the heat conduction of the electrodes 11 and 12, and overheating of the inner surfaces of the electrodes 11 and 12 is prevented. The

  As shown in FIG. 1, the air supply pipes 62 and 66 are connected to an air supply source 70 via a flow rate adjustment valve 69, and the flow rate of air supplied to the refrigerant flow paths 64 and 68 by the flow rate adjustment valve 69 is as follows. It has come to be adjusted. A control signal is sent to the flow rate adjusting valve 69 from a cooling control unit 71 as cooling control means, and a detection signal from the electrode temperature detector 72 is sent to the cooling control unit 71. . Accordingly, the flow rate of the cooling air as the cooling medium supplied to the refrigerant flow paths 64 and 68 is adjusted based on the electrode temperature detected by the electrode temperature detector 72, and the inner surface temperatures of the electrodes 11 and 12 are adjusted. .

  The voltage supplied to the electrodes 11 and 12 is set to an arbitrary value by the thyristor stack 33, and the flow rate of the object to be heated flowing in the flow path 18 is set by the pump provided in the supply pipe described above. As described above, when Joule heat is generated in an object to be heated and the object to be heated is sterilized, the Joule heat is heated to the sterilization temperature. On the other hand, when the voltage supplied to the object to be heated is increased and a high electric field is applied to the microorganism cells floating in the object to be heated, the Coulomb force acts on the microorganism cells, The cell membrane is damaged by the Coulomb force, and a phenomenon that a fine hole opens on the surface, that is, an electroporation phenomenon occurs. When the object to be heated is Joule-heated while applying a high electric field to the microorganisms to such an extent that electroporation is not repaired, the cells are destroyed and microorganisms such as bacteria can be killed in a short time.

  The electric field necessary for causing the electroporation phenomenon in the cell is the heat-resistant bacterium contained in the object to be heated if an electric field of 0.2 kV or more per unit dimension of 1 mm is applied, assuming that the dimension between the electrodes 11 and 12 is W. Turned out to be completely killed. For example, if the dimension W is 10 mm, the heat-resistant bacteria can be completely killed by supplying a voltage of 2 kV or more to the both electrodes 11 and 12 from the output transformer 35. At that time, in order to prevent the temperature of the heated object from rising excessively, the flow rate in the flow path 18 is sterilized only by Joule heat so that the heated object passes through the flow path 18 in about 0.0014 seconds. It will be set faster than the case.

  As described above, when the object to be heated is heated by Joule heat and sterilized by electroporation, the object to be heated passes through the flow path 18 in a short time. It is necessary to adjust with high accuracy, and by setting the current value between the electrodes, partial overheating of the object to be heated can be prevented, and high-quality heat treatment can be performed.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, although the illustrated heater body 10 forms an electrode pair with plate-like electrodes 11 and 12, as shown in Patent Document 1, a heater body may be formed using an annular electrode. . When the annular electrode is used, the main body of the heater has a cylindrical shape. Therefore, the cooling unit is attached to the main body of the heater so as to surround the cylindrical main body of the heater. In the illustrated case, the cooling medium is air, and the heater main body 10 is cooled by the cooling air. However, the cooling liquid may be the cooling medium.

It is a schematic block diagram which shows the heating apparatus of the food and drink which is one embodiment of this invention. It is an expanded sectional view which shows the heater main body shown by FIG. It is the sectional view on the AA line in FIG. It is a block diagram which shows the power supply unit and current control part which were shown by FIG. It is a characteristic diagram which shows the electric current distribution in the flow path between electrodes.

Explanation of symbols

10 Heater body 11, 12 Electrode 13 Spacer 15 Inflow side joint (inlet)
16 Outflow side joint (outlet)
18 Flow path 31 Power supply unit 32 AC power supply terminal 33 Thyristor stack (rectifier)
34 Inverter 35 Output transformer 41 Current controller 42 Programmable controller 43 Operation panel 44 Product temperature detector 45 Current setting unit 46 Thyristor controller 47 Inverter controllers 56 and 58 Cooling units 62 and 66 Air supply pipes 64 and 68 Refrigerant flow path 69 Flow control valve 71 Cooling control unit 72 Electrode temperature detector

Claims (3)

A food and drink heating apparatus that heats food and drink having fluidity as a heated object by Joule heat,
A heater main body provided with an inlet and an outlet of an object to be heated, wherein a flow path is formed from the inlet to the outlet and is exposed to the flow path and an electrode pair is provided;
A rectifier that converts current from an AC power source into direct current, an inverter that converts direct current from the rectifier into high frequency, a power supply unit having a transformer that boosts and supplies high frequency current from the inverter to the electrode pair;
A product temperature detector that is provided in the heater main body and detects the temperature of an object to be heated by current supplied from the transformer to the electrode pair while flowing in the flow path;
A current detector for detecting a current value supplied to the electrode pair;
A food and drink heating apparatus comprising: current control means for controlling a current supplied from the power supply unit to the electrode pair based on a signal from the product temperature detector and a signal from the current detector. .   2. The apparatus for heating food and drink according to claim 1, wherein an electrode temperature detector for detecting a temperature of the electrode pair and a refrigerant flow path for cooling the heater main body are provided, and the heater main body is cooled to perform the heating. A cooling unit that cools the inner peripheral surface of the flow channel of the machine main body by heat conduction, and a cooling control unit that controls a cooling amount of the heater main body by the cooling unit based on a signal of the electrode temperature detector. A heating apparatus for food and drink.   3. A food and drink heating apparatus according to claim 1 or 2, wherein a voltage of 0.2 kV / mm or more per 1 mm distance between electrodes is applied to the electrode pair, and the cell membrane of the microorganism is destroyed by Joule heat and electric field effect. Food and drink heating apparatus characterized by sterilizing and heating.

Images