JP2009005583A - Alternate-current high electric-field sterilization device for fluid food material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alternate-current high electric-field sterilization device for fluid food material as a continuous-type one, suppressed from generating sparks, even when subjecting a high-viscosity fluid food material, such as, mayonnaise to sterilization. <P>SOLUTION: The alternate-current high electric-field sterilization device for fluid food material is structured by forming a flow path through which the fluid food material flows in a direction parallel to a pair of parallel electrode plates, between the plates; and loading alternate-current high voltage between the electrode plates to sterilize the fluid food material in the flow path. The electrode plates are equipped with a heat elimination means for drawing heat from the fluid food material which flows, in contact with the surface at the flow path side of the plate. The heat elimination means is provided with a fin member, made of well thermal-conductive material at the face opposite to the flow path of the electrode plate for example, and is provided with a blowing means for blowing cool air to the fin member. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an apparatus for continuously sterilizing various fluid food materials (including beverages) such as fruit juice, jam, meat juice, vegetable soup, milk, mayonnaise and the like by an alternating current high electric field sterilization method.

  In general, as a method for sterilizing various liquid food materials, a method in which the liquid food material is heated and sterilized at a high temperature is frequently used. In this case, as an apparatus for continuously sterilizing the liquid food material, the liquid food material is continuously flowed into the pipeline, while the pipeline is heated from the outside by an appropriate heating means, and the liquid in the pipeline is In general, food materials are sterilized by indirectly heating them.

  By the way, when the liquid food material is sterilized by heating from the outside as described above, it is necessary to hold the liquid food material at that temperature for a certain period of time. In particular, if the heating temperature is low, it is necessary to extend the heat holding time to ensure sterilization. On the other hand, if the heating temperature is relatively high, it is possible to relatively shorten the heating and holding time. However, if the heating temperature is high, useful ingredients in the liquid food material, such as vitamin C, etc. The nutritional components of the product may be destroyed, and the fragrance component that brings about the fragrance and the color component that produces the color tone may be destroyed or changed, which may impair the commercial value. There is a limit.

  Therefore, when the liquid food material is sterilized by external heating, it is essential to hold the liquid food material for a long time at a temperature at which the nutritional components, fragrance, and color in the liquid food material are not impaired. For example, when sterilizing at 115 ° C. by an external heating method, it is said that it is necessary to hold for 4 minutes or more in order to sufficiently sterilize. And when applying such external heating and heat sterilization by a continuous method, it is possible to secure a sufficient time for the liquid food material to stay in the heating part by lengthening the pipe line of the part heated from the outside. Therefore, the line length of the entire heating device has to be long, so that the entire equipment is enlarged and the equipment cost is inevitably increased.

  By the way, recently, a liquid food material is passed between narrow electrodes facing each other, and a high voltage of alternating current is applied between the electrodes and sterilized by an alternating high electric field generated between the electrodes, that is, so-called alternating high electric field sterilization. The method is proposed by patent document 1, patent document 2, etc., for example.

  According to this AC high electric field sterilization method, when the liquid food material passes between the electrodes, the liquid food material is not only sterilized by heating at a high temperature, but also a sterilizing effect due to the AC high electric field is provided. It is possible to shorten the time of exposure to high temperature, and as a result, it is possible to minimize the destruction and change of food material components.

  Although the basic concept of the alternating current high electric field sterilization technology is shown in the above-mentioned patent document 1 and patent document 2, this alternating current high electric field sterilization technology is applied to liquid food manufacturers on an actual mass production scale. There are various inconveniences for efficient continuous sterilization of a large amount of liquid food material by carrying out complete continuation in order to introduce it into the food production process, especially an electrode that applies an alternating high electric field to liquid food material that flows continuously The specific configuration in the vicinity of the portion has not yet reached a practical level.

  Therefore, the present inventors have continued research and development of the apparatus for practical application of the alternating current high electric field sterilization method on a mass production scale. In the development process, as a specific configuration in the vicinity of the electrode portion suitable for applying an alternating high electric field to the liquid food material that is continuously supplied, an apparatus as shown in FIGS. It is proposed in 270634, and further experiments and examinations for practical use are repeated.

  Here, the apparatus shown in FIGS. 6 and 7 will be described. As a whole, a heat insulating material such as PEEK resin is interposed between a pair of parallel electrodes 11A and 11B made of a corrosion resistant conductive material such as titanium. A flat spacer plate 13 is sandwiched, and the spacer plate 13 penetrates from one plate surface to the other plate surface and extends in a direction along the plate surface (vertical direction in the illustrated example). 15 is formed. As will be described later, this elongated hole 15 is for defining and forming a flow path 17 between the electrode plates. The elongated hole 15 is formed in an oval shape as a whole in plan view, and is formed at the end in the length direction. The inner surfaces (curved surfaces) are tapered surfaces 15A and 15B, respectively.

  Furthermore, in one electrode plate 11A of the pair of electrode plates 11A and 11B, an inlet 19A is formed at a position corresponding to one end 15A of the long hole 15 of the spacer plate 13, and the other electrode plate is formed. An outlet 19 </ b> B is formed in 11 </ b> B at a position corresponding to the other end 15 </ b> B of the long hole 15 of the spacer plate 13. In addition, a flanged hollow short cylindrical introduction member 21A is attached to the outside of the inlet 19A of the electrode plate 11A with a plurality of screws 25 via an insulating packing 23A, and the outside of the outlet 19B of the electrode plate 11B. Similarly, a flanged hollow short cylindrical lead-out member 21B is attached with a plurality of screws 27 via an insulating packing 23B.

  Then, at a predetermined position on each surface of the spacer plate 13 facing the electrode plates 11 </ b> A and 11 </ b> B, that is, at a position corresponding to the peripheral edge of the long hole 15, the ellipse continues along the peripheral edge of the long hole 15. A concave groove 29A and a concave groove 29B for inserting an O-ring are formed. The electrode plates 11A, 29A, 29B are fitted with at least part of the cross-sections of the O-rings 31A, 31B made of an insulating electrical insulating material having excellent heat resistance such as silicon rubber in the concave grooves 29A, 29B. The apparatus as a whole is in a state where the O-rings 31A and 31B are elastically compressed and deformed by tightening between the electrodes 11A and 11B by a plurality of screws (or bolts and nuts) 35 from one side or both sides of the 11B through an insulating washer 33. Assembled. At this time, the flow path 17 between the electrode plates formed by the long holes 15 of the spacer plate 13 is sealed between the electrode plates 11A and 11B and the spacer plate 13 by the O-rings 31A and 31B. Become.

  Insulating collars 39 are inserted into the screw through holes 37 in the electrode plates 11A and 11B. Moreover, the part of the code | symbol 41 in electrode plate 11A, 11B is a screw hole for screw screwing, and the part of the code | symbol 43 in the spacer plate 13 is a through-hole for screw insertion.

  When the liquid food material is sterilized by the AC high electric field method using the apparatus shown in FIGS. 10 to 13 as described above, the liquid food material to be sterilized is continuously introduced from the outside into the introduction member 21A. . The liquid food material continuously introduced into the introduction member 21A passes through the inlet 19A of the electrode plate 11A and flows into the inter-electrode plate flow path 17 defined by the long holes 15 of the spacer plate 13, and the flow path. 17 flows along the length direction of the long hole 15 and is discharged from the outlet member 21B to the outside through the outlet 19B of the electrode plate 11B. In the meantime, by applying an alternating high voltage between the electrode plates 11A and 11B, the liquid food material is continuously sterilized in the flow path 17 in the long hole 15. Here, the AC high voltage applied between the electrode plates 11A and 11B is 50 to 100 V or more per 1 mm of the distance between the electrode plates 11A and 11B (≈the thickness of the spacer plate 13), usually from several hundred V per 1 mm. High voltage of 1000V or higher. Further, although the interval between the electrode plates 11A and 11B itself varies depending on the flow rate or the like, it is generally a narrow width of about 0.5 mm to about 20 mm, and therefore the voltage actually applied between the electrode plates 11A and 11B. Becomes a remarkably high voltage of at least several hundred V or more, usually 1000 to 2000 V or more.

Also, the AC high voltage application time for the liquid food material, that is, the residence time of the liquid food material in the flow path 17 varies depending on the object, but is usually within 1 second, for example, an extremely short time of 0.1 second. Is common.
Japanese Patent No. 2848591 Japanese Patent No. 2964037

  In the AC high electric field sterilization method, since a high voltage is applied in the flow path between extremely narrow electrode plates as described above, there is a fundamental problem that sparks are easily generated between the electrode plates.

  If sparks occur between the electrode plates in this way, the surface of the electrode plates suddenly becomes extremely hot and locally melts or is damaged, or the liquid food material components burn on the electrode surface and the quality of the liquid food material It will cause deterioration. In addition, if a spark is generated, an excessively large current flows and the power output suddenly becomes unstable, or the electrode device is damaged, making it difficult to perform stable operation as it is. In addition, as described above, once the electrode surface is locally melted due to the occurrence of sparks or the food material component is burnt on the electrode surface, if the electrode is reused or continuously used, the sparks generated by the unevenness on the electrode surface further spark. Is likely to occur, and the operation is practically impossible at all.

  Here, the power source of the AC high electric field sterilizer is often provided with a safety device so that an excessive current does not flow. In this case, if an excessive current flows due to the occurrence of a spark, the power supply is immediately stopped. Even in this case, the operation is temporarily stopped and productivity is hindered. Even if the power supply is shut down, it is possible to reuse the electrode due to food material components scorching on the electrode surface or local melting or damage of the electrode surface during the period from the occurrence of spark to the power shutdown. It is often difficult.

  Therefore, in putting the AC high electric field sterilization method into practical use, it is an important issue to suppress the generation of sparks as much as possible.

  When an alternating high electric field is applied between the electrodes, if there is a pointed portion (edge portion) on the surface of the opposing electrode, current concentration occurs in that portion, and sparks are more likely to occur. Therefore, in the proposed AC high electric field sterilization apparatus of Japanese Patent Application No. 2006-270634 shown in FIG. 6 and FIG. 7, the formation positions of the concave grooves 29A and 29B into which the O-rings 31A and 31B are inserted are arranged on the side of the electrode plates 11A and 11B. Rather than being on the spacer plate 13 side, the edge portions existing on the surfaces of the electrode plates 11A and 11B are reduced, and the electrode surfaces facing the inlet 19A and outlet 19B are tapered surfaces of the spacer plate 13. By covering with 15A and 15B, it was possible to significantly reduce the occurrence of sparks as compared with the prior art.

  However, as a result of further experiments and examinations by the present inventors, in the case of a low-viscosity fluid food material such as a liquid close to water, it is possible to significantly reduce the occurrence of sparks by the above-mentioned idea. However, in the case of a fluid food material having a relatively high viscosity, such as mayonnaise, it has been found that although it can suppress the occurrence of sparks to some extent, it has not reached a practical level. .

  Therefore, the present invention suppresses the frequency of occurrence of sparks even when a relatively high viscosity fluid food material is targeted, and thus the AC high electric field sterilization method is actually applied to a relatively high viscosity fluid food material. It is an object to provide an apparatus that can be applied to the above.

  When the inventors repeated experiments and examinations on the occurrence of sparks between the electrodes in the AC high electric field sterilizer, a phenomenon in which the fluid food material is overheated in the region near the electrode plate surface in the flow path, that is, A temperature difference (so-called temperature unevenness) occurs between the central area in the flow path and the area near the electrode plate surface, bumping occurs in the fluid food material heated near the electrode plate surface, and bubbles due to bumping are generated. It was found that this is the main cause of sparks. And especially in this kind of alternating current high electric field sterilizer, since the interval between the electrode plates is remarkably narrow, about 0.5 to 20 mm, it has been found that even if fine bubbles are generated, sparks are generated. .

  Furthermore, when a relatively high viscosity fluid food material is targeted, the viscous resistance to the electrode plate surface is large, so the flow rate of the fluid food material flows in contact with the electrode plate surface in the center between the electrode plates. It becomes significantly smaller than the vicinity (so-called laminar flow occurs), and the flow velocity varies in the direction of the cross section of the flow path. If the flow velocity of the fluid food material is reduced in the region near the electrode plate surface in this way, In that region, it became clear that the tendency of overheating due to the self-resistance heat generation of the flowable food material became stronger, and as a result, the generation of bubbles and consequently the occurrence of sparks was likely to occur.

  And based on such novel knowledge of the present inventors, in order to develop a device that can perform AC high electric field sterilization without causing the occurrence of sparks on a fluid food material having a relatively high viscosity, intensive experiments and examinations As a result, the electrode plate for applying an alternating high voltage to the flowable food material is provided with a heat removal means for removing heat from the flowable food material flowing in contact with the flow path side surface of the electrode plate. As a result, it has been found that even a fluid food material having a relatively high viscosity can be stably sterilized with an alternating current and high electric field without causing the occurrence of sparks, and the present invention has been made.

  Specifically, the AC high electric field sterilizer according to the invention of claim 1 defines a flow path for flowing a fluid food material in a direction parallel to the plate surface of the electrode plate between a pair of parallel electrode plates. In the AC high electric field sterilization apparatus in which an alternating high voltage is applied between the pair of electrode plates in the flow path to sterilize the flowable food material in the flow path, A heat removal means is provided for removing heat from the fluid food material flowing in contact with the flow path side surface of the electrode plate.

  Moreover, the AC high electric field sterilization apparatus of the invention of claim 2 is the AC high electric field sterilization apparatus according to claim 1, wherein the heat removal means is provided on a surface opposite to the flow path in the pair of electrode plates. A fin member made of a highly heat-conductive material protruding from the surface is provided.

  The AC high electric field sterilizer according to the invention of claim 3 is the AC high electric field sterilizer according to claim 2, further comprising a blowing means for blowing cold air to the fin member. It is what.

  Furthermore, the AC high electric field sterilizer according to the invention of claim 4 is the AC high electric field sterilizer according to claim 3, further comprising electrode plate temperature detecting means for detecting the temperature of each electrode plate, Food material outlet temperature detecting means for detecting the temperature of the flowable food material at the outlet, and the air blowing means sends air according to the detection temperatures of the electrode plate temperature detecting means and the food material outlet temperature detecting means. Control means for controlling is provided.

  Furthermore, the AC high electric field sterilizer according to the invention of claim 5 is the AC high electric field sterilizer according to claim 1, wherein a cooling medium passage is provided in each of the electrode plates, and a liquid refrigerant is supplied to the cooling medium passage. It is configured to remove heat from the flowable food material flowing in contact with the flow path side surface of the electrode plate by flowing.

  Furthermore, the AC high electric field sterilizer according to the invention of claim 6 is the AC high electric field sterilizer according to any one of claims 1 to 5, wherein an electrical insulating property is provided between the pair of parallel electrode plates. A spacer plate made of a material is sandwiched, and the spacer plate is formed with a long hole for forming a dew compartment that penetrates from one plate surface to the other plate surface and extends in a direction along the plate surface, and One electrode plate of the pair of electrode plates has an inflow opening formed at a position corresponding to one end of the long hole of the spacer plate, and the other electrode plate has a long hole of the spacer plate. An outflow port is formed at a position corresponding to the other end of the gas flow channel, and a flow path from the inflow port to the outflow port through the long hole of the spacer plate is defined.

  An AC high electric field sterilization apparatus according to a seventh aspect of the invention is the AC high electric field sterilization apparatus according to any one of the first to fifth aspects, wherein the spacer is made of an electrically insulating material between a pair of parallel electrode plates. A plate is sandwiched, and the spacer plate is formed with a long hole for a flow path partition that extends from one plate surface to the other plate surface and extends in a direction along the plate surface. In one of the electrode plates, an inflow opening is formed at a position corresponding to one end of the long hole of the spacer plate, and the other of the long holes of the spacer plate is formed in the other electrode plate. An outlet is formed at a position corresponding to the end on the side, a flow path from the inlet to the outlet through the elongated hole of the spacer plate is formed, and the peripheral portion of the elongated hole of the spacer plate and Between each of the corresponding electrode plates, an elastic insulating material is used. An O-ring is inserted, and the flow path is sealed to the outside by the O-ring by tightening between both electrode plates, and the liquid to be sterilized from the inlet to the flow path Liquid food material in the flow path is introduced by continuously introducing the food material and discharging the liquid food material in the flow path continuously from the outlet and applying an alternating high voltage between the pair of electrode plates. Constructed to sterilize the material, and further, in the peripheral edge portion of the long hole on both plate surfaces of the spacer plate, each forming a continuous groove along the circumferential direction of the long hole, corresponding to the groove The surface of the electrode plate is a flat surface, and at least part of the cross section of the O-ring is fitted into the concave groove so that the space between the spacer plate and the electrode plate is sealed by the O-ring. To do.

  The AC high electric field sterilization apparatus according to claim 8 is the AC high electric field sterilization apparatus according to claim 7, wherein inner surfaces of both end portions in the length direction of the long holes in the spacer plate are tapered surfaces. The inflow port and the outflow port are configured to face the tapered surface on the flow path side.

  According to the AC high electric field sterilization apparatus of the fluid food material of the present invention, an excessive temperature rise of the fluid food material in contact with the surface of the electrode plate on the flow path side is provided by providing a heat removal means on the electrode plate. Therefore, even in the case of a fluid food material having a relatively high viscosity, the occurrence of bumping on the surface of the electrode plate can be suppressed and the occurrence of sparks can be prevented, so that the electrode plate surface is melted or damaged by the spark. It is possible to effectively prevent the fluid food material from scorching on the electrode plate surface and to stabilize the operation. Therefore, the AC high electric field sterilization method is applied to the fluid food with relatively high viscosity such as mayonnaise. It can be applied to materials.

  1 to 3 show the configuration of an embodiment of the AC high electric field sterilizer according to the present invention. 1 and 2, the same components as those of the prior art AC high electric field sterilizer shown in FIGS. 6 and 7 are denoted by the same reference numerals, and the details thereof are omitted.

  In FIG. 1 to FIG. 3, an inlet 19 </ b> A of the flow path 17 between the electrode plates 11 </ b> A and 11 </ b> B is provided on the outer surface (surface opposite to the flow path 17) of each electrode plate 11 </ b> A and 11 </ b> B. A sheet-shaped heat diffusion sheet 51 made of a material having a good thermal conductivity, for example, an aluminum material, is in surface contact with the outer surface of the portion excluding the vicinity of the outlet 19B as much as possible. Further, a plurality of fin members 53 (four for each electrode plate in the illustrated example) are arranged in parallel on the front side of the heat diffusion sheet 51 as heat extraction means. These fin members 53 are made of a good heat conductive material such as an aluminum material, and are formed such that a plurality of thin plate-like fin portions 53B protrude in parallel with each other at right angles from the plate-like base portion 53A. ing. Each fin member 53 and the thermal diffusion sheet 51 are fixed to the electrode plates 11A and 11B by screws 55 penetrating them.

  Although not shown in FIGS. 1 to 3, cold air (usually air at normal temperature or air previously cooled to a temperature lower than normal temperature) is blown to the fin portion 53B at a position corresponding to the fin portion 53B. Blowing means for attaching, for example, a blower fan is provided.

  The configuration other than the points described above, in particular, the configuration of the internal flow path portion, is the same as that of the AC high electric field sterilizer according to the prior art shown in FIGS. However, in FIGS. 1 to 3, for simplification of the drawings, the introduction member 21 </ b> A, the lead-out member 21 </ b> B, and the screw 35 shown in FIGS. 6 and 7 are removed.

  In the above place, if an alternating current high voltage is applied between the electrode plates 11A and 11B, a fluid food material to be sterilized is continuously introduced from the outside into the flow path 17 through the inlet 19A. As already described with reference to FIGS. 6 and 7, the alternating high electric field sterilization of the fluid food material is continuously performed in the flow path 17. At this time, in the flow path 17, heat is generated due to the inherent resistance of the fluid food material and the temperature rises. However, as already described, in the region near the electrode plates 11 A and 11 B, the center between the electrode plates 11 A and 11 B is Compared with the vicinity of the position (flow path center position), the temperature tends to be higher, but the fin member 53 is attached to the outer surface side of the electrode plates 11A and 11B via the heat diffusion sheet 51. The heat of the fluid food material flowing in the vicinity of the electrode plates 11A and 11B is transferred by heat conduction from the electrode plates 11A and 11B to the fin member 53 through the heat diffusion sheet 51, and the fin portion 53B of the fin member 53 having a large surface area. Radiates heat to the external space. At this time, if the air blowing means (not shown) is operated to blow cool air to the fin portion 53B, the heat radiation effect from the fin portion 53B can be further enhanced. By removing heat from the fluid food material in the vicinity of the electrode plates 11A and 11B in this manner, the fluid food material is prevented from reaching a high temperature in the vicinity thereof.

  Here, for example, in the case of a fluid food material having a relatively high viscosity such as mayonnaise, as already described, the flow velocity becomes small due to viscous resistance in the region along the surface of the electrode plates 11A and 11B, so-called laminar flow occurs. For this reason, in the portions in contact with the surfaces of the electrode plates 11A and 11B, the time in contact with the electrode plates 11A and 11B becomes much longer than in the vicinity of the central portion, and as a result, the fluidity in the vicinity of the electrode plates 11A and 11B. Although the food material tends to excessively rise in temperature, the region contacting the electrode plates 11A and 11B via the electrode plates 11A and 11B by the heat removal action by the fin member 53 and further the air blowing means as described above. Since the heat of the fluid food material is taken away, even in the case of a fluid food material having a high viscosity, it is avoided that the temperature rises excessively at the portions in contact with the electrode plates 11A and 11B. It can, as a result, it can effectively prevent the spark occurs by bumping of liquid food material in the vicinity of its (generation of bubbles).

  Further, the distance between the electrode plates 11A and 11B is extremely narrow as about 0.5 to 20 mm as described above, and the fluid food material near the surface of the electrode plates 11A and 11B rises excessively and becomes narrow due to bumping. If bubbles occur between the electrodes, the electric field distribution between the electrode plates 11A and 11B becomes non-uniform, and there is a risk that a uniform sterilization effect cannot be obtained. It is possible to maintain a high bactericidal effect reliably and stably.

  Furthermore, by removing heat from the side of the electrode plate, the temperature of the electrode plate becomes lower than the temperature of the fluid food material in contact with the electrode plate. , Denaturation) is also prevented. That is, when the temperature of the electrode plate is higher than the temperature of the fluid food material, the fluid food material is likely to be scorched or scaled due to solidification in contact with the electrode plate surface, but the temperature difference between the two is reversed. By doing so, the occurrence of scaling can also be prevented.

  It should be noted that by operating the air blowing means as described above and blowing cool air to the fin member 53 and performing so-called blast cooling (forced air cooling), the heat removal effect is remarkably enhanced. It is desirable to provide control means for controlling the operation, for example, control means for on / off control, or control means for controlling the air volume (fan rotation amount). If the control means is provided in the air blowing means in this way, it is more reliable by adjusting the heat removal effect by controlling the air blowing means according to the electrode plate temperature or the temperature of the flowable food material on the outlet side of the flow path. In addition, the occurrence of sparks can be prevented. That is, in order to prevent the occurrence of sparks, it is advantageous to have a high heat removal effect. However, if the heat removal effect is excessively increased, the overall temperature rise of the flowable food material is reduced, which is sufficient due to insufficient heating. Therefore, it may be difficult to obtain a proper sterilizing effect, and therefore it is desirable to remove heat moderately. Therefore, as described above, the heat removal effect is adjusted by controlling the air blowing means according to the electrode plate temperature or the temperature of the flowable food material at the outlet of the flow path, so that heat is appropriately removed without causing insufficient heating. It is possible to reliably prevent the occurrence of sparks.

  Specifically, for example, as shown in FIG. 4, the back surface of each electrode plate is placed at a position corresponding to the outflow port 19B in one electrode plate 11A and a position corresponding to the inflow port 19A in the other electrode plate 11B. Thin sensor insertion holes 61A and 61B are formed from the side to the position near the surface, and temperature sensors 63A and 63B such as thermocouples are used as electrode plate temperature detection means in the sensor insertion holes 61A and 61B. Is inserted so as to be positioned near the surface of the electrode plate. On the other hand, a temperature sensor 65 is arranged as a food material outlet temperature detecting means for detecting the temperature of the fluid food material at a substantially central position near the outlet of the outlet 19B. And in the control part of the ventilation means which is not shown in figure, each of detection temperature TA1 and TA2 by temperature sensor 63A, 63B as electrode plate temperature detection means does not exceed detection temperature TB of temperature sensor 65 as food material exit detection means. Thus, it is set as the structure which controls on / off of a ventilation means or controls the air volume (rotation speed of a fan). Here, the electrode plate temperatures TA1 and TA2 detected by the temperature sensors 63A and 63B are temperatures near the flow path side surface of the electrode plates 11A and 11B, and are therefore regions in contact with the electrode plate surface in the flow path 17. It can be said that the temperature is close to the temperature of the fluid food material. On the other hand, the temperature TB detected by the temperature sensor 65 can be regarded as the overall average temperature of the flowable food material at the outlet of the flow path 17. Therefore, controlling TA1 and TA2 so as not to exceed TB results in the temperature of the fluid food material in the region in contact with the electrode plate surface in the channel 17 and the fluid food in the center region of the channel. This means that the difference from the temperature of the material is controlled so as not to become large.

  When actually performing the control as described above, the blower is turned off in the initial state, and when TA1 and TA2 are compared with TB, at least one of TA1 and TA2 exceeds TB The forced air cooling may be started by turning on the air blowing means. Of course, the set temperature difference between TA1, TA2 and TB that turns on the blowing means can be determined as appropriate. For example, the setting is made so that the blowing means is turned on when TA1 and TA2 are 2 ° C. or more higher than TB. You may do it. Alternatively, it may be controlled to change the air volume of the blowing means continuously or stepwise according to the temperature difference between TA1, TA2 and TB.

  In the example of FIG. 4, unlike the example of FIG. 2, the tapered surfaces 15 </ b> A and 15 </ b> B are not formed on the spacer plate 13 because of the relationship with the detection position of the electrode plate temperature. Of course, the tapered surfaces 15A and 15B may be formed on the spacer plate 13, and the electrode plate temperature detection position may be slightly moved.

  Furthermore, when the initial temperature of the fluid food material (the temperature of the fluid food material flowing into the inlet 19A) is high, the temperature of the fluid food material flowing in the vicinity of the electrode plate surface inevitably increases. Therefore, the initial temperature of the fluid food material is measured in the vicinity of the inlet 19A (or measured in the previous flow path), and the air volume of the blowing means is controlled according to the initial temperature. Is also possible.

  In addition, the voltage or current between the electrodes may be increased in order to increase the target heating temperature difference (difference between the inflow side temperature and the outflow side temperature). Therefore, the air volume of the blowing means can be controlled according to the voltage or current in the power supply device.

  In the above-described embodiment, the air cooling method is applied as the heat removal means, and this air cooling method is most advantageous in terms of cost compared with other heat removal means such as water cooling or oil cooling. Depending on the situation, the heat may be removed using a liquid refrigerant such as water or oil.

  For example, as shown in FIG. 5, in the electrode plate 11A (11B), a plurality of through holes 71 penetrating the inside thereof are formed in parallel to the plate surface, and the space between these through holes 71 is outside the electrode plate. The U-shaped coupling pipe 73 is combined to form a liquid cooling medium passage 75 as a whole, and the cooling water or the liquid cooling medium passage 75 is supplied from the inlet 77A on one end side to the outlet 77B on the other end side. A liquid refrigerant such as cooling oil may be continuously flowed.

  Of course, a separate cooling jacket may be provided on the outer surface side of the electrode plates 11A and 11B, and cooling water or cooling oil may flow through the jacket.

  When water is used as the liquid cooling medium, it is necessary to completely separate the cooling water circulation system on the one electrode plate side and the cooling water circulation system on the other electrode plate side. is there. That is, if the cooling water of both electrode plates is made common, there is a possibility that the electrode plates may be electrically short-circuited via the cooling water, and therefore the cooling water path is completely electrically connected. Must be separated and insulated.

  The experiment example using the alternating current high electric field sterilizer shown in FIGS.

Mayonnaise is used as the flowable food material, the opposing area of the electrode plate is 20 mm ² , the flow path length is 4 mm, and the gap between the electrode plates is 5 mm. The average temperature of the flowable food material on the inlet side and the average of the flowable food material on the outlet side The high voltage electric field sterilization was carried out at a flow rate of 120 L / hr and a flow rate of 133 cm / sec with the voltage set to 500 V so that the difference ΔT with respect to temperature was approximately 10 ° C. In this experiment, it is difficult to directly measure the temperature of the flowable food material in the region near the electrode plate surface. Therefore, the temperature inside the electrode plate (near the surface) in the portion near the outlet of the electrode plate is difficult. The temperature of the portion was measured, and this outlet side electrode plate temperature was regarded as the temperature T1 of the fluid food material in the region near the electrode plate surface. Separately, the temperature of the fluid food material was measured at the location exiting from the outlet, and this was regarded as the average outlet side temperature (outlet side average temperature) T2 of the fluid food material.

  As a result, when no fin member is provided, the difference between T1 and T2 is about 15 ° C., but when the fin member is provided, the difference between T1 and T2 is reduced to about 10 ° C. Turned out to be. Furthermore, it has been found that the difference between T1 and T2 is reduced within 1 ° C. by operating the blower fan.

  The reduction in the temperature difference between T1 and T2 in this way is that the temperature of the fluid food material in the region near the electrode plate surface and the temperature of the fluid food material in the region near the center of the flow path. It means that the difference has become smaller. That is, it means that the fluid food material was not excessively heated in the vicinity of the electrode plate surface with respect to the vicinity of the center portion of the flow path. Therefore, the effect of the present invention is clear from this embodiment.

It is a front view of the alternating current high electric field sterilizer of one Example of this invention. It is a partial notch front view of the alternating current high electric field sterilizer shown by FIG. It is a left view of the alternating current high electric field sterilizer shown by FIG. It is a partial notch front view of the alternating current high electric field sterilizer of other Examples of this invention. It is a partial notch side view of the electrode plate in the alternating current high electric field sterilizer of further another Example of this invention. It is a vertical front view of the alternating current high electric field sterilizer which the inventor proposed previously. It is a right view which shows a spacer in the position of the VII-VII line of FIG.

Explanation of symbols

11A electrode plate 11B electrode plate 13 spacer plate 15 long hole 15A taper surface 15B taper surface 17 flow channel 19A inflow port 19B outflow port 29A concave surface 29B concave surface 31A O-ring 31B O-ring 51 heat diffusion sheet 53 fin member (heat extraction means)
63A, 63B Temperature sensor as electrode plate temperature detection means 65 Temperature sensor as food material outlet temperature detection means 75 Liquid cooling medium passage

Claims (8)

A flow path for flowing a fluid food material is defined between a pair of parallel electrode plates in a direction parallel to the plate surface of the electrode plate, and an alternating high voltage is applied between the pair of electrode plates in the flow path. Then, in the alternating current high electric field sterilizer that sterilizes the fluid food material in the flow path,
An alternating current high electric field sterilization apparatus, wherein the pair of electrode plates is provided with heat removal means for removing heat from the fluid food material flowing in contact with the flow path side surface of the electrode plates. In the AC high electric field sterilizer according to claim 1,
An AC high electric field characterized in that, as the heat removal means, a fin member made of a highly heat-conductive material protruding from the surface of the pair of electrode plates opposite to the flow path is provided. Sterilizer. In the AC high electric field sterilizer according to claim 2,
The AC high electric field sterilizer further includes a blowing means for blowing cold air to the fin member. In the AC high electric field sterilizer according to claim 3,
Furthermore, it comprises an electrode plate temperature detecting means for detecting the temperature of each electrode plate, and a food material outlet temperature detecting means for detecting the temperature of the flowable food material at the outlet of the flow path, and the blowing means The AC high electric field sterilizer is characterized in that is provided with a control means for controlling the blowing according to the detected temperatures of the electrode plate temperature detecting means and the food material outlet temperature detecting means. In the AC high electric field sterilizer according to claim 1,
Each of the electrode plates is provided with a cooling medium passage, and by flowing a liquid refrigerant through the cooling medium passage, heat is removed from the fluid food material flowing in contact with the flow path side surface of the electrode plate. An AC high electric field sterilizer characterized by the above. In the alternating current high electric field sterilizer according to any one of claims 1 to 5,
A spacer plate made of an electrically insulating material is sandwiched between the pair of parallel electrode plates. The spacer plate penetrates from one plate surface to the other plate surface and extends in a direction along the plate surface. A long hole for forming a flow channel section is formed, and one of the pair of electrode plates has an inlet formed at a position corresponding to one end of the long hole of the spacer plate, The other electrode plate has an outlet formed at a position corresponding to the other end of the long hole of the spacer plate, and a flow path extending from the inlet to the outlet through the long hole of the spacer plate is defined. An alternating current high electric field sterilizer characterized by being formed. In the alternating current high electric field sterilizer according to any one of claims 1 to 5,
A spacer plate made of an electrically insulating material is sandwiched between a pair of parallel electrode plates, and the spacer plate has a flow path extending from one plate surface to the other plate surface in a direction along the plate surface. A partitioning long hole is formed, and one of the pair of electrode plates has an inflow opening formed at a position corresponding to one end of the long hole of the spacer plate. In the electrode plate, an outlet is formed at a position corresponding to the other end of the long hole of the spacer plate, and a flow path from the inlet to the outlet through the long hole of the spacer plate is defined. Further, an O-ring made of an elastic insulating material is inserted between the peripheral portion of the long hole of the spacer plate and each of the corresponding electrode plates, and the O-ring is tightened between the two electrode plates. Configuration in which the flow path is sealed to the outside The liquid food material to be sterilized is continuously introduced into the flow path from the inlet, and the liquid food material in the flow path is continuously discharged from the outlet, and the pair of electrodes It is configured to sterilize the liquid food material in the flow path by applying an alternating high voltage between the plates, and further to the peripheral portions of the long holes on both plate surfaces of the spacer plate, respectively, in the circumferential direction of the long holes And a surface of the electrode plate corresponding to the groove is a flat surface, and at least a part of the cross-section of the O-ring is fitted into the groove to form the spacer plate and the electrode. An AC high electric field sterilizer characterized by sealing between the plates with an O-ring. In the AC high electric field sterilizer according to claim 7,
The inner surface of both ends in the length direction of the long hole in the spacer plate is a tapered surface, and the inflow port and the outflow port of the electrode plate are respectively configured to face the tapered surface on the flow path side, AC high electric field sterilizer.

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