JPH07313124A - Heating and sterilizing method, heating and sterilizing device and high-frequency heater in heating and sterilizing device - Google Patents

Abstract

PURPOSE:To uniformly heat a target food to be sterilized, to improve operation efficiency of sterilizing treatment and not to cause interference of the target food to be sterilized with electrodes. CONSTITUTION:This high-frequency heater 1 is provided in a heating and sterilizing device for sending high-frequency electric power supplied from a high-frequency generating circuit to a space between opposing high-frequency electrodes 2 consisting of an upper electrode 21 and a lower electrode 22, subjecting a chilled food P laid between the opposing electrodes to induction heating and sterilizing. A pair of an upper and a lower conveyor belts 4 composed of an upper belt 41 and a lower belt 42 are installed so as to cover the electrode faces of the upper electrode 21 and the lower electrode 22. A heating space S by high-frequency heating is formed at a gap part between the upper belt 41 and the lower belt 42 and the chilled food P in a sandwiched state in between a pair of the belts is supplied to the heating space S.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for heat sterilizing various kinds of food (standard products) packaged in a fixed shape, a heat sterilizer, and a counter electrode for high frequency power from a high frequency generating circuit through a transformer. The present invention relates to a high-frequency temperature raising device in a heat sterilization device for supplying temperature to foodstuffs to heat the foodstuffs interposed between the opposed electrodes.

[0002]

2. Description of the Related Art Recently, various kinds of cooked foods have been filled in a bag-like container (chilled container) made of a plastic sheet, or a so-called chilled food of a fixed shape wrapped with a plastic tray can easily decorate a dining table. It is in the spotlight due to the convenience it can have. Chilled foods include salads such as potato salad and macaroni salad,
Typical examples include prepared dishes such as Chikuzen-ni and Yamani-ni. These chilled foods reach a temperature suitable for bacterial growth while being naturally cooled after being filled in a chilled container, and if this temperature is maintained for a long time, bacteria will reproduce again in the chilled container. .

Therefore, in order to prevent the re-propagation of such bacteria, a chilled food is subjected to heat sterilization before shipment in a food factory. This heat sterilization treatment usually includes a temperature raising step, a temperature holding step and a cooling step. In the conventional temperature raising step, the chilled food is heated to a sterilization temperature of about 70 ° C. by boiling or applying steam, and then transferred to a temperature holding step in which the sterilization temperature is maintained for a predetermined time. The temperature maintaining step is performed by loading the temperature maintaining chamber in which the indoor atmosphere is maintained at the sterilization temperature by an electric heater or the like with the chilled food for a predetermined time. In this temperature holding step, the chilled food is substantially sterilized.

Then, in the next cooling step, in order to prevent the temperature suitable for bacterial growth from reaching a long time, a cooling treatment is carried out in which the chilled food is forcibly cooled by spraying cold water or immersing in cold water. To be done.

By the way, in the conventional heat sterilization treatment of chilled foods as described above, the temperature rising time in the heating process is as long as several tens of minutes, and as a result, the most prominent characteristic of chilled foods is the food itself. In addition to the loss of flavor and freshness, there was a problem that the heat sterilization treatment could not be efficiently performed due to the long heating time.

Therefore, in order to solve the above-mentioned conventional inconvenience, a microwave heating sterilization technique for irradiating a material to be heated with microwaves to raise the temperature has been developed, and the heating time can be shortened. In terms of aspect, it is showing great power. Regarding microwave heat sterilization technology for food products, see Jikho 59-34.
No. 311, Gazette 60-8710, Gazette 6
No. 0-21975, or JP-A-60-1209.
No. 70 publication and the like.

[0007]

However, in the microwave heating sterilization, there is a heating chamber consisting of a closed space in which microwaves do not leak for uniformly irradiating the object to be heated with microwaves, and uniform heating in this heating chamber. Various devised structures for are needed. Therefore, there is a problem in that the heat treatment capacity is small in spite of the large scale of the equipment, resulting in a very expensive equipment.

[0008] Microwaves have a low permeability to the inside of the object to be heated, and the thickness of the object to be heated is at most 10 mm to 20 mm.
There is a limit to the extent to which uniform heating can be performed by microwaves, and there is a problem that it is extremely difficult to uniformly heat a material having a thickness of more than 20 mm to its central portion. In particular, when high-speed heating is performed, the temperature difference between the surface layer portion and the central portion of the object to be heated becomes large, which causes a disadvantage that a uniform temperature distribution cannot be obtained.

Further, even if the object to be heated is a thin object having a thickness of 10 mm or less, if the object has a planar shape of, for example, about 10 cm square or more, the microwave frequency is very high, and thus heating is performed. There is a problem that the variation of the electric field strength in the room is large, it is difficult to uniformly heat the object to be heated, and the variation of the heating temperature is very large.

By the way, most of the sterilized foods such as chilled foods to be subjected to heat sterilization have conventionally been light weight products of 1 kg or less, but in recent years, chilled food products such as chilled food products for weighting 2 to 5 kg have been heated. There is a trend toward sterilization. However, in the case of targeting such a heavy object, it is impossible to cope with the problem by the microwave heating having the above problems.

Therefore, it is conceivable to apply high frequency heating to the temperature raising step in order to increase the temperature raising rate. That is, the object to be heated such as chilled food is placed between the high frequency electrodes oscillating the high frequency, and the object to be heated is dielectrically heated with the high frequency to uniformly heat the object to be heated from the inside. By doing so, it is expected that the heating time will be shortened and that the application to the application of continuously heating a large amount of heavy objects will be expected.

By the way, when heating an object to be heated by using a high frequency wave, it is preferable that the object to be heated is brought into contact with the upper and lower electrodes in order to improve the heating efficiency. It is necessary to push an object to be heated between the electrodes and perform dielectric heating by high frequency for a predetermined time.
Therefore, when applying the high-frequency device to the temperature raising process of the heat sterilizer, a belt conveyor is used, and the upper electrode is placed at the same height as the upper surface of the object to be heated that is placed and transferred on the belt conveyor. It is conceivable that the object to be heated is transferred between the electrodes while the object to be heated is in contact with the upper electrode.

However, when the object to be heated is moved in contact with the electrodes, the object to be heated is displaced on the conveyor belt in the transfer direction and the width direction due to sliding resistance, and is unevenly distributed on the belt. The condition is not stable, which causes a decrease in efficiency.In an extreme case, the container is damaged and the contents are exposed.
Inconvenience such as contaminating the electrodes occurs.

Regarding the use of high frequency waves for thawing frozen foods, Japanese Patent Publication No. 51-15100, Japanese Patent Publication No. 55-46152, and Japanese Patent Publication No. 60-97.
No. 84, Japanese Patent Publication No. 62-34386, Japanese Patent Publication No. 4
Although it is described in Japanese Patent Publication No.-70757, Japanese Patent Publication No. 5-840, etc., it is not suitable for heat sterilization of foods.

The present invention has been made to solve the above-mentioned problems, and is an effective heat sterilization method, heat sterilization apparatus, and belt conveyor using a high frequency of a standard product such as chilled food. It is an object of the present invention to provide a high-frequency heating device in a heat sterilization device in which interference between a standard product and electrodes does not occur during transfer of the standard product between electrodes.

[0016]

The heat sterilization method according to claim 1 of the present invention supplies high-frequency power supplied from a high-frequency generation circuit between opposing electrodes consisting of an upper electrode and a lower electrode, and between the opposing electrodes. A heating and sterilizing method of dielectrically heating an intervening standard product to raise the temperature, wherein the standard product is introduced between the upper electrode and the lower electrode to rapidly raise the temperature to the sterilization temperature, and this heating process. It is characterized in that it comprises a temperature holding step for holding the temperature of the standard product derived from the above for a predetermined time and a cooling step for cooling the standard product derived from this temperature maintaining step.

The heat sterilizer according to claim 2 of the present invention comprises:
A heating and sterilization device that supplies high-frequency power supplied from a high-frequency generation circuit between opposing electrodes consisting of an upper electrode and a lower electrode, and heats a fixed product interposed between the opposing electrodes by dielectric heating to raise the temperature. A heating device for rapidly raising the temperature to the sterilization temperature, a temperature holding device for holding the temperature of the standard product heated to the sterilization temperature for a predetermined time, a cooling device for cooling the standard product after the temperature is maintained for the predetermined time, and It is characterized in that it comprises a transfer means for transferring a fixed product, which is provided between the upper electrode and the lower electrode of the temperature raising device and is laid down to the cooling device via the temperature holding device. Is.

According to a third aspect of the present invention, there is provided a high frequency heating device for heating and sterilizing apparatus, wherein high frequency power supplied from a high frequency generating circuit is supplied between opposing electrodes composed of an upper electrode and a lower electrode, and between the opposing electrodes. In a high-frequency heating device in a heating and sterilizing device that dielectrically heats an interposed food product, a pair of upper and lower conveyor belts including an upper belt and a lower belt are provided so as to cover the electrode surfaces of the upper electrode and the lower electrode. The food is transported while being sandwiched between the pair of belts.

According to a fourth aspect of the present invention, there is provided a high-frequency heating device for a heat sterilization apparatus according to the third aspect, wherein at least one of the upper electrode and the lower electrode is movable up and down. It is characterized in that the vertical width dimension of the temperature raising space can be adjusted by the vertical movement of these components.

According to a fifth aspect of the present invention, there is provided a high frequency heating device for a heat sterilization apparatus according to the third or fourth aspect, wherein the upper belt and the lower belt are from the same drive source. It is characterized in that it is configured to orbit at the same speed by obtaining power.

The high frequency heating device in the heat sterilizer according to claim 6 of the present invention is the high frequency heating device in the heat sterilizer according to any one of claims 3 to 5, wherein the lower belt is more than the upper belt. Is also projected upstream,
A height adjusting portion is provided on the upper surface of the protruding lower belt so as to equalize the height of the food to a predetermined height.

The high frequency heating device in the heat sterilization device according to claim 7 of the present invention is the high frequency heating device in the heat sterilization device according to any one of claims 3 to 6, wherein the conveyor belt has a revolving speed. It is characterized in that it can be changed.

[0023]

According to the heat sterilization method and the heat sterilization apparatus of the above-mentioned claims 1 and 2, the fixed product to be heat sterilized is introduced between the upper electrode and the lower electrode in the temperature raising step (temperature raising apparatus). Then, the temperature is rapidly raised to the sterilization temperature, the temperature is raised in the next temperature holding step (temperature holding device) and the temperature is held for a predetermined time, substantial sterilization treatment is performed in this step, and the cooling step (cooling device) ), The cooling prevents the temperature suitable for the growth of bacteria from being maintained for a long time, and is discharged out of the system as a sterilized regular product.

As described above, since the dielectric heating by high frequency is applied in the heating step, the heating rate can be remarkably increased as compared with the conventional ordinary heating method, and the microwave heating is extremely high. It is possible to perform uniform heating of thick or heavy objects that cannot be handled, and therefore target large quantities of standard products (food) and maintain the prescribed sterilization temperature without losing their flavor and freshness. It is possible to reach it.

Further, in particular, in the heat sterilization apparatus according to the second aspect, since the conveying means for conveying the fixed product through each device is provided, the fixed product is continuously supplied to this conveying means. As a result, the heat sterilization treatment is efficiently performed. There is no particular limitation on the type of transport means,
A conveyor belt is preferably used. The conveyor belt may be one that penetrates each device,
The devices separated for each device may be connected via a connecting portion.

According to the high-frequency heating device in the heat sterilizer of the third aspect, the high-frequency generating circuit is provided to the upper electrode and the lower electrode arranged on the back surface of the conveyor belt formed by the upper belt and the lower belt. By supplying the high frequency electric power of 1, the heating space is formed in the gap between the upper belt and the lower belt by heating the food. The food is heated to a predetermined sterilization temperature while moving in the heating space by sequentially supplying the food to be sterilized to the gap between the upper belt and the lower belt in the state where the heating space is formed. .

The electrode surface of the upper electrode is covered with the upper belt, and since the upper belt moves as the food moves, the food does not interfere with the upper electrode and contaminate the electrode. Further, since the food moves in the temperature-raising space while being sandwiched between the upper belt and the lower belt, the thickness of the food is made uniform, the temperature distribution in the food becomes substantially uniform, and Sterilization unevenness is effectively suppressed.

According to the high-frequency temperature raising device in the heat sterilization device of the fourth aspect, the upper electrode and the lower electrode are
Since at least one is configured to be able to move up and down, the vertical width of the temperature raising space is adjusted according to the bulk (height) of the food, and the distance between the food and the electrode is always small and constant.

According to the high frequency heating device in the heat sterilizer of the fifth aspect, since the upper belt and the lower belt are powered at the same drive source and rotate at the same speed, the upper belt is rotated. The difference in speed between the lower belt and the lower belt does not deform the food.

According to the high-frequency temperature raising device in the heat sterilization apparatus of the sixth aspect, the lower belt is projected to the upstream side of the upper belt, and the height of the food is predetermined on the upper surface of the protruding lower belt. Since the height adjusting unit that equalizes the height dimension is provided, the vertical width of the food is evened before being supplied to the temperature raising space, which facilitates the introduction of the food into the temperature raising space.

According to the high frequency heating device in the heat sterilization device of the seventh aspect, since the conveyor belt is configured so that the orbiting speed can be changed, the conveyor belt can be heated in the heating space according to the type and weight of the food. The residence time of can be adjusted.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view showing the flow of a heat sterilizer to which a high-frequency heating device according to the present invention is applied.
(A) is a process chart, and (B) is a graph showing changes with time of the temperature of the chilled food in each process. First, (a) in the figure
As shown in FIG. 6, the process of the heat sterilization device to which the high-frequency heating device 1 of the present invention is applied is a temperature raising process X1 for raising the temperature of the chilled food P to a predetermined sterilization temperature, and a temperature raising process in the temperature raising process X1. A configuration including a temperature holding step X2 for holding the sterilization temperature of the raised chilled food P1 for a predetermined time to sterilize it, and a cooling step X3 for cooling the sterilized chilled food P2 after holding the temperature for a predetermined time to approximately room temperature. Have. Then, the high-frequency temperature raising apparatus 1 of the present invention is applied in the temperature raising step X1.

In the temperature raising step X1, high-frequency power supplied from a high-frequency generation circuit is supplied between opposing electrodes composed of an upper electrode and a lower electrode, and a fixed product interposed between the opposing electrodes is dielectrically heated to chill a chilled product. A temperature raising device for rapidly raising the temperature of the food P2 to the sterilization temperature is applied, and the temperature holding step X2
Is provided with a predetermined temperature holding device that holds the temperature of the standard product heated to the sterilization temperature for a predetermined time. Further, the cooling step X3 is provided with a cooling device such as a water-cooled cooling device that cools the standard product after the temperature is maintained for a predetermined time.

Further, a conveying means for conveying the chilled food P2 is interposed between the upper electrode and the lower electrode of the temperature raising device, and is laid on the cooling device via the temperature holding device. In this embodiment, a conveyor belt is used as the above-mentioned conveying means.

A single conveyor belt may be provided so as to penetrate each device, or a plurality of conveyor belts may be installed for each device or for each appropriate section to transfer the chilled food P2 at a predetermined transfer. You may be able to transfer at the department. Further, the conveying means is not limited to the conveyor belt, and a conveying vehicle carrying the chilled food P2 may be run, or the chilled food P2 may be pressed by the pressing rod to be supplied into the apparatus. May be.

In the temperature raising step X1, the chilled food P is subjected to high frequency induction heating in the high frequency temperature raising device 1, and as shown in FIG. The temperature is raised to ℃).

In the temperature maintaining step X2, the temperature maintaining chamber is maintained at a predetermined sterilization temperature by heating with an electric heater or application of steam, and the temperature-controlled chilled food P1 is heated in the temperature maintaining chamber. Is retained for a predetermined time as shown in (b) of FIG. 1 to perform a substantial sterilization treatment.

In the cooling step X3, the sterilized chilled food P2 is cooled to approximately room temperature by spraying cooling water or the like. By this cooling treatment, it is possible to avoid maintaining a temperature suitable for bacterial growth for a long period of time, and effectively suppress the re-growth of bacteria.

The high-frequency heating apparatus 1 of the present invention is particularly the heating step X1 in the high temperature sterilization apparatus comprising the above-mentioned steps.
It is related to.

FIG. 2 is a partially cutaway perspective view showing an example of the high-frequency heating apparatus according to the present invention, and FIG. 3 is a side view.
4 is a plan view and FIG. 5 is a front view. As shown in these figures, the high-frequency heating apparatus 1 of the present invention has a pair of upper and lower high-frequency counter electrodes 2 each having an upper electrode 21 and a lower electrode 22 for heating various foods to a predetermined sterilization temperature. The provided temperature raising device body 10 and the high frequency generating means 3 for supplying high frequency power to the high frequency counter electrode 2 of the temperature raising device body 10.
(FIG. 4).

In this embodiment, salads such as potato salad and macaroni salad, prepared foods such as boiled Chikuzen and edible wild plants were deaerated and sealed in a bag-shaped chilled container made of a synthetic resin sheet. The chilled food P is selected as a target for heat sterilization. However, the high-frequency heating apparatus 1 of the present invention is not limited to the chilled food P as the food to be sterilized, and can be applied to so-called packed food in which various kinds of cooked foods are packed in a thin wrap. Is.

The temperature raising device main body 10 has a horizontally long casing 11 having a chilled food P supply port 12 on one side and a chilled food P discharge port 13 on the other side, and the inside of the casing 11. And a pair of upper and lower conveyor belts 4 composed of an upper belt 41 and a lower belt 42, which are movably circulated. These conveyor belts 4
A material made of, for example, a synthetic resin having high-frequency transmission performance is applied as the material. In this embodiment, the one made of polytetrafluoroethylene is used.

The lower belt 42 is provided in the lower half of the casing 11, and the lower front roller 42 is rotatably provided around the support shaft at the supply port 12 and the discharge port 13.
a, lower rear roller 42b, and both rollers 4
It is stretched around a plurality of lower auxiliary rollers 42c installed at appropriate places below the 2a and 42b. A drive motor 43 is installed below the rear roller 42b.
The rotational drive of is transmitted to the rear roller 42b via the lower transmission belt 43a. Therefore, by driving the drive motor 43, this rotation is transmitted to the lower belt 42 via the lower transmission belt 43a and the rear roller 42b, and the lower belt 42 circulates clockwise in FIGS. 2 and 3. ing.

In this embodiment, one drive motor 4
However, the present invention is not limited to the case where both the belts 41 and 42 are driven by the single drive motor 43, and the respective belts 41 and 42 are operated. Two drive motors may be provided for 42.

As shown in FIG. 3, a glass-covered peep window 15 is provided at an appropriate central portion of the side portion of the casing 11 in the vertical direction. From this peep window 15, a conveyor belt inside the casing 11 is provided. The movement status of No. 4 and the temperature rising status of the chilled food P can be visually observed.

The upper belt 41 is provided in the upper half of the casing 11 so as to face the lower belt 42 and is provided on the upper front roller 41a located at the supply port 12 and on the downstream side of the upper front roller 41a. Front pressing roller 41c, upper rear roller 41b provided above the lower rear roller 42b, and upper rear roller 4
It is stretched over a rear pressing roller 41d provided immediately upstream of 1b and an upper auxiliary roller 41f arranged at an appropriate position above these rollers 41a, 41b, 41c, 41d.

A tension roller 41g for tensioning the upper belt 41 by an appropriate urging means is provided between the pair of upper auxiliary rollers 41f 'provided on the downstream side of the upper rear roller 41b so as to be vertically movable. Has been. A pair of lower auxiliary rollers 42f 'and a tension roller 42g similar to the above are provided on the downstream side of the lower rear roller 42b.

The lower rear roller 42b and the upper rear roller 41b have the same diameter, and they are the upper transmission belt 43.
bound by b. Therefore, when the drive motor 43 is driven, this rotation is transmitted to the lower rear roller 42b via the lower transmission belt 43a, and further transmitted to the upper rear roller 41b via the upper transmission belt 43b. And the upper belt 41 rotate at the same peripheral speed.

The chilled food product is placed between the downward surface of the upper belt 41 between the front pressing roller 41c and the rear pressing roller 41d and the upward surface of the lower front roller 42a and the lower rear roller 42b. A temperature raising space S is formed in which P is passed to raise the temperature.

The front pressing roller 41c is disposed below the upper front roller 41a. Therefore, the upper belt 41 located between the upper front roller 41a and the front pressing roller 41c is formed with a downwardly inclined portion 44 toward the downstream side. When the chilled food P is bulky due to the inclined portion 44, the chilled food P is deformed to the height of the temperature rising space S as it moves downstream, and the chilled food P is easily guided to the temperature rising space S. There is.

The upstream side of the lower belt 42 projects forward in the horizontal direction from the upstream side of the upper belt 41.
Then, in order to accommodate the protruding upper belt 41, the lower half of the casing 11 projects forward of the upper half, and the upper portion for taking over the chilled food P from the upstream equipment is opened to this portion. Are formed. By exposing the lower belt 42 at the transfer portion 14 in this manner, transfer of the chilled food P is facilitated.

A pre-height adjusting section 5 for the chilled food P is provided in the transfer section 14. This advance height adjustment unit 5
Are provided in the width direction of the lower belt 42, and lower end portions on both sides of the support frame body 51 have an inverted U-shape and are erected on both side edge portions of the takeover portion 14, and the support frame body 51 of the support frame body 51. It is composed of an adjusting roller 52 which is vertically movable between both side portions. An adjusting handle 53 having a male screw screwed on a rotation shaft is provided at the center of the upper portion of the support frame 51. By rotating the adjusting handle 53 in the forward and reverse directions, the adjusting roller 52 is moved up and down to adjust. The gap formed between the roller 52 and the lower belt 42 can be adjusted.

In the present invention, the flat plate-shaped upper electrode 21 is arranged on the back surface side of the upper belt 41, the surface of which faces the temperature rising space S, in the proximity of the upper belt 41 or in the sliding state. A flat plate-shaped lower electrode 22 is arranged on the back surface side of the lower belt 42 whose front surface faces the temperature raising space S in the proximity of the lower belt 42 or in a sliding state. In this embodiment, two sets of high-frequency counter electrodes 2 each consisting of a pair of upper electrode 21 and lower electrode 22 are provided in the temperature raising space S in series. The high frequency counter electrodes 2 are not limited to two sets, and may be one set or three or more sets.

The lower electrode 22 is fixed in the casing 11, while the upper electrode 21 is vertically movable. In order to move the upper electrode 21 up and down, the upper auxiliary roller 41f is provided inside the casing 11.
And the electrode elevating mechanism 6 is provided between the upper electrode 21 and the upper electrode 21.

The electrode lifting mechanism 6 is mounted and fixed on a support plate F horizontally arranged between a going belt and a returning belt of an upper belt 41 provided in the upper half of the casing 11. A motor 61, a direction changer 62 that converts the rotation of a rotary shaft 61a of the lift motor 61 into vertical movement, and a rack shaft that is provided in the direction changer 62 and penetrates a support plate F to be connected to the upper electrode 21. And 63. An unillustrated pinion that is concentric with the rotating shaft 61a is provided in the direction changer 62, and the pinion and the rack shaft 63 mesh with each other. Therefore, when the rotary shaft 61a is rotated by the rotation drive of the lifting motor 61, this rotation is converted into vertical movement of the rack shaft 63 via the pinion.

The lower end of the rack shaft 63 penetrating the support plate F is fixed to a connecting plate 64 extending horizontally downstream, and the connecting plate 64 and the upper electrode 21 are connected to each other by a connecting rod 65.
Are connected through.

A boss portion 65b is provided at the lower end of the connecting rod 65 so as to be vertically movable within a predetermined range. The boss portion 65b is fixed to the upper electrode 21 and the connecting rod 65b is fixed. A coil spring 65a is fitted in the connector 65 between the connecting plate 64 and the boss portion 65b. The coil spring 65a is biased in the direction in which the connecting plate 64 and the boss portion 65b are separated from each other, so that the boss portion 65 is biased by the biasing force of the coil spring 65a.
When meeting b, the upper electrode 21 is always pressed downward.

A screw shaft may be used instead of the rack shaft 63 of the direction changer 62. This screw shaft is screwed to a bearing provided with a female screw provided on the support plate F, and the rotation of the rotating shaft 61a extending in the horizontal direction is converted into the rotation of the screw shaft extending in the vertical direction via a bevel gear or the like. By converting, the screw shaft can be moved up and down.

In this embodiment, as shown in FIG.
For each upper electrode 21, one lifting motor 61 and two direction changers 62 are employed, and the two direction changers 62 are connected to a long common rotating shaft 61a. One connecting plate 64 is fixed to the lower ends of a pair of rack shafts 63 provided in the converter 62. Five connecting rods 65 are provided on the lower surface of the connecting plate 64, and the lower ends of the five connecting rods 65 are the upper surface of the upper electrode 21 and are fixed at a target position with respect to the center of gravity thereof. Has been done.

Therefore, the elevating motor 61 is driven to lower the connecting rod 65 through the rotary shaft 61a, the rack shaft 63 and the connecting plate 64 with respect to the upper electrode 21 at the height position shown by the chain double-dashed line in FIG. By doing so, the upper electrode 21 descends as shown by the solid line and presses the upper belt 41 downward, so that the vertical width of the temperature raising space S formed between the upper belt 41 and the lower belt 42 is narrow. On the contrary, by vertically driving the elevating motor 61 and raising the upper electrode 21, the vertical width of the temperature raising space S becomes wider.

In this embodiment, the vertical width of the temperature raising space S is changed by raising and lowering the upper electrode 21, but the present invention changes the vertical width of the temperature raising space S. It is not limited to the raising and lowering of the driving means 21, but may be performed by raising and lowering the lower electrode 22, or may be performed by raising and lowering both the upper electrode 21 and the lower electrode 22.

FIG. 8 is a block diagram showing an example of the high frequency generating means according to the present invention. As shown in this figure, the high-frequency generating means 3 includes a control circuit 31 that controls the high-frequency temperature raising device 1 in an integrated manner, an operation section 32 for inputting various operation data to the control circuit 31, and a pair of operation circuits 32. It is composed of a high frequency generator 33 that generates high frequency power to be supplied to the high frequency counter electrode 2. In this embodiment, two sets of high frequency generators 33 are provided corresponding to the two sets of high frequency counter electrodes 2.
Is provided.

The control circuit 31 controls driving of each unit and supply of electric power to the high frequency generating unit 33 based on the operation data input through the operating unit 32.

The operation section 32 has a start button 32a,
Stop button 32b, raising button 32c for driving the lifting motor 61 so that the upper electrode 21 rises, upper electrode 2
An operation button 320 including a descent button 32d for driving the elevating motor 61 so that 1 descends, a speed dial 32e for setting the rotation speed of the drive motor 43, and the like are provided, and the type, weight, etc. of the chilled food P are displayed. A data input key 321 for inputting is provided.

The start button 32a and the stop button 3
The operation signal from 2b is output to a required circuit section as a control signal via the control circuit 31. Then, when the start button 32a is operated, the operation of the high frequency generator 33 is started, the drive motor 43 is started to be driven, and when the stop button 32b is operated, the operation of the high frequency generator 33 is stopped, and The rotational drive of the drive motor 43 is also stopped.

The up button 32c and the down button 3
The operation signal from 2d is transmitted as a control signal to the lift motor 61 via the control circuit 31, and the lift motor 61 is rotationally driven to adjust the height of the upper electrode 21.

The signal corresponding to the manipulated variable from the speed dial 32e is transmitted to the drive motor 43 as a control signal corresponding to the manipulated variable via the control circuit 31.
3 is rotationally driven at a rotational speed commensurate with the operation amount.

The high frequency generator 33 includes a power supply circuit 34.
And a high-frequency generation circuit 35 that receives power from the power supply circuit 34 to generate a high frequency, and a matching circuit 36 provided on the downstream side of the high-frequency generation circuit 35. Power supply circuit 3
Reference numeral 4 serves to convert a 220V commercial power supply into a DC power supply of a predetermined level. The high frequency generation circuit 35 is a self-excited oscillation type high frequency generation circuit that obtains a predetermined level of DC voltage from the power supply circuit 34 and generates high frequency energy of a required level. Further, the matching circuit 36 is a circuit for matching the high-frequency generating circuit 35 and the load (chilled food P) passing between the pair of high-frequency counter electrodes 2, and includes a transformer 37 and a matching capacitor (not shown). have.

One end of the input side coil L1 of the transformer 37 is grounded, and one end of the output side coil L2 is connected to the upper electrode 21.
The other end is connected to the lower electrode 22, and a balanced circuit is formed on the load circuit side. As a balanced circuit, the transformer 37
The output side coil L2 may be grounded in the middle. Further, when the high frequency generation circuit 35 is composed of a balanced circuit, it is not particularly necessary to use the transformer 37 to perform coupling with the balanced circuit on the load side including the counter electrode.

It should be noted that the present invention is not limited to the transformer 37 configured by the balanced circuit as described above, and employs an unbalanced circuit in which one end of the output side coil L2 is grounded. May be.

Further, the control circuit 31 uses the conveyor belt 4
The circulatory speed of the conveyor belt 4 is controlled by the drive motor 43 so that the sterilization temperature of the chilled food P during transfer is controlled to a predetermined temperature, or experimentally beforehand according to the type, amount and thickness of the chilled food P. The obtained power supply amount can be set. A data input key 3 for inputting the type, weight, thickness, etc. of the chilled food P on the operation unit 32.
21 is provided, and when the above-mentioned input is made from the data input key 321, the output power from the power supply circuit 34 is set based on the arithmetic program stored in advance.

Further, the control circuit 31 uses the data input key 3
The electric power calculated and set based on the data such as the type and weight of the chilled food P input from 21 is individually controlled so as to be supplied to the high frequency counter electrode 2. in this case,
The electric power from the power supply circuit 34 can be adjusted by intermittent driving and supplied to the high frequency generation circuit 35. Therefore, by adjusting one or both of the length of the driving time and the driving frequency per unit time, the calculated and set electric power is supplied to the high frequency generation circuit 35.
Can be supplied to.

When setting the power supply, the tuning conditions may be sequentially shifted. Alternatively, if the power supply level is fixed, the power supply circuit 34 and the high frequency generation circuit 3
It is also possible to adopt a predetermined required value as the rating of 5. The power is set, for example, by the high frequency generator 3 on the downstream side.
If 3 is made relatively smaller than the high-frequency generator 33 on the upstream side, effects such as effective prevention of overheating of the chilled food P can be obtained.

When the high frequency is intermittently supplied, for example, when the driving time and the rest time are both set to about 5 seconds, the heat given during the driving time is diffused in the rest time. That is, the temperature distribution is made uniform, that is, uniform heating is performed.

The operation of the present invention will be described below. First, the up / down width (gap distance d) between the upper belt 41 and the lower belt 42 through which the chilled food P to be sterilized passes through is set by operating the up button 32c and the down button 32d of the operation unit 32 shown in FIG. Also, speed dial 32e
The transfer speed of the chilled food P is set by operating. Further, the data input key 321 is operated to input the operation data such as the type of chilled food P, the weight per one, and the number of arrays per row of the belt width, the row interval, and the like as required.

When the activation button 32a of the operating section 32 is subsequently operated, the high frequency generating section 33 is driven to start supplying the high frequency counter electrode 2 with a predetermined or predetermined electric power according to the above calculation result, and the upper electrode 21 and The temperature rising space S is formed between the lower electrodes 22, and the upper belt 41 and the lower belt 42 are rotated at the same speed by the rotational driving of the drive motor 43.

In this state, the chilled food P is fed from the previous step to the lower belt 4 on the upstream side of the pre-height adjusting section 5 of the takeover section 14.
2 is aligned and placed. Then, the chilled food P is sent to the downstream side by the movement of the lower belt 42, the height of the chilled food P is first adjusted to the height of the first stage by the adjusting roller 52 of the pre-height adjusting unit 5, and the upper belt is continued. The inclined portion 44 of 41 is lowered.

As the chilled food P moves to the downstream side, as shown in FIG. 6, the chilled food P is sequentially pressed by the inclined portion 44 of the upper belt 41 moving at the same speed as the lower belt 42, and the height of the chilled food P is increased. Enters the temperature rising space S formed on the downstream side of the front pressing roller 41c in a uniform pressure equalizing state. Then, the chilled food P is exposed to the electric field between the high-frequency counter electrodes 2 composed of the upper electrode 21 and the lower electrode 22 while moving to the downstream side while being sandwiched between the upper belt 41 and the lower belt 42, so that the chilled food P has a predetermined temperature. The temperature of the conveyor belt 4 is increased, and the conveyor belt 4 is discharged from the downstream end. Note that FIG. 7 shows a state in which the upper electrode is lowered in order to heat the chilled food P having a lower bulk than that shown in FIG.

According to the high-frequency heating device in the heat sterilizer of the present invention, as described above in detail, the chilled food P is held between the pair of upper and lower conveyor belts 4 provided in the casing 11 of the heating device main body 10. Since the chilled food P is configured to move in the temperature-raising space S in a controlled state, even if the height of the chilled food P varies due to the serving, the height is made uniform by the sandwiching and the chilled food by high frequency. The effect of raising the temperature of P becomes uniform, and inconveniences such as the remaining of the portion that has not reached the sterilization temperature remain effectively.

Further, since the upper belt 41 also moves at the same speed as the lower belt 42, the chilled food P sandwiched between them.
There is no possibility that the shape is deformed or the chilled container of the packaging material is broken and the contents are scattered on the conveyor belt 4.

Further, since the high frequency generator 33 for applying a high frequency to the pair of high frequency counter electrodes 2 is basically composed of a balanced circuit, the electric field distributions between the upper electrode 21 and the lower electrode 22 are equal when the positive and negative sides are the same. Therefore, the temperature is raised more uniformly.

(Test Example) In order to confirm the effect of high-frequency temperature rise, the chilled food is placed in contact with and sandwiched between flat counter electrodes, and a high-frequency electric field is generated between the counter electrodes to remove the chilled food. The test which heats and changes with time of the temperature rise and the temperature distribution in chilled food P was implemented.

The specifications of the test apparatus are as follows. High-frequency frequency: 13.56 MHz Maximum output: 1.5 KW (Test example 1) 1.0 KW (Test example 2) Sample specifications for chilled food used in the test Types of sample food: potato salad, macaroni salad, spaghetti salad 3 types Sample weight: 1 kg Sample volume: Vertical 185 mm × horizontal 240 mm × height 22 m
m Packaging form: All samples were filled in a chilled container made of a synthetic resin sheet, deaerated, and then sealed.

The measurement contents are as follows. Temperature measuring device: Fiber optic thermometer Number of measuring points: 12 measuring points are set at approximately equal intervals per sample Heating time: 4 to 9 minutes.

FIG. 9 shows Test Example 1 (high frequency output 1.5K).
W) and Test Example 2 (high-frequency output 1.0 KW) are graphs showing changes over time in temperature rise, in which time (minutes) is set on the horizontal axis and temperature is set on the vertical axis. In the graph, black circles indicate potato salad, white circles indicate macaroni salad, and black triangles indicate spaghetti salad. The solid line shows Test Example 1 and the dotted line shows Test Example 2.

As can be seen from this graph, when the sterilization level temperature is 70 ° C., when the high frequency output is 1.5 KW, the level is reached in 4 to 5 minutes and the output becomes 1.0 K.
In the case of W, it can be seen that it takes 5 to 6 minutes. The graph of FIG. 9 is an example of the time-dependent change in temperature rise for four types of salads. By collecting such data for all foods, it is possible to apply the above-mentioned increase of foods when applying the device of the present invention. Residence time in the warm space S (belt 4
1, 42) can be set.

FIG. 10 shows Test Example 1 (high frequency output 1.5K).
Immediately before the heat censoring of (W) was dispersed at substantially equal intervals 9
It is a plan view showing a two-dimensional temperature distribution of a part, (a)
Represents potato salad, (b) represents macaroni salad, and (c) represents spaghetti salad. Table 1 shows the average value (x _ave ) and standard deviation (σ) of the temperature distribution.
It is a list showing.

[0088]

[Table 1]

As shown in FIG. 10 and Table 1, there was very little variation in any of the samples, and the standard deviation values were 1.69 ° C. for potato salad and 1.4 for macaroni salad.
The temperature was 0 ° C and the spaghetti salad was 0.94 ° C. Since the variation is small in this way, reliable uniform heating can be performed, and the inconvenience of uneven temperature is effectively prevented.

A calculation formula showing the relationship between the residence time in the temperature rising space S of each food to be heated and the heating temperature inside each food may be stored in the control circuit 31. Then, when the type of food is input from the data input key 321, the calculation formula of the food is applied and the heating space S
Is calculated so that a control signal based on the calculation result is transmitted to the drive motor 43, and the drive motor 43 receiving this control causes the food to retain the calculation result in the temperature rising space S. It is also possible to perform automatic control such as driving at a rotational speed.

The above formula can be easily obtained by performing a regression analysis if there is data on the change in temperature with time as shown in FIG. In this regression analysis, for example, when the time on the horizontal axis of the graph of FIG. 9 is x and the temperature on the vertical axis is y, set a regression equation such as y = A + B · ln (x + 1). Is possible. And
The value of A, which is the y-intercept, and the value of B, which is the regression coefficient, are obtained by calculating with a predetermined statistical method based on a plurality of sets of x values and y values corresponding to each other, which are measured values. be able to.

Table 2 shows the actual calculation formulas obtained for each chilled food of Test Example 1 for each brand.
The table also shows the value of the correlation coefficient r.

[0093]

[Table 2]

When the initial temperature of the food differs from the value of A in the table, the actual initial temperature of the food may be used instead of the value of A. The correlation constant r is a standard indicating that the closer it is to 1, the larger the correlation is, but all are 0.9 or more, which shows that the above regression equation is extremely reliable.

Then, using such a regression equation, the residence time of the food in the temperature rising space S is determined. One example of how to determine it is, for example, a chilled food of spaghetti salad. explain. The high-frequency output is set to 1.5 Kw, and it can be used in a temperature environment of 60 ° C or higher.
The condition is to stay for a minute.

Then, the equations in Table 2 above are applied,
First, the time until the spaghetti salad reaches 60 ° C is calculated. The calculation formula is x = exp {(y-10.4268) /36.7554} -1. Substituting 60 for y in this equation, x = 2.85
(Minutes) is obtained. In other words, it takes 2.85 minutes to reach 60 ° C, so 60 ° C or more
A dwell time of a total of 4.85 minutes is required.

The regression equations shown in Table 2 have two types of high-frequency output of 1.5 KW and 1.0 KW as the conditions and the food weight is 1 kg each, but high-frequency output other than the above is adopted. Also, if the food weight is different,
It is necessary to obtain the regression equations that match them in advance.
In order to obtain such a regression equation, it is preferable to select a high-frequency output, food weight, and other factors that cause fluctuations as independent variables and perform multiple regression analysis in advance.

[0098]

According to the heat sterilization method and the heat sterilization apparatus according to the first and second aspects of the present invention, the regular products to be heat sterilized are the upper electrode and the lower electrode in the temperature raising step (temperature raising apparatus). Introduced in between and rapidly heated to the sterilization temperature, the temperature is raised in the next temperature holding step (temperature holding device) and the temperature is held for a predetermined time, and substantial sterilization is performed in this step, followed by cooling. It is cooled in the process (cooling device), and this cooling prevents the temperature suitable for the growth of bacteria from being maintained for a long time, and is discharged to the outside of the system as a sterilized regular product.

As described above, since the dielectric heating by the high frequency is applied in the temperature raising step, the temperature raising rate can be remarkably increased as compared with the conventional normal heating method, and the microwave heating is extremely high. It is possible to perform uniform heating of thick or heavy objects that cannot be handled, and therefore target large quantities of standard products (food) and maintain the prescribed sterilization temperature without losing their flavor and freshness. It is possible to reach it.

Further, in particular, in the heat sterilization apparatus according to the second aspect, since the conveying means for conveying the fixed product through each device is provided, the fixed product is continuously supplied to this conveying means. By doing so, the heat sterilization treatment is continuously performed, which is convenient for efficient sterilization treatment.

According to the high-frequency temperature raising device in the heat sterilizer of the third aspect of the present invention, high-frequency waves are generated in the upper electrode and the lower electrode arranged on the back surface of the conveyor belt formed by the upper belt and the lower belt. By supplying high-frequency power from the circuit, a temperature rising space is formed in the gap between the upper belt and the lower belt by heating the food. In the state where the temperature rising space is formed, the food to be sterilized is sequentially supplied to the gap between the upper belt and the lower belt, whereby the temperature of the food is increased while moving in the temperature rising space.

The electrode surface of the upper electrode is covered with the upper belt, and since the upper belt moves with the movement of the food, the food does not interfere with the upper electrode and contaminate the electrode. Further, since the food moves in the temperature-raising space while being sandwiched between the upper belt and the lower belt, the thickness of the food is made uniform, the temperature distribution in the food becomes substantially uniform, and The sterilization unevenness is effectively suppressed, which is convenient for increasing the temperature of food.

According to the high-frequency temperature raising device in the heat sterilizer according to claim 4 of the present invention, at least one of the upper electrode and the lower electrode is configured to be movable up and down.
The vertical width of the heating space is adjusted according to the bulk (height) of the food, so that the distance between the food and the electrode is always small and constant.

According to the high-frequency temperature raising device in the heat sterilizer according to claim 5 of the present invention, the upper belt and the lower belt are rotated at the same speed by receiving power from the same driving source. Deformation of the food due to the speed difference between the upper belt and the lower belt does not occur.

According to the high-frequency temperature raising device in the heat sterilizer of the sixth aspect of the present invention, the lower belt is projected to the upstream side of the upper belt, and the height of the food is placed on the upper surface of the lower belt. Since the height adjusting unit for equalizing the predetermined height dimension is provided, the vertical width of the food is evened before being supplied to the temperature raising space, which facilitates introduction of the food into the temperature raising space.

According to the high frequency heating device in the heat sterilizer of claim 7 of the present invention, the conveyor belt is configured so that the orbiting speed can be changed, so that the heating space is increased according to the type and weight of the food. The residence time within can be adjusted.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a flow of a heat sterilizer to which a high-frequency heating device according to the present invention is applied, (a) is a process diagram, and (b) is a time-dependent change in temperature of chilled food in each process. It is a graph shown.

FIG. 2 is a partially cutaway perspective view showing an example of a high-frequency temperature raising device in the heat sterilization device according to the present invention.

FIG. 3 is a side view of FIG.

FIG. 4 is a plan view of FIG.

FIG. 5 is a front view of FIG.

FIG. 6 is a partially enlarged side view of a main part of FIG. 2, showing a state in which chilled food is supplied between electrodes.

7 is a partially enlarged side view of the main part of FIG. 2, showing a state in which the upper electrode is lowered.

FIG. 8 is a block diagram showing an example of a high frequency generator according to the present invention.

FIG. 9 is a graph showing changes with time in temperature rise when a chilled food product is subjected to a high-frequency temperature rising process.

FIG. 10 is a plan view showing a two-dimensional temperature distribution at nine measurement points dispersed at substantially equal intervals at one time point before the heating is cut off in Test Example 1 (high-frequency output 1.5 KW). As food to be sterilized, (i) is potato salad,
(B) uses macaroni salad and (C) uses spaghetti salad.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High-frequency heating device 10 Main body of heating device 11 Casing 12 Supply port 13 Discharge port 14 Handover part 15 Viewing window 2 High-frequency counter electrode 21 Upper electrode 22 Lower electrode 3 High-frequency generation means 31 Control circuit 32 Operation part 320 Operation button 32a Start button 32b Stop button 32c Up button 32d Down button 32e Speed dial 321 Data input key 33 High frequency generator 34 Power supply circuit 35 High frequency generation circuit 36 Matching circuit 37 Transformer L1 Input side coil L2 Output side coil 4 Conveyor belt 41 Upper belt 41a Upper front Roller 41b Upper rear roller 41c Front pressing roller 41d Rear pressing roller 42 Lower belt 42a Front roller 42b Rear roller 42c Auxiliary roller 43 Drive motor 43a Lower transmission belt 43b Upper transmission belt 4 The inclined portion 5 beforehand height adjusting unit 51 supporting frame 52 adjusted rollers 53 adjust the handle 6 electrode elevating mechanism 61 elevating motor 62 direction converter 63 rack shaft 64 connecting plate 65 connecting rod F supporting plate P chilled food

Claims (7)

[Claims] 1. A heat sterilization method in which high-frequency power supplied from a high-frequency generation circuit is supplied between opposed electrodes composed of an upper electrode and a lower electrode, and a fixed product interposed between the opposed electrodes is heated by dielectric heating. There is a temperature raising step of introducing a standard product between the upper electrode and the lower electrode to rapidly raise the temperature to the sterilization temperature, and a temperature holding process of retaining the temperature of the standard product derived from the temperature raising process for a predetermined time. And a cooling step of cooling the standard product derived from the temperature holding step, the heat sterilization method. 2. A heat sterilizer for supplying high-frequency power supplied from a high-frequency generation circuit between opposing electrodes composed of an upper electrode and a lower electrode, and heating a fixed product interposed between the opposing electrodes by dielectric heating to raise the temperature. There is a temperature raising device that rapidly heats the standard product to the sterilization temperature, a temperature holding device that holds the temperature of the standard product that has been heated to the sterilization temperature for a predetermined time, and cool the standard product after holding the temperature for the predetermined time. A cooling device, and a transfer means for transferring a fixed product, which is interposed between the upper electrode and the lower electrode of the temperature raising device and is laid down to the cooling device via the temperature holding device. A heat sterilizer. 3. A heating and sterilizing apparatus for supplying high-frequency power supplied from a high-frequency generating circuit between opposing electrodes composed of an upper electrode and a lower electrode, and heating food by dielectrically heating the food interposed between the opposing electrodes. In the high frequency heating device,
A pair of upper and lower conveyor belts including an upper belt and a lower belt are provided so as to cover the respective electrode surfaces of the upper electrode and the lower electrode, and the food is transferred while being sandwiched between the pair of belts. A high-frequency temperature raising device in a heat sterilizer. 4. The upper electrode and the lower electrode are configured such that at least one of them can be raised and lowered, and the vertical width dimension of the temperature rising space can be adjusted by vertical movement of these. The high-frequency temperature raising device in the heat sterilization device according to 3. 5. The high frequency booster for a heat sterilizer according to claim 3, wherein the upper belt and the lower belt are configured to rotate at the same speed by receiving power from the same driving source. Warming device. 6. The lower belt is projected further upstream than the upper belt, and a height adjusting portion is provided on the upper surface of the lower belt so as to even out the height of the food to a predetermined height. The high frequency heating device in the heat sterilizer according to any one of claims 3 to 5. 7. The conveyor belt is configured so that the circulating speed can be changed.
The high-frequency heating device in the heat sterilizer according to any one of 1.