JP2006204808A - Food heating method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating apparatus finding optimal operating conditions for various types of utilizations such as sterilization, steaming and baking of each foods and allowing the easy setting of the optimal conditions and to suppress the inflow of outside air and the outflow of steam, and to facilitate maintenance such as cleaning and a check of an apparatus inside. <P>SOLUTION: This food heating apparatus is provided with a secondary heating device 10 heating primary steam generated from another heating source by dielectric heating or induction heating and producing secondary high-temperature steam, a plurality of nozzles 17-24 dispersedly disposed in a closed space (s) and supplying the secondary high-temperature steam to the closed space, an exhaust steam circulating passage 13 connecting an exhaust port 29 exhausting exhaust steam from the closed space to the secondary heating device 10, a highly heat-resistant blower 27 interposed in the exhaust steam circulating passage, and valve mechanisms 41 and 41 provided in a channel 12 supplying the primary steam to the secondary heating device 10 and the exhaust steam circulating passage 13 and adjusting the supply ratio of the primary steam. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heating apparatus for performing cooking, cooking, baking of food surfaces, sterilization of food products, blanching of vegetables, etc., and a heating method using the same, using steam at 150 to 300 ° C., Based on primary steam produced by a heating device such as a general steam boiler, this was secondarily heated by a secondary heating device using dielectric heating or induction heating to generate high-temperature steam, and this high-temperature steam was filled. This is performed by transporting a conveyor on which food is placed in a closed space. At this time, it is possible to arbitrarily adjust the operating conditions in accordance with the purpose of sterilization and cooking of the food.

Conventionally, methods and apparatuses for performing baking, heat cooking, sterilization, steaming, and the like of foods using superheated steam are known.
For example, Patent Document 1 (Japanese Patent Laid-Open No. 2003-325340) uses normal pressure superheated steam and circulates and uses this superheated steam, thereby reducing the amount of exhaust and improving thermal efficiency. A firing apparatus that can reduce the firing cost and save space is disclosed.

  Moreover, in patent document 2 (Unexamined-Japanese-Patent No. 2004-121431), the heating temperature by superheated steam can be adjusted by making the position of the injection port of a superheated steam injection nozzle variable with respect to a to-be-heated material. A method and apparatus for heating an object to be heated such as food by superheated steam is disclosed.

JP 2003-325340 A JP 2004-121431 A

However, these conventional heating devices using superheated steam have the following problems.
That is, first, the conventional apparatus uses a combustion system such as gas or kerosene for the secondary heating apparatus, so that generation of exhaust gas is inevitable and there is a problem in safety. Furthermore, the optimum operating conditions such as the temperature, humidity and other conditions of superheated steam supplied to the heating device have not yet been found for individual foods. For example, for heat sterilization of food, it is more efficient to use wet heat than dry heat, and the quality degradation of food can be minimized. For this purpose, the closed space can be easily set to the optimum humidity condition. It is necessary to. However, the conventional heating apparatus has not yet proposed a means for easily setting the optimum humidity condition.

  As for the operation method of cooking and baking of food, the former is suitable for high humidity and the latter is suitable for low humidity. However, depending on the type of food, baking can be performed under high humidity. The amount of superheated steam supplied is a major factor. However, the relationship between the humidity and the supply amount of secondary superheated steam has not been clarified yet.

  In addition, conventionally, an attempt has been made to control by using excessive energy in order to make the temperature distribution inside the heating apparatus constant. In addition, the closed space where food and superheated steam are brought into contact cannot be made completely sealed because the conveyor on which the food is placed enters and exits, and steam flows out from the entrance / exit of the conveyor or is closed from the outside. It is very difficult to control the temperature of the closed space due to the inflow of outside air. Normally, noren was attached to the inlet to prevent ingress of air and outflow of steam. There are unsanitary issues that have not yet been resolved.

  Also, dirt that sticks in the heating device cabinet, especially oils and fats, and scales due to scorching, are mainly structured by dry cleaning such as wiping or scrubbing without using water because the device does not have a cleaning structure. Due to the cleaning method, there were problems such as residue from cleaning and stickiness such as odor.

  In view of the problems of the prior art, the present invention has no problem in safety, finds optimum operating conditions for various uses such as sterilization, steaming, baking, etc. of individual foods, and easily sets optimum conditions. An object of the present invention is to realize a heating device that can be performed, to suppress the inflow of outside air into the closed space and the outflow of steam from the closed space, and to facilitate maintenance such as cleaning and inspection inside the device.

  In order to achieve the above object, the food heating device of the present invention is a device that continuously heats food in a closed space surrounded by a high heat-resistant panel while conveying the food with a high heat-resistant conveyor that penetrates the closed space. A secondary heating device that heats water vapor generated in another heating source to 150 to 350 ° C. by dielectric heating or induction heating, and a plurality of nozzles that are distributed in the closed space and supply the high-temperature water vapor to the closed space And an exhaust steam circulation path connecting the heating device with an exhaust port for exhausting exhaust steam from the enclosed space, a high heat resistant blower interposed in the exhaust steam circulation path, and a primary to the secondary heating device It is provided with a flow path for supplying water vapor and a valve mechanism provided in the exhaust steam circulation path and capable of adjusting a supply ratio of primary water vapor.

In the apparatus of the present invention, primary steam is produced using, for example, a factory boiler around the apparatus. This primary water vapor is heated to 150 to 350 ° C. by a secondary heating device using dielectric heating or induction heating, and this secondary high temperature water vapor is brought into contact with food in a closed space and heated to sterilize and cook. In the apparatus of the present invention, steam is brought into contact with food under normal pressure. The same is true in the secondary heating device, but the primary steam may be supplied to the secondary heating device at a high pressure, and for these reasons, there may be slight pressure fluctuations.
The initial heating rate of the food is accelerated by steam condensation from 150 ° C. Since the amount of heat of water vapor is eight times that of dry heat heating, cooking and sterilization can be performed in a shorter time.
In the apparatus of the present invention, not only water vapor condensation but also radiant heat transfer by a high heat-resistant panel and convective heat transfer by water vapor are added to enable high-efficiency heat transfer.

  The exhaust steam after heating the food is sucked from the exhaust port by the high heat resistance blower, returned to the secondary heating device through the exhaust steam circulation path, and reheated by the secondary heating device. At this time, the primary water vapor is appropriately replenished as supplemental water vapor. At this time, the primary water vapor amount and the exhaust steam amount can be adjusted by the valve mechanism, and the mixing ratio of both can be adjusted.

  In the apparatus of the present invention, preferably, a plurality of nozzle tubes are dispersedly arranged above and below the conveyor, and the nozzle tubes arranged above the entrance and exit of the closed space are arranged in a direction perpendicular to the food conveyance direction. A straight type, and the nozzle openings of these nozzle pipes are directed directly downward, the other than the straight type nozzle pipe is a loop type, and the nozzle opening of the loop type nozzle pipe arranged at the upper central portion of the conveyor is the center of the closed space The nozzle opening of the loop type nozzle tube disposed below is inclined directly downward.

The entrance opening and the exit opening on the upper surface side of the conveyor need to allow foods placed on the conveyor to enter and exit. Therefore, it is necessary to make the opening large, so that inflow of outside air and outflow of water vapor are likely to occur. However, the outflow of steam to the outside and the inflow of outside air from the outside can be prevented by the air curtain effect of the steam discharged from the straight type nozzle pipe arranged near the inlet and outlet above the conveyor.
Further, the loop type nozzle tube provided on the upper center side of the conveyor plays a role of maintaining the steam atmosphere in the upper center portion of the closed space at a constant temperature. Further, when the loop type nozzle pipe steam disposed below the conveyor is blown directly down, it is possible to form an atmosphere that rises almost immediately at the same time as the steam and wraps from the back side of the food.

In the apparatus of the present invention, preferably, an inspection door that can be opened and closed is provided on a side wall surface of the casing that forms the closed space along the longitudinal direction of the conveyor, and a bottom plate that forms the bottom surface of the casing is removable. A drain outlet is provided on the bottom plate so that the inside of the housing can be cleaned. This makes it possible to reach the conveyor rail, back wall, nozzle tube, etc., enabling manual cleaning using water and hot water, and detaching the bottom plate that forms the bottom surface to quickly store the cleaning wastewater. It becomes possible to discharge outside. In addition, if the material of the apparatus and member which comprise an apparatus is made into alkali resistance, it will become possible to respond also to an alkali washing or a weak acid detergent.
In the apparatus of the present invention, preferably, a caster is provided at the lower part of the casing that houses the heating apparatus main body so that the casing can be moved.

  In the food heating apparatus having the above-described configuration, the method of the present invention monitors the temperature state of the closed space by a temperature sensor that detects the temperature of the closed space, and proportionally controls the rotation speed of the blower based on this data information. By adjusting, the temperature of the closed space is controlled to 150 to 350 ° C., and the outlet side water vapor temperature is monitored by a temperature sensor that detects the temperature of the outlet side water vapor of the secondary heating device, and based on this data information Then, the temperature of the outlet side steam of the heating device is controlled by adjusting the output of the secondary heating device by proportional control.

In the method of the present invention, preferably, a temperature sensor is provided in the vicinity of the food conveyed by the conveyor in the closed space, and the temperature condition in the vicinity of the food is monitored. Accordingly, the rotational speed of the blower can be controlled based on the temperature condition in the vicinity of the food.
Further, the method of the present invention preferably adjusts the relative humidity of water vapor in the closed space by adjusting the supply amount of primary water vapor to the secondary heating device and the temperature of the closed space when cooking or baking food. Control to 3-6% RH. At the time of firing, it is suitable to set the relative humidity to 3%, and a far-infrared effect can also be produced, which can be burnt. On the other hand, when cooking, it is suitable to set the relative humidity to the 6% side.

  According to the apparatus of the present invention, a secondary heating device that heats water vapor generated by another heating source to 150 to 350 ° C. by dielectric heating or induction heating, and the high-temperature water vapor distributed in the closed space are disposed in the closed space. A plurality of nozzles to be supplied; an exhaust port that exhausts exhaust steam from the closed space; and a heat exhaust circuit that connects the heating device; a high heat-resistant blower interposed in the exhaust steam circuit; By providing a flow path for supplying primary steam to the secondary heating device and a valve mechanism for adjusting the supply ratio of primary steam, provided in the exhaust steam circulation path, not only steam condensation but also a high heat-resistant panel In addition to radiant heat transfer and convective heat transfer by steam, it enables high-efficiency heat transfer and circulates and uses exhaust steam, reducing the amount of exhaust steam and improving thermal efficiency. Reduced heating costs To allow space.

In addition, since the secondary heating device does not use a combustion method such as gas or kerosene, it is highly safe and uses a secondary heating device using dielectric heating or induction heating, so that heating can be performed in a short time, and 150 to Due to the low oxygen state using high-temperature steam at 350 ° C, the oxidation of fats and oils, the generation of oxides from other food ingredients are suppressed, the destruction of vitamins is suppressed, and the preservability of heat-treated foods is improved. In addition, it has the effect of preventing fading of food.
The present invention can be widely applied to food cooking, sterilization, blanching, vegetable peeling, fruit peeling, and the like.

  In the apparatus of the present invention, preferably, a plurality of nozzle pipes are arranged in a distributed manner above and below the conveyor, and the nozzle pipes arranged above the inlet and outlet of the closed space are arranged in a direction perpendicular to the food conveying direction. The nozzle opening of these nozzle pipes is directly below, and the other than the straight nozzle pipe is a loop type, and the nozzle opening of the loop type nozzle pipe disposed above the conveyor is inclined toward the center of the closed space. In addition, it is possible to optimize the prevention of steam outflow and the entry of outside air necessary for continuous processing by configuring the nozzle opening of the loop type nozzle tube arranged below to be directly below. And the space atmosphere on the front, back, top, bottom, right and left sides of the food can be wrapped with uniform high-temperature steam set to optimum conditions.

Preferably, an inspection door is provided on a side wall surface of the casing that forms the closed space along the longitudinal direction of the conveyor, a bottom plate that forms a bottom surface of the casing is detachable, and a drain outlet is provided on the bottom plate. By making the inside of the housing washable, it is possible to reach the conveyor rail, back wall, nozzle tube, etc., enabling manual washing with water and hot water, and making the bottom surface removable. As a result, the washing waste water can be quickly discharged out of the warehouse. In addition, if the material of the apparatus and member which comprise an apparatus is made into alkali resistance, it will become possible to respond also to an alkali washing or a weak acid detergent.
Preferably, a caster is provided at the lower part of the casing containing the heating device main body, and the casing can be moved, so that when changing the layout of the line, it is possible to change the primary steam piping etc. It becomes possible to move to the place. Currently, high-mix low-volume production accounts for a large proportion, and layout changes are being made every day or every hour. By providing a caster at the bottom of the housing, it is possible to meet such needs.

According to the method of the present invention, in the food heating apparatus having the above configuration, the temperature state of the closed space is monitored by the temperature sensor that detects the temperature of the closed space, and the rotation speed of the blower is proportional to the data information. By adjusting by control, the temperature of the closed space is controlled to 150 to 350 ° C., and the outlet side water vapor temperature is monitored by a temperature sensor that detects the temperature of the outlet side water vapor of the secondary heating device. By adjusting the output of the secondary heating device based on the above, by controlling the temperature of the outlet-side water vapor of the secondary heating device, the water vapor temperature in the closed space is always maintained at the optimum temperature set. Therefore, it is possible to quickly cope with various uses of individual foods.
Moreover, abnormal overheating of the secondary heating device can be prevented by controlling the temperature of the outlet side steam of the secondary heating device.

  In the method of the present invention, preferably, a temperature sensor is provided in the vicinity of the food conveyed by the conveyor in the closed space, and the temperature condition in the vicinity of the food is monitored, so that the blower is based on the temperature condition in the vicinity of the food. By controlling the number of rotations and setting the atmosphere conditions in the closed space based on the temperature conditions in the vicinity of the food, excessive supply of steam can be prevented and energy loss can be suppressed.

  In the method of the present invention, preferably, when steaming or baking the food, the relative humidity of the water vapor in the closed space is adjusted by adjusting the supply amount of the primary water vapor to the secondary heating device and the temperature of the closed space. By controlling to 3 to 6% RH, heat treatment can be performed at a relative humidity suitable for baking or steaming.

Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this example are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only.
FIG. 1 is a sectional elevation view of a first embodiment of the apparatus of the present invention, FIG. 2 is a sectional plan view of the first embodiment, and FIG. 3 is a system diagram of a control system of the first embodiment.

  1-3, 1 is the housing | casing which forms the closed space inside, and is supported by the base 25, and the inlet_port | entrance where the heated food w mounted on the conveyor belt 4 and the conveyor belt 4 enters and exits. It has an opening 2 and an outlet opening 3. The inner wall surrounding the closed space s of the housing 1 is covered with a high heat resistance panel (not shown). The conveyor belt 4 is made of a material having high heat resistance, is wound around the inlet-side driven sprocket 5 and the outlet-side drive sprocket 6, is driven by the drive motor 9, and conveys the food w placed on the conveyor belt 4. To do.

7 is a casing covering the inlet side sprocket 5, 8 is a casing covering the outlet side sprocket 6, and 9 is an electric motor for driving the outlet side driving sprocket 6. Reference numeral 26 denotes a bottom plate that divides the inside of the housing 1 up and down to form a closed space s. The bottom plate 26 is detachably provided to facilitate cleaning of the inside of the housing 1 and is inclined obliquely. In addition, a drain outlet 47 with an on-off valve is provided on the inclined lower side. A chain belt 30 is wound around the sprocket 6 and the drive motor 9.
Reference numeral 10 denotes a secondary heater that heats the primary steam by inducing circulation current in the primary steam supplied by the high-frequency current sent from the high-frequency generator 11 shown in FIG. 3 to generate heat. Primary steam produced by a boiler installed in a factory or the like is supplied to the secondary heater 10 from the primary steam line 12 via the circulation line 13 and is secondarily heated by the secondary heater 10. A high frequency with a frequency of 5 to 40 kHz is supplied from the high frequency generator.

The primary steam secondary-heated by the secondary heater 10 becomes high-temperature steam at 150 to 350 ° C., and branches up and down in the housing 1 through the outlet-side circulation conduit 14 of the secondary heater 10. The lower nozzle pipes 21, 22, and 23 connected to the lower header 16 are supplied to the upper header 15 and the lower header 16, and further supplied to the upper nozzle pipes 17, 18, 19, and 20 connected to the upper header 15. And 24.
Reference numeral 29 denotes a suction port provided above the closed space s, which is connected to the circulation line 13. The circulation line 13 is connected to the primary steam line 12 in the middle, and a circulation blower 27 is interposed. The secondary heater 10 is connected. Reference numeral 28 denotes a drive motor for the circulation blower 27. In FIG. 2, 45 is an inspection door provided along the conveying direction of the conveyor belt 4.

Next, the control system of the first embodiment will be described with reference to FIGS. In the figure, 31 is a temperature sensor provided in the closed space s. As shown in FIG. 4, the detected value of the temperature sensor 31 is sent to the comparator 34, and the set value set by the temperature setter 32. The difference between the set value and the detected value is proportionally processed by the proportional controller 33, and the rotational speed of the circulation blower 27 is controlled based on the proportionally processed value.
Reference numeral 35 denotes a temperature sensor that detects the outlet water vapor temperature provided in the outlet-side circulation pipe 14 of the secondary heater 10, and the detected value of the temperature sensor 35 is sent to the comparator 37 as shown in FIG. The difference between the set value and the detected value is proportionally processed by the proportional controller 36, and output control of the high-frequency generator 11 (based on the proportionally processed value) 0 to 100%) to control the water vapor temperature at the outlet of the secondary heater 10.

In FIG. 3, 40 is a flow rate adjusting valve provided in the circulation line 13, and 41 is a flow rate adjusting valve provided in the primary steam line 12. By appropriately adjusting these valves, it is possible to adjust not only the flow rates of exhaust steam and primary steam circulated from the closed space s but also the mixing ratio of both. Reference numeral 42 denotes a radiator that cools the heating panel in the secondary heater 10 by circulating cooling water in the secondary heater 10 through circulation lines 43 and 44.
Reference numeral 46 denotes a caster provided at the lower portion of the casing 1, and the casing 1 can be moved to a desired location by making the base 25 extendable and contractible.

In the apparatus of the first embodiment, the primary steam is mixed with the exhaust steam discharged from the closed space s and supplied to the secondary heater 10 where the secondary steam is heated to a set temperature of 150 to 350 ° C. High-temperature steam is supplied to the nozzle tubes 17 to 24 through the upper header 15 and the lower header 16. The apparatus normally contacts the food with steam under normal pressure. Although it is the same also in the secondary heater 10, primary steam may be supplied to the secondary heater 10 at a high pressure, and there may be some pressure fluctuations for these reasons.
As shown in FIGS. 1 and 2, the nozzle pipes 17 and 20 arranged at the inlet and outlet of the housing 1 above the conveyor belt 4 are linear and the nozzle opening is arranged directly below. Therefore, the water vapor is ejected directly below as indicated by arrows a and d, whereby the inflow of postcards from the inlet opening 2 and the outlet opening 3 and the outflow of water vapor in the housing 1 can be prevented.

On the other hand, as shown in FIGS. 1 and 2, the other nozzle tubes 18, 19, 21, 22, 23, and 24 have a loop shape. Among these, the nozzle tube 19 is angled by about 15 degrees toward the inner side. The nozzle tube 18 is angled approximately 345 degrees toward the inside of the chamber, and as a result, steam is supplied toward the central portion of the closed space s as indicated by arrows c and b. The steam atmosphere can be maintained at a constant temperature.
In addition, the nozzle pipes 21 to 24 arranged at the lower part of the conveyor belt 4 are all loop-shaped and the nozzle openings are all directed downward, so that the steam is jetted downward as indicated by arrows e to h. An atmosphere that wraps from the back side of the food w is formed.
For this reason, these nozzle tubes can wrap the front and rear, left and right, and upper and lower spaces of the food w with uniform water vapor, and can maintain an optimum atmosphere for the heat treatment.

  Further, as shown in FIG. 2, this apparatus is provided with an inspection door 45 that can be opened and closed along the conveying direction of the conveyor belt 4 so that the bottom plate 26 that forms the bottom surface of the housing 1 can be attached and detached. By providing the drain opening 47 with the on-off valve on the lower side of the inclination, the inside of the warehouse can be easily cleaned and inspected. That is, during normal operation, the portion where the rail of the conveyor contacts the net is guided by the weight of the net and transports food, but when cleaning, the net can be lifted and the contact portion can be manually washed. Also, as a cleaning method in the storage, primary steam is sprayed to peel and dissolve the oils and fats exuded from the baking residue and food. Further, the members in the chamber are selected for alkali resistance, and after removing and dissolving the dirt components, an alkaline detergent is sprayed. Next, the sponge is used to remove dirt components by friction, such as by hand washing. Further, the scale component solidified by baking or the like is washed with an acid, rinsed with spray of warm water, and completed.

In addition, a temperature sensor 31 is provided in the closed space s, and a temperature sensor 35 is provided in the outlet-side circulation path 14 of the secondary heater 10, and the control shown in FIG. 4 is performed to determine the temperature in the closed space s and the secondary heater. 10 outlet-side water vapor temperature can be maintained at the set temperature, so that optimum conditions can be set according to the type of food w and the use of heat treatment such as sterilization and cooking, and abnormal overheating of the secondary heater 10 can be performed. It can be prevented in advance. In the secondary heater 10, overheating of the hot plate (not shown) can be effectively prevented by the cooling water cooled by the radiator 42.
The flow rate adjusting valves 40 and 41 provided in the circulation line 13 and the primary steam line 12 allow free supply of exhaust steam and primary steam exhausted from the closed space s to the secondary heater 10 and the mixing ratio of both. For example, the heating capacity can be increased by increasing the amount of steam supplied to the nozzle tube, or the mixing ratio of both can be adjusted to adjust the relative humidity to 3-6%. This makes it possible to set the optimum conditions for cooking or baking the food.

In the apparatus of this embodiment, the steam temperature supplied to the nozzle tube is 150 to 350 ° C., the steam circulation rate is 1 to 35 m ³ / min, the conveyor speed is 30 m / sec, and the primary water vapor amount is 1 to 70 kg / H. It was found that it is optimal for sterilization and cooking environment.
As described above, according to the first embodiment, not only the steam condensation but also the radiant heat transfer by the high heat-resistant panel and the convection heat transfer by the steam are added to enable high efficiency heat transfer and to circulate the exhaust steam. Therefore, it is possible to reduce the amount of exhaust steam and improve the thermal efficiency, thereby reducing the heating cost and saving space.

In addition, the secondary heater 10 does not use a combustion method such as gas or kerosene, so it has high safety and is in a low oxygen state using high-temperature steam at 150 to 350 ° C., so that oxidation of fats and oils and other food components This suppresses the formation of oxides from the food, suppresses the destruction of vitamins, improves the preservability of the heat-treated food, and has the effect of preventing the food from fading.
If the temperature sensor 31 is disposed in the vicinity of the food W transported by the conveyor belt 4, the rotational speed of the blower 27 is controlled based on the temperature in the vicinity of the food by monitoring the temperature in the vicinity of the food. By setting the atmospheric conditions of the closed space based on the temperature conditions in the vicinity, excessive supply of steam can be prevented and energy loss can be suppressed.
In addition, high-mix low-volume production accounts for a large proportion, and layout changes are being made every day or every hour. According to the present embodiment, the caster 46 is attached to the lower part of the housing 1 so that the housing 1 can be moved, so that when the line layout is changed, the primary steam pipe is simply changed. It is possible to move to the location of the location, and to cope with frequent layout changes.

The second embodiment in which the frozen raw material (hamburger beef) is sterilized using the apparatus of the first embodiment will be described.
As the previous stage, FIG. 5 shows the result of examining the atmospheric temperature distribution in the closed space s using the apparatus of the first embodiment. That is, the temperature of the closed space s is set to 240 ° C., and the ambient temperature measurement result of about 10 mm from the surface of the test piece when the test piece with the temperature sensors attached at the six front and rear positions is moved on the conveyor belt for 60 seconds. Indicates. As shown in the figure, the atmosphere around 10 mm from the surface of the test piece is heated to 200 ° C. in 20 seconds, and the air curtain effect is exerted by the nozzle tubes 20 and 17 provided near the inlet and near the outlet. I understand that.

In the second embodiment, the temperature of the closed space s is set to 200 ° C., and the operation result for the purpose of allowing the frozen meat surface temperature to be raised to 80 ° C. in 30 seconds after the introduction of the apparatus is shown in the temperature graph of FIG. Shown in FIG. 6 shows the measurement of the surface temperature of the frozen meat from the entrance to the exit of the housing 1, and it can be seen from FIG. 6 that the object is almost achieved.
Cell count at this time (coliform bacteria) are pretreated: For 1.0 × ¹⁰ 3 / 100cm ^2, after treatment: was not detected / 100 cm ^2.

Next, a description will be given of a third embodiment in which the apparatus of the first embodiment is applied to surface sterilization of sugar beet (eggaki). When intended for omelette surface temperature 80 ° C. 30 seconds, by treatment of 180 ° C. 1 min for internal temperature setting, cell count (coliform bacteria) are pretreated: For 1.0 × ¹⁰ 3 / 100cm ² After treatment: not detected / 100 cm ² . In addition, there was almost no change in the appearance of both the yellow portion and the grilled portion.
(A) of FIG. 7 is a graph which measured the external appearance change of the yellow part, (b) is a graph which measured the external appearance of the burning part. This graph is a chromaticity diagram of L ^* a ^* b ^* color system specified by JIS (JISZ8729), where lightness is represented by L ^* , chromaticity is represented by a ^* (red direction), and b ^* (yellow direction). . The color becomes brighter as the value increases, and the color becomes duller as the viewing position decreases. As can be seen from FIG. 7, the brightness and chromaticity hardly change even after 2 minutes.

  Next, a description will be given of a fourth embodiment in which the apparatus of the first embodiment is applied to heating and baking of a frozen hamburger. The inside temperature was set to 320 ° C., and the core temperature of 90 ° C. for 1 second was finished with 130 g of hamburger and 8 minutes was completed with 70 g of hamburger and the core temperature of 90 ° C. was finished for 1 second. At this time, cooking worthy of sterilization effect + formation of the grilled surface by baking + edible was possible.

Next, a fifth embodiment in which the apparatus of the first embodiment is applied to spinach blanching will be described. The inside temperature was set to 200 ° C., about 2 bundles of 5 kg of spinach per 1 m ^{2 of} the mesh belt were laminated, and blanching spinach characterized by a crisp texture with a crisp texture after 1 minute treatment could be cooked. The yield was 98.7%.

  According to the present invention, the heating speed is high, the processing efficiency is high, there is no safety problem, and it is most suitable for various uses such as thawing, heating, sterilization, steaming, baking, drying, and blanching of individual foods. It is possible to realize a heating method and a heating apparatus capable of easily setting conditions.

1 is a sectional elevation view of a first embodiment of the device of the present invention. 2 is a cross-sectional plan view of the first embodiment. FIG. It is a systematic diagram of the control system of the first embodiment. It is a block diagram of the control apparatus of the said 1st Example. It is a diagram which shows the measurement result of the test piece movement atmosphere temperature in 2nd Example of this invention. It is a graph which shows the measurement result of the test piece surface temperature in 2nd Example of this invention. (A) And (b) is a graph which shows the external appearance measurement result in 3rd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Case 2 Inlet opening 3 Outlet opening 4 Conveyor belt 5 Driven sprocket 6 Drive sprocket 7, 8 Casing 9, 28 Drive motor 10 Secondary heater 11 High frequency generator 12 Primary steam line 13, 14 Circulation line 15 Upper header 16 Lower header 17, 18, 19, 20, 21, 22, 23, 24 Nozzle pipe 25 Base 26 Bottom plate 27 Circulating blower 29 Suction port 30 Chain belt 31, 35 Temperature sensor 40, 41 Flow control valve 42 Radiator 43, 44 Cooling water circulation line 45 Inspection door 46 Caster 47 Drain outlet with on-off valve

Claims (7)

  In a device that continuously heats food in a closed space surrounded by a high heat-resistant panel while transporting food on a high-heat-resistant conveyor that penetrates the closed space, the primary water vapor generated by another heating source is dielectrically heated or A secondary heating device for producing secondary high-temperature steam by heating to 150 to 350 ° C. by induction heating, a plurality of nozzles distributed in the closed space and supplying the secondary high-temperature steam to the closed space, and the closed space The exhaust steam circulation path connecting the exhaust device for exhausting the exhaust steam from the heating device, the high heat resistant blower interposed in the exhaust steam circulation channel, and the flow for supplying the primary steam to the secondary heating device A food heating apparatus comprising a valve mechanism and a valve mechanism provided in the exhaust steam circulation path and capable of adjusting a supply rate of primary steam.   A plurality of nozzle tubes are arranged in a distributed manner above and below the conveyor, and the nozzle tubes arranged above the inlet and outlet of the closed space are arranged in a direction perpendicular to the direction of food conveyance, and the nozzle tubes The nozzle opening is directly below, the loop type other than the straight type nozzle pipe is a loop type, the nozzle type of the loop type nozzle pipe arranged above the conveyor is inclined toward the center side of the closed space, and the loop type arranged below 2. The food heating apparatus according to claim 1, wherein the nozzle opening of the nozzle tube is directed downward.   An inspection door is provided on a side wall surface of the casing that forms the closed space along the longitudinal direction of the conveyor, a bottom plate that forms the bottom surface of the casing is detachable, a drain outlet is provided in the bottom plate, and the inside of the casing The food heating apparatus according to claim 1, wherein the food can be washed.   2. The food heating apparatus according to claim 1, wherein a caster is provided at a lower portion of a casing that houses the heating apparatus main body, and the casing is movable.   In the food heating apparatus according to claim 1, by monitoring the temperature state of the closed space by a temperature sensor that detects the temperature of the closed space, and adjusting the rotational speed of the blower by proportional control based on this data information, The temperature of the closed space is controlled to 150 to 350 ° C., and the outlet water vapor temperature is monitored by a temperature sensor that detects the temperature of the outlet water vapor of the secondary heating device, and the secondary heating is performed based on this data information. A food heating method, wherein the temperature of the outlet side water vapor of the secondary heating device is controlled by adjusting the output of the device by proportional control.   The food heating method according to claim 4, wherein a temperature sensor is provided in the vicinity of the food conveyed by the conveyor in the closed space, and the temperature condition in the vicinity of the food is monitored.   When cooking or baking food, the relative humidity of water vapor in the closed space is controlled to 3 to 6% RH by adjusting the supply amount of primary water vapor to the secondary heating device and the temperature of the closed space. The food heating method according to claim 4.

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