JP5811689B2 - Production method of packaged cooked rice - Google Patents

Description

  The present invention relates to a method for producing packaged cooked rice that can be produced in a very short time, including an immersion step.

  In recent years, cooked cooked rice that has been cooked for a few minutes in a microwave oven or heated in hot water for a few dozen minutes has appeared. This is a product called wrapping cooked rice (sterile packed cooked rice), which has become widespread in singles and working families.

  Conventionally, this type of packaged cooked rice is manufactured as follows. In other words, heat-resistant synthetic resin container is filled with full-size rice and water, the rice is cooked with heat by microwave or steam, and after cooking, gas is replaced in the container and sealed, To do.

  The packaged cooked rice produced in this way is distributed with the container sealed, so that there is an advantage that microbial contamination is prevented, and that oxygen scavenger is unnecessary because gas replacement is performed.

  Among the methods for producing the packaged cooked rice, there is one for the purpose of producing in a short time (see Patent Document 1). This is a container filled with rice and cooked water, and the container is heated to a temperature exceeding 100 ° C. by irradiation with microwaves in a pressurized atmosphere. This is a method for producing packaged cooked rice in which the cooked rice water is boiled vigorously (cooking) and cooked evenly.

  However, in the method for producing packaged cooked rice described in Patent Document 1, although it is possible to cook rice in a short time, the contents in the container are scattered around due to the sudden boiling phenomenon of the cooked water during the decompression. In particular, a strong adhesive such as a stick sticks to the flange portion of the container, and it is necessary to remove the deposit when sealing the film for sealing. Moreover, it is necessary to remove the dew condensation water which arises in the flange part of a container at the time of rice cooking.

  For this reason, in the manufacturing method of the packaged cooked rice that can be cooked in an extremely short time including the soaking time, there is a manufacturing method in which dirt such as sticking or condensed water does not adhere to the flange portion of the container during cooking. It is strongly desired.

JP 2007-295834 A

  In view of the above problems, an object of the present invention is to provide a manufacturing method in which contents in a container are not scattered around during cooking in a rice cooking method for packaging rice in a very short time.

In order to solve the above-mentioned problems, the present invention provides a rice supply step of charging a predetermined amount of rice into a container having an open top, a hydration step of filling the container with a predetermined amount of cooked water, and injection of pressurized steam. And cooking the rice in the chamber using two heat sources simultaneously by microwave irradiation , a water supply step of adding supplemented rice water after the rice cooking step, and sealing and packaging the container after the water supply step In the manufacturing method of packaged cooked rice including a step, a technical means was provided in which a groove forming step for forming a groove in the layer of the rice grains in the container was provided in the previous step of the rice cooking step.

Also, before in about front Ki炊rice Engineering introduce pressurized steam into the chamber, introducing pressurized air, it took technical means of.

  Furthermore, in the groove forming step, the groove is formed by inserting an insertion rod from above the container and moving the insertion rod relative to the container.

  In the rice cooking method of the present invention, a groove serving as a escape path for steam generated during rice cooking is formed in the layer of rice grains, so that the groove becomes a path for the steam, and rice grains and rice balls in the container are scattered outside the container during rice cooking. Can be prevented. For this reason, dirt, such as a stick, does not adhere to the flange part of a container.

  Further, in the method for producing packaged cooked rice of the present invention, when using two heat sources such as microwave and pressurized steam at the same time, the pressurized air is introduced before the pressurized steam is introduced, so that the inside of the chamber is pressurized. The amount of pressurized steam necessary for increasing the pressure in the chamber can be reduced, and the amount of condensed water generated in the chamber can be reduced. For this reason, there exists an effect which prevents that dew condensation water adheres to the flange part of a container at the time of rice cooking.

It is a schematic plan view which concerns on the manufacturing apparatus of the packaged cooked rice of this invention. It is the schematic which shows structures, such as a container automatic supply part, the ultraviolet sterilization part, a rice measurement filling part, a groove | channel formation part, a pressurized rice cooking part, and a stirring part, in the manufacturing apparatus. It is a schematic sectional drawing of the pressurization heating apparatus 9 which comprises a pressurized rice cooking part. It is the schematic which shows the structure of the sealing packaging part which performs the sealing of a container opening part. It is the sectional side view which showed the structure of the heat-pressure sterilization part (retort sterilization). It is a flowchart for demonstrating a rice cooking process. It is a control graph of the heating conditions which showed the relationship between the pressurization conditions in a rice cooking process, microwave irradiation conditions, and the temperature in trays. It is the figure which showed the liquid level of the rice cooking water with which it filled in the container. It is the schematic of a groove formation part. It is a figure which shows the state in which the groove | channel was formed in the layer of the rice grain in a container.

  Hereinafter, it will be described in detail with reference to the drawings. FIG. 1 is a schematic plan view of a packaging cooked rice production apparatus according to the present invention, and FIG. 2 is a container automatic supply unit, an ultraviolet sterilization unit, a rice weighing and filling unit, a groove forming unit, a pressurized rice cooking unit, and an agitation in the production device. FIG. 3 is a schematic cross-sectional view for illustrating the structure of a pressure heating apparatus used in the pressure rice cooker, and FIG. 4 is a diagram illustrating vacuum cooling, gas replacement, and the like in the same chamber. It is the schematic which shows the structure of the sealing packaging part which performs the sealing of a container opening part.

  In FIG.1 and FIG.2, the code | symbol 1 is a manufacturing apparatus of the packaged cooked rice which concerns on this invention, and the code | symbol 2 is a container automatic supply part. The container automatic supply unit 2 stacks a large number of heat-resistant synthetic resin containers (containers) 2c and waits in a plurality of rows (for example, four rows), and a container reservoir 2a from the bottom of the container reservoir 2a. The container supply unit 2b automatically picks up the containers in a row one by one. The containers 2c are continuously supplied to the conveyor device 3 in four horizontal rows.

  In the conveyor device 3, a chain 3e is wound around a pair of sprockets 3a and 3b and auxiliary sprockets 3c and 3d, and a large number of container receiving pallets 3f are attached to the chain 3e with a gap therebetween. The container receiving pallet 3f can accommodate four containers 2c in four rows and one column in one pallet 3f, and sequentially conveys a plurality of containers 2c in an aligned manner. ing.

  The container receiving pallet 3f is formed with a hole for fitting the lower portion of the container 2c, and the container 2c is structured to be accommodated in the container receiving pallet 3f in a state of being fitted into the hole. In addition, the number of containers accommodated in the pallet is not limited to four, and may be appropriately increased or decreased depending on the manufacturing scale and conditions of the packaged cooked rice.

  In the next step of the container automatic supply unit 2, an ultraviolet sterilization unit 4 is provided to sterilize the inside of the container with ultraviolet rays. In addition, it is desirable to suck and remove the dust and foreign matter in the container 2c using a foreign matter suction device or the like before or after this step.

  In the next step of the ultraviolet sterilization unit 4, a rice weighing and filling unit 5 is provided, and the container 2c is filled with a predetermined amount, for example, a portion of rice (rice supply step). The rice weighing and filling unit 5 may be a known combination weighing machine capable of weighing and discharging at high speed. As shown in FIG. 2, the washed rice that is a raw material is put into a hopper 5a at the upper center and supplied to an intermediate hopper 5c provided on the side by a conical feeder 5b at the center. The intermediate hopper 5c stores a predetermined amount of raw material and then discharges it to the plurality of weighing hoppers 5d. Then, the measurement values of the plurality of measurement hoppers 5d are combined so as to achieve the target weight value, and the raw materials that match the combination are supplied to each container 2c via the collecting chute 5e, the discharge valve 5f, and the hopper 5g.

  In addition, it is good to introduce | transduce the raw material rice so that layer thickness may become uniform at the bottom part of the container 2c. By doing in this way, the heating nonuniformity by the heating using a microwave can be prevented.

  As a raw material to be supplied to the rice weighing and filling unit 5, commercially available non-washed rice is preferable, but it may be polished rice, embryo rice having a high germ survival rate, separated rice and brown rice. What needs to be washed such as polished rice, germinated rice, and split rice needs to be dehydrated or dried to a predetermined moisture in advance and prepared so as not to stay in the rice weighing and filling unit 5.

  In the next step of the rice weighing and filling unit 5, a primary hydration unit 6 is provided, and rice cooking water is filled into the container 2 c from the nozzle 6 a of the primary hydration unit 6. The amount of rice cooking water to be filled may be less than half of the conventional amount required to cook rice in the container 2c and about 1/7 to 1/10. This is because the present invention cooks rice with the container open, and uses the moisture contained in the pressurized steam, which is one of the heat sources, for the rice cooking water. Moreover, by reducing the amount of cooked rice water to be filled to the minimum necessary, heating energy can be minimized and heating efficiency (production efficiency) can be improved.

  In addition, although the filling amount of the rice cooking water in the primary hydration process in the primary hydration part 6 can be reduced to about 1/10 compared with the past, it should be appropriately determined depending on the intended hardness of the cooked cooked rice. That's fine.

  Moreover, considering the thermal efficiency in the below-mentioned rice cooking process, it is desirable to use warm water for rice cooking water, and what is necessary is just to use rice cooking water of 50 degreeC or more, more desirably about 60 to 80 degreeC. Although it is possible to use rice cooking water at room temperature, the heating time in the rice cooking process becomes long. For this reason, in this invention, the heating apparatus (not shown) is provided separately, and after heating rice cooking water to predetermined temperature, this rice cooking water is thrown into the container 2c.

  The groove forming part 12 is provided in the next step of the primary water addition part 6. In the groove forming part 12, a groove is formed in the layer of rice grains charged in the container 2c and laminated.

  Here, the groove forming portion 12 will be described with reference to FIG. FIG. 9 is a schematic view of the groove forming portion 12, and reference numeral 55 denotes an insertion rod for inserting the lower end portion into the container. The insertion rod 55 is connected to the horizontal frame 57 and is configured to be movable in the front-rear direction along the horizontal frame 57 along the horizontal frame 57 by driving means (not shown). The horizontal frame 57 is connected to the vertical frame 56, and is configured to be movable in the vertical direction along the vertical frame 56 by a driving means (not shown). That is, the insertion rod 55 is configured such that the lower end can be taken in and out of the container 2c and can be moved in the front-rear direction in the container 2c in a state where the end is inserted into the container 2c. . Note that the container 2c may be moved in the left-right direction instead of the front-rear direction, and the container 2c may be configured to be movable in the front-rear direction or the left-right direction with respect to the insertion rod 55.

In the next step of the groove forming unit 12, a pressurized rice cooking unit 25 is provided, and the rice in the container 2 c is cooked in the pressurized rice cooking unit 25 by two heat sources of microwave and pressurized steam.

  Here, the pressurization heating apparatus 9 which comprises the pressurized rice cooking part 25 is demonstrated using FIG. FIG. 3 is a schematic cross-sectional view of the pressure heating device 9. Reference numeral 30 denotes a hydraulic cylinder, and the base plate 31 is moved up and down along the column 32 by the lifting and lowering operation of the hydraulic cylinder 30. A plurality of supports 34 are erected on the upper surface of the base plate 31, and the lower chamber 35 is supported by the supports 34. Reference numeral 36 denotes a microwave oscillation device, which is connected to the upper chamber 38 by a waveguide 37. The lower chamber 35 is configured to be pushed upward by the lifting and lowering operation of the hydraulic cylinder 30. When pushed up, the lower chamber 35 is pressed against the upper chamber 38 in a state where the container receiving pallet 3f located above the lower chamber 35 is sandwiched. . Each of the upper chamber 38 and the lower chamber 35 is provided with a recess that can accommodate the container 2c. When the lower chamber 35 is pushed up by the recess, a chamber 40 that is a sealed space is formed. The In the present embodiment, since four containers 2c are accommodated in four horizontal rows in one container receiving pallet 3f, four chambers 40 are simultaneously formed in four horizontal rows. FIG. 3 shows a state in which the chamber 40 is formed.

  A waveguide 37 is connected to the chamber 40 on the upper side, and the microwave oscillated by the microwave oscillation device 36 is irradiated through the waveguide 37. In this embodiment, one chamber 40 is irradiated with 3 kW microwaves (frequency: 2.5 GHz, wavelength: 12 cm) from the two microwave oscillators 36.

  The output of the microwave oscillator 36 is not limited to 3 kW, and may be changed to an appropriate output depending on the production conditions of aseptically packaged cooked rice. The upper chamber 38 is provided with a choke 39 to prevent the irradiated microwave from leaking outside.

  The chamber 40 has a structure in which pressurized steam or pressurized air is introduced from a pipe 42. The pipe 42 is connected to a switching valve 60, and pipes 61 and 62 are connected to the switching valve 60.

An air compressor (air compressor) provided separately is connected to the pipe 62, and the pressurized air generated by the air compressor is supplied with a pressure reducing valve 63, an electromagnetic valve 64, a pressure gauge 65, and a switching valve. 60 and then sent into the chamber 40. Further, the pressure of the pressurized air introduced into the chamber 40 may be set slightly higher than the target internal pressure in the chamber 40.

A steam generator (boiler) and a steam cleaner (not shown) provided separately are connected to the pipe 61, and the pressurized steam generated by the steam generator passes through the steam cleaner. , The pressure reducing valve 43, the electromagnetic valve 44, the pressure gauge 45, and the switching valve 60 are sent into the chamber 40.

In the present invention, a steam cleaning device is provided because the pressurized steam is directly brought into contact with rice as food. In addition, the pressure of the pressurized steam introduced into the chamber 40 may be set slightly higher than the target internal pressure in the chamber 40.

  Note that a shielding plate (not shown) is provided at the connection between the chamber 40 and the waveguide 37. Of course, this shielding plate is one that transmits microwaves but does not leak steam or pressurized air.

  A packing 41 is provided in order to prevent pressurized steam and pressurized air from leaking out of the chamber 40 formed by pressing the lower chamber 35 against the upper chamber 38 with the container receiving pallet 3f sandwiched therebetween. The airtightness of the chamber 40 is maintained by the packing 41.

  When lowering the atmospheric pressure in the chamber 40, the pressurized steam in the chamber 40 is discharged from the pipe 46. The pipe 46 is connected to an electromagnetic valve 47, a speed controller 48, and an electromagnetic valve 49 that are provided separately. By controlling the electromagnetic valve 47, the speed controller 48, and the electromagnetic valve 49, the pressure in the chamber 40 is predetermined. Can be stepped down at a speed of Further, since the lower chamber 35 moves up and down by the lifting and lowering movement of the hydraulic cylinder 30, a flexible pipe 46 is used.

  In the next process of the pressure rice cooker 25, the ingredient supply part 27 (the ingredient supply process) is disposed (see FIGS. 1 and 2). As shown in FIG. 2, the material supply unit 27 is configured to be able to measure and supply an arbitrary amount of material from the material tank 27a in order to measure and supply various materials into each container 2c.

  The container 2c supplied with the ingredients in the ingredient supply step is sent to the secondary hydration unit 10 (see FIGS. 1 and 2). In the secondary water addition part 10, the stirring water required in order to make ingredients with rice and stirring is filled from the nozzle 10a (secondary addition process). Although it is easier to stir if filled with a lot of the stirring water, on the other hand, the content in the container is likely to scatter around when stirring, so the amount of stirring water charged considering the ease of stirring and the prevention of scattering And

  Moreover, it is desirable to use the stirring water whose temperature is 50 to 60 degreeC in consideration of the taste of the packaged cooked rice to be produced. For this reason, in the present invention, a separate heating device is provided (not shown), and the stirring water is supplied to the container 2c after heating the stirring water to a predetermined temperature. Of course, it is also possible to use stirring water at room temperature. In addition, the said stirring water is not limited to water, You may use the liquid mixture of a seasoning liquid or a seasoning liquid, and water.

  In this embodiment, a secondary hydration process for filling the stirring water after the ingredient supply process for supplying ingredients is provided, but there is no problem even if the ingredients supply process and the secondary hydration process are switched in order. There is no.

  After the stirring water is added, the container 2c is sent to the stirring unit 26, and the cooked rice and ingredients in the container 2c are stirred by the stirring unit 26. In addition, the stirring here may use a machine and may stir manually.

  After the stirring step, a predetermined amount of supplemented rice water is added to each container 2c in order to supplement each container 2c with rice cooking water for finishing rice cooking and rice cooking adjustment (for adjusting the hardness of cooked rice). 11a can be supplied to the container 2c.

  The sealed wrapping part 7 is provided in the next step of the tertiary hydration part 11. In addition, between the container discharge side of the tertiary hydration unit 11 and the sealed packaging unit 7, a container transfer device 8, a lateral feed conveyor 13, and a pushing means 29 are disposed and discharged from the tertiary hydration unit 11. Further, each container 2c (temporary product) is transferred to the sealed packaging portion 7. The pushing means 29 is for extruding and feeding the transferred container 2c to the sealed packaging part 7 (see FIG. 1).

  The container transfer device 8 includes a conveyor belt wound around a plurality of rollers, a pushing mechanism that can be reciprocated horizontally by an air cylinder, and a pushing member attached to the pushing mechanism. The container 2c... Transported in the step is transferred to the transverse feed conveyor 13.

  In FIG. 1, the lateral feed conveyor 13 is provided to arrange the manufacturing apparatus 1 in a “U” shape. However, when the installation area is large and no folding is necessary, the lateral feed conveyor 13 is omitted. Can do.

  The containers 2c conveyed by the lateral feed conveyor 13 are sent to the product supply device 15 by the push-in device 29, and are accommodated by the product alignment device 16 in alignment with the pallet in four horizontal rows and one vertical row.

  In the chamber 24, the hermetic packaging portion 7 is for gas-substituting the container 2c to hermetically seal the upper opening. The sealed packaging unit 7 includes a conveyor device 18, and a radiation thermometer 19 and a chamber 24 are sequentially arranged from the upstream side of the conveyor device 18. In the chamber 24, a line seal unit 20, a knurled seal unit 21, and The container flange cooling unit 22 is sequentially disposed.

  In the conveyor device 18, a chain 18c is wound around a pair of sprockets 18a and 18b, and a large number of container receiving pallets 18d are attached to the chain 18c with a gap therebetween. In each of the container receiving pallets 18d, four holding holes (not shown) for arranging the containers 2c in four horizontal four rows and one vertical row are arranged in parallel.

  The radiation thermometer 19 is configured to detect the temperature in the container 2c. For the chamber 24, the container 2c is supplied, and the inside of the chamber 24 is filled with nitrogen gas, carbon dioxide gas, or the like, so that the gas in the container 2c is replaced and the upper opening of the container 2c is hermetically sealed. It is configured so that it can.

  The knurled seal portion 21 is for knurling the peripheral edge portion of the seal surface of the container 2c in order to prevent the seal surface of the container 2c sealed and packaged by the line seal portion 20 from being swollen. Further, the container flange cooling part 22 is for cooling the peripheral part of the sealing surface of the container 2c which is knurled.

  In the above manufacturing flow, each container 2c has a section in which the upper part is opened with rice inside, and foreign substances such as germs may be mixed in this state. In order to prevent mixing, it is desirable to perform each process in the clean booth 10 until sealed packaging is performed in the sealed packaging unit 7.

  In the next step of the hermetic packaging portion 7, a heat and pressure sterilization portion 23 is disposed (see FIGS. 1 and 5). The heat and pressure sterilization unit 23 is a step in which the container 2c whose upper opening is hermetically sealed in the previous step is placed in the heat and pressure sterilization unit 23 and sterilized.

  The heat and pressure sterilization unit 23 may use a known device (retort sterilization device). For example, a high-temperature and high-pressure cooking sterilizer (trade name: Flavor Ace) manufactured by Nisaka Manufacturing Co., Ltd. can be used. As shown in FIG. 5, the heat and pressure sterilization unit 23 includes a processing tank 23 b that has an open / close door 23 a and can seal the inside of the room. The treatment tank 23b is connected to a pressurized air supply pipe 23c for supplying pressurized air into the sealed chamber, and is connected to the sealed chamber from an exhaust pipe 23d for exhausting the pressurized air in the sealed chamber and the hot water tank 23g. A hot water supply pipe 23e for supplying hot water and a water distribution pipe 23f for discharging hot water after use in a sealed room are connected to each other.

  When the sterilization process is performed in the processing tank 23b, an alignment plate in which a plurality of the containers 2c are arranged in multiple stages is placed in the processing tank 23b, and then controlled and operated under the heating and pressurizing condition described later. Although the above is a hot water heating type in which the container 2c is immersed in hot water, a steam heating type in which heating steam is filled in the room and heated may be used.

  Hereinafter, a method for producing packaged cooked rice using the packaged cooked rice production apparatus 1 will be described.

  As shown in FIGS. 1 and 2, the container 2c is taken out from the container automatic supply unit 2 and supplied to the container receiving pallet 3f, and the containers 2c are arranged in four horizontal rows and one vertical row and are sequentially conveyed.

  Then, after the container 2 c is sterilized by the ultraviolet sterilization unit 4, the rice weighing and filling unit 5 is reached. In addition, before and after this step, the foreign matter in the container 2c may be removed by a foreign matter suction device or the like.

  In the rice weighing and filling unit 5, a predetermined amount of rice sterilized in advance in the container 2c is sequentially weighed and filled. Packed cooked rice (packed cooked rice) is mainly produced for individual consumption (for one person), and the amount of rice to be filled is about 65 grams to 100 grams. In this example, about 74 g of rice was filled.

  Next, in the container 2c, about 70 ° C. cooked rice water (warm water) sterilized in advance is sequentially weighed and filled in each container 2c by the primary hydration unit 6. In this example, about 7.4 g (cc) of cooked rice water was filled.

  The container 2 c filled with the rice cooking water is sent to the groove forming unit 12. In the groove forming unit 12, a groove forming process is performed in which a groove is formed in the layer of rice grains charged into the container 2c.

  The groove forming step will be described with reference to FIG. FIG. 10 shows a state in which the grooves 58 and 59 are formed in the rice grain layer in the container 2 c in the groove forming portion 12. When the container 2c filled with rice grains and rice cooking water is sent to the groove forming portion 12, the insertion rod 55 descends along the vertical frame 56, and the lower end 66 of the insertion rod 55 is the rice grains in the container 2c. Inserted into the layer. At that time, it is desirable that the tip 66 approaches the bottom surface of the container 2c. However, it is not preferable that the tip 66 is in contact with the bottom surface of the container 2c. When the insertion rod 55 is inserted into the rice grain layer in the container 2c, the insertion rod 55 moves along the horizontal frame 57 in either the forward direction, the backward direction, or the front-rear direction with respect to the conveyance direction of the container 2c. . At this time, since the tip 66 of the insertion rod 55 is inserted into the rice grain layer in the container 2c, a groove is formed in the rice grain layer by the movement.

  In addition, it is preferable that the cross section of the insertion rod 55 is round so that the insertion rod 55 can easily move in the rice grain layer and the rice grain is not damaged. The diameter of the insertion rod 55 is about 1.5 mm to 3.0 mm.

By the way, although one insertion rod 55 is shown in FIG. 9, in this embodiment, two insertion rods 55 are installed in a direction perpendicularly intersecting the transport direction of the container 2c. The tips 66 of the two insertion rods 55 are simultaneously inserted into the rice grain layer in the container 2c. Thus, two grooves are formed in the rice grain layer in the container 2c. Note that the number of the insertion rods 55 is not limited to two, and may be appropriately changed according to the manufacturing method.

  The container 2c provided with grooves in the rice grain layer in the groove forming step is sent to the pressure rice cooker 25. In the pressure rice cooker 25, the rice cooking process including making the rice filled in the container 2c absorb the rice cooking water in a very short time is performed.

  This rice cooking process is demonstrated using FIG.6 and FIG.7. FIG. 6 is a flowchart for explaining the rice cooking process, and FIG. 7 shows the internal pressure in the chamber 40 and the temperature of the rice cooking water in the rice cooking process.

  First, the container 2c sent to the pressure heating device 9 disposed in the pressure rice cooker 25 is accommodated in the chamber 40 formed by pushing up the lower chamber 35 (step S1). Is formed, the pressurized air whose pressure is adjusted by the pressure reducing valve 65 is opened into the chamber 40 through the switching valve 60 by opening the electromagnetic valve 64, and the inside of the chamber 40 is pressurized with the predetermined air. Pressurization is performed until the internal pressure is reached (step S2). The pressurization with the pressurized air to be introduced is performed until the internal pressure in the chamber 40 becomes about half of the pressurization with the pressurized steam in the subsequent process. In this embodiment, the process is performed until the pressure reaches 0.15 MPa. As shown in FIG. 7, the time required to pressurize to 0.15 MPa is about 1 second after the chamber 40 is formed.

    When the pressure in the chamber increases to the predetermined internal pressure, the solenoid valve 64 is closed to stop the supply of pressurized air, the pressure reducing valve 43 is opened and the switching valve 60 is switched to generate pressurized steam whose pressure has been adjusted. Then, the electromagnetic valve 44 is opened and sent into the chamber 40 through the feed pipe 42, and the inside of the chamber 40 is pressurized with pressurized steam (step S4).

  In the present invention, the pressure in the chamber is increased by the pressurized air before the pressurized steam is introduced, so that the amount of pressurized steam to be introduced can be reduced, and the amount of condensed water generated by this effect can be reduced. It becomes possible to reduce.

  The pressurization by the pressurized steam to be introduced is such that the internal pressure in the chamber 40 is about 0.2 to 0.5 MPa, preferably about 0.25 to 0.4 MPa, more preferably about 0.3 MPa to 0.38 MPa. To do. In this embodiment, the internal pressure in the chamber 40 is increased to 0.32 MPa. As shown in FIG. 7, the time required to pressurize to 0.32 MPa is about 6 seconds.

  There is a close relationship between the internal pressure in the chamber 40 and the boiling point of the cooked rice water to be heated. The higher the atmospheric pressure, the higher the boiling point, and the lower the pressure value, the lower the boiling point. If the boiling point becomes too high, it may cause a decrease in taste, and if the boiling point is low, rice immersion (water absorption of cooked water) cannot be performed sufficiently in a short time. The internal pressure within 40 needs to be determined.

  Moreover, after completion | finish of injection | throwing-in of pressurized air, the microwave irradiation by the microwave oscillation apparatus 36 is started (step S3). Therefore, step S4 and step S3 are started simultaneously. Note that step S4 and step S3 may be started with a time difference, but in order to perform the rice cooking process in a short time, it is desirable to start them simultaneously.

  In addition to heating by microwave irradiation, by simultaneous heating with two heat sources by heating with pressurized steam, the temperature of the cooked water in the container 2c exceeds 100 ° C, preferably 102 ° C to 140 ° C, more preferably 140 ° C. (Step S5 (heating process)). Since the inside of the chamber 40 is pressurized, the cooked rice water can be heated to a temperature exceeding 100 ° C. In the present embodiment, since the internal pressure in the chamber 40 is increased to 0.32 MPa, the boiling point of water is also increased, and the temperature of the cooked water is increased to 140 ° C. And it cooks (heats) for the predetermined time in the state which maintained this temperature.

  The said time is suitably set by conditions, such as the quantity of the rice thrown into the container 2c, the boiling point of cooked rice water, or the hardness of the cooked rice after the target rice cooking. In this embodiment, as shown in FIG. 7, the time is set to 14 seconds. In addition, the temperature of the vapor | steam in the chamber 40 when the internal pressure in the chamber 40 is 0.32 MPa will also be 140 degreeC.

  After heating for a predetermined time (19 seconds in this embodiment) by microwave irradiation, the microwave irradiation is stopped, the electromagnetic valve 44 is closed, the electromagnetic valve 47 is opened, and the speed controller 48 gradually controls. Then, the internal pressure in the chamber 40 is lowered to atmospheric pressure (step S6 (step-down step)). The internal pressure in the chamber 40 is lowered so that the atmospheric pressure is reached when about 7 seconds have elapsed from the start of the pressure reduction (step S7). At that time, the solenoid valve 49 is opened at the time of the pressure reduction, and the inside of the chamber 40 is surely decompressed to the same level as the atmospheric pressure. Actually, it takes about 2 seconds for the pressure in the chamber 40 to drop to normal pressure after the electromagnetic valve 49 is opened.

  When the internal pressure in the chamber 40 is rapidly reduced to normal pressure (atmospheric pressure), the boiling point in the chamber 40 is lowered to 100 ° C., so that the boiling point of the rice cooking water in the container 2c is also lowered. For this reason, even after the microwave irradiation is stopped, it is possible to reduce the pressure to atmospheric pressure while maintaining boiling of the cooked rice water heated to a temperature exceeding 100 ° C. in the container 2c. That is, the heat required for cooking rice can be used efficiently. Moreover, since all the cooked water in a container is boiled, it becomes possible to cook rice uniformly in the container 2c uniformly by the active motion of the boiling cooked water.

  By the way, in this invention, it is one of the characteristics that there is little quantity of the rice cooking water with which the container 2c is filled. Normally, in the rice cooking process, as shown in FIG. 8A, the rice cooking water level 51 is above the rice layer, and the rice is completely immersed in the rice cooking water. However, as shown in FIG.8 (b), in this invention, the liquid level 52 of cooked water is located below a rice grain layer. For this reason, when cooking water boils vigorously and evaporates in the rice cooking process, it is necessary for the steam to pass through the rice grain layer. In the present invention, the grooves 58 and 59 are formed in the rice grain layer during rice cooking. Therefore, these grooves 58 and 59 serve as a passage for the steam. Therefore, it is possible to prevent rice grains, rice balls and the like from being scattered around the container 2c due to the boiling pressure of the steam generated from the rice cooking water.

  The amount (weight) of cooked water filled in the container 2c in the primary hydration process of the present invention is less than half of the amount (weight) of rice charged in the container 2c in the rice supply process, about 1/7 to 1/10. It's okay. This is because the present invention cooks rice with the container open, and uses the moisture contained in the pressurized steam, which is one of the heat sources, for the rice cooking water. In addition, by reducing the amount of rice cooking water to be filled to the minimum necessary, heating energy (production efficiency) can be improved by minimizing heating energy required during the rice cooking process.

  When the internal pressure in the chamber 40 is reduced to the same level as the atmospheric pressure, the pressure reduction process ends. At this time, all the rice cooking water filled in the primary hydration unit 6 is absorbed by the rice grains. For this reason, rice cooking water does not remain in the container 2c taken out from the pressure heating device 9 alone. In other words, the cooked rice water does not spill even when the container 2c is tilted. In the present invention, the rice cooking process is performed in a pressurized state because rice cooking water is absorbed by the rice as a raw material in a short time.

  In addition, since the time required for the said rice cooking process can be changed freely, according to the manufacturing conditions of cooked rice, what is necessary is just to change suitably between 20 seconds-60 seconds, Preferably it is 20 seconds-40 seconds. In that case, the respective times of the heating step and the decompression step may be appropriately changed. In this embodiment, 27 seconds are set as shown in FIG.

  By the way, since steam is used in the present invention, condensed water may be generated in the chamber 40. For this reason, although not shown, it is desirable that a means for discharging condensed water to the pressurizing and heating device 9, for example, a drain trap or the like is provided in the pipe 46.

  The container 2c that has finished the rice cooking process is sent to the ingredient supply unit 27 that performs the ingredient supply process as the next process by the conveyor device 3, and the ingredients are appropriately supplied to the container 2c.

  The container 2c which has completed the ingredient supply process is sent to the secondary hydration unit 10 by the conveyor device 3 in order to perform the secondary hydration process which is the next process. In the secondary water addition part 10, the stirring water for stirring sterilized beforehand is measured and filled sequentially. The container 2c filled with the stirring water is sent to the stirring unit 26 that performs the stirring process.

  In the stirring unit 26, the cooked rice in the container 2c and the ingredients supplied in the previous process are stirred. In addition, when the packaged rice to manufacture is white rice, an ingredient supply process, a secondary hydration process, and a stirring process can be skipped.

  The container 2c that has completed the stirring process is sent to the tertiary hydration unit 11 by the conveyor device 3 in order to perform a tertiary hydration process that is the next process. In the tertiary hydration part, the amount of supplemented rice water required for retorting the cooked rice in the container 2c is charged.

  In this example, a tertiary hydration step is provided after the stirring step, but the tertiary hydration step can be omitted by adding an amount of water necessary for the retort treatment in the secondary hydration step.

  In the present invention, the process after the tertiary hydration process is a post-treatment process. A general method can be used for this post-processing process. The container 2c to which supplementary rice water necessary for retort processing is supplied in the tertiary hydration process passes through the container transfer device 8, the lateral feed conveyor 13, the pushing device 29, the product supply device 15, and the product alignment device 16, and the radiation thermometer 19 , The temperature of the cooked rice is detected by the radiation thermometer 19, and the temperature of the product is controlled. Thereafter, the product is carried into the sealed packaging portion 7 as the next step.

  As for the container 2c sent to the sealed packaging part 7, the opening edge (flange) of the container 2c is sealed with the sterilized film 7a. The reason why this sealing is performed after rice cooking is to smoothly increase and decrease the pressure in the container 2c when the internal pressure in the chamber 40 is increased and decreased in the rice cooking process.

  The sealed packaging unit 7 performs gas replacement and sealed packaging of the container 2c (FIGS. 1 and 4). When the container 2c is carried into the chamber 24 of the sealed packaging part 7, first, a vacuum generator (not shown) of the chamber 24 is operated to depressurize the chamber 24 to a vacuum state, Quickly cool the cooked rice to 75 ° C. As a result, it is possible to suppress the propagation of germs and increase the efficiency of gas replacement. When the pressure is reduced, the air in the container 2c is naturally sucked out. Next, gas replacement is performed by filling the chamber 24 under vacuum with nitrogen gas or carbon dioxide gas.

  After the gas replacement, the entire circumference of the flange of the container 2 c is sealed by the line seal portion 20 in the chamber 24. In the knurled seal portion 21, a knurled seal for preventing drooling is applied to the container 2 c, and then cooling is performed in the container flange cooling section 22 to complete complete sealed packaging of the container 2 c.

  As shown in FIGS. 1 and 5, a plurality of sealed and packaged containers 2 c are arranged on an alignment plate by, for example, an operator or a robot, and the alignment plate is multi-staged (for example, 8 levels). Overlapping. Next, the multi-stage alignment dish (a plurality of trays 2c) is taken as one lot, and the open / close door 23a is opened in the treatment tank 23b of the heat and pressure sterilization unit 23 (retort sterilizer), for example, 3 lots (24 in total). A plurality of trays 2c are supplied and set, the door 23a is closed, and the inside of the processing tank 23b is sealed (see FIG. 5). Next, pressurized air is supplied into the processing tank 23b and hot water is supplied, and the temperature in the processing tank 23b is raised to, for example, 115 ° C., and this state is maintained for 35 minutes to perform a heat and pressure sterilization process. . As a result, the cooked rice in the completely sealed and packaged container 2c is completely sterilized, and is subjected to finish rice cooking processing such as the core of the cooked rice to be completely alphalated (100% alpha). (Moisture is about 60% to 65%).

  After the retort processing is completed in the heat and pressure sterilization section 23, the container 2c is taken out from the processing tank 23b and subjected to water removal work, and after inspection such as pinhole check and weight check, it is packaged and packed. Will be shipped as.

  According to the above-described method for producing packaged cooked rice, the rice cooking process can be performed in 27 seconds. Since the process (except for the retort process) that requires the most time in the manufacturing method is the rice cooking process, the time required for one process is 27 seconds. Moreover, since the time required for each said process can be changed freely, what is necessary is just to change suitably according to the manufacturing conditions of packaged cooked rice.

  The production method of the present invention can be applied not only to packaged cooked rice, but also to other food production methods as long as the heating method is the same.

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus of packaged cooked rice 2 Container automatic supply part 3 Conveyor apparatus 4 Ultraviolet sterilization part 5 Rice measurement filling part 6 Primary hydration part 7 Sealed packaging part 8 Container transfer apparatus 9 Pressure heating apparatus 10 Secondary hydration part 11 Tertiary hydration Section 12 Groove forming section 13 Cross feed conveyor 15 Product supply apparatus 16 Product alignment apparatus 18 Conveyor apparatus 19 Radiation thermometer 20 Wire seal section 21 Knurl seal section 22 Container flange cooling section 23 Heating and pressure sterilization section 24 Chamber 25 Pressure rice cooking section 26 Stirring unit 27 Material supply unit 29 Pushing device 30 Hydraulic cylinder 31 Base plate
32 Support 33 Elevating guide 34 Support 35 Lower chamber
36 Microwave Oscillator 37 Waveguide 38 Upper Chamber 39 Choke 40 Chamber 41 Packing 42 Pipe 43 Pressure Reducing Valve 44 Electromagnetic Valve 45 Pressure Gauge 46 Pipe 47 Electromagnetic Valve 48 Speed Controller 49 Electromagnetic Valve 51 Rice Cooking Water Level 52 Rice Cooking Water Liquid level 55 Insertion rod 56 Vertical frame 57 Horizontal frame 60 Switching valve 61 Feeding pipe 62 Feeding pipe 63 Pressure reducing valve 64 Solenoid valve 65 Pressure gauge 66 Tip

Claims (3)

A rice supply step of charging a predetermined amount of rice into a container having an open top;
A hydration step of filling the container with a predetermined amount of cooked rice water ;
A cooking step of rice the rice in a chamber using two heat sources by the irradiation of the charged and microwave pressurized steam at the same time,
A water supply step of adding supplemental rice water after the rice cooking step;
Sealing and packaging the container after the water supply step;
A method for producing packaged cooked rice containing
A method for producing packaged cooked rice, wherein a groove forming step for forming grooves in a layer of rice grains in the container is provided in a pre-process of the rice cooking process.
In the炊rice Engineering degree method of packaging cooked rice according to claim 1, wherein prior to introducing pressurized steam into the chamber, characterized by introducing pressurized air. 2. The packaging according to claim 1, wherein, in the groove forming step, the groove is formed by inserting an insertion rod from above the container and moving the insertion rod relative to the container. A method for producing cooked rice.