JP2019033719A - Manufacturing method of instant rice and device therefor - Google Patents

Abstract

To provide a manufacturing method of instant rice which is restorable more quickly than prior art by promoting absorption of water or impregnation of water into rice grain during rice cooking or the like.SOLUTION: In a manufacturing method of instant rice including cooking rice after forming a gelatinization layer on a rice grain surface layer part by a compression heating treatment of a raw material rice, then conducting a dry treatment on the rice, the compression heating treatment is a compression digestion treatment by saturated stream and includes a process for generating fine cracks in whole rice particle surface by reducing pressure quickly after holding compression state for a specified time, and further a swelling impregnation process for impregnating rice after rice cooling and swelling the same is set, and the swelling impregnation process conducts swelling of rice while water transport by supplying rice and impregnation water into a piping.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an instant rice that is reconstituted with hot water or the like and eats, and more particularly to a method and apparatus for producing instant rice that can be eaten in a shorter time than before without cooking with a microwave oven or the like.

  Conventionally, in an instant rice manufacturing method in which raw rice is steamed under pressure to form an alpha (α) layer on the surface of the rice grain, and then cooked and dried, the formation of the alpha layer makes it relatively While boil-out is prevented and the product yield is improved, the pre-swelling of the rice grains does not progress because the alpha absorption layer impedes water absorption into the rice grains during cooking, so the high temperature in the drying process after cooking Expansion and drying are performed (see Patent Document 1). Thereby, the water absorbency at the time of cooking rice increases, it swells plumply, and an external appearance improves.

  However, since the thing of patent document 1 performs the expansion drying by high temperature, it is what is called a "pop confectionery" -like texture, is lacking in graininess, and is exhibiting a slightly baked color. Moreover, due to the lack of water absorption during rice cooking by the pregelatinized layer on the rice grain surface and the slow water permeation rate during restoration, the hot water return time required about 8 minutes.

JP 2013-51889 A

  In view of the above problems, an object of the present invention is to provide a method for producing instant rice that can be restored faster than before by promoting water absorption and water penetration into rice grains during rice cooking.

In order to achieve the above object, the invention according to claim 1
In the method for producing instant rice, the raw rice is cooked after being heated under pressure to form a pregelatinized layer on the surface of the rice grain, and then dried.
The pressure heat treatment is a pressure steaming treatment with saturated steam, and includes a step of rapidly reducing the pressure after maintaining the pressure state for a certain period of time to cause minute cracks on the entire surface of the rice grain, and after the rice cooking A swelling soaking step to swell and swell the cooked rice is provided,
In the swelling soaking step, technical means was taken to swell the cooked rice while supplying the cooked rice and soaking water into the pipe and transporting the water.

  The invention according to claim 2 is characterized in that, in the pressurizing and heat treatment, the pressure is reduced to atmospheric pressure within 5 to 90 seconds after being pressurized to 0.10 to 0.30 MPa and held for 30 to 120 seconds. To do.

  The invention according to claim 3 may be configured such that the moisture content of the rice grains immediately after the rice cooking is 60 to 70%, and the moisture content of the rice grains after the swelling soaking is 75 to 80%.

According to the method for producing instant rice of the present invention, in the pressure heat treatment in the pre-cooking process of rice cooking, while forming a pregelatinized layer on the surface layer portion of the rice grain, a fine crack is caused on the entire surface of the rice grain by rapid decompression, In addition, when the pregelatinized layer is formed into a dense glassy material, water is evenly and promptly absorbed into the rice grains from minute cracks of the whole rice grains during the immersion of the cooked rice in the next step.
And in this case, in order to swell the cooked rice while supplying the cooked rice and the dipping water into the pipe and transporting the water, the dipped water is absorbed into the inside of the rice grains (at a higher rate) while stirring the cooked rice. Swelling can be performed, and a sufficient porous structure can be formed inside the rice grains in the immediate drying treatment.
By forming this porous structure, water permeation at the time of restoration proceeds more rapidly, and hot water reconstitution can be performed faster than before.
Further, the rice grain surface layer portion is formed into a dense glassy material, so that the rice grains do not collapse or elute during cooking and swelling soaking, and the yield is improved as compared with the conventional case.

  According to the second aspect of the present invention, after maintaining the high pressure state for 30 to 120 seconds, the pressure is reduced to atmospheric pressure at a time within 5 to 90 seconds. Vitrification and uniform formation of moderately sized microcracks can be effectively reproduced over the entire surface of the rice grain.

  According to the invention described in claim 3, by adjusting the cooked water and setting the water content of the cooked rice immediately after cooking to 60 to 70%, the swelling of the rice grains in the next dipping process proceeds smoothly, It can reach a moisture content of 75 to 80%, which is the target of swelling immersion, in a short time.

It is a manufacturing flowchart in the manufacturing method of the instant rice by embodiment of this invention. It is a schematic explanatory drawing of the apparatus for implementing each process of the manufacturing method of the instant rice by this embodiment. It is explanatory drawing of the pressurization and rapid pressure reduction in the pressurization heat processing by this embodiment. It is an expanded cross-sectional photograph of the rice grain at the time of depressurizing for 10 seconds after pressurizing and steaming at 0.3 MPa. It is the expanded cross-sectional photograph of the rice grain at the time of reducing pressure similarly for 30 seconds. It is the enlarged cross-sectional photograph of the rice grain at the time of reducing pressure similarly for 60 seconds. It is a figure which shows another embodiment of the apparatus for implementing a swelling immersion process.

Hereinafter, an embodiment of the present invention will be described with reference to the flowchart of FIG. 1 and the schematic explanatory diagram of the apparatus of FIG.
The raw rice in the present invention is generally polished white rice that has a water content of 16% or less, and there is no particular variety restriction. Raw rice may be raw rice before washing or soaking, or so-called unwashed rice.

Step S1: Pressurized steaming process This pressurized steaming process uses saturated steam to form a thin pregelatinized layer on the surface of the rice grain without alphatizing the raw rice to the center prior to the subsequent rice cooking process. A pressure heat treatment is performed. A conventionally known steam cooker 101 may be used as an apparatus for performing this process. For example, as shown in FIG. 2, the steam cooker 101 has a net conveyor 103 for carrying rice grains in a sealed pressurized heating tank 102, and a raw material above the conveyance start end side of the net conveyor 103. In order to hold the inside of the pressurized heating tank 102 in an airtight manner, the supply pipe 104 faces the processed material discharge pipe 105 below the conveyance end side, respectively. Are provided with rotary valves 106, 107 and the like. Further, a pressurized heating steam (saturated steam) supply pipe 108 and a discharge pipe 109 are connected to the pressurized heating tank.

In the pressure steaming step of step S1, the pressure in the tank 102 is gradually increased by supplying saturated steam in a pressure-heated state into the pressure-heating tank 102. The pressure is raised to 0.3 MPa, preferably 0.3 MPa, and the state is maintained for 30 to 120 seconds, preferably 60 seconds, and then the discharge pipe 109 is opened for 5 to 90 seconds, preferably 10 seconds. The pressure is rapidly reduced to atmospheric pressure at once (see FIG. 3).
Although the pregelatinized layer is formed on the surface part of the rice grain by the pressure steaming step, the processing temperature is higher at 0.3 MPa (140 ° C. or higher) when 0.1 MPa and 0.3 MPa are compared. The pregelatinized layer tends to be formed relatively thick. On the other hand, in the case of 0.1 MPa, since the pregelatinized layer is relatively thin, both have a slightly different texture. Therefore, instant rice with different texture can be created by changing the pressure.
Note that the supply of the saturated water vapor is not a supply of only saturated water vapor, but by using the saturated water vapor and compressed air in combination to increase the pressure efficiency and prevent the formation of condensed water. it can.

In the pressurized steaming step S1, a pregelatinized layer of about 0.1 to 0.5 mm in the surface part of the rice grain is formed, and microcracks are generated substantially uniformly over the entire surface of the rice grain by the rapid pressure reduction. This microcrack is formed to a length of about 100 μm when the pressure is rapidly reduced from 0.3 MPa to atmospheric pressure in 10 seconds (see FIG. 4), and is a point-like hole when the pressure is reduced for 30 seconds at the same pressure ( 5), almost no change is observed after 60 seconds of pressure reduction (see FIG. 6). On the other hand, in the case of rapid depressurization for a short time of less than 5 seconds, there are problems that the rice grains are blown down violently and cracks are uneven.
Moreover, the pregelatinized layer of the rice grain surface layer part is formed into a dense glass by the rapid decompression treatment.

Step S2: Rice Cooking Process In this rice cooking process S2, the pressure steaming process is performed to form a dense pregelatinized layer on the surface layer portion, and the rice grains that have generated substantially uniform microcracks over the entire surface are completely covered to the core. It is the process of making it alpha. As a rice cooker, it can select suitably from well-known rice cookers, such as steam type rice cooking and a pot type rice cooking. For example, as shown in FIG. 2, a pot-type rice cooker 201 whose induction source is a heat source can be adopted as the rice cooker. The pot-type rice cooker 201 includes a rice distribution unit including a charging hopper 202, a rice distribution device 203, and a water addition device 204, a conveyance unit including a pot transfer device 206 that transfers the rice cooking tank 205 after rice distribution, and a rice cooking tank 205. The main part is comprised from the some rice cooking part 207 which accommodates and cooks for every pot. When cooking with such a rice cooker, the cooked water is adjusted by the water adding device 204 so that the moisture content of the cooked rice immediately after cooking is 62-70%, which is higher than the usual 60-62%. For example, about twice the weight of rice grain water is added to the rice cooker 205 as cooking water, the immersion time in the kettle is set to 15 minutes, the rice cooking time is set to 20 minutes, the steaming time is set to 15 minutes, and the rice cooking time is set to 50 minutes. It is good to adjust to.

In the rice cooking step S2, the dense and vitreous pregelatinized layer formed on the surface layer part makes it difficult for the rice grain to boil, thereby obtaining the grain feel of the restored rice grain. As a factor that hinders smooth water absorption of the rice grains, microcracks are evenly formed on the entire surface of the rice grain, and water absorption from the microcracks to the inside of the rice grain is promoted uniformly, and alpha conversion is completely performed to the center of the rice grain. Is called.
After the completion of rice cooking, the pot type rice cooking apparatus 201 shown in FIG. 2 is transferred from the rice cooking unit 207 to the roller conveyor 208 by the pot transfer device 206, and transferred from the roller conveyor 208 to the reversing unit 209 and then reversed. The part 209 takes out the cooked rice in the rice cooker 205 and supplies the cooked rice to the next process. At this time, a large lump of cooked rice is formed only by reversing by the reversing unit 209. For example, as shown in FIG. It is better to send it to the next process later.

Step S3: Swelling soaking process In the swelling soaking process S3, the cooked rice cooked in the rice cooking process S2 is soaked in warm water at a temperature of 50 to 90 ° C, preferably 70 ° C for 40 to 60 minutes. In this swelling soaking step S3, swelling is performed by absorbing water so that the moisture content of the rice grains is 75 to 80%. At this time, the rice grains do not lose their shape due to the dense pregelatinized layer on the surface of the rice grains, and the water is actively immersed from the microcracks. In addition, even if the rice grain swells, for example, the volume becomes about 1.5 times, the presence of the microcracks does not cause the rice grain to split greatly in the longitudinal direction, and the rice grain surface expands and swells sufficiently. Is possible.

As an apparatus for performing this swelling dipping process, for example, as shown in FIG. 2, a swollen dipping apparatus 301 that swells cooked rice while supplying the rice and dipping water to the pipe and transporting the water is adopted. Can do. This swelling dipping device 301 is used for carrying out swelling dipping in a tube while transporting the mixed rice cooked with water over 40 to 60 minutes while mixing the raw material tank 302 for mixing the cooked rice and hot water at a predetermined ratio. A long and curved continuous transport pipe 303, a liquid feed pump 304 connected to the transport start end side 303a of the continuous transport pipe 303, and a cooked rice after swelling immersion connected to the transport end side 303b of the continuous transport pipe 303 Can be widely supplied to a net conveyor or the like, a drainage recovery unit 306 that collects solid and liquid from the rice and hot water from the discharge pipe 305 to recover wastewater, and hot water to the raw material tank 302 side. And an immersion water supply unit 307 for supplying the main part.
The drainage recovery unit 306 includes a drainage collection receptacle 309, a recovery pump 310, a screen 311 for filtering the drainage, and a temporary storage tank 312 for temporarily storing the filtered drainage via a pipe line 313. I have contacted you.
The immersion water supply unit 307 includes a relay pump 314 that transfers the waste water from the temporary storage tank 312 and an immersion water storage tank 315 that adds and mixes fresh water to the filtered waste water via a pipe line 316. The immersion water storage tank 315 is provided with a new water pipe 317 for supplying new water, and a water feed pump 318 and a water supply nozzle 319 for supplying the immersion water to the raw material tank 302. Is provided.
The immersion water storage tank 315 is provided with a heater (not shown) for raising the temperature of the stored immersion water to 50 to 90 ° C.

The continuous transport pipe 303 may be a stainless steel sanitary pipe. For example, the continuous transport pipe 303 may be a long and curved tube by combining a plurality of nominal dimensions 4S having an outer diameter of 101.6 mm and 180 ° elbow pipes (curved pipes). You just need to create a tube. In the case of nominal size 4S, the length of the pipe is 8m to 20m, the transport time is 20 to 60 minutes, the flow rate is 0.01m / sec, and it is transported very slowly so as to prevent crushing and collapse of the rice grains. It is preferable to do this.

  In such a swelling soaking step S3, the rice grains are swollen and the stickiness of the surface of the cooked rice is removed to promote single grain formation. Further, when the temperature of the immersion water is set to 70 ° C. or higher, there is an effect of suppressing the growth of sterilizers. However, when the temperature exceeds 90 ° C., the elution of the surface of the rice grains starts, and the yield decreases, which is not preferable.

Step S4: Drying process The swollen cooked rice after the swelling dipping process 3 reaches the drying process S4. In this drying step S4, the swollen cooked rice is placed on a net conveyor or the like, ventilated with hot air at 100 to 130 ° C. for 25 to 60 minutes, and the moisture of the rice grains is dried to 5 to 10%. At this time, after the moisture in the swollen rice grains is removed, a porous structure is formed as a trace (porous), and thereby water absorption into the rice grains at the time of restoration proceeds more rapidly. Become.

As the apparatus 401 for performing the drying process, for example, as shown in FIG. 2, a high-temperature drying apparatus 402 and a low-temperature drying apparatus 403 are combined. If it is made to dry by applying, the deterioration of quality can be suppressed.
Both the high-temperature drying device 402 and the low-temperature drying device 403 are provided with a rotatable net conveyor 404, and hot air from a hot air generator (not shown) is supplied from below the net conveyor 404. The exhaust fan 405 can exhaust the exhaust after drying outside the apparatus. Here, the high-temperature drying device 402 is preferably dried until the hot air temperature from the hot air generator is 110 to 130 ° C., the passage time is 5 to 15 minutes, and the moisture of the cooked rice is about 20 to 30%. The low-temperature drying device 403 is preferably dried until the hot air temperature from the hot air generator is 70 to 100 ° C. and the passage time is 60 to 90 minutes, and the water content of the cooked rice is 10% or less.

[Example]
Prepared Koshihikari refined rice from Hiroshima Prefecture in 2015 (90% yield, 14% moisture content), pressurized to 0.3MPa with saturated steam at 144 ° C for 120 seconds, and held for 60 seconds without washing and soaking Immediately after this, the pressure was rapidly reduced to normal pressure in 10 seconds. As a result, a pregelatinized layer was formed on the surface part of the rice grain, and minute cracks were generated substantially uniformly on the entire surface of the rice grain. The water content of the rice grains at this time was 18%. Next, using a kettle-type rice cooker, rice was cooked for 45 minutes to obtain cooked rice with a moisture content of 66%.

Next, the swelling immersion process was performed using the swelling immersion apparatus 301 (refer FIG. 2). The raw material tank 302 was supplied with cooked rice obtained with the rice cooker and supplied with immersion water at a temperature of 50 to 90 ° C. from the water supply nozzle 319. Then, the cooked rice was swollen while supplying the cooked rice and the immersion water into the continuous transport pipe 303 and transporting them with water. As a result, it was possible to sufficiently swell the rice grains by absorbing the immersion water while stirring the cooked rice. At that time, crushing and collapsing of the rice grains could be prevented by transporting very slowly at a transport time of 20 to 60 minutes and a flow rate of 0.01 m / second. The water content of the rice grains after swelling was 75-80%.

  And the hot air of 130 degreeC was ventilated for 30 minutes with the wind speed of 7.5 m / sec with respect to the rice grain after swelling, and it dried so that it might become 8% of moisture content.

Table 1 shows the results of a restoration test for comparing the instant rice obtained in the example with the instant rice that was not subjected to the rapid pressure reduction in the pressure cooking step. Each sample was 50 g, and 90 ml of water and hot water were added to each stand pack container to restore and eat.
As a result, in this example, it was 5 minutes when hot water was added and 25 minutes in the case of water, and the taste was excellent with an appropriate grain feeling. Moreover, the yield with respect to the raw material rice was 81.35%, which exceeded the yield of about 70% by the conventional manufacturing method.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be implemented in various modes by making appropriate changes.

  FIG. 7 is a schematic view showing another embodiment of an apparatus for performing a swelling dipping process. The swelling dipping device 501 includes a water tank 502, a net-like endless belt 503 immersed in the water tank 502, and a driving pulley section 504 that rotates. A drive motor (not shown) is connected to the drive pulley unit 504. The water tank 502 is formed in a box shape whose upper surface is open, and an endless belt 503 that is rotationally driven is stretched between pulleys 505 so as to immerse the cooked rice and take out the cooked rice after soaking. . A draining part 506 is also provided for draining water adhering to the cooked rice.

However, the water tank type swelling immersion apparatus 501 of FIG. 7 has many problems as compared with the continuous transport pipe type swelling immersion apparatus 301 of FIG. For example, in the water tank system, it is conceivable that the rice grains are broken by an impact when dropping the rice on the net-like endless belt 503. In addition, the cooked rice flows out from the net of the endless belt 503 and the cooked rice settles at the bottom of the water tank, which may deteriorate the yield. Furthermore, since the water tank upper surface is opened, sanitary property is bad and it is unsanitary.
On the other hand, the continuous transport pipe system has the advantage that the continuous transport pipe is composed of a straight sanitary pipe and an elbow pipe, so that it can be easily disassembled and easily cleaned by connecting with a clamp band or the like. is there.

  INDUSTRIAL APPLICABILITY According to the present invention, instant rice with excellent resilience and high yield can be mass-produced, which is extremely useful.

S1 Pressure Steaming Process S2 Rice Cooking Process S3 Swelling Soaking Process S4 Drying Process 101 Steam Cooker 201 Pot Type Rice Cooker 301 Swelling Soaking Apparatus 401 Drying Apparatus

Claims (4)

In the method for producing instant rice, the raw rice is cooked after being heated under pressure to form a pregelatinized layer on the surface of the rice grain, and then dried.
The pressure heat treatment is a pressure steaming treatment with saturated steam, and includes a step of rapidly reducing the pressure after maintaining the pressure state for a certain period of time to cause minute cracks on the entire surface of the rice grain, and after the rice cooking A swelling soaking step to swell and swell the cooked rice is provided,
The method for producing instant rice is characterized in that the swelling soaking step swells the cooked rice while supplying the cooked rice and the soaking water into the pipe and transporting them with water.   The method for producing instant rice according to claim 1, wherein the pressurizing and heating treatment is performed by pressurizing to a pressure of 0.10 to 0.30 MPa and holding for 30 to 120 seconds, and then reducing the pressure to atmospheric pressure within 5 to 90 seconds. .   The method for producing instant rice according to claim 1 or 2, wherein the moisture content of the cooked rice immediately after cooking is 60 to 70%, and the moisture content of the rice grains after the swelling soaking is 75 to 80%. It is an apparatus for producing instant rice, in which raw rice is heated under pressure to form a pregelatinized layer on the rice grain surface layer, and then cooked and then dried.
A pressure cooker that performs pressure steaming with saturated steam, and a rice cooker that rapidly reduces pressure after maintaining the pressurized state for a certain period of time to cause micro cracks on the entire surface of the rice grain, and further includes the rice cooker By providing a swelling dipping device to swell and swell the cooked rice after cooking,
The apparatus for producing instant rice, wherein the swelling dipping device includes a continuous transport pipe that swells cooked rice while supplying the rice and dipping water into the pipe and transporting the water.