Rice cooker

Abstract

To provide a rice cooker capable of increasing an amount of starch that comes out of rice.SOLUTION: A rice cooker includes: a pot; a heating part for heating the pot; a lid body capable of closing the opening of the pot; a temperature detection part for detecting the temperature of rice to be cooked; and a control part for controlling the heating part. The control part is configured to perform a rice cooking process including processes of preheating, first temperature raising, elution promotion, second temperature raising, and a boiling maintaining process. The preheating process is a process for heating the rice to be cooked, and maintaining the detection temperature of the temperature detection part at a preheating temperature. The first temperature raising process is a process for raising the detection temperature to an elution temperature higher than the preheating temperature and lower than about 100°C. The elution promotion process is a process for maintaining the detection temperature at the elution temperature and urging the elution of starch from rice. The second temperature raising process is a process for raising the detection temperature from the elution temperature to about 100°C. The boiling maintaining process is a process for maintaining the boiling of the rice to be cooked.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a rice cooker.

Background Art

[0002] Conventionally, as this type of rice cooker, for example, the one described in Patent Document 1 is known. The rice cooker (heating cooker) described in Patent Document 1 includes a pot that houses an object to be cooked containing rice and water, a heating unit that heats the pot, a discharge unit that discharges the solution in the pot to the outside of the pot, and a control unit that controls the heating unit and the discharge unit.

[0003] The control unit controls the heating unit and the discharge unit and executes a rice cooking process that is performed in the order of a temperature rising process, a boiling maintaining process, a discharging process, and a steaming process. The temperature rising process is a process of heating the pot to heat the object to be cooked to about 100°C. The boiling maintaining process is a process of maintaining the boiling of the object to be cooked until a predetermined time has elapsed since the boiling of the object to be cooked. The discharging process is a process of discharging the liquid in the pot to the outside of the pot by the discharge unit. The steaming process is a process of vaporizing the excess moisture in the pot by reheating the pot until the temperature of the pot reaches a predetermined temperature.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The rice cooker of Patent Document 1 still has room for improvement from the viewpoint of increasing the amount of starch eluted from rice.

[0006] Therefore, an object of the present disclosure is to solve the above problems and provide a rice cooker capable of increasing the amount of starch eluted from rice.

Means for Solving the Problems

[0007] The rice cooker according to the present disclosure includes a pot for containing the rice and water to be cooked, a heating unit for heating the pot, a lid that can be opened and closed between a closed position for closing the opening of the pot and an open position for opening the opening, a temperature detection unit for detecting the temperature of the rice and water to be cooked, and a control unit for controlling the heating unit based on the detected temperature of the temperature detection unit. It is provided with The control unit includes a preheating step of heating the rice and water to be cooked and maintaining the detected temperature of the temperature detection unit at a preheating temperature, a first temperature rising step of raising the detected temperature from the preheating temperature to an elution temperature that is higher than the preheating temperature and lower than about 100°C, an elution promotion step of maintaining the detected temperature at the elution temperature to promote the elution of starch from the rice, a second temperature rising step of raising the detected temperature from the elution temperature to about 100°C, and a boiling maintenance step of maintaining the boiling of the rice and water to be cooked after the second temperature rising step. It is configured to execute a rice cooking process including a rice cooker.

Advantages of the Invention

[0008] According to the present disclosure, the amount of starch eluted from the rice can be increased.

Brief Description of the Drawings

[0009]

Figure 1

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Figure 10

Mode for Carrying Out the Invention

[0010] <Findings on which the present disclosure is based> With the increasing trend towards health consciousness, the demand for foods with lower calories (lower heat content) than in the past has been increasing. While rice is a staple food in Asian countries including Japan, it contains a large amount of starch, which is a polysaccharide, and has a large amount of calories per unit weight. Therefore, without changing the rice used, the development of a rice cooker capable of reducing the calories of the cooked rice has been underway. For example, in the rice cooker described in Patent Document 1, the amount of calories of the cooked rice is reduced by removing the starch eluted from the rice into the liquid contained in the rice to be cooked together with the liquid. Specifically, in the discharging step, a part of the liquid contained in the rice to be cooked is discharged from the internal space of the pot to the outside of the pot by the discharging portion. As a result, the starch eluted into the liquid by the start of the discharging step is removed from the rice to be cooked.

[0011] However, in conventional rice cookers, little starch elutes from the rice into the liquid contained in the food to be cooked. Therefore, in the rice cooker described in Patent Document 1, there is a problem that the amount of starch removed from the food to be cooked by discharging the liquid is small, and the amount of reduction of saccharides in the cooked rice is small.

[0012] On the other hand, in general rice cooking that is not aimed at low-calorie cooked rice, the starch eluted into the liquid contained in the food to be cooked adheres to the rice as it approaches the end of cooking, thereby improving the taste of the cooked rice. From this, the fact that little starch elutes from the rice into the liquid contained in the food to be cooked is also a problem from the viewpoint of improving the taste of the cooked rice in general rice cooking. That is, in both general rice cooking and rice cooking aimed at low-calorie cooked rice, it is desired to increase the amount of starch eluting from the rice into the liquid contained in the food to be cooked.

[0013] Therefore, as a result of intensive studies to increase the amount of starch eluting from the rice, the present inventors newly found that the amount of starch eluting from the rice increases at an elution temperature higher than the preheating temperature and lower than about 100°C as compared with the temperature below the preheating temperature. Further, based on this finding, the present inventors conceived a configuration of a rice cooker provided with an elution promotion step of maintaining the food to be cooked at the elution temperature between the preheating step and the rice cooking maintenance step in the rice cooking process. According to this configuration, since the elution of starch from the rice into the liquid contained in the food to be cooked is promoted as compared with the rice cooking process without the elution promotion step, the amount of starch eluting from the rice can be increased. Based on the above novel finding, the present inventors have arrived at the following disclosure.

[0014] According to the first aspect of the present disclosure, a pot containing food to be cooked including rice and water, a heating unit that heats the pot, a lid that is openable and closable between a closed position that closes the opening of the pot and an open position where the opening is open, a temperature detection unit that detects the temperature of the food to be cooked, A control unit that controls the heating unit based on the detected temperature of the temperature detection unit, is provided, The control unit, a preheating step of heating the rice to be cooked and maintaining the detected temperature of the temperature detection unit at a preheating temperature; a first temperature rising step of raising the detected temperature from the preheating temperature to an elution temperature that is higher than the preheating temperature and lower than about 100°C; an elution promotion step of maintaining the detected temperature at the elution temperature to promote elution of starch from the rice; a second temperature rising step of raising the detected temperature from the elution temperature to about 100°C; a boiling maintenance step of maintaining boiling of the rice to be cooked after the second temperature rising step; is configured to execute a rice cooking process including: A rice cooker is provided.

[0015] According to a second aspect of the present disclosure, further includes a variety selection unit capable of selecting the variety of rice included in the rice to be cooked from a plurality of rice varieties, The control unit, in the elution promotion step, maintains the detected temperature at the elution temperature for a predetermined elution time, and is configured to change at least one of the elution time and the elution temperature according to the variety selected in the variety selection unit. A rice cooker according to the first aspect is provided.

[0016] According to a third aspect of the present disclosure, the control unit has a storage unit in which combinations of varieties selectable in the variety selection unit and the amylose content of rice are stored, The control unit, the lower the amylose content in the variety selected in the variety selection unit, the lower the elution temperature, and is configured to maintain the detected temperature at the elution temperature in the elution promotion step. A rice cooker according to the second aspect is provided.

[0017] According to a fourth aspect of the present disclosure, the variety selection unit is configured to be able to select the variety of rice included in the object to be cooked from a plurality of rice varieties including jasmine rice and basmati rice, the control unit, when jasmine rice is selected in the variety selection unit, lowers the elution temperature compared to when basmati rice is selected, is configured to maintain the detected temperature at the elution temperature in the elution promotion step. A rice cooker according to the second or third aspect is provided.

[0018] According to a fifth aspect of the present disclosure, a liquid discharge unit that is controlled by the control unit and discharges the liquid contained in the object to be cooked to the outside of the pot; a storage unit that is provided outside the pot and stores the liquid discharged from the internal space by the liquid discharge unit; further comprising, the control unit, executes a rice cooking process including the preheating step, the first temperature raising step, the elution promotion step, the second temperature raising step, the boiling maintenance step, and a steaming step of steaming the rice after the boiling maintenance step, in the elution promotion step or a step after the elution promotion step, is configured to control the liquid discharge unit to discharge the liquid contained in the object to be cooked to the storage unit one or more times, the liquid discharged to the storage unit is configured to be held in the storage unit until the end of the steaming step. A rice cooker according to any one of the first to fourth aspects is provided.

[0019] According to a sixth aspect of the present disclosure, further comprises a variety selection unit capable of selecting the variety of rice included in the object to be cooked from a plurality of rice varieties, the control unit, has a storage unit in which a combination of the varieties selectable in the variety selection unit and the amylose content of the rice is stored, The lower the amylose content in the variety selected by the variety selection unit, the more the number of times of discharging the liquid contained in the object to be cooked is increased. Provided is a rice cooker according to the fifth aspect.

[0020] According to the seventh aspect of the present disclosure, The rice cooker further includes a variety selection unit capable of selecting the variety of rice contained in the object to be cooked from a plurality of rice varieties. The control unit has a storage unit in which combinations of varieties selectable by the variety selection unit and the amylose content of rice are stored. The lower the amylose content in the variety selected by the variety selection unit, the shorter the time from the start of the elution promotion step to the start of the first discharge of the liquid contained in the object to be cooked is configured. Provided is a rice cooker according to the fifth or sixth aspect.

[0021] According to the eighth aspect of the present disclosure, The lid has an outer lid and an inner lid attached to the outer lid and closing the opening of the pot when the lid is in the closed position. The liquid discharge unit is provided in the inner lid, and has a communication hole that fluidly communicates the internal space and the outside of the pot when the lid is in the closed position, is provided in the inner lid, and is controlled by the control unit to move between a closed position for closing the communication hole and a communication position for opening the communication hole. and has The storage unit is provided in the inner lid and is configured to store the liquid discharged from the internal space to the outside of the pot through the communication hole. The control unit, in at least one of the second temperature raising step and the boiling maintaining step, while maintaining the pressure valve in the closed position, heats the pot by the heating unit to pressurize the internal space to a pressure higher than the atmospheric pressure. By moving the pressure valve to the communication position and reducing the pressure in the internal space from the pressurized pressure, at least a part of the liquid contained in the object to be cooked is discharged to the storage portion through the communication hole due to the pressure difference between the internal space and the outside of the pot. Provide a rice cooker according to any one of the fifth to seventh aspects.

[0022] According to the ninth aspect of the present disclosure, It further includes a variety selection unit capable of selecting the variety of rice contained in the object to be cooked from a plurality of rice varieties. The control unit, has a storage unit in which combinations of varieties selectable in the variety selection unit and the amylose content of rice are stored. The lower the amylose content of the variety selected in the variety selection unit, the lower the pressurized pressure, and the internal space is configured to be depressurized from the pressurized pressure. Provide a rice cooker according to the eighth aspect.

[0023] According to the tenth aspect of the present disclosure, It further includes a variety selection unit capable of selecting the variety of rice contained in the object to be cooked from a plurality of rice varieties including jasmine rice and basmati rice. When basmati rice is selected in the variety selection unit, the control unit is configured to increase the pressurized pressure compared to when jasmine rice is selected, and to depressurize the internal space from the pressurized pressure. Provide a rice cooker according to the eighth or ninth aspect.

[0024] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following description, terms indicating specific directions or positions (for example, terms including "up", "down", "right", "left", "front", "rear") are used based on the normal posture of the rice cooker with the lid in the closed position. However, the use of these terms is for facilitating the understanding of the present disclosure with reference to the drawings, and the technical scope of the present disclosure is not limited by the meanings of these terms. Further, the following description is merely illustrative in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0025] <First Embodiment> A rice cooker according to a first embodiment of the present disclosure will be described. FIG. 1 is a schematic cross-sectional view of the rice cooker according to the first embodiment of the present disclosure.

[0026] As shown in FIG. 1, the rice cooker according to the present embodiment includes a substantially bottomed cylindrical rice cooker main body 1 having a pot storage portion 11 formed therein, and a pot 2 stored in the pot storage portion 11 and containing an object to be cooked rice including rice and water. The pot 2 has a pot bottom portion 21, a peripheral wall portion 22 extending upward from the pot bottom portion 21, and a flange portion 23 extending outward from the upper edge of the peripheral wall portion 22. The upper edge of the peripheral wall portion 22 constitutes the upper opening of the pot 2.

[0027] An outer lid 3 having a hollow structure that can open and close the opening of the pot storage portion 11 is attached to the upper portion of the rice cooker main body 1. A substantially disk-shaped inner lid 4 that can seal the upper opening of the pot 2 is detachably attached to the lower surface side of the outer lid 3 (the side covering the upper opening of the pot 2). In the present embodiment, the outer lid 3 and the inner lid 4 constitute a lid that can open and close the upper opening of the pot 2 freely. The lid can be opened and closed between a closed position where the inner lid 4 closes the upper opening of the pot 2 and an open position where the upper opening of the pot 2 is opened.

[0028] The pot storage part 11 of the rice cooker main body 1 is formed in a concave shape that is recessed downward from the upper surface 1a of the rice cooker main body 1. The pot storage part 11 has a cylindrical side wall part 111 arranged so that a predetermined gap is formed with respect to the peripheral wall part 22 of the stored pot 2, and a bottom part 112 arranged so that a predetermined gap is formed with respect to the bottom part 21 of the pot 2. The upper surface 1a of the rice cooker main body 1 supports the flange part 23 of the pot 2 around the pot storage part 11.

[0029] In the rice cooker shown in FIG. 1, a heating part 5 for heating the pot 2 and the internal space SP1 of the pot 2 is attached. In this specification and the claims, the "internal space of the pot" means the space surrounded by the inner lid 4, the bottom part 21 of the pot, and the peripheral wall part 22 when the lid body is in the closed position. Further, the "outside of the pot" means a place outside the part of the inner lid 4 facing the internal space, the bottom part 21 of the pot, and the peripheral wall part 22 when the lid body is in the closed position.

[0030] The heating part 5 has an inner-bottom heating coil 51, an outer-bottom heating coil 52, a wall heating coil 53, and an inner-lid heating coil 54. The inner-bottom heating coil 51, the outer-bottom heating coil 52, and the wall heating coil 53 are provided inside the rice cooker main body 1 and inductively heat the pot 2. The inner-bottom heating coil 51 is arranged to face the periphery of the central part of the bottom part 21 of the pot 2 through the bottom part 112 of the pot storage part 11. The outer-bottom heating coil 52 is arranged to face the corner part of the bottom part 21 of the pot 2 through the bottom part 112. The wall heating coil 53 is arranged to face the peripheral wall part 22 of the pot 2 through the side wall part 111.

[0031] An opening is provided in the central part of the bottom part 112 of the pot storage part 11. A pot temperature sensor 12 for measuring the temperature of the pot 2 is arranged at the opening so as to be able to contact the bottom part 21 of the pot 2 stored in the pot storage part 11.

[0032] The temperature of the pot 2 detected by the pot temperature sensor 12 correlates with the temperature of the internal space SP1 of the pot 2. Therefore, based on the detected temperature of the pot temperature sensor 12, the temperature of the internal space SP1 can be estimated. Here, the temperature of the internal space SP1 is substantially the same as the temperature of the object to be cooked. For example, the temperature of the internal space SP1 is calculated by multiplying the detected temperature of the pot temperature sensor 12 by a correlation coefficient obtained experimentally. This calculation process is performed, for example, in the control unit 13 described later. In this case, the temperature of the object to be cooked is detected by the pot temperature sensor 12 and the control unit 13. The pot temperature sensor 12 and the control unit 13 are an example of the "temperature detection unit" in the present disclosure.

[0033] The outer lid 3 includes an upper outer member 31 and a lower outer member 32 that constitute the outer contour of the outer lid 3. A hinge member (not shown) is provided at the rear portion of the outer lid 3 to connect the lid body to the rice cooker main body 1 so as to be openable and closable between a closed position and an open position. The lid body opens and closes between the closed position and the open position by rotating about the hinge member.

[0034] The lower outer member 32 is provided with a recess 321 that is recessed upward at a position facing the inner lid 4 in the vertical direction. A lid body internal space SP2 is formed between the recess 321 and the inner lid 4. The lid body internal space SP2 is outside the pot 2. A steam passage 33 that fluidly communicates the lid body internal space SP2 and the outside of the rice cooker is connected to the top surface of the recess 321 facing the inner lid 4. The steam passage 33 has a first opening end 331 that opens to the top surface of the recess 321 and a second opening end 332 that opens to the upper outer member 31. Note that a steam cylinder having a cylindrical portion inserted into the steam passage 33 may be detachably attached from the upper outer member 31 side to the steam passage 33.

[0035] FIG. 2 is a perspective view of the inner lid in the rice cooker of FIG. 1. As shown in FIGS. 1 and 2, the inner lid 4 includes a substantially disk-shaped inner lid body 41, an annular pot packing 42 protruding downward from the peripheral edge of the inner lid body 41, and an annular outer lid packing 43 provided around the central portion in a plan view of the inner lid 4 and protruding upward. As shown in FIG. 1, the inner lid body 41 has an upper surface 41a facing the outer lid 3 when the inner lid 4 is attached to the outer lid 3, and a lower surface 41b which is the opposite surface. The pot packing 42 contacts the inner surface of the peripheral wall portion 22 of the pot 2 when the lid body is in the closed position. Thereby, the upper opening of the pot 2 is sealed by the inner lid 4. The outer lid packing 43 contacts the inner wall surface of the recess 321 when the inner lid 4 is attached to the outer lid 3. Thereby, the gap between the outer lid 3 and the inner lid 4 is sealed in the recess 321.

[0036] In the inner lid 4, a part of the inner portion of the outer lid packing 43 constitutes a storage portion 44 for storing the liquid discharged from the internal space SP1 to the lid body internal space SP2. In the present embodiment, the storage portion 44 is configured as a part of the inner lid body 41 and is flat. Specifically, the storage portion 44 is a portion of the inner lid body 41 that is not covered by a liquid receiving portion 45, which will be described later, among the outer lid packing 43.

[0037] The storage portion 44 is provided with a steam discharge hole 411 for discharging steam from the internal space SP1, and a communication hole 412 that enables fluid communication between the internal space SP1 and the lid body internal space SP2 when the lid body is in the closed position. A steam temperature sensor (not shown) for detecting the temperature of the steam in the lid body internal space SP2 or the steam passage 33 may be provided in the recess 321 or the steam passage 33.

[0038] The inner lid 4 has a pressure regulating valve 61 that can open and close the steam discharge hole 411. The pressure regulating valve 61 is a valve that suppresses the internal space SP1's pressure from rising above a predetermined value (e.g., 1.5 atmospheres) higher than the atmospheric pressure. In this embodiment, the pressure regulating valve 61 is composed of a closing member 611 that closes the steam discharge hole 411 and a spring 612 that biases the closing member 611 downward to close the steam discharge hole 411. According to this configuration, when the pressure in the internal space SP1 rises above a predetermined value higher than the atmospheric pressure, the closing member 611 moves upward against the biasing force of the spring 612 due to the pressure, and the steam discharge hole 411 is opened. On the other hand, when the pressure in the internal space SP1 drops below the predetermined value, the closing member 611 is biased by the spring 612 and moves downward to close the steam discharge hole 411 again. By repeating the opening and closing of the steam discharge hole 411, the pressure in the internal space SP1 is maintained below the predetermined value.

[0039] Note that the pressure regulating valve 61 may be composed of a ball and close the steam discharge hole 411 by its own weight. In this case, when the pressure in the internal space SP1 becomes greater than its own weight (e.g., when it becomes 1.5 atmospheres or more), the pressure regulating valve 61 is pushed only by the pressure in the internal space SP1, moves away from the steam discharge hole 411, and opens the steam discharge hole 411.

[0040] The inner lid 4 has a pressure valve 62 configured to be movable between a closed position that closes the communication hole 412 and a communication position that opens the communication hole 412. The communication hole 412 and the pressure valve 62 are an example of the "liquid discharge part" in the present disclosure. Usually, the pressure valve 62 is maintained in the closed position by a spring attached to the pressure valve 62. When the pressure valve 62 is in the closed position, the communication hole 412 is blocked, so the pressure in the internal space SP1 can rise to a predetermined value at which the steam discharge hole 411 is opened by the pressure regulating valve 61. On the other hand, when the pressure valve 62 is in the communication position, the communication hole 412 is opened, so the internal space SP1 is in fluid communication with the outside of the rice cooker via the communication hole 412, the inner space of the lid SP2, and the steam passage 33. Thereby, when the pressure valve 62 is in the communication position, the pressure in the internal space SP1 becomes the same atmospheric pressure as the outside of the rice cooker.

[0041] The outer lid 3 is provided with a pressure valve moving mechanism 63 that moves the pressure valve 62 between a closed position and a communication position. The pressure valve moving mechanism 63 is configured to press the pressure valve 62 downward and move it from the closed position to the communication position under the control of a control unit 13 described later. Thereby, the pressure in the internal space SP1 can be reduced from a pressure higher than the atmospheric pressure to the atmospheric pressure. As a specific configuration of the pressure valve moving mechanism 63, a conventionally known configuration can be adopted. When the pressing of the pressure valve 62 by the pressure valve moving mechanism 63 stops, the pressure valve 62 moves back to the closed position by a spring attached to the pressure valve 62.

[0042] As shown in FIGS. 1 and 2, when the inner lid 4 is attached to the outer lid 3, the inner lid 4 has a liquid receiving portion 45 that is located between the storage portion 44 and the hinge member of the outer lid 3 in a plan view of the inner lid 4. FIG. 2 shows the rotation axis A1 of the hinge member assuming a state where the inner lid 4 is attached to the outer lid 3. As shown in FIG. 2, the liquid receiving portion 45 is located between the storage portion 44 and the rotation axis A1 in the front-rear direction. Further, the liquid receiving portion 45 is located between the storage portion 44 and the rear portion 415 of the inner lid 4 in the front-rear direction. The liquid receiving portion 45 is configured to hold the liquid stored in the storage portion 44 when the lid body moves from the closed position to the open position.

[0043] As shown in FIG. 2, the liquid receiving portion 45 has a shape that is recessed from the storage portion 44 toward the hinge member along the front-rear direction of the rice cooker. In the present embodiment, the liquid receiving portion 45 has a substantially semicircular shape in a plan view of the inner lid 4 and is located biased toward the rear of the rice cooker inside the outer lid packing 43. The curved portion in the plan view of the liquid receiving portion 45 is located along the outer lid packing 43. On the other hand, the straight portion in the plan view of the liquid receiving portion 45 forms the opening surface 451 of the liquid receiving portion 45. The opening surface 451 extends in a direction intersecting the inner lid body 41 and is adjacent to the storage portion 44. Note that the shape of the liquid receiving portion 45 in the plan view may be circular, elliptical, polygonal, or the like.

[0044] The liquid receiving part 45 may be integrated with the inner lid main body 41 or may be detachable from the inner lid main body 41. In the present embodiment, the liquid receiving part 45 is detachably fixed to the upper surface 41a of the inner lid main body 41. By configuring the liquid receiving part 45 to be detachable from the inner lid main body 41, the cleanability inside the liquid receiving part 45 is improved.

[0045] As shown in FIG. 1, the inner lid heating coil 54 is provided inside the outer lid 3 having a hollow structure and is arranged so as to surround the recess 321 in a plan view of the outer lid 3. The inner lid heating coil 54 inductively heats the inner lid 4 including the storage part 44. When the inner lid 4 is heated by the inner lid heating coil 54, the internal space SP1 and the object to be cooked are also heated by the heat radiation from the inner lid 4.

[0046] In addition, the outer lid 3 is provided with a display operation part 34 that displays various information such as a rice cooking course and a rice cooking time, and can select a specific rice cooking course from a plurality of rice cooking courses such as a white rice course, a brown rice course, a white rice (soft) course, and a quick cooking course. In the present embodiment, at the display operation part 34, it is possible to select the variety of rice contained in the object to be cooked, that is, the variety of rice to be cooked, from a plurality of rice varieties. The display operation part 34 is an example of the "variety selection part" in the present disclosure. For example, the user can select the variety of rice to be cooked from the rice varieties shown in Table 1 via the display operation part 34. Table 1 below shows an example of rice varieties classified into three groups according to the amylose content of the rice.

[0047]

Table 1

[0048] High amylose rice is, for example, a group of varieties in which the amylose content in the entire components constituting the rice is 25% or more. Medium amylose rice is, for example, a group of varieties in which the amylose content is 17% or more and less than 25%. Low amylose rice is, for example, a group of varieties in which the amylose content is less than 17%.

[0049] Further, the display operation unit 34 may be configured to be able to select the amylose content of the rice to be cooked from three groups: high amylose rice, medium amylose rice, and low amylose rice shown in Table 1.

[0050] The display operation unit 34 includes, for example, a liquid crystal display that displays various information such as a cooking course and cooking time, and a plurality of buttons that, in addition to selecting a cooking course, instruct the execution of starting, canceling, reserving, etc. of cooking. While referring to the various information displayed on the liquid crystal display, the user can select a specific cooking course and cooking time with the plurality of buttons and instruct the start of cooking.

[0051] The rice cooker according to the present embodiment includes a pressure detection unit 35 that directly or indirectly detects the pressure in the internal space SP1. In the present embodiment, the pressure detection unit 35 is a pressure sensor provided on the outer lid 3. The pressure sensor is provided between the outer lid 3 and the inner lid 4, and measures the pressure in a pressure measurement space that is in fluid communication with the internal space SP1 through a hole portion (not shown) provided in the inner lid 4. The pressure sensor is, for example, an absolute pressure sensor, a gauge pressure sensor that indicates the pressure based on the atmospheric pressure, or a differential pressure sensor that indicates the differential pressure with respect to an arbitrary pressure (for example, the pressure outside the rice cooker).

[0052] A control unit 13 is mounted inside the rice cooker main body 1. The control unit 13 includes a storage unit that stores a plurality of cooking sequences for cooking rice. Here, the "cooking sequence" refers to a cooking procedure in which, when performing each process such as preheating, temperature increase, boiling maintenance, steaming, etc. in order, the energization time, heating temperature, heating time, heating output, etc. are determined in advance for each process.

[0053] In the present embodiment, the storage unit stores the combination of the rice varieties that can be selected by the display operation unit 34 and the amylose content of the rice in each variety. For example, as shown in Table 1, the storage unit stores the combination of three groups according to the amylose content and the rice varieties corresponding to each group. Note that the storage unit may store the combination of the rice variety and the numerical value of the amylose content of the variety.

[0054] Each rice cooking sequence corresponds to one of a plurality of rice cooking courses. The control unit 13 controls the heating unit 5 and the pressure valve moving mechanism 63 based on the rice cooking course selected by the display operation unit 34, the detected temperature of the pot temperature sensor 12, the hardness of the rice after cooking, and the detected pressure of the pressure detection unit 35, and executes the rice cooking process. Here, as described above, the control unit 13 can detect the temperature of the object to be cooked based on the detected temperature of the pot temperature sensor 12. Therefore, the control unit 13 can execute the rice cooking process based on the detected temperature of the object to be cooked.

[0055] Next, the operation of the pressure type rice cooker according to the present embodiment will be described. FIG. 3 is a graph showing the relationship between the detected temperature of the pot temperature sensor, the temperature of the object to be cooked, the pressure in the internal space, and the open / closed state of the pressure valve when rice cooking is performed by the rice cooker according to the first embodiment of the present disclosure.

[0056] First, the pot 2 containing the object to be cooked including rice and water is set in the pot storage unit 11 by the user. Thereafter, the user selects a rice cooking course and the amount of rice to be cooked using the display operation unit 34. For example, the rice cooking courses are provided for each rice variety shown in Table 1 and correspond to rice cooking sequences for performing rice cooking suitable for each variety. One rice cooking sequence may correspond to a plurality of rice cooking courses (that is, the varieties of rice to be cooked). For example, in any case where the rice cooking course for Koshihikari, Akitakomachi, Sasaniwaki, or Kirara 397 shown in Table 1 is selected, the control unit 13 may execute the rice cooking process based on the same rice cooking sequence suitable for medium amylose rice.

[0057] FIG. 3 shows an example of rice cooking when the rice cooking course corresponding to the medium amylose variety is selected by the display operation unit 34. After the selection of the rice cooking course or the rice cooking time and when rice cooking start is instructed, the rice cooking process is started under the control of the control unit 13. When the rice cooking process is started, first, the preheating process is started.

[0058] The preheating process is a process of immersing rice in water at a temperature lower than the gelatinization start temperature (about 60°C) so that the rice can be sufficiently gelatinized up to the central part of the rice in a later process, and allowing the rice to absorb water in advance. In the preheating process, the control unit 13 heats the object to be cooked rice via the pot 2, and controls the heating unit 5 so as to maintain the temperature of the object to be cooked rice detected based on the detected temperature of the pot temperature sensor 12 at a predetermined preheating temperature. The preheating temperature is, for example, lower than the gelatinization temperature of the rice, and is 50°C in the present embodiment. As shown in FIG. 3, after the control unit 13 drives the heating unit 5 to raise the temperatures of the pot 2 and the object to be cooked rice to 50°C, the control unit 13 adjusts the heating amount (for example, the amount of electric power) of the heating unit 5 so as to maintain the temperature of the object to be cooked rice at 50°C. The heating amount of the heating unit 5 is controlled, for example, by duty control.

[0059] Also, at the start of the preheating process, the control unit 13 moves the pressure valve 62 to the communication position, and controls the pressure valve moving mechanism 63 so as to maintain the pressure valve 62 at the communication position during the preheating process. Thereby, the communication hole 412 is maintained in an open state during the preheating process.

[0060] When a predetermined time elapses from the start of the preheating process according to the selected rice cooking course, the process proceeds to the first temperature rising process. In the example shown in FIG. 3, at the time when 14 minutes have elapsed since the start of rice cooking, the process has shifted from the preheating process to the first temperature rising process.

[0061] The first temperature rising process is a process of raising the temperature of the object to be cooked rice from the preheating temperature to the elution temperature. The elution temperature is a temperature at which the elution of starch from the rice into the liquid contained in the object to be cooked rice is promoted, and is higher than the preheating temperature and lower than about 100°C. The control unit 13 heats the pot 2 and controls the heating unit 5 so that the temperature of the object to be cooked rice rises to the elution temperature. Also, in the present embodiment, the control unit 13 controls the pressure valve moving mechanism 63 so as to maintain the pressure valve 62 at the communication position during the first temperature rising process. Thereby, the pressure in the internal space SP1 is continuously maintained at atmospheric pressure from the preheating process.

[0062] When the temperature of the cooked rice reaches the elution temperature, the process shifts from the first temperature increase step to the elution promotion step. In the example shown in Fig. 3, at the point when 17 minutes have elapsed since the start of rice cooking, the process has shifted from the first temperature increase step to the elution promotion step.

[0063] The elution promotion step is a step of promoting the elution of starch from rice by maintaining the temperature of the cooked rice at the elution temperature for a predetermined elution time T1. In the elution promotion step, the control unit 13 controls the heating amount of the heating unit 5 so as to maintain the temperature of the cooked rice at the elution temperature for the elution time T1. In the present embodiment, the control unit 13 controls the heating amount of the heating unit 5 so as to maintain the temperature of the cooked rice at 80°C, which is the elution temperature, for 15 minutes.

[0064] Here, the findings regarding the relationship between the starch elution amount from rice and the elution temperature will be described. Fig. 4 is a graph showing the starch elution amount from rice for each temperature of the cooked rice. Fig. 4 shows the starch elution amount (per 100 g of rice) when 475 g of water is added to 300 g of medium amylose rice and cooked at the gelatinization start temperature (60°C) or at 80 - 90°C for a certain period of time. As shown in Fig. 4, the elution amount when cooked at 80 - 90°C is increased by more than 5 times compared to the elution amount when cooked at the gelatinization start temperature. From this result, it is considered that in the rice cooking process, by cooking the rice at a temperature higher than the preheating temperature and lower than about 100°C, the starch elution amount from rice can be increased.

[0065] Fig. 5 is a graph showing the starch elution amount from rice with different amylose contents for each temperature of the cooked rice. Fig. 5 shows the starch elution amount (per 100 g of rice) when 475 g of water is added to 300 g each of low amylose rice, medium amylose rice, and high amylose rice and cooked at the gelatinization start temperature, 80°C, 85°C, and 90°C. As shown in Fig. 5, the elution amount in each variety is larger at 80°C, 85°C, and 90°C, which are the elution temperatures, than at 60°C, which is the gelatinization start temperature.

[0066] Focusing on low amylose rice and medium amylose rice, the starch elution amount increases as the temperature decreases within the range of elution temperature. From this, when cooking low amylose rice or medium amylose rice, from the perspective of maximizing the starch elution amount from the rice, it is considered better to lower the elution temperature within the range of the elution temperature. Specifically, in cooking rice of varieties belonging to low amylose rice or medium amylose rice, the elution temperature is preferably 85°C rather than 90°C, and more preferably 80°C.

[0067] On the other hand, focusing on high amylose rice, the starch elution amount increases as the temperature increases within the range of elution temperature, in contrast to low amylose rice and medium amylose rice. From this, when cooking high amylose rice, from the perspective of maximizing the starch elution amount from the rice, it is considered better to increase the elution temperature within the range of the elution temperature. Specifically, in cooking high amylose rice, the elution temperature is preferably 85°C rather than 80°C, and more preferably 90°C.

[0068] Figure 6 is a graph showing the starch elution amount from jasmine rice and basmati rice for each temperature of the object to be cooked. Figure 6 shows the starch elution amount (per 100 g of rice) when 475 g of water was added to 300 g each of jasmine rice, which is medium amylose rice, and basmati rice, which is high amylose rice, and cooked at the gelatinization start temperature, 80°C, 85°C, and 90°C. Similar to the results shown in Figure 5, the starch elution amount of jasmine rice, which is medium amylose rice, increases as the temperature decreases within the range of elution temperature. On the other hand, for basmati rice, which is high amylose rice, the starch elution amount increases as the temperature increases within the range of elution temperature.

[0069] Also, within the range of elution temperature, the elution amount from basmati rice is about 1 / 4 to 1 / 3 of the elution amount from jasmine rice. This is considered to be due to the fact that basmati rice contains more protein compared to jasmine rice. That is, in basmati rice, it is considered that the protein hinders the elution of starch.

[0070] Based on the above findings, in the rice cooker according to the present embodiment, the elution temperature and the elution time T1 are adjusted within a range higher than the preheating temperature and lower than about 100°C according to the variety of rice to be cooked or the amylose content in the variety.

[0071] The control unit 13 is configured to change at least one of the elution time T1 and the elution temperature according to the variety selected in the display operation unit 34. For example, the control unit 13 is configured to lower the elution temperature as the amylose content in the variety selected in the display operation unit 34 is lower. In the present embodiment, when medium amylose rice or low amylose rice is selected, the control unit 13 sets the elution temperature to 80°C, and when high amylose rice is selected, the control unit 13 sets the elution temperature to 90°C. By adjusting the elution temperature according to the amylose content of the rice to be cooked, the amount of starch eluted from the rice in the elution promotion step can be increased.

[0072] More specifically, the control unit 13 is configured to lower the elution temperature when jasmine rice is selected in the display operation unit 34 than when basmati rice is selected. In the present embodiment, when basmati rice is selected, the control unit 13 sets the elution temperature to 90°C, and when jasmine rice is selected, the control unit 13 sets the elution temperature to 80°C.

[0073] Also, for example, when a variety belonging to medium amylose is selected, the control unit 13 sets the elution time T1 to 15 minutes, and when a variety belonging to high amylose is selected, the control unit 13 sets the elution time T1 to 20 minutes. According to the above findings, when the temperature of the object to be cooked in the elution promotion step is restricted, the amount of starch eluted from the rice at that temperature varies depending on the amylose content of the rice. In such a case, by adjusting the elution time T1 according to the amylose content of the rice to be cooked, even when a variety of rice for which it is difficult for starch to elute at that temperature is cooked, the amount of starch eluted from the rice can be further increased.

[0074] When a predetermined elution time T1 has elapsed since the start of the elution promotion step, the process shifts from the elution promotion step to the second temperature increase step. In the example shown in FIG. 3, when 32 minutes have elapsed since the start of rice cooking, the process has shifted from the elution promotion step to the second temperature increase step.

[0075] The second temperature increase step is a step of heating the pot 2 with high heat until the temperature of the object to be cooked reaches about 100°C. In the second temperature increase step, the control unit 13 controls the heating unit 5 so that the pot 2 is rapidly heated and the temperature of the object to be cooked reaches about 100°C. In the present embodiment, the control unit 13 controls the heating unit 5 so that the temperature of the object to be cooked reaches 100°C. Note that the control unit 13 may control the heating unit 5 so that the temperature of the object to be cooked reaches a temperature near 100°C. The temperature near 100°C is, for example, a temperature within the range of 100 ± 5°C.

[0076] Also, the control unit 13 controls the pressure valve moving mechanism 63 so as to move the pressure valve 62 to the closed position at the start of the second temperature increase step and maintain it in the closed position during the second temperature increase step. Thereby, since the communication hole 412 is closed, the pressure in the internal space SP1 can rise to a predetermined pressure (for example, 1.5 atmospheres) at which the steam discharge hole 411 is opened by the vaporization of water in the internal space SP1 into steam.

[0077] When the temperature of the object to be cooked reaches about 100°C, the process shifts from the second temperature increase step to the boiling maintenance step. In the example shown in FIG. 3, when 35 minutes have elapsed since the start of rice cooking, the temperature of the object to be cooked reaches 100°C, and the process has shifted from the second temperature increase step to the boiling maintenance step.

[0078] The boiling maintenance step is a step of boiling and maintaining the liquid contained in the object to be cooked after the second temperature increase step. In the boiling maintenance step, the gelatinization of the rice further progresses, and the degree of gelatinization of the rice is raised to about 50 - 80%.

[0079] In the boiling maintenance process, the control unit 13 controls the pressure valve moving mechanism 63 so as to maintain the pressure valve 62 at the closed position until the pressure in the internal space SP1 rises to the pressurized pressure P1 higher than the atmospheric pressure. In the present embodiment, the pressurized pressure P1 is 1.2 atmospheres. The boiling point of the liquid contained in the rice to be cooked rises as the pressure in the internal space SP1 rises. The control unit 13 controls the heating unit 5 so that the temperature of the rice to be cooked approaches the boiling point of water at the pressure in the internal space SP1.

[0080] In the example shown in FIG. 3, the pressure in the internal space SP1 reaches 1.2 atmospheres, which is the pressurized pressure P1, 36 minutes after the start of rice cooking. After the pressure in the internal space SP1 reaches the pressurized pressure P1, the control unit 13 maintains the pressure in the internal space SP1 at the pressurized pressure P1 for a predetermined time T2. In the present embodiment, the predetermined time T2 is 5 minutes. Specifically, the control unit 13 repeatedly moves the pressure valve 62 between the closed position and the communication position so that the detected pressure of the pressure detection unit 35 becomes the pressurized pressure P1. In FIG. 3, the state in which the pressure valve 62 repeatedly moves between the closed position and the communication position to keep the pressure in the internal space SP1 constant is shown at the "adjustment" position.

[0081] When the predetermined time T2 elapses, the control unit 13 controls the pressure valve moving mechanism 63 to move the pressure valve 62 to the communication position. As a result, the communication hole 412 is opened, and the internal space SP1 is depressurized from the pressurized pressure P1 to the atmospheric pressure.

[0082] The state of the internal space SP1 before and after the start of the depressurization will be described with reference to FIGS. 7 and 8. FIG. 7 is a schematic cross-sectional view showing the state of the liquid and rice in the pot before the depressurization in the boiling maintenance process. FIG. 8 is a schematic cross-sectional view showing the state of the liquid and rice in the pot during the depressurization in the boiling maintenance process.

[0083] As shown in FIG. 7, in the internal space SP1 before the depressurization, the entire rice contained in the rice to be cooked is covered with bubbles formed by the liquid contained in the rice to be cooked. In FIG. 7, the upper surface 72 of the bubble is shown by a solid line.

[0084] When the depressurization of the internal space SP1 starts, the liquid contained in the rice to be cooked is sucked toward the communication hole 412 due to the pressure difference between the internal space SP1 and the internal space SP2 of the lid. Also, as the internal space SP1 is depressurized, the boiling point of the liquid contained in the rice to be cooked drops rapidly. As a result, the liquid present in the internal space SP1 becomes a state of bumping boiling where a large amount of bubbles are generated. As a result, as shown in FIG. 8, the upper surface of the liquid present in the internal space SP1 (for example, the upper surface 72 of the bubbles) moves upward from the position before depressurization shown in FIG. 7.

[0085] As a result of the above-described suction and bumping boiling, at least a part of the liquid contained in the rice to be cooked enters the internal space SP2 of the lid through the communication hole 412 as shown in FIG. 8. That is, at least a part of the liquid contained in the rice to be cooked is discharged to the outside of the pot 2. On the other hand, since the pressure in the internal space SP2 of the lid is lower than the pressurizing pressure P1 (for example, atmospheric pressure), further upward movement of the liquid is suppressed. As a result, the liquid that has entered the internal space SP2 of the lid is stored in the storage portion 44.

[0086] Also, the rice contained in the rice to be cooked is sucked toward the communication hole 412 together with the liquid during depressurization and moves upward in the internal space SP1. At this time, the rice contained in the rice to be cooked is in a state where gelatinization has progressed and has viscosity on the surface, and adheres to adjacent grains of rice or the inner surface of the pot 2. Therefore, when the whole rice is pulled upward, as shown in FIG. 8, the upper surface 71 of the rice moves upward and the gaps between the grains of rice expand.

[0087] Also, due to the bumping boiling of the liquid caused by depressurization, the water located in the gaps between the grains of rice greatly increases its volume during the process of vaporizing into steam and rapidly flows upward through the gaps between the grains of rice. Due to this flow of steam, the gaps between the grains of rice are further expanded.

[0088] When the liquid contained in the object to be cooked rice is discharged to the outside of the rice cooker 2 (for example, the storage unit 44) during the rice cooking process, the ratio of the weight of water to the weight of rice in the object to be cooked rice (water addition ratio) may be larger than the appropriate water addition ratio in the dry cooking method. For example, when cooking rice with an appropriate water addition ratio of 1.5 in the dry cooking method using the rice cooker according to this embodiment, the water addition ratio may be 2.0. Further, the water addition ratio may be changed according to the size (for example, storage volume) of the storage unit 44 within a range larger than the appropriate water addition ratio in the dry cooking method.

[0089] During the depressurization of the internal space SP1, the suction to the communication hole 412 and the bumping boiling in the internal space SP1 weaken as the pressure in the internal space SP1 approaches the atmospheric pressure. Thereby, the moving speed of the liquid from the internal space SP1 to the storage unit 44 also decreases.

[0090] In this embodiment, the control unit 13 controls the pressure valve moving mechanism 63 so as to move the pressure valve 62 to the communication position and then maintain it at the communication position. The pressure in the internal space SP1 reaches the atmospheric pressure 30 seconds after the pressure valve 62 moves to the communication position. When the pressure in the internal space SP1 reaches the atmospheric pressure, the depressurization in the boiling maintenance process ends.

[0091] Here, the rice cooker according to this embodiment is configured to hold the liquid stored in the storage unit 44 until the end of the steaming process, that is, until the end of the rice cooking process. Thereby, since the liquid once discharged to the outside of the rice cooker 2 does not return to the object to be cooked rice, the starch eluted in the liquid is removed from the object to be cooked rice, and the cooking of low-calorie rice is realized.

[0092] For example, the upper opening of the communication hole 412 may be located above the upper surface 41a of the inner lid body 41. In this case, the liquid stored in the storage portion 44 cannot enter the communication hole 412 unless it moves upward above the upper opening of the communication hole 412 against gravity. Therefore, even when the pressure difference between the internal space SP1 and the lid internal space SP2 is small, it is possible to suppress the liquid stored in the storage portion 44 from returning to the internal space SP1 through the open communication hole 412.

[0093] Also, for example, the control unit 13 may control the pressure valve moving mechanism 63 to return the pressure valve 62 to the closed position again when the pressure in the internal space SP1 has dropped to atmospheric pressure or before that point in time. In this case, since the communication hole 412 is closed when the pressure difference between the internal space SP1 and the lid internal space SP2 becomes small, it is possible to suppress the liquid stored in the storage portion 44 from returning to the internal space SP1 after decompression.

[0094] Due to the movement of the liquid in the storage portion 44 due to decompression and the vaporization due to bumping boiling, in the internal space SP1 after decompression, most of the liquid contained in the rice to be cooked is lost. When most of the water contained in the rice to be cooked is lost from the internal space SP1, the temperature of the bottom portion 21 of the pot 2 can rise above the boiling point of water corresponding to the pressure in the internal space SP1. When it is detected that the detected temperature of the pot temperature sensor 12 has reached a predetermined temperature (for example, 130°C) above the boiling point, or when a predetermined time corresponding to the selected rice cooking course has elapsed since the start of the boiling maintenance step, the steaming step is entered. In the example shown in FIG. 3, at the point in time when 44 minutes have elapsed since the start of rice cooking, the detected temperature of the pot temperature sensor 12 has reached 130°C, and the process has shifted from the boiling maintenance step to the steaming step.

[0095] The steaming step is a step of evaporating excess moisture using the residual heat and steaming the rice. The control unit 13 controls the pressure valve moving mechanism 63 to maintain the pressure valve 62 in the communication position until the end of the steaming step, that is, until the end of the rice cooking step.

[0096] Further, in the steaming process, the control unit 13 stops the heating operations of the inner-bottom heating coil 51, the outer-bottom heating coil 52, and the wall heating coil 53 that heat the pot 2. Alternatively, the control unit 13 controls the heating amounts of the inner-bottom heating coil 51, the outer-bottom heating coil 52, and the wall heating coil 53 so as to maintain the temperature of the pot 2 at 100°C.

[0097] On the other hand, in the steaming process, the control unit 13 controls the heating amount of the inner lid heating coil 54 so that the temperature of the storage unit 44 is maintained at 100°C or higher. When the temperature of the storage unit 44 is 100°C or higher, the liquid stored in the storage unit 44 vaporizes in the inner lid space SP2 and is discharged to the outside of the rice cooker through the steam passage 33 (see FIG. 1). As a result, the liquid stored in the storage unit 44 decreases as the steaming process progresses. Here, in the steaming process, the amount of heat required to be applied to the pot 2 is small, and the power consumption of the inner-bottom heating coil 51, the outer-bottom heating coil 52, and the wall heating coil 53 that heat the pot 2 is small. Therefore, a large amount of power can be allocated to the inner lid heating coil 54 within the range of power available in the rice cooker. Therefore, in the steaming process, the liquid stored in the storage unit 44 can be vaporized with high power efficiency.

[0098] The steaming process ends when a predetermined time has elapsed since the start of the steaming process. Thereby, all the rice cooking processes are completed. In the present embodiment, the steaming process is performed for 4 minutes, and all the rice cooking processes are completed when 48 minutes have elapsed since the start of rice cooking.

[0099] After the rice cooking is completed, the lid is opened to the open position by the user in order to take out the cooked rice. FIG. 9 is a perspective view showing the inner lid of FIG. 2 when the lid is in the closed position and the open position. When the lid is in the closed position, the storage unit 44 and the liquid receiving unit 45 are located at substantially the same height in the vertical direction and are adjacent to each other in the front-rear direction. Therefore, in the inner lid space SP2, the liquid is stored straddling the inside of the storage unit 44 and the liquid receiving unit 45.

[0100] When the lid is opened toward the open position as indicated by the arrow in FIG. 9, the storage portion 44 moves upward relative to the liquid receiving portion 45. Further, the substantially disk-shaped inner lid body 41 is inclined such that the front portion 414 of the inner lid body 41 is positioned above the rear portion 415. Thereby, the liquid stored in the storage portion 44 flows on the upper surface 41a of the inner lid body 41 and is accommodated in the liquid receiving portion 45 through the opening surface 451. Therefore, when the lid is opened, it is possible to suppress the liquid stored in the storage portion 44 from leaking to the outside of the lid.

[0101] According to the rice cooker according to the present embodiment, the control unit 13 executes a rice cooking process having an elution promotion process between the preheating process and the boiling maintenance process. In the elution promotion process, the control unit 13 maintains the object to be cooked at an elution temperature higher than the preheating temperature and lower than about 100°C. Thereby, it is possible to promote the elution of starch from the rice into the liquid contained in the object to be cooked as compared with the case where the preheating process is continued for the time corresponding to the elution promotion process. Therefore, the amount of starch eluting into the liquid can be increased.

[0102] In rice cooking in which the liquid contained in the object to be cooked is not actively discharged, the amount of starch adhering to the rice increases due to an increase in the amount of starch eluting into the liquid. Thereby, when the rice is put into the mouth, sweetness can be easily felt and the taste of the rice is improved.

[0103] The ease of elution of starch from rice varies depending on the variety of rice. According to the rice cooker according to the present embodiment, at least one of the elution time T1 and the elution temperature in the elution promotion process is changed according to the variety of rice selected on the display operation unit 34. Thereby, the elution time T1 and the elution temperature can be adjusted according to the ease of elution of starch in the rice to be cooked. Therefore, the amount of starch eluting into the liquid contained in the object to be cooked can be further increased.

[0104] As described above, the inventors of the present invention have clarified that the temperature at which the amount of eluted starch increases varies depending on the amylose content of rice. According to the rice cooker according to the present embodiment, the elution temperature in the elution promotion step is within a range higher than the preheating temperature and lower than about 100°C, and is made lower as the amylose content of the rice to be cooked is lower. Thereby, even if the variety of the rice to be cooked is various, the amount of starch eluted into the liquid contained in the object to be cooked can be increased.

[0105] For example, the elution temperature when cooking jasmine rice is made lower than the elution temperature when cooking basmati rice. Thereby, compared with the case where the elution promotion step is performed at a constant elution temperature (for example, the elution temperature when cooking basmati rice) regardless of the variety of the rice to be cooked, the amount of starch eluted into the liquid contained in the object to be cooked during the cooking of jasmine rice can be further increased.

[0106] In contrast, the elution temperature when cooking basmati rice is made higher than the elution temperature when cooking jasmine rice. Thereby, compared with the case where the elution promotion step is performed at a constant elution temperature (for example, the elution temperature when cooking jasmine rice) regardless of the variety of the rice to be cooked, the amount of starch eluted into the liquid contained in the object to be cooked during the cooking of basmati rice can be further increased.

[0107] Further, according to the rice cooker according to the present embodiment, the liquid contained in the object to be cooked is discharged from the internal space SP1 to the storage unit 44 in the elution promotion step or a step subsequent to the elution promotion step. The liquid discharged to the storage unit 44 is held in the storage unit 44 until the end of the steaming step, that is, until the end of the rice cooking step. Thereby, in the elution promotion step, the starch eluted into the liquid contained in the object to be cooked can be removed from the object to be cooked. Therefore, more starch can be removed from the object to be cooked, and the calorie content of the cooked rice can be reduced.

[0108] Further, according to the rice cooker according to the present embodiment, due to the pressure difference between the internal space SP1 and the internal space SP2 of the lid, the liquid contained in the object to be cooked is discharged from the internal space SP1 to the storage portion 44. According to this configuration, it is possible to discharge the liquid without newly providing a member such as a pump for sucking the liquid from the internal space SP1. Therefore, while suppressing the increase in size and the complexity of the structure of the rice cooker, it is possible to reduce the starch contained in the object to be cooked and reduce the calorie content of the cooked rice.

[0109] <Second Embodiment> With reference to FIG. 10, the rice cooker according to the second embodiment of the present disclosure will be described. FIG. 10 is a graph showing the relationship between the detected temperature of the pot temperature sensor, the temperature of the object to be cooked, the pressure in the internal space, and the open / closed state of the pressure valve when cooking is performed by the rice cooker according to the second embodiment of the present disclosure. In FIG. 10, different from the example shown in FIG. 3, an example of cooking is shown when a rice cooking course corresponding to the variety of low amylose rice is selected by the display operation unit 34.

[0110] The rice cooker according to the second embodiment is different from the rice cooker according to the first embodiment in that the discharge of the liquid contained in the object to be cooked is performed twice from the second temperature rising step to the boiling maintaining step. In the following description of the second embodiment, the same components as those of the rice cooker according to the first embodiment may be denoted by the same reference numerals and the description thereof may be omitted.

[0111] As shown in FIG. 10, at the start of the second temperature rising step (the 32-minute time point in FIG. 10), the control unit 13 controls the pressure valve moving mechanism 63 to move the pressure valve 62 to the closed position. As a result, the communication hole 412 is closed, and the pressure in the internal space SP1 rises from the atmospheric pressure.

[0112] When the pressure in the internal space SP1 reaches the pressurizing pressure P1 in the second temperature rising process, the control unit 13 controls the pressure valve moving mechanism 63 to move the pressure valve 62 to the communication position. As a result, the first decompression occurs in the internal space SP1, and a part of the liquid contained in the object to be cooked is discharged to the storage unit 44. In the example shown in FIG. 10, the pressure in the internal space SP1 reaches 1.2 atmospheres, which is the pressurizing pressure P1, 1 minute and 30 seconds after the start of the second temperature rising process (at the 33 minute and 30 second time point from the start of cooking).

[0113] Here, in the cooking of low amylose rice shown in FIG. 10, compared with the cooking of medium amylose rice shown in FIG. 3, the time T3 from the start of the elution promotion process to the start of the first discharge of the liquid contained in the object to be cooked is shorter. That is, in the cooking of low amylose rice, the first discharge is accelerated. Specifically, the time T3 is 24 minutes in the cooking of medium amylose rice (see FIG. 3), while it is 16 minutes and 30 seconds in the cooking of low amylose rice (see FIG. 10).

[0114] Thus, the control unit 13 may be configured to shorten the time from the start of the elution promotion process to the start of the first discharge of the liquid contained in the object to be cooked as the amylose content in the variety selected on the display operation unit 34 is lower.

[0115] After the start of decompression, when the pressure in the internal space SP1 drops to atmospheric pressure or before that time point, the control unit 13 controls the pressure valve moving mechanism 63 to return the pressure valve 62 to the closed position again. As a result, the communication hole 412 is closed, and the first decompression in the internal space SP1 ends. In the present embodiment, the control unit 13 controls to return the pressure valve 62 to the closed position 30 seconds after the start of decompression (at the 34 minute time point from the start of cooking). When the communication hole 412 is closed, the pressure in the internal space SP1 turns to rise again.

[0116] As shown in Fig. 10, the temperature of the rice to be cooked reaches 100°C at the 35th minute from the start of cooking, and shifts from the second temperature rising step to the boiling maintaining step, similar to the example shown in Fig. 3. After the pressure in the internal space SP1 reaches the pressurizing pressure P1 again (at the 36th minute in Fig. 10), the control unit 13 maintains the pressure in the internal space SP1 at 1.2 atm, which is the pressurizing pressure P1, for 3 minutes. That is, in this embodiment, the predetermined time T2 is 3 minutes.

[0117] When the predetermined time T2 has elapsed, the control unit 13 controls the pressure valve moving mechanism 63 to move the pressure valve 62 to the communication position. As a result, the communication hole 412 is opened, and the second depressurization in the internal space SP1 is performed. That is, the second discharge of the liquid contained in the rice to be cooked is performed.

[0118] Here, the depressurization in the internal space SP1 was once in the cooking of medium amylose rice shown in Fig. 3, while it is twice in the cooking of low amylose rice shown in Fig. 10. Thus, the control unit 13 may be configured to increase the number of discharges of the liquid contained in the rice to be cooked as the amylose content in the variety selected on the display operation unit 34 is lower.

[0119] Also, the control unit 13 may lower the pressurizing pressure P1 as the amylose content in the variety selected on the display operation unit 34 is lower. For example, when medium amylose rice is selected, the control unit 13 may set the pressurizing pressure P1 to 1.2 atm, and when low amylose rice is selected, the control unit 13 may set the pressurizing pressure P1 to 1.1 atm.

[0120] The liquid contained in the rice to be cooked gradually becomes viscous due to the elution of starch from the rice. The viscosity of the liquid increases as the amylose content of the rice is lower. Therefore, when the amylose content of the rice to be cooked is low, the liquid to be discharged is likely to cause clogging in the discharge path (for example, the communication hole 412) from the internal space SP1 to the storage unit 44.

[0121] According to the rice cooker according to the present embodiment, the number of times of discharging the liquid contained in the object to be cooked increases as the amylose content of the rice to be cooked is lower. When discharging a certain amount of the liquid, the larger the number of times of discharging the liquid, the smaller the discharge amount per discharge. Thereby, when the amylose content of the rice to be cooked is low and the viscosity of the liquid contained in the object to be cooked is high, it is possible to suppress the liquid from causing clogging of the discharge path. Therefore, the liquid contained in the object to be cooked can be discharged more reliably by the desired amount.

[0122] Also, according to the rice cooker according to the present embodiment, the time T3 from the start of the elution promotion step to the start of the first discharge of the liquid contained in the object to be cooked is shortened as the amylose content of the rice to be cooked is lower. That is, in the rice cooking step, the first discharge of the liquid is performed earlier as the amylose content of the rice to be cooked is lower. Thereby, when the amylose content of the rice to be cooked is low, the liquid contained in the object to be cooked can be discharged while its viscosity is relatively low. Therefore, it is possible to suppress the liquid from causing clogging of the discharge path.

[0123] Also, according to the rice cooker according to the present embodiment, the pressurizing pressure P1 before depressurization is lowered as the amylose content of the rice to be cooked is lower. That is, in the rice cooking step, the pressure difference between the internal space SP1 and the outside of the pot 2 before depressurization is reduced as the amylose content of the rice to be cooked is lower. Thereby, the discharge amount per discharge of the liquid contained in the object to be cooked is reduced, and the time required for one discharge is shortened. Therefore, it is possible to suppress the liquid from causing clogging of the discharge path.

[0124] Further, the control unit 13 may increase the pressurizing pressure P1 when basmati rice is selected in the display operation unit 34 compared to when jasmine rice is selected. For example, when basmati rice is selected, the control unit 13 may set the pressurizing pressure P1 to 1.25 atm, and when jasmine rice is selected, the control unit 13 may set the pressurizing pressure P1 to 1.05 atm.

[0125] In the cooking of basmati rice, compared with the cooking of other varieties of rice, amylose is less likely to elute from the rice into water. This is thought to be due to the fact that basmati rice contains more protein than other varieties of rice. In fact, the protein content of basmati rice is higher than that of jasmine rice, which belongs to the same indica rice. As a method of increasing the amount of starch eluted from basmati rice, it is conceivable to increase the elution time T1 in the elution promotion step. However, if the elution time T1 is lengthened, the time required for cooking rice will be prolonged, which may impair the convenience of the rice cooker as a cooking appliance.

[0126] According to the rice cooker according to this embodiment, the pressurization pressure P1 when basmati rice is cooked is made higher than the pressurization pressure P1 when jasmine rice is cooked. The higher the pressure in the internal space SP1, the higher the boiling point of the liquid contained in the object to be cooked. Therefore, when basmati rice is cooked, the temperature of the liquid contained in the object to be cooked before depressurization, that is, the temperature of the liquid before discharge, becomes higher. As a result, the denaturation and decomposition of the protein contained in basmati rice further progress, and the starch becomes more likely to elute. Therefore, it is possible to further promote the elution of starch from basmati rice into water while suppressing the prolongation of the cooking time.

[0127] Note that the present disclosure is not limited to the above-described embodiment, and can be implemented in various other modes. For example, in the above, in at least one of the second temperature-rising step and the boiling-maintaining step, the liquid contained in the object to be cooked is discharged from the internal space SP1 by the pressure difference between the internal space SP1 and the internal space SP2 of the lid body. However, the present disclosure is not limited to this. For example, in general rice cooking where the purpose is not to cook low-calorie rice, the above discharge may not be performed. Even when the discharge is not performed, since the starch eluting into the liquid contained in the object to be cooked increases, the starch adhering to the cooked rice increases, and thus the effect of improving the taste of the rice can be obtained.

[0128] Also, when discharging the liquid, the rice cooker may include a liquid discharge unit such as an electric pump that sucks the liquid contained in the rice to be cooked. In this case, even when the pressure difference between the internal space SP1 and the outside of the pot 2 is small or non-existent, the liquid contained in the rice to be cooked can be discharged from the internal space SP1. Therefore, the control unit 13 can control the liquid discharge unit so as to discharge the liquid contained in the rice to be cooked to the storage unit one or more times in the elution promotion step or any step after the elution promotion step.

[0129] Also, in the above, the control unit 13 is configured to control the pressure valve moving mechanism 63 to maintain the pressure valve 62 in the communication position after the final depressurization in the rice cooking process. However, the present disclosure is not limited to this. For example, the control unit 13 may control the pressure valve moving mechanism 63 to return the pressure valve 62 to the closed position again after the start of the depressurization. In this case, in the rice cooking process after the depressurization, the boiling point of the water contained in the rice to be cooked can be made higher than 100°C, so more heat can be applied to the rice.

[0130] Also, in the first embodiment, the control unit 13 is configured to move the pressure valve 62 to the communication position when a predetermined time T2 has elapsed after the pressure in the internal space SP1 reaches the pressurization pressure P1. However, the present disclosure is not limited to this. The timing for moving the pressure valve 62 to the communication position for depressurization may be, for example, when a predetermined time has elapsed since the start of the boiling maintenance step, or when the detected temperature of the pot temperature sensor 12 reaches a predetermined temperature. Also, the timing may be when the rising speed of the detected temperature of the pot temperature sensor 12 becomes a predetermined speed or more, or when the rising speed of the detected pressure of the pressure detection unit 35 becomes less than a predetermined speed. Also, the predetermined time T2 may be 0 seconds. That is, the control unit 13 may move the pressure valve 62 to the communication position when the detected pressure of the pressure detection unit 35 reaches the pressurization pressure P1.

[0131] Also, in the second embodiment, the control unit 13 is configured to move the pressure valve 62 to the communication position when the pressure in the internal space SP1 reaches the pressurizing pressure P1. However, the present disclosure is not limited to this. The timing for moving the pressure valve 62 to the communication position for decompression may be, for example, when a predetermined time has elapsed since the start of the second temperature increase step, or when the detected temperature of the pot temperature sensor 12 reaches a predetermined temperature.

[0132] Also, in the second embodiment, the control unit 13 is configured to control the pressure valve 62 to return to the closed position 30 seconds after the start of decompression in the second temperature increase step. However, the present disclosure is not limited to this. For example, the predetermined time until the control for returning the pressure valve 62 to the closed position is performed after the start of decompression may be an assumed time required for the pressure drop from the pressurizing pressure P1 to the atmospheric pressure obtained by experiments, or a time shorter than the assumed time. Also, for example, the control unit 13 may move the pressure valve 62 to the closed position when the detected pressure of the pressure detection unit 35 reaches the atmospheric pressure or a predetermined pressure greater than the atmospheric pressure.

[0133] Also, in the second embodiment, the discharge of the liquid contained in the object to be cooked is performed twice in total in both the second temperature increase step and the boiling maintenance step. However, the present disclosure is not limited to this. The discharge of the liquid may be performed, for example, only in the second temperature increase step and not in the boiling maintenance step. Also, the number of discharges of the liquid may be three or more.

[0134] Also, in the above, the control unit 13 is configured to control the inner lid heating coil 54 to heat the storage unit 44 in the steaming step and vaporize the liquid stored in the storage unit 44. However, the present disclosure is not limited to this. For example, the control unit 13 may control the inner lid heating coil 54 to heat the storage unit 44 after the start of decompression in the boiling maintenance step and vaporize the liquid stored in the storage unit 44.

[0135] Also, in the above description, the storage portion 44 is configured as a part of the inner lid body 41 and is flat, but the present disclosure is not limited to this. For example, the storage portion 44 may be provided as a recess in which a part of the inner lid body 41 is recessed downward. At this time, the communication hole 412 may be located outside the storage portion 44 in a plan view of the inner lid 4. In this case, the liquid stored inside the storage portion 44 cannot reach the communication hole 412 unless it moves upward against gravity while the lid body is in the closed position. Thereby, even when the communication hole 412 is maintained in an open state after the decompression, it is possible to suppress the liquid stored in the storage portion 44 from returning to the internal space SP1.

[0136] Also, in the above description, the heating portion 5 is a coil that inductively heats the pot 2, but for example, it may be an electric heater.

[0137] Also, in the above description, the temperature of the internal space SP1 is estimated based on the detected temperature of the pot temperature sensor 12, but the present disclosure is not limited to this. For example, the rice cooker may include a temperature detection sensor disposed between the outer lid 3 and the pot 2 instead of or in addition to the pot temperature sensor 12. In this case, the temperature of the internal space SP1 may be directly measured by the temperature detection sensor.

[0138] Also, in the above description, the pressure detection portion 35 is a pressure sensor that directly measures the pressure of the internal space SP1, but the present disclosure is not limited to this. For example, the pressure detection portion 35 may be built in the control portion 13 and may be a pressure estimation portion that estimates the pressure of the internal space SP1 based on the detected temperature of the pot temperature sensor 12 or the temperature detection sensor. In this case, the pressure estimation portion estimates the pressure of the internal space SP1 based on the saturated vapor pressure of water at various temperatures stored in the memory of the control portion 13 and the detected temperature.

[0139] By appropriately combining any of the various embodiments or variations thereof, it is possible to achieve the respective effects. Also, combinations of embodiments with each other, combinations of examples with each other, or combinations of an embodiment and an example are possible, and combinations of features from different embodiments or examples are also possible.

[0140] This disclosure has been fully described in connection with preferred embodiments with reference to the accompanying drawings, but various modifications and alterations will be apparent to those skilled in the art. Such modifications and alterations should be understood to be included therein as long as they do not depart from the scope of this disclosure as defined by the appended claims.

Industrial Applicability

[0141] According to this disclosure, since the amount of starch eluted from rice can be increased, it is useful in household or commercial rice cookers, or cooking appliances having a rice cooking function.

Explanation of Signs

[0142] 1 Rice cooker main body 1a Upper surface 2 Pot 3 Outer lid 4 Inner lid 5 Heating section 11 Pot storage section 12 Pot temperature sensor 13 Control section 21 Bottom of the pot 22 Peripheral wall section 23 Flange section 31 Upper outer housing member 32 Lower outer housing member 33 Steam passage 34 Display operation section 35 Pressure detection section 41 Inner lid main body 41a Upper surface 41b Lower surface 42 Pot packing 43 Outer lid packing 44 Reservoir 45 Liquid receiving part 51 Bottom inner heating coil 52 Bottom outer heating coil 53 Wall heating coil 54 Inner lid heating coil 61 Pressure regulating valve 62 Pressure valve 63 Pressure valve moving mechanism 71 Upper surface of rice 72 Upper surface of bubbles 111 Side wall part 112 Bottom part 321 Recess 331 First opening end 332 Second opening end 411 Steam discharge hole 412 Communication hole 414 Front part 415 Rear part 451 Opening surface 611 Closing member 612 Spring SP1 Internal space SP2 Inner space of lid

Claims

1. A pot containing the rice to be cooked, which contains rice and water, A heating unit for heating the pot, A lid that can be opened and closed between a closed position closing the opening of the pot and an open position where the opening is released, A temperature detection unit for detecting the temperature of the rice to be cooked, A control unit for controlling the heating unit based on the detected temperature of the temperature detection unit, and is provided with The control unit A preheating step of heating the rice to be cooked and maintaining the detected temperature of the temperature detection unit at a preheating temperature, A first temperature rising step of raising the detected temperature from the preheating temperature to an elution temperature that is higher than the preheating temperature and lower than about 100°C, An elution promotion step of maintaining the detected temperature at the elution temperature to promote the elution of starch from the rice, A second temperature rising step of raising the detected temperature from the elution temperature to about 100°C, After the second temperature rising step, a boiling maintenance step of maintaining the boiling of the rice to be cooked, and is configured to execute a rice cooking process including A rice cooker.

2. It further includes a variety selection unit capable of selecting the variety of rice included in the rice to be cooked from a plurality of rice varieties, The control unit In the elution promotion step, the detected temperature is maintained at the elution temperature for a predetermined elution time, and is configured to change at least one of the elution time and the elution temperature according to the variety selected in the variety selection unit, The rice cooker according to Claim 1.

3. The control unit has a storage unit in which the combination of the varieties selectable in the variety selection unit and the amylose content of the rice is stored, The control unit The lower the amylose content in the variety selected by the variety selection unit, the lower the elution temperature. In the elution promotion step, the detection temperature is maintained at the elution temperature. The rice cooker according to claim 2.

4. The variety selection unit is configured to be able to select the variety of rice included in the object to be cooked from a plurality of rice varieties including jasmine rice and basmati rice. The control unit When jasmine rice is selected in the variety selection unit, the elution temperature is set lower than when basmati rice is selected. In the elution promotion step, the detection temperature is maintained at the elution temperature. The rice cooker according to claim 2 or 3.

5. A liquid discharge unit controlled by the control unit to discharge the liquid contained in the object to be cooked to the outside of the pot, A storage unit provided outside the pot for storing the liquid discharged from the internal space of the pot by the liquid discharge unit, further comprising The control unit executes a rice cooking process including the preheating step, the first temperature rising step, the elution promotion step, the second temperature rising step, the boiling maintenance step, and a steaming step of steaming the rice after the boiling maintenance step, In the elution promotion step or a step after the elution promotion step, the liquid discharge unit is controlled to discharge the liquid contained in the object to be cooked to the storage unit one or more times. The liquid discharged to the storage unit is configured to be held in the storage unit until the end of the steaming step. The rice cooker according to any one of claims 1 to 3.

6. further comprising a variety selection unit capable of selecting the variety of rice included in the object to be cooked from a plurality of rice varieties, The control unit It has a storage unit that stores the combination of the varieties selectable in the variety selection unit and the amylose content of rice. The lower the amylose content in the variety selected in the variety selection unit, the more the number of times of discharging the liquid contained in the object to be cooked is increased. The rice cooker according to claim 5.

7. It further includes a variety selection unit capable of selecting the variety of rice contained in the object to be cooked from a plurality of rice varieties. The control unit It has a storage unit that stores the combination of the varieties selectable in the variety selection unit and the amylose content of rice. The lower the amylose content in the variety selected in the variety selection unit, the shorter the time from the start of the elution promotion step to the start of the first discharge of the liquid contained in the object to be cooked. The rice cooker according to claim 5.

8. The lid has an outer lid and an inner lid attached to the outer lid and closing the opening of the pot when the lid is in the closed position. The liquid discharge part A communication hole provided in the inner lid and fluidly connecting the internal space and the outside of the pot when the lid is in the closed position, A pressure valve provided in the inner lid, controlled by the control unit, and moving between a closed position for closing the communication hole and a communication position for opening the communication hole, has The storage part is provided in the inner lid and configured to store the liquid discharged from the internal space to the outside of the pot through the communication hole. The control unit, in at least one of the second temperature rising step and the boiling maintaining step, While maintaining the pressure valve in the closed position, the pot is heated by the heating unit to pressurize the internal space to a pressure higher than the atmospheric pressure. The pressure valve is moved to the communication position to reduce the pressure in the internal space from the pressurized pressure, so that at least a part of the liquid contained in the rice to be cooked is discharged to the storage portion through the communication hole due to the pressure difference between the internal space and the outside of the pot. The rice cooker according to claim 5.

9. The rice cooker further includes a variety selection unit capable of selecting the variety of rice contained in the rice to be cooked from a plurality of rice varieties. The control unit has a storage unit in which a combination of the varieties selectable in the variety selection unit and the amylose content of the rice is stored. The lower the amylose content in the variety selected in the variety selection unit, the lower the pressurized pressure, and the internal space is depressurized from the pressurized pressure. The rice cooker according to claim 8.

10. The rice cooker further includes a variety selection unit capable of selecting the variety of rice contained in the rice to be cooked from a plurality of rice varieties including jasmine rice and basmati rice. When basmati rice is selected in the variety selection unit, the control unit is configured to increase the pressurized pressure compared to when jasmine rice is selected, and to depressurize the internal space from the pressurized pressure. The rice cooker according to claim 8.

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